New trainer from SZD Bielsko [Archive]

Basil

June 21st 07, 12:35 PM

Having been responsible for the maintenance of a 4 Puchacz trainer
fleet for some years and noticing that the fuselage is a Puchacz
fuselage I hope they get the following bits sorted out before
production.

1. They bungy sprung main undercarriage is awful. The Polish bungies
last half a season. American ones last two seasons but are quite
expensive and the design means that all the bronze pivot bushes are
heavily loaded all the time and wear rapidly.

2. The spring cable reel that retains the canopy when open brakes
every year and the glider is dangerous until it is fixed (the cable
when not retracted can lasso the rear stick.

3. All the Polish wheels need replacing with Tost or Cleverland. The
main wheel needs a disk brake. The bearing and brake arrangement on
the Polish wheels is very difficult to maintain.

4. The plastic gears in the wing route used to operate the airbrakes
cause a lot of backlash in the airbrake mechanism. They didn't work
well in the Puchacz, Bocian, Jantar etc. Its time to change the
airbrake mechanism.

5. The cables that operate the trim tabs in the elevator are single
strand and not spring tempered. They are routed through the elevator
hinge line and are flexed every time the elevator is moved. The
factory ones fail every year. (replacements from the local model shop
last several years but of course aren't approved).

The Puchacz was almost a good trainer, let down by serviceability
issues and being slightly too easy to spin. The Perkoz could be good
if they would just fix the above.

On Wed, 20 Jun 2007 17:00:29 -0700,
wrote:

>SZD Bielsko is in the final phase of testing of "new" 2 seat glider
>designed for initial and advanced training. It will be fully aerobatic
>with 17.5 m wings and with 20 m wings it becomes pretty good x-c
>sailplane with L/D of 41.8. The reason I am saying "new" with
>quotation marks is that the glider was designed in the late 80-ties
>and bears name SZD 54 Perkoz. But the SZD Bielsko is working right now
>to bring the glider into production.
>http://www.szd.com.pl/pdf/szd-54_perkoz_doku_en.pdf
>
>Jacek
>Washington State

On Wed, 20 Jun 2007 17:00:29 -0700,
wrote:

>SZD Bielsko is in the final phase of testing of "new" 2 seat glider
>designed for initial and advanced training. It will be fully aerobatic
>with 17.5 m wings and with 20 m wings it becomes pretty good x-c
>sailplane with L/D of 41.8. The reason I am saying "new" with
>quotation marks is that the glider was designed in the late 80-ties
>and bears name SZD 54 Perkoz. But the SZD Bielsko is working right now
>to bring the glider into production.
>http://www.szd.com.pl/pdf/szd-54_perkoz_doku_en.pdf
>
>Jacek
>Washington State

[email protected]

June 21st 07, 01:34 PM

for a trainer 40:1 is plenty. heck 18:1 is plenty, as proven by the
multitudes of pilots trained in 2-22 and 2-33 Schweizers over the
years. We're not talking about an open class nationals competitor
here.

Bill Daniels

June 21st 07, 02:30 PM

This comment is solely about trainer L/D and not this specific trainer.

L/D IS important especially if you operate from a field where nearby
landings are hazardous. Students ( and for that matter some instructors)
aren't good at judging just how far they can glide. In this situation,
extra performance is what gets them home after a mis-judgement. L/D then
becomes a safety factor.

There's no downside to training in higher performance unless the instructor
THINKS there is. If the instructor is afraid of high performance gliders,
he will pass that fear on to his students.

Bill Daniels

> wrote in message
ups.com...
> for a trainer 40:1 is plenty. heck 18:1 is plenty, as proven by the
> multitudes of pilots trained in 2-22 and 2-33 Schweizers over the
> years. We're not talking about an open class nationals competitor
> here.
>

[email protected]

June 21st 07, 02:42 PM

On Jun 21, 8:30 am, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> This comment is solely about trainer L/D and not this specific trainer.
>
> L/D IS important especially if you operate from a field where nearby
> landings are hazardous. Students ( and for that matter some instructors)
> aren't good at judging just how far they can glide. In this situation,
> extra performance is what gets them home after a mis-judgement. L/D then
> becomes a safety factor.
>
> There's no downside to training in higher performance unless the instructor
> THINKS there is. If the instructor is afraid of high performance gliders,
> he will pass that fear on to his students.
>
> Bill Daniels
>
> > wrote in message
>
> ups.com...
>
>
>
> > for a trainer 40:1 is plenty. heck 18:1 is plenty, as proven by the
> > multitudes of pilots trained in 2-22 and 2-33 Schweizers over the
> > years. We're not talking about an open class nationals competitor
> > here.- Hide quoted text -
>
> - Show quoted text -

true Bill. as usual you got it right. with the flat fields to the
horizon in central Iowa ive never had to worry about those issues you
have to deal with teaching in Colorado.

Bruce

June 21st 07, 02:53 PM

In my experience 'low maintenance' and 'robust' are more important
characteristics in an ab-initio trainer than 'high L/D ratio'.

IMHO trainers are all about compromises, the ASK21 is a very good compromise.
You CAN get a trainer with > 44:1 - But you will pay in price, ground handling
and hangar space - to mention only a few. Why does Lasham have a fleet of K13s?

Now if there was a way to get any glass installed as trainer at my club... We
fly vintage Bergfalkes, and a Blanik because they are robust, repairable and
cheap - not because of their L/D (all < 30:1) or their control harmony, or
aerobatic capability. Although the L13 is a great aerobatic trainer.

My primary concern with the Puchacz/Perkoz design would be the big canopy frame
obstructing the back seat pilot's vision. Never flown either, but it looks
substantial, and right in the field of vision.

If the list of woes below is accurate the Pooch would make a poor trainer. Fails
the low maintenance test.

Cheers
Bruce

Basil wrote:
> Having been responsible for the maintenance of a 4 Puchacz trainer
> fleet for some years and noticing that the fuselage is a Puchacz
> fuselage I hope they get the following bits sorted out before
> production.
>
> 1. They bungy sprung main undercarriage is awful. The Polish bungies
> last half a season. American ones last two seasons but are quite
> expensive and the design means that all the bronze pivot bushes are
> heavily loaded all the time and wear rapidly.
>
> 2. The spring cable reel that retains the canopy when open brakes
> every year and the glider is dangerous until it is fixed (the cable
> when not retracted can lasso the rear stick.
>
> 3. All the Polish wheels need replacing with Tost or Cleverland. The
> main wheel needs a disk brake. The bearing and brake arrangement on
> the Polish wheels is very difficult to maintain.
>
> 4. The plastic gears in the wing route used to operate the airbrakes
> cause a lot of backlash in the airbrake mechanism. They didn't work
> well in the Puchacz, Bocian, Jantar etc. Its time to change the
> airbrake mechanism.
>
> 5. The cables that operate the trim tabs in the elevator are single
> strand and not spring tempered. They are routed through the elevator
> hinge line and are flexed every time the elevator is moved. The
> factory ones fail every year. (replacements from the local model shop
> last several years but of course aren't approved).
>
> The Puchacz was almost a good trainer, let down by serviceability
> issues and being slightly too easy to spin. The Perkoz could be good
> if they would just fix the above.
>
>
> On Wed, 20 Jun 2007 17:00:29 -0700,
> wrote:
>
>> SZD Bielsko is in the final phase of testing of "new" 2 seat glider
>> designed for initial and advanced training. It will be fully aerobatic
>> with 17.5 m wings and with 20 m wings it becomes pretty good x-c
>> sailplane with L/D of 41.8. The reason I am saying "new" with
>> quotation marks is that the glider was designed in the late 80-ties
>> and bears name SZD 54 Perkoz. But the SZD Bielsko is working right now
>> to bring the glider into production.
>> http://www.szd.com.pl/pdf/szd-54_perkoz_doku_en.pdf
>>
>> Jacek
>> Washington State
>
>
> On Wed, 20 Jun 2007 17:00:29 -0700,
> wrote:
>
>> SZD Bielsko is in the final phase of testing of "new" 2 seat glider
>> designed for initial and advanced training. It will be fully aerobatic
>> with 17.5 m wings and with 20 m wings it becomes pretty good x-c
>> sailplane with L/D of 41.8. The reason I am saying "new" with
>> quotation marks is that the glider was designed in the late 80-ties
>> and bears name SZD 54 Perkoz. But the SZD Bielsko is working right now
>> to bring the glider into production.
>> http://www.szd.com.pl/pdf/szd-54_perkoz_doku_en.pdf
>>
>> Jacek
>> Washington State

Stefan

June 21st 07, 03:19 PM

Bill Daniels wrote:

> Beautiful! I love a one piece canopy.

All I see is that big structural element which seems to severely limit
the instructors vision. Not exactly what I would call safe in a glider
focused on primary training.

Sandro Rodriguez

June 21st 07, 03:28 PM

> L/D IS important especially if you operate from a field where nearby
> landings are hazardous. Students ( and for that matter some instructors)
> aren't good at judging just how far they can glide. In this situation,
> extra performance is what gets them home after a mis-judgement.

An instructor who cannot reliably judging his glide range should
immediately have pulled his instructor license. I don't know about the
place where you fly, but where I do, no student will be sent to his
check ride before he has demonstrated that he masters the calculations
in flight. Extra performance doesn't add any safety, it just shifts the
numbers in the calculations.

--=JJay=--[_2_]

June 21st 07, 03:39 PM

Stefan napisaÅ‚(a):
> All I see is that big structural element which seems to severely limit
> the instructors vision. Not exactly what I would call safe in a glider
> focused on primary training.

From what you're saying I can see that you have never flown Puchacz.
I'm instructor and I've spent some time in the back seat of this glider,
never had any problems with visibility. The Perkoz seems to be better
when it comes to visibility so don't worry. Besides what is more
important in a trainer is a visibility from the front seat, where
student place is.

Regards
--
--=JJay=--
www.aeroklub.deblin.pl, my photos on airliners.net - http://tiny.pl/rcwl

Stefan

June 21st 07, 04:04 PM

--=JJay=-- schrieb:

> From what you're saying I can see that you have never flown Puchacz.

You're correct, my statement was based only on theoretical geometrical
considerations.

> Besides what is more important in a trainer is a visibility from the
> front seat, where student place is.

I couldn't disagree more.

Roy Bourgeois

June 21st 07, 04:21 PM

I am an active CFI who has taught in or flown virtually all of the 2-place
gliders (ranging from 2-22 to ASH-25). It is important to remember that a
trainer needs to be reasonably robust and reasonably insurable. While I
read many opinions about the benefits of ab initio training on some of the
really sleek 2 place gliders - I don't know any club that really would
allow a first solo in a Duo Discus or DG-1000. I also don't know any
insurance company that would tolerate it. So - it seems to me that SZD
really understands it market and will likely sell a bunch of these
ships. I hope that they do. IMHO there really is a need for a good solid
2 place trainer that can go on the market for around 60,000 Euro ($80,000)
for the basic ship.

Roy B.

Ray Lovinggood

June 21st 07, 05:49 PM

The 'new' SZD two place ship does look interesting,
but is it a better 'mid price range' trainer than the
PW6? What about the Peregrine (nee KR-02)? And, of
course, the tried and true Blaniks (L-13 and L-23).

Is the Peregrine even alive these days?

Oh yea, how about that other new two seater, the Taunus.
That's a nice looking ship! Even available as a self-launcher,
I think.

Ray Lovinggood
Carrboro, North Carolina, USA

At 15:24 21 June 2007, Roy Bourgeois wrote:
>I am an active CFI who has taught in or flown virtually
>all of the 2-place
>gliders (ranging from 2-22 to ASH-25). It is important
>to remember that a
>trainer needs to be reasonably robust and reasonably
>insurable. While I
>read many opinions about the benefits of ab initio
>training on some of the
>really sleek 2 place gliders - I don't know any club
>that really would
>allow a first solo in a Duo Discus or DG-1000. I also
>don't know any
>insurance company that would tolerate it. So - it
>seems to me that SZD
>really understands it market and will likely sell a
>bunch of these
>ships. I hope that they do. IMHO there really is
>a need for a good solid
>2 place trainer that can go on the market for around
>60,000 Euro ($80,000)
>for the basic ship.
>
>Roy B.
>
>
>
>

Ian

June 21st 07, 06:11 PM

On 21 Jun, 14:30, "Bill Daniels" <bildan@comcast-dot-net> wrote:

> There's no downside to training in higher performance unless the instructor
> THINKS there is. If the instructor is afraid of high performance gliders,
> he will pass that fear on to his students.

A high performance glider will always be slippery, which means it will
accelerate fast, which means that elevator/attitude/speed control will
be harder to learn. Won't it?

Ian

Bruce

June 21st 07, 07:30 PM

Bill Daniels wrote:
> This comment is solely about trainer L/D and not this specific trainer.
>
> L/D IS important especially if you operate from a field where nearby
> landings are hazardous. Students ( and for that matter some instructors)
> aren't good at judging just how far they can glide. In this situation,
> extra performance is what gets them home after a mis-judgement. L/D then
> becomes a safety factor.
>
> There's no downside to training in higher performance unless the instructor
> THINKS there is. If the instructor is afraid of high performance gliders,
> he will pass that fear on to his students.
>
> Bill Daniels
>
> > wrote in message
> ups.com...
>> for a trainer 40:1 is plenty. heck 18:1 is plenty, as proven by the
>> multitudes of pilots trained in 2-22 and 2-33 Schweizers over the
>> years. We're not talking about an open class nationals competitor
>> here.
>>
>
>
I agree conditionally.

This is one area where the old crates make better trainers, as the difference in
effective glide ratio is much more affected by wind. The safe circuit differs
markedly with a 1:26 L/D and a wind component that can be a significant fraction
of stall speed. So it is easier to teach the mental calculations required, and
when to draw the line in terms of the - Is it safe to launch? decision.

A higher penetration , higher performance trainer makes the distances involved a
little bigger, so they may be harder to judge. In this instance I believe higher
performance may lower safety.

The downside of training exclusively in low performance gliders is that
transition to even a moderate performance single seater is more difficult.

Bruce

Martin Gregorie[_1_]

June 21st 07, 07:43 PM

Bruce wrote:
>
> My primary concern with the Puchacz/Perkoz design would be the big
> canopy frame obstructing the back seat pilot's vision. Never flown
> either, but it looks substantial, and right in the field of vision.
>
I've ridden back seat in the Puchacz once or twice. Rear vision is a bit
restricted, but the main thing I noticed was internal reflections in
that long, glass tunnel.

There's one possible disadvantage that I'm surprised the nobody has
mentioned: replacing Puchacz/Perkoz canopies is much more expensive than
replacing K-21 or G.103 canopies due to the sheer single piece size.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Gary Emerson

June 21st 07, 08:30 PM

wrote:
> SZD Bielsko is in the final phase of testing of "new" 2 seat glider
> designed for initial and advanced training. It will be fully aerobatic
> with 17.5 m wings and with 20 m wings it becomes pretty good x-c
> sailplane with L/D of 41.8. The reason I am saying "new" with
> quotation marks is that the glider was designed in the late 80-ties
> and bears name SZD 54 Perkoz. But the SZD Bielsko is working right now
> to bring the glider into production.
> http://www.szd.com.pl/pdf/szd-54_perkoz_doku_en.pdf
>
> Jacek
> Washington State
>

hopefully the issues of Puchacz spins don't present with this glider
too. They look very similar.

Roy Bourgeois

June 21st 07, 09:05 PM

There's no downside to training in higher performance unless the instructor
> THINKS there is. If the instructor is afraid of high performance gliders,
> he will pass that fear on to his students.
>
> Bill Daniels
With all due respect I am not sure that this portion of the debate is
meaningful until the participants clarify and agree upon what it is they
are "training" for. If we are training for advanced cross country,
competition, or step up to high performance single seats then the
observation is correct. If we are ab initio training in hope to solo the
student in the subject glider then we need something robust, insurable for
student pilots, and economical for the typical club. Higher performance
rarely serves those needs - so there is a downside.

Roy B.

Tim Mara

June 21st 07, 09:38 PM

"Martin Gregorie" > wrote in message
...
> Bruce wrote:

>
> There's one possible disadvantage that I'm surprised the nobody has
> mentioned: replacing Puchacz/Perkoz canopies is much more expensive than
> replacing K-21 or G.103 canopies due to the sheer single piece size.
>

Why would this cost more? Almost all glider canopies (made by Mecplex or
Weiss in Germany who make nearly all current glider canopies) are molded in
one piece and then cut in two for gliders like the K21 with separate front
and rear canopies, so even if you only need the front canopy for a K21 you
would be paying for the cost of both pieces anyway.
tim

--
Please visit the Wings & Wheels website at www.wingsandwheels.com

[email protected]

June 22nd 07, 03:03 AM

> Oh yea, how about that other new two seater, the Taunus.
> That's a nice looking ship! Even available as a self-launcher,
> I think.

The Taurus could make an excellent trainer. It is however a tailwheel
glider, for some that may present a problem.
We had hoped to have one for display at Oshkosh/AirVenture but that is
not going to happen. The first one to a USA customer is scheduled for
this fall. More than 12 have been delivered so far.

It is available as a pure glider, selflauncher with a Rotax 503 and
soon in an electric launch version.

Robert Mudd
Pipistrel, Taurus dealer

June 22nd 07, 03:36 AM

IT may be.. but we've never seen it here... I wonder where the LLC keeps it.
It also says it was built in 1991.. not really a "new" glider.
BT

"Frank Whiteley" > wrote in message
ups.com...
> N9439G is registered in Las Vegas, NV.
>
> On Jun 20, 8:12 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>> Beautiful! I love a one piece canopy. We need more trainers like this.
>>
>> The only small thing I see from the pictures that might concern me is the
>> external mass ballances on the elevator. Many glilder fields are less
>> than
>> perfectly clear of debris. It looks as if it might be possible a chunk
>> of
>> that debris (or a unused tow rope) might get lodged between the
>> stabilizer
>> and the mass balance horn on the takeoff roll. This has happened on older
>> gliders.
>>
>> If there's still time in the development phase for these mass ballances
>> to
>> be internalized, doing so might improve the glider's marketability.
>>
>> Bill Daniels
>>
>> > wrote in message
>>
>> oups.com...
>>
>> > SZD Bielsko is in the final phase of testing of "new" 2 seat glider
>> > designed for initial and advanced training. It will be fully aerobatic
>> > with 17.5 m wings and with 20 m wings it becomes pretty good x-c
>> > sailplane with L/D of 41.8. The reason I am saying "new" with
>> > quotation marks is that the glider was designed in the late 80-ties
>> > and bears name SZD 54 Perkoz. But the SZD Bielsko is working right now
>> > to bring the glider into production.
>> >http://www.szd.com.pl/pdf/szd-54_perkoz_doku_en.pdf
>>
>> > Jacek
>> > Washington State
>
>

Bill Daniels

June 22nd 07, 03:53 AM

"Ian" > wrote in message
ps.com...
> On 21 Jun, 14:30, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>
>> There's no downside to training in higher performance unless the
>> instructor
>> THINKS there is. If the instructor is afraid of high performance
>> gliders,
>> he will pass that fear on to his students.
>
> A high performance glider will always be slippery, which means it will
> accelerate fast, which means that elevator/attitude/speed control will
> be harder to learn. Won't it?
>
> Ian
>

No. The student just learns what is presented. They are largely unaware of
these 'percieved' difficulties - unless the instructor makes a big deal of
how difficult a particular glider is to fly. The hand/eye coordination just
isn't that difficult to learn. It's the INSTRUCTOR who makes a glider hard
to fly.

Slick gliders are 'hard' to fly only if one has a preconception they are.
The Duo Discus, for instance, is a real pussycat. Even non pilots have no
problem with "elevator/attitude/speed control" if you just tell them to
keep the nose on the horizon.

In fact I'm tempted to say that there are no difficult gliders - at least
none made in the last 30 years. I've never flown a glass glider that
presented the slightest problem. Now a Bell 47 helicopter, THAT is hard to
fly.

Bill Daniels

Bill Daniels

June 22nd 07, 04:02 AM

"Bruce" > wrote in message
...
> Bill Daniels wrote:
>> This comment is solely about trainer L/D and not this specific trainer.
>>
>> L/D IS important especially if you operate from a field where nearby
>> landings are hazardous. Students ( and for that matter some instructors)
>> aren't good at judging just how far they can glide. In this situation,
>> extra performance is what gets them home after a mis-judgement. L/D then
>> becomes a safety factor.
>>
>> There's no downside to training in higher performance unless the
>> instructor THINKS there is. If the instructor is afraid of high
>> performance gliders, he will pass that fear on to his students.
>>
>> Bill Daniels
>>
>> > wrote in message
>> ups.com...
>>> for a trainer 40:1 is plenty. heck 18:1 is plenty, as proven by the
>>> multitudes of pilots trained in 2-22 and 2-33 Schweizers over the
>>> years. We're not talking about an open class nationals competitor
>>> here.
>>>
>>
>>
> I agree conditionally.
>
> This is one area where the old crates make better trainers, as the
> difference in effective glide ratio is much more affected by wind. The
> safe circuit differs markedly with a 1:26 L/D and a wind component that
> can be a significant fraction of stall speed. So it is easier to teach the
> mental calculations required, and when to draw the line in terms of the -
> Is it safe to launch? decision.

How so? A 2-33 stalls (really) at about 40 MPH. My Nimbus 2C stalls at
38mph and I can turn inside a 1-26 if the ballast tanks are dry. If I open
the dive brakes to the point they want to rest, the Nimbus 2C glides about
like a 2-22. If I open them all the way it's 1:1 at 55mph.

>
> A higher penetration , higher performance trainer makes the distances
> involved a little bigger, so they may be harder to judge. In this instance
> I believe higher performance may lower safety.

Yes harder, but the errors will be on the safe side - i.e. the HP glider
will go farther than the student is willing to believe.

>
> The downside of training exclusively in low performance gliders is that
> transition to even a moderate performance single seater is more difficult.

You bet! And once you have created the mind set that higher performance
glider are difficult to fly - they WILL be more difficult to fly for that
student.

Bill Daniels

Bill Daniels

June 22nd 07, 04:08 AM

"Roy Bourgeois" > wrote in message
...
>
> There's no downside to training in higher performance unless the
> instructor
> > THINKS there is. If the instructor is afraid of high performance
> > gliders,
> > he will pass that fear on to his students.
> >
> > Bill Daniels
> With all due respect I am not sure that this portion of the debate is
> meaningful until the participants clarify and agree upon what it is they
> are "training" for. If we are training for advanced cross country,
> competition, or step up to high performance single seats then the
> observation is correct. If we are ab initio training in hope to solo the
> student in the subject glider then we need something robust, insurable for
> student pilots, and economical for the typical club. Higher performance
> rarely serves those needs - so there is a downside.
>
> Roy B.
>
Are you saying a K-21 or a DG 505 are not insurable for student pilots? I
think they are. The K21 is a VERY robust glider and a great trainer - so is
the 505.

Bill Daniels

Frank Whiteley

June 22nd 07, 06:11 AM

Actually, I thought I read in some club NL that it was in Oregon.
Maybe they have one of the Nevada corporations that were being pitched
on the radio a couple of years ago;^)

Frank

On Jun 21, 8:36 pm, "BT" > wrote:
> IT may be.. but we've never seen it here... I wonder where the LLC keeps it.
> It also says it was built in 1991.. not really a "new" glider.
> BT
>
> "Frank Whiteley" > wrote in message
>
> ups.com...
>
> > N9439G is registered in Las Vegas, NV.
>
> > On Jun 20, 8:12 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> >> Beautiful! I love a one piece canopy. We need more trainers like this.
>
> >> The only small thing I see from the pictures that might concern me is the
> >> external mass ballances on the elevator. Many glilder fields are less
> >> than
> >> perfectly clear of debris. It looks as if it might be possible a chunk
> >> of
> >> that debris (or a unused tow rope) might get lodged between the
> >> stabilizer
> >> and the mass balance horn on the takeoff roll. This has happened on older
> >> gliders.
>
> >> If there's still time in the development phase for these mass ballances
> >> to
> >> be internalized, doing so might improve the glider's marketability.
>
> >> Bill Daniels
>
> >> > wrote in message
>
> oups.com...
>
> >> > SZD Bielsko is in the final phase of testing of "new" 2 seat glider
> >> > designed for initial and advanced training. It will be fully aerobatic
> >> > with 17.5 m wings and with 20 m wings it becomes pretty good x-c
> >> > sailplane with L/D of 41.8. The reason I am saying "new" with
> >> > quotation marks is that the glider was designed in the late 80-ties
> >> > and bears name SZD 54 Perkoz. But the SZD Bielsko is working right now
> >> > to bring the glider into production.
> >> >http://www.szd.com.pl/pdf/szd-54_perkoz_doku_en.pdf
>
> >> > Jacek
> >> > Washington State

Colin Field[_2_]

June 22nd 07, 08:30 AM

At 19:36 21 June 2007, Gary Emerson wrote:

>hopefully the issues of Puchacz spins don't present
>with this glider
>too. They look very similar.

The fact that the Puchacz spins so positively and effectively
with the 'correct' control inputs is one reason why
it's such a popular training glider. Pupils need to
be taught the situations in which a glider will spin,
what they can do to prevent a spin, and how to quickly
recognise one and recover from it if it does occur.
It means they will fly a lot safer in gliders which
might not spin as readily, by not flying too slowly
and unco-ordinated in thermal turns for example, because
they don't only KNOW but HAVE EXPERIENCE that this
method of flying might result in a spin.

One of the main reasons our club bought 2 Puchaczs
was because they spin so well, and we realise the importance
of spin training. Before we had Bocians, which also
spin well.

Don't Disregard Dangling the Dunlop!

Bert Willing

June 22nd 07, 09:10 AM

We have trained ab.initio and soloed students in a Janus B. No difference
whatsoever in training/soloing students in a Ka7 (which we did in another
club).

"Roy Bourgeois" > wrote in message
...
>
> There's no downside to training in higher performance unless the
> instructor
> > THINKS there is. If the instructor is afraid of high performance
> > gliders,
> > he will pass that fear on to his students.
> >
> > Bill Daniels
> With all due respect I am not sure that this portion of the debate is
> meaningful until the participants clarify and agree upon what it is they
> are "training" for. If we are training for advanced cross country,
> competition, or step up to high performance single seats then the
> observation is correct. If we are ab initio training in hope to solo the
> student in the subject glider then we need something robust, insurable for
> student pilots, and economical for the typical club. Higher performance
> rarely serves those needs - so there is a downside.
>
> Roy B.
>
>
>
>

Bruce

June 22nd 07, 09:10 AM

Bill Daniels wrote:
> "Bruce" > wrote in message
> ...
>> Bill Daniels wrote:
>>> This comment is solely about trainer L/D and not this specific trainer.
>>>
>>> L/D IS important especially if you operate from a field where nearby
>>> landings are hazardous. Students ( and for that matter some instructors)
>>> aren't good at judging just how far they can glide. In this situation,
>>> extra performance is what gets them home after a mis-judgement. L/D then
>>> becomes a safety factor.
>>>
>>> There's no downside to training in higher performance unless the
>>> instructor THINKS there is. If the instructor is afraid of high
>>> performance gliders, he will pass that fear on to his students.
>>>
>>> Bill Daniels
>>>
>>> > wrote in message
>>> ups.com...
>>>> for a trainer 40:1 is plenty. heck 18:1 is plenty, as proven by the
>>>> multitudes of pilots trained in 2-22 and 2-33 Schweizers over the
>>>> years. We're not talking about an open class nationals competitor
>>>> here.
>>>>
>>>
>> I agree conditionally.
>>
>> This is one area where the old crates make better trainers, as the
>> difference in effective glide ratio is much more affected by wind. The
>> safe circuit differs markedly with a 1:26 L/D and a wind component that
>> can be a significant fraction of stall speed. So it is easier to teach the
>> mental calculations required, and when to draw the line in terms of the -
>> Is it safe to launch? decision.
>
> How so? A 2-33 stalls (really) at about 40 MPH. My Nimbus 2C stalls at
> 38mph and I can turn inside a 1-26 if the ballast tanks are dry. If I open
> the dive brakes to the point they want to rest, the Nimbus 2C glides about
> like a 2-22. If I open them all the way it's 1:1 at 55mph.
>
Perhaps I was unclear here. The low performance trainer typically has a limited
speed range it can fly in. If the wind factor is a significant fraction of stall
speed then you have a lot less speed range available. For example maneuvering
speed in a Bergfalke II/55 is only 120km/h - it stalls at ~60km/h. At 120km/h
the L/D is such that you can just about fly a circuit without leaving the
vertical confines of the runway. You can get the same L/D with a glass ship, but
you can't emulate the ultra low wingloading, and high drag airframe. All the
penetration of a well thrown newspaper.

>> A higher penetration , higher performance trainer makes the distances
>> involved a little bigger, so they may be harder to judge. In this instance
>> I believe higher performance may lower safety.
>
> Yes harder, but the errors will be on the safe side - i.e. the HP glider
> will go farther than the student is willing to believe.

True - the higher performance trainer generally has a safety advantage (more
options and greater margin, better control)- but the bigger distances mean more
exposure to variable conditions. Have watched someone fail to make it back to
the runway because of complacency by instructor. From the close in circuit the
low performance guys were doing he would have been able to reach the alternate
runway when the wind picked up. From further out, the time exposed to the
headwind put him in a no - win situation.

>
>> The downside of training exclusively in low performance gliders is that
>> transition to even a moderate performance single seater is more difficult.
>
> You bet! And once you have created the mind set that higher performance
> glider are difficult to fly - they WILL be more difficult to fly for that
> student.
>
> Bill Daniels
>
>
Many of my worst habits come from learning my initial judgment in a vintage. I
know I'm not gifted, but the transition from a Bergfalke to a 15m standard class
single seater was interesting...
That is why I like the K21 so much. Similar performance to the kind of single
seater many students will move up to - and a pleasure to fly.

Gary Emerson

June 22nd 07, 12:28 PM

Sorry dude, nice try. There are a number of reported cases with
Puchaczs spinning all the way down, in some cases with two instructors
on board. There is no denying (you can try) that this particular ship
can establish itself into a non-recoverable spin. While spinability is
important, it's unsafe if it may (even rarely) enter into a
non-recoverable situation.

Colin Field wrote:
> At 19:36 21 June 2007, Gary Emerson wrote:
>
>> hopefully the issues of Puchacz spins don't present
>> with this glider
>> too. They look very similar.
>
> The fact that the Puchacz spins so positively and effectively
> with the 'correct' control inputs is one reason why
> it's such a popular training glider. Pupils need to
> be taught the situations in which a glider will spin,
> what they can do to prevent a spin, and how to quickly
> recognise one and recover from it if it does occur.
> It means they will fly a lot safer in gliders which
> might not spin as readily, by not flying too slowly
> and unco-ordinated in thermal turns for example, because
> they don't only KNOW but HAVE EXPERIENCE that this
> method of flying might result in a spin.
>
> One of the main reasons our club bought 2 Puchaczs
> was because they spin so well, and we realise the importance
> of spin training. Before we had Bocians, which also
> spin well.
>
>
>
> Don't Disregard Dangling the Dunlop!
>
>

Al Eddie

June 22nd 07, 02:28 PM

At 11:30 22 June 2007, Gary Emerson wrote:

>non-recoverable spin

Define.

And before you do, read the accident reports...!

Al

Andreas Maurer

June 22nd 07, 03:23 PM

On 22 Jun 2007 13:28:04 GMT, Al Eddie
> wrote:

>>non-recoverable spin
>
>Define.
>
>And before you do, read the accident reports...!

In Germany there were at least wo spin-related accidents during winch
launches, in both cases instructors on board. Iirc no survivors.

Bye
Andreas

Bill Daniels

June 22nd 07, 04:05 PM

"Andreas Maurer" > wrote in message
...
> On 22 Jun 2007 13:28:04 GMT, Al Eddie
> > wrote:
>
>>>non-recoverable spin
>>
>>Define.
>>
>>And before you do, read the accident reports...!
>
> In Germany there were at least wo spin-related accidents during winch
> launches, in both cases instructors on board. Iirc no survivors.
>
>
>
> Bye
> Andreas

Unfortunately, instructors differ quite a bit in their spin knowledge. I
recall spin training instruction for my CFI. (Actually I already knew about
spins from gliders.) I announced to my right seat instructor that we would
do three turns and recover within 10 degrees of the entry heading. (That's
the WWII Instructor Pilot standard.)

I picked a road intersection that would give a good ground reference and
spun the C-150 to the right starting on a north heading. (I already knew
this particular C-150 would continue 3/4 turn after anti-spin controls were
applied.) As we passed north on the first turn, I heard my instructor
mumbling to himself - he was counting what he thought were turns reaching
'three' as we pass north for the first time. As north came up again he
reached 'six' - his voice increasing in pitch. I applied anti-spin controls
on an east heading and the C-150 stopped auto-rotation on a north heading
precisely three turns after entry as my instructor spoke 'nine'. I had a
hard time convincing him we did only three turns.

Spins are a good example of perception vs reality problems. People read and
hear hangar talk about spins and develop "spin phobia". This fear degrades
their performance. Apparently, instructors are no exception.

I rode with one very senior ATP who had been taking aerobatic instruction in
a Citabria. We intended two turns in a L-23 but as we went around for the
third time, I had to point out that the Blanik requires forward stick to
achieve a recovery. This pilot expected the glider to recover with only
opposite rudder.

So, don't assume that a glider has bad spin behavior just because they've
been spun in by instructors.

Bill Daniels

John Scott

June 22nd 07, 04:25 PM

The SZD-54 is located at Meadowlake Airport in Colorado Springs. It is
flying.

John

Andreas Maurer

June 22nd 07, 04:43 PM

On Fri, 22 Jun 2007 09:05:05 -0600, "Bill Daniels"
<bildan@comcast-dot-net> wrote:

>So, don't assume that a glider has bad spin behavior just because they've
>been spun in by instructors.

Given the fact that other gliders did not spin in during a winch
launch with an instructor in board, odds are that these accidents were
not completely the pilot's fault, don't you agree?

Bye
Andreas

Roy Bourgeois

June 22nd 07, 05:02 PM

>
Are you saying a K-21 or a DG 505 are not insurable for student pilots? I
think they are. The K21 is a VERY robust glider and a great trainer - so is
the 505.

Bill Daniels

Bill: Both are excellent gliders - and probably anything is insurable at
some price. My point is that you cannot look at the issue of "training"
without examining both the cost involved in the acquisition and insuring
of your "trainers" and what type of training you are going to use them
for. To make an extreme example, how many 2-33s can we buy and insure for
the cost of one 505? How many clubs are going to use their shiny new $100K
asset for a 15 year old's first solo? Clubs make these decisions all of
the time and I have seen over and over with many clubs that the high
performance "trainer" is never used for ab initio training if a lesser
performing (and cheaper) 2-place is available. Examples: Sugarbush has both
ASK-21s and Blaniks but first solo training is always on the Blanik. SS
Boulder has a 505 and a G-103 but first solo training is on the G103.
Franconia has a G-103 and a 2-33 but teaches and solos on the Schweizer. I
could give 10 more examples. This is frequently driven by insurance
requirements.

I agree with your comments that High Performance gliders are no more
difficult to fly than low performance (although there are some differences
in teaching on them). But as somebody who is very concerned with the high
entry cost to our sport (I am the CFI in charge of my club's youth program)
I see the financial "downside" of the higher performance trainers. The
truth is, every training glider decision is a mix of cost, performance,
maintenance issues, repairability, modernity, staff instructor comfort, and
relationship to what else is in the fleet. Depending on how you assign
values to those factors - you can "make a case" for almost anything.

Roy

Bill Daniels

June 22nd 07, 05:39 PM

No doubt that the insurance premium on a more expensive glider is greater
but insurance is a fixed cost. Divide the premium by the yearly hours to
get hourly insurance costs. The most expensive glider to insure on an
hourly basis is the one that doesn't get flown much. I know a guy who owns
a 1-26 and flies it maybe twice a year. His hourly insurance rate must be
$200/hr.

A popular high performance trainer may well have a low hourly insurance
costs. An ugly, low performance trainer may have a higher hourly insruance
rate if the nice one gets flown more.

The really huge advantage of modern high performance trainers is that they
attract new members and keep the old ones. I offer two examples: The
Philadelphia Soaring Council and the Soaring Society of Boulder - there are
many more. There is a very good case to be made for operating really nice
equipment.

On the other hand, it's not hard to find clubs who have reduced their
equipment and insurance costs to the minimum and, in the process, reduced
their membership to the minimum. They are related.

On a slightly different tack, if a club mandates solo in old, cheap
equipment, that says they don't trust the new member students or their
instructors. If a club can't trust its instructors, it has a far worse
problem than the training gliders.

Bill Daniels

"Roy Bourgeois" > wrote in message
...
>
> >
> Are you saying a K-21 or a DG 505 are not insurable for student pilots? I
> think they are. The K21 is a VERY robust glider and a great trainer - so
> is
> the 505.
>
> Bill Daniels
>
> Bill: Both are excellent gliders - and probably anything is insurable at
> some price. My point is that you cannot look at the issue of "training"
> without examining both the cost involved in the acquisition and insuring
> of your "trainers" and what type of training you are going to use them
> for. To make an extreme example, how many 2-33s can we buy and insure for
> the cost of one 505? How many clubs are going to use their shiny new
> $100K
> asset for a 15 year old's first solo? Clubs make these decisions all of
> the time and I have seen over and over with many clubs that the high
> performance "trainer" is never used for ab initio training if a lesser
> performing (and cheaper) 2-place is available. Examples: Sugarbush has
> both
> ASK-21s and Blaniks but first solo training is always on the Blanik. SS
> Boulder has a 505 and a G-103 but first solo training is on the G103.
> Franconia has a G-103 and a 2-33 but teaches and solos on the Schweizer.
> I
> could give 10 more examples. This is frequently driven by insurance
> requirements.
>
> I agree with your comments that High Performance gliders are no more
> difficult to fly than low performance (although there are some differences
> in teaching on them). But as somebody who is very concerned with the high
> entry cost to our sport (I am the CFI in charge of my club's youth
> program)
> I see the financial "downside" of the higher performance trainers. The
> truth is, every training glider decision is a mix of cost, performance,
> maintenance issues, repairability, modernity, staff instructor comfort,
> and
> relationship to what else is in the fleet. Depending on how you assign
> values to those factors - you can "make a case" for almost anything.
>
> Roy
>
>
>
>

Roy Bourgeois

June 22nd 07, 06:08 PM

On a slightly different tack, if a club mandates solo in old, cheap
equipment, that says they don't trust the new member students or their
instructors. If a club can't trust its instructors, it has a far worse
problem than the training gliders.

Bill Daniels
Bill - You point to SSB as an example of the kind of club you want - but
they do exactly what I am talking about which is to use their 505 for
advanced training and do training and first solos in the old G103. (my son
Dan is the maintenance chief for that G103) Same with
Sugarbush, Franconia, GBSC and virtually every club that has a high
performance and a low performance 2 seater.

You argue that better equipment attracts new members and you are right. I
argue that lower cost attracts youth into the sport - and I am right. It's
all in how you value things. I've been in gliding for 33 years hand seen
this debate for most of them (I have been director of 6 clubs, member of
10, past SSA Director, etc.). I have learned that there are 2 types of
students: Those who have time but not money and those who have money but
little time. You run very different clubs (with very different equipment)
depending upon which constituency you serve. But - if you take the big
picture, you don't denigrate one club model compared to another.

Roy

Maciek

June 22nd 07, 07:20 PM

> can establish itself into a non-recoverable spin.

below an altitude of 100m no spin is rocoverable.

Mat

Bill Daniels

June 22nd 07, 07:42 PM

"Roy Bourgeois" > wrote in message
...
>
> On a slightly different tack, if a club mandates solo in old, cheap
> equipment, that says they don't trust the new member students or their
> instructors. If a club can't trust its instructors, it has a far worse
> problem than the training gliders.
>
> Bill Daniels
> Bill - You point to SSB as an example of the kind of club you want - but
> they do exactly what I am talking about which is to use their 505 for
> advanced training and do training and first solos in the old G103. (my son
> Dan is the maintenance chief for that G103) Same with
> Sugarbush, Franconia, GBSC and virtually every club that has a high
> performance and a low performance 2 seater.
>
> You argue that better equipment attracts new members and you are right. I
> argue that lower cost attracts youth into the sport - and I am right.
> It's
> all in how you value things. I've been in gliding for 33 years hand seen
> this debate for most of them (I have been director of 6 clubs, member of
> 10, past SSA Director, etc.). I have learned that there are 2 types of
> students: Those who have time but not money and those who have money but
> little time. You run very different clubs (with very different equipment)
> depending upon which constituency you serve. But - if you take the big
> picture, you don't denigrate one club model compared to another.
>
> Roy
>
Roy, I think we agree across the board. The SSB Grob Twin II is a fine
trainer that attracts both youth and more afluent members. BTW, if you look
hard at training costs, it isn't the glider that costs so much, it's launch
costs. I've long been on record favoring winches for the majorityof
training flights.

It's the kind of decrepit trainer that was recently removed from Boulder
Airport by another club that I was writing about. It's those things that
drive clubs to extinction.

Bill Daniels

brtlmj

June 22nd 07, 08:06 PM

> trainer that attracts both youth and more afluent members. BTW, if you look
> hard at training costs, it isn't the glider that costs so much, it's launch
> costs.

In my (very limited) experience, fleet costs affect joining fee and
annual fees. Those can be a significant part of total flying costs for
a young person.

Bartek

Ian

June 22nd 07, 09:10 PM

On 22 Jun, 15:23, Andreas Maurer > wrote:
> On 22 Jun 2007 13:28:04 GMT, Al Eddie
>
> > wrote:
> >>non-recoverable spin
>
> >Define.
>
> >And before you do, read the accident reports...!
>
> In Germany there were at least wo spin-related accidents during winch
> launches, in both cases instructors on board. Iirc no survivors.

How many gliders can recover from a spin which starts on the winch
launch? I really don't think the Puchacz can be blamed in such cases.

Ian

Ian

June 22nd 07, 09:14 PM

On 22 Jun, 16:43, Andreas Maurer > wrote:
> On Fri, 22 Jun 2007 09:05:05 -0600, "Bill Daniels"
>
> <bildan@comcast-dot-net> wrote:
> >So, don't assume that a glider has bad spin behavior just because they've
> >been spun in by instructors.
>
> Given the fact that other gliders did not spin in during a winch
> launch with an instructor in board, odds are that these accidents were
> not completely the pilot's fault, don't you agree?

The Puchacz is not, alas, the only glider to have spun in off a winch
launch.

Mind you, I recall a site check at a Large UK Club in a winch launched
Puchacz. At the top of the launch the instructor kept telling me to
pull back more, even when pre-stall buffet could be felt. And that was
only two weeks after an AEI flight had spun in off the winch, fatally
for the pupil.

My conclusion: some instructors shouldn't be flying, and some clubs
shouldn't be operating.

Ian

Bruce

June 22nd 07, 09:28 PM

Ian wrote:
> On 22 Jun, 15:23, Andreas Maurer > wrote:
>> On 22 Jun 2007 13:28:04 GMT, Al Eddie
>>
>> > wrote:
>>>> non-recoverable spin
>>> Define.
>>> And before you do, read the accident reports...!
>> In Germany there were at least wo spin-related accidents during winch
>> launches, in both cases instructors on board. Iirc no survivors.
>
> How many gliders can recover from a spin which starts on the winch
> launch? I really don't think the Puchacz can be blamed in such cases.
>
> Ian
>
>
I know of at least one incident with a Ka7 or 8.

In this case the early solo pilot allowed the attitude to get too high and spun
while under power from the winch. He managed to recover and arrive in one piece
if a little shaken. I gather he was circa 800 feet when the aircraft departed
from controlled flight.

Score 1 for sheer luck...

Dan G

June 22nd 07, 10:21 PM

On Jun 22, 4:08 am, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> Are you saying a K-21 or a DG 505 are not insurable for student pilots?

In the UK it's just about possible to insure a K21 for first solo
(premium is around one-seventh the value of the glider), but the cost
of insuring a 505, 1000 or Duo for the same is astronomical. Sure you
could do it but you'd never get the money back - no-one would pay the
incredible soaring fees needed. I think I know one 500 that's insured
for solos, but every other Janus, Duo or 1000 I've seen or flown was
Silver C minimum for P1. Even then the soaring fees were twice a K21.

I belong to the low money/high time group, and high-performance
gliders are the bane of my life. Our club offers winch launches at
half the price of others and that's mainly down to having a fleet of
K13s instead K21s. I could never have afforded to learn to fly
otherwise. Visiting other clubs with shiny fleets always hurts my
wallet.

Dan

Paul Hanson

June 23rd 07, 08:51 AM

At 20:36 22 June 2007, Bruce wrote:
>Ian wrote:
>> On 22 Jun, 15:23, Andreas Maurer wrote:
>>> On 22 Jun 2007 13:28:04 GMT, Al Eddie
>>>
>>> wrote:
>>>>> non-recoverable spin
>>>> Define.
>>>> And before you do, read the accident reports...!
>>> In Germany there were at least wo spin-related accidents
>>>during winch
>>> launches, in both cases instructors on board. Iirc
>>>no survivors.
>>
>> How many gliders can recover from a spin which starts
>>on the winch

There is an awful lot of talk (most of it old arguments
BTW) about the SZD 50-3 on this thread, with as much
speculation as before. I would like to remind those
who can only site Puchaz horror stories, that we are
talking aoubt a completely new glider. It has a new
wing with a thinner profile/planform, lots of carbon,
interchangable 17.5-20m tips, a new tail on it, and
has a different layup schedule in the fuse, leaving
it with a +9 to -6 G-load rating. The 50-3 was desinged
in 78' I believe, the Perkoz in 91'. Do you really
think they were not able to anylize and address any
shorcomings in the Puchaz after all those years of
study and advances in technology?
Come on, it is a completely new aircraft; it just uses
some of the same molds and parts as the 50-3. I sure
wish I could have gotten that one for $15,000 a while
back.....

Paul Hanson
"Do the usual, unusually well"--Len Niemi

Andreas Maurer[_1_]

June 23rd 07, 10:34 PM

On Fri, 22 Jun 2007 13:10:28 -0700, Ian >
wrote:

>How many gliders can recover from a spin which starts on the winch
>launch? I really don't think the Puchacz can be blamed in such cases.

Sorry to repeat myself, but how many primary trainers really DO enter
an unintentional spin during a winch launch with an instructor on
board?

In my opinion a primary trainer (the one that is used for early solo
flights) cannot be spin-resistent enough.

Bye
Andreas

Dan G

June 23rd 07, 11:11 PM

On Jun 23, 10:34 pm, Andreas Maurer > wrote:
> On Fri, 22 Jun 2007 13:10:28 -0700, Ian >
> wrote:
>
> >How many gliders can recover from a spin which starts on the winch
> >launch? I really don't think the Puchacz can be blamed in such cases.
>
> Sorry to repeat myself, but how many primary trainers really DO enter
> an unintentional spin during a winch launch with an instructor on
> board?

Why do people think instructors are invulnerable? I know instructors
who've destroyed gliders.

>
> In my opinion a primary trainer (the one that is used for early solo
> flights) cannot be spin-resistent enough.

That was the rationale behind the K21, which was designed to German
requirements. Unfortunately all single seat gliders will spin, so
training solely on spin-resistant gliders is a receipe for disaster
and has no doubt cost lives. The Pooch is an excellent training glider
as it does what any single seater will do - spin if provoked.

Tales of "unrecoverable" spins in pooches are probably due to the idea
that the low tail can blank the rudder (actually it won't). In reality
a pooch will always recover with standard spin recovery technique. If
you claim otherwise, please provide a reference to an accident report
stating so.

Dan

Andreas Maurer[_1_]

June 23rd 07, 11:58 PM

On Sat, 23 Jun 2007 15:11:13 -0700, Dan G > wrote:

>Why do people think instructors are invulnerable? I know instructors
>who've destroyed gliders.

Me too... but even the worst instructor should not be able to spin a
*basic trainer* during a winch launch.

>That was the rationale behind the K21, which was designed to German
>requirements. Unfortunately all single seat gliders will spin, so
>training solely on spin-resistant gliders is a receipe for disaster
>and has no doubt cost lives.

Definitely.
But I am convinced that the non-spinnable ASK-21 safed more lifes than
it cost.

Spin-training in a truly spinnable glider is certainly necessary -
but a student pilot on his first solo flights needs a glider that is
as safe as possible.

Bye
Andreas

Vaughn Simon

June 24th 07, 12:33 AM

"Andreas Maurer" > wrote in message
...
>
> Spin-training in a truly spinnable glider is certainly necessary -
> but a student pilot on his first solo flights needs a glider that is
> as safe as possible.

Thank you Andreas! I am a believer in spin training, (and even insisted on
it pre-solo) but as a CFIG I always thought it to be of primary importance that
all of my students actually survive the training experience.

It is possible to design a trainer that will do a very convincing spin
without that same trainer being even vaguely spin-prone.

Vaughn

Jeffrey Banks

June 24th 07, 02:38 AM

The ASK-21 has a kit to work the spin training issue.

http://en.wikipedia.org/wiki/Image:Spin_kit_on_an_ASK-21.JPG

I prefer to train in a Blanik...because it is a more
tempermental glider to
fly than a K-21 and then I prefer to solo students
in the ASK-21 because it
is much easier and safer to fly.

I have not used the spin kit, however if a club did
not have a Blanik type in
the fleet (that will drop a wing) then the kit is probably
the best all around
choice. If an ASK-21 is chosen for a basic all around
trainer.

It would be intersting to see how the SZD trainer is
for wing dropping.

Ian

June 24th 07, 03:48 PM

On 23 Jun, 23:58, Andreas Maurer > wrote:

> Spin-training in a truly spinnable glider is certainly necessary -
> but a student pilot on his first solo flights needs a glider that is
> as safe as possible.

Indeed. But he shouldn't /know/ that.

Ian

Ian

June 24th 07, 03:55 PM

On 23 Jun, 22:34, Andreas Maurer > wrote:
> On Fri, 22 Jun 2007 13:10:28 -0700, Ian >
> wrote:
>
> >How many gliders can recover from a spin which starts on the winch
> >launch? I really don't think the Puchacz can be blamed in such cases.
>
> Sorry to repeat myself, but how many primary trainers really DO enter
> an unintentional spin during a winch launch with an instructor on
> board?

Do you mean how many do, or how many can?

> In my opinion a primary trainer (the one that is used for early solo
> flights) cannot be spin-resistent enough.

I disagree. I think the glider used for training should spin like a
top. The learner needs to know that this is something which can
happen, can be recovered from, and really shouldn't be allowed to
happen near the ground.

I like K21's, but their lack of spinnability is a mennace. I jave
flown at three different clubs where the message given - effectively -
to student pilots is "Today we are going to learn about something
called a spin. To do that, we are going to need a different glider
from the one you normally fly in, and we are going to have to do very
strange things to the controls." Subliminal message: "This won't
happen to you unless you want it to."

My first spin was in a Bocian - the one I was used to flying in as an
ab-initio, at Portmoak. One day my instructor said "You are flying to
slowly and over-ruddering your turns at the hill. One day you will
scare yourself ****less doing that. Let me demonstrate. I have
control..."

And he proceeded to scare me ****less. So I learned that spinning was
something which could happen to /me/ in gliders /I flew/, doing /
perfectly normal things/ - albeit not very competently.

I do not this a message of "Let's land and go up in a completely
different aircraft" would have made anything like the same
impression ...

Ian

Ian

June 24th 07, 03:58 PM

On 23 Jun, 23:11, Dan G > wrote:

> Tales of "unrecoverable" spins in pooches are probably due to the idea
> that the low tail can blank the rudder (actually it won't). In reality
> a pooch will always recover with standard spin recovery technique. If
> you claim otherwise, please provide a reference to an accident report
> stating so.

I think it's laziness. So few training two-seaters need full spin
recovery (especially the bits about "pause" and "until the spinning
stops") that people who fly them get used to the "stop pro-spin input
and recover" method. Which does not work on a Puchacz or a Bocian -
or, as far as I can see, on most things made in Poland.

Ian

Tony Verhulst

June 24th 07, 04:39 PM

> And he proceeded to scare me ****less. So I learned that spinning was
> something which could happen to /me/ in gliders /I flew/, doing /
> perfectly normal things/ - albeit not very competently.
>
> I do not this a message of "Let's land and go up in a completely
> different aircraft" would have made anything like the same
> impression ...

"a spin is a normal mode of flight - unsuitable for landing" unknown
British aerodynamicist.

Pretty much all students in my club http://soargbsc.com get spin
training. And not the kind where you yank the nose up 30 degrees and
then stomp on the rudder at the top. I slow the glider way down and
start a turn (at altitude) and tell the student that we're simulating a
runway overshoot while turning from base to final. I add bottom rudder
to "help the turn along" and over she goes and the nose never got above
the horizon. It's a wake up call for many and the mantra to maintain
speed and coordination in the pattern (sorry, circuit :-) ), finally
means something.

Tony V.

[email protected]

June 24th 07, 04:40 PM

On Jun 23, 3:51 am, Paul Hanson
> wrote:
> ... The 50-3 was desinged in 78' I believe, the Perkoz in 91'.
> ... Come on, it is a completely new aircraft; it just uses
> some of the same molds and parts as the 50-3.

"Completely New Aircraft", but:
- designed in 1991 (16 years ago)...
- uses some of the same molds...

I wish them all the best, but this hardly uses all the
knowledge now available to us in 2007...

Best Regards, Dave "YO"

Colin Field[_2_]

June 24th 07, 05:03 PM

At 15:43 24 June 2007, wrote:
>On Jun 23, 3:51 am, Paul Hanson
> wrote:
>> ... The 50-3 was desinged in 78' I believe, the Perkoz
>>in 91'.
>> ... Come on, it is a completely new aircraft; it just
>>uses
>> some of the same molds and parts as the 50-3.
>
>'Completely New Aircraft', but:
>- designed in 1991 (16 years ago)...
>- uses some of the same molds...
>
>I wish them all the best, but this hardly uses all
>the
>knowledge now available to us in 2007...
>
>Best Regards, Dave 'YO'
>

I see where you're coming from, but I think it's only
just become financially feasible for them to enter
production recently. Plus, the technology and material
developments since then (even though it's 16 years
ago), while substantial, are not as relevant to them
since they're designing a 'lower'-performance, fully
aerobatic trainer which is financially sensible for
most clubs.

As for a previous idea about 'optimising' the aerofoil
to give better performance, as well as the cost considerations
I imagine that the one they are using at the moment
is both good at climbing, gives effective speed control,
and importantly for a fully aerobatic trainer has both
plenty of strength and inverted performance which has
more stability and better performance than many of
our modern high-speed aerofoils. These are important
characteristics for a trainer- but I wonder if they've
allowed it a higher Vne to enhance its suitability
for aerobatics.

I too wish them the best of luck with this new plane-
I've done ALL of my training in Puchaczs, and would
very much like to try a flight in the Perkoz.

Colin Field[_2_]

June 24th 07, 05:03 PM

Edward Lockhart[_2_]

June 24th 07, 05:06 PM

Ian

June 24th 07, 05:22 PM

On 24 Jun, 16:39, Tony Verhulst > wrote:

> Pretty much all students in my clubhttp://soargbsc.comget spin
> training. And not the kind where you yank the nose up 30 degrees and
> then stomp on the rudder at the top.

One CFI (that's "Chief" over here, USAnians) I knew was very fond of
spinning - in a Bocian - from perfectly coordinated thermalling turns.
More than one experienced pilot on a site check came down having
learned something very useful.

Ian

Andreas Maurer

June 25th 07, 12:51 PM

On Sun, 24 Jun 2007 07:55:39 -0700, Ian >
wrote:

>Do you mean how many do, or how many can?

How many *do*.
Pretty easy to stall any glider during a winch launch if you
intentionally pull back fully.

>I disagree. I think the glider used for training should spin like a
>top. The learner needs to know that this is something which can
>happen, can be recovered from, and really shouldn't be allowed to
>happen near the ground.

.... and if it happens...?
A benign glider significantly increases the chance of survival,
doesn't it?

Bye
Andreas

Ian

June 25th 07, 05:08 PM

On 25 Jun, 12:51, Andreas Maurer > wrote:
> On Sun, 24 Jun 2007 07:55:39 -0700, Ian >
> wrote:

> >I disagree. I think the glider used for training should spin like a
> >top. The learner needs to know that this is something which can
> >happen, can be recovered from, and really shouldn't be allowed to
> >happen near the ground.
>
> ... and if it happens...?
> A benign glider significantly increases the chance of survival,
> doesn't it?

On the same principal training gliders could be fitted with elevator
backstops so that pupils could pull back as hard as they liked on the
winch with no danger of stalling.

Ian

Bill Daniels

June 25th 07, 07:21 PM

"Ian" > wrote in message
oups.com...
> On 25 Jun, 12:51, Andreas Maurer > wrote:
>> On Sun, 24 Jun 2007 07:55:39 -0700, Ian >
>> wrote:
>
>> >I disagree. I think the glider used for training should spin like a
>> >top. The learner needs to know that this is something which can
>> >happen, can be recovered from, and really shouldn't be allowed to
>> >happen near the ground.
>>
>> ... and if it happens...?
>> A benign glider significantly increases the chance of survival,
>> doesn't it?
>
> On the same principal training gliders could be fitted with elevator
> backstops so that pupils could pull back as hard as they liked on the
> winch with no danger of stalling.
>
> Ian
>

How about watching the airspeed? If you maintain a margin over the loaded
stall speed, there no chance of stalling.

As for the ASK-21, you don't gain anything from pulling back anyway. The
highest winch launches are when the glider is flown at the best L/D angle of
attack - that's about neutral elevator..

Bill Daniels

Dan G

June 25th 07, 08:01 PM

On Jun 25, 7:21 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>
> How about watching the airspeed? If you maintain a margin over the loaded
> stall speed, there no chance of stalling.
>
> As for the ASK-21, you don't gain anything from pulling back anyway. The
> highest winch launches are when the glider is flown at the best L/D angle of
> attack - that's about neutral elevator..

Bill - Ian was being sarcastic...

Dan

Ian

June 25th 07, 09:35 PM

On 25 Jun, 19:21, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> "Ian" > wrote in message

> > On the same principal training gliders could be fitted with elevator
> > backstops so that pupils could pull back as hard as they liked on the
> > winch with no danger of stalling.

> How about watching the airspeed? If you maintain a margin over the loaded
> stall speed, there no chance of stalling.

That wasn't quite my point ...

However, drawing from what you say, we all agree, don't we, that
training and early solo gliders have to be suitable for pilots who
can't fly very well? The argument is therefore whether a good glider
at this stage is one which is easy or difficult to fly.

My personal belief is that it shouldn't be too easy. It's all very
well having a trainer which won't spin - and it would be easy enough
to make one which was almost impossible to stall - but these early
stages are surely the time when the foundations should be laid for
later. That's why the BGA has every ab initio in the UK religiously
checking the flaps on a K13 every time they launch.

I don't think a trainer has to be, or should be, vicious. It doesn't
have to flick into a spin, or invert on recovery, but I do think it
should spin easily and require a full recovery procedure.

As a parallel, I do a fair bit of sailing. When people ask me how to
learn, I always tell them to start, even if just for a few times, in a
dinghy rather than a yacht. Dinghy sailing teaches fast responses and
attentiveness: it's easy to slow down things for a keel boat but much
harder to go the other way. I still make a point of hiring a Wayfarer
at a local sailing centre a couple of times a year, preferably on a
good blowy day, to remind myself what it's like and sharpen my
responses.

Ian

Bill Daniels

June 26th 07, 12:50 AM

"Dan G" > wrote in message
oups.com...
> On Jun 25, 7:21 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>>
>> How about watching the airspeed? If you maintain a margin over the
>> loaded
>> stall speed, there no chance of stalling.
>>
>> As for the ASK-21, you don't gain anything from pulling back anyway. The
>> highest winch launches are when the glider is flown at the best L/D angle
>> of
>> attack - that's about neutral elevator..
>
> Bill - Ian was being sarcastic...
>
>
> Dan
>

OK, I accept the sarcasm and appologise for being sharp.

However, in the US there are many glider pilots who have never flown a winch
launch and instinctively fear nose high attitudes. Even joking about full
up elevator and stalls on the wire is terrifying to them. I felt I had to
make it clear that you should not be anywhere near the stalling AOA.

Adding to my concern is that the ubiquitous US Schweizer 2-33 does use full
up elevator on a winch launch due to the unfortunate position of the release
hook. A pilot transitioning to even a docile a trainer like a ASK-21 could
be in trouble if he misunderstands the difference.

It also concerns me that pilots with much experience on aero tow
transitioning to winch launch may have never considered the need to monitor
airspeed on a launch since the tug pilot has always done that for them.

Bill Daniels

Marc Ramsey[_2_]

June 26th 07, 01:54 AM

Bill Daniels wrote:
> Adding to my concern is that the ubiquitous US Schweizer 2-33 does use full
> up elevator on a winch launch due to the unfortunate position of the release
> hook. A pilot transitioning to even a docile a trainer like a ASK-21 could
> be in trouble if he misunderstands the difference.

True CG hooks were an option for 2-33s, and could probably still be
retrofitted if desired. A second Schweizer hook is mounted ahead of the
main wheel, to the left of the skid. From recent experience, the
handling during launch is similar to a K-13...

Marc

Sandro Rodriguez

June 26th 07, 08:45 AM

Bill Daniels schrieb:

> Adding to my concern is that the ubiquitous US Schweizer 2-33 does use full

Ubiquitous? I've never seen one in my life. Ok, I'm living in Europe.

> up elevator on a winch launch due to the unfortunate position of the release
> hook. A pilot transitioning to even a docile a trainer like a ASK-21 could
> be in trouble if he misunderstands the difference.

That's what instructors are for.

> It also concerns me that pilots with much experience on aero tow
> transitioning to winch launch may have never considered the need to monitor
> airspeed on a launch since the tug pilot has always done that for them.

That's what instructors are for.

Sally W

June 26th 07, 09:00 AM

At 20:36 25 June 2007, Ian wrote:
<snip>
>
>As a parallel, I do a fair bit of sailing. When people
>ask me how to
>learn, I always tell them to start, even if just for
>a few times, in a
>dinghy rather than a yacht. Dinghy sailing teaches
>fast responses and
>attentiveness: it's easy to slow down things for a
>keel boat but much
>harder to go the other way. I still make a point of
>hiring a Wayfarer
>at a local sailing centre a couple of times a year,
>preferably on a
>good blowy day, to remind myself what it's like and
>sharpen my
>responses.

But there are dinghies and dinghies... Learning on
a Wayfarer is as much K21-like as any dinghy can be
- it demands a lot of provocation to capsize given
that most sailing schools have an armoury of small
sails that get hoisted on a faintly breezy day for
beginners. Of course if you put up the full sails
then it's livelier, but also physically a bit too demanding
for many beginners due to the size of the full rig.

Learning on a Laser with full rig would be far too
much for most beginners, as would Fireballs and many
other racing machines. OTOH a GP14 is a great dinghy
to learn in (IMHO) and so is a Heron. At school we
sailed Enterprises which can be a bit much (not to
mention a bit fragile) but we were teenagers, fit &
fearless.

However, I do agree that anyone wanting to learn to
sail should do so in dinghies whatever their ambitions,
not just on the grounds you mention, but also in terms
of safety, cost and accessability. Safety might seem
odd, but keel boats with their much larger sails, winches
and so on have an additional set of dangers not present
in dinghies.

Bill Daniels

June 26th 07, 03:41 PM

"Sandro Rodriguez" > wrote in message
...
> Bill Daniels schrieb:
>
>> Adding to my concern is that the ubiquitous US Schweizer 2-33 does use
>> full
>
> Ubiquitous? I've never seen one in my life. Ok, I'm living in Europe.
>
>> up elevator on a winch launch due to the unfortunate position of the
>> release hook. A pilot transitioning to even a docile a trainer like a
>> ASK-21 could be in trouble if he misunderstands the difference.
>
> That's what instructors are for.
>
>> It also concerns me that pilots with much experience on aero tow
>> transitioning to winch launch may have never considered the need to
>> monitor airspeed on a launch since the tug pilot has always done that for
>> them.
>
> That's what instructors are for.

Sandro, you are assuming US instructors have winch experience. Some do,
many don't.

Bill Daniels

Stefan

June 26th 07, 04:44 PM

Bill Daniels schrieb:

> Sandro, you are assuming US instructors have winch experience. Some do,
> many don't.

So you're saying that instructors with no winch launch experience teach
winch launches? Apalling. Or are you just saying that pilots with no
winch launch experience learn to winch launch on a try and error basis?
Apalling, too. (Besides my surprize that this should be legal.)

Bill Daniels

June 26th 07, 05:29 PM

"Stefan" > wrote in message
.. .
> Bill Daniels schrieb:
>
>> Sandro, you are assuming US instructors have winch experience. Some do,
>> many don't.
>
> So you're saying that instructors with no winch launch experience teach
> winch launches? Apalling. Or are you just saying that pilots with no winch
> launch experience learn to winch launch on a try and error basis?
> Apalling, too. (Besides my surprize that this should be legal.)

Neither.

At a minimum, US pilots and instructors need a logbook entry showing they
have had instruction in ground launch techniques. In fact, most are
responsible enough to go much further in learning what they need to know.
Nonetheless, there seems to be a lot of misunderstandings about basic winch
technique.

I spend a lot of time doing winch training. One of the big
misunderstandings I encounter is the assumption that all winch launches are
made with full-up elevator. That's why I reacted to the earlier post.

Bill Daniels

Ian

June 26th 07, 05:54 PM

On 26 Jun, 17:29, "Bill Daniels" <bildan@comcast-dot-net> wrote:

> I spend a lot of time doing winch training. One of the big
> misunderstandings I encounter is the assumption that all winch launches are
> made with full-up elevator. That's why I reacted to the earlier post.

There is at least one large club in England which teaches this as the
right way to winch launch. They aren't worried about spins, because
their gliders are unspinnable and they aren't worried about cable
breaks because they chaneg the cables regularly. So that's all right
then.

Ian

Sally W

June 26th 07, 06:49 PM

At 14:42 26 June 2007, Bill Daniels wrote:
>
>'Sandro Rodriguez' wrote in message
...
>> Bill Daniels schrieb:
>>
>>> Adding to my concern is that the ubiquitous US Schweizer
>>>2-33 does use
>>> full
>>
>> Ubiquitous? I've never seen one in my life. Ok, I'm
>>living in Europe.
>>
>>> up elevator on a winch launch due to the unfortunate
>>>position of the
>>> release hook. A pilot transitioning to even a docile
>>>a trainer like a
>>> ASK-21 could be in trouble if he misunderstands the
>>>difference.
>>
>> That's what instructors are for.
>>
>>> It also concerns me that pilots with much experience
>>>on aero tow
>>> transitioning to winch launch may have never considered
>>>the need to
>>> monitor airspeed on a launch since the tug pilot has
>>>always done that for
>>> them.
>>
>> That's what instructors are for.
>
>Sandro, you are assuming US instructors have winch
>experience. Some do,
>many don't.

But surely only the ones with winch experience teach
winch launching? So it's not an issue? And surely
no-one goes from aerotow to winching without getting
some instruction?

Marc Ramsey

June 26th 07, 07:00 PM

Sally W wrote:
> At 14:42 26 June 2007, Bill Daniels wrote:
>> 'Sandro Rodriguez' wrote in message
>> ...
>>> Bill Daniels schrieb:
>>>
>>>> Adding to my concern is that the ubiquitous US Schweizer
>>>> 2-33 does use
>>>> full
>>> Ubiquitous? I've never seen one in my life. Ok, I'm
>>> living in Europe.
>>>
>>>> up elevator on a winch launch due to the unfortunate
>>>> position of the
>>>> release hook. A pilot transitioning to even a docile
>>>> a trainer like a
>>>> ASK-21 could be in trouble if he misunderstands the
>>>> difference.
>>> That's what instructors are for.
>>>
>>>> It also concerns me that pilots with much experience
>>>> on aero tow
>>>> transitioning to winch launch may have never considered
>>>> the need to
>>>> monitor airspeed on a launch since the tug pilot has
>>>> always done that for
>>>> them.
>>> That's what instructors are for.
>> Sandro, you are assuming US instructors have winch
>> experience. Some do,
>> many don't.
>
> But surely only the ones with winch experience teach
> winch launching? So it's not an issue? And surely
> no-one goes from aerotow to winching without getting
> some instruction?

You probably have spent much time in the United States 8^)

Marc Ramsey

June 26th 07, 07:04 PM

Sally W wrote:

> But surely only the ones with winch experience teach
> winch launching? So it's not an issue? And surely
> no-one goes from aerotow to winching without getting
> some instruction?

Correction:

You probably haven't spent much time in the United States 8^)

Cats

June 26th 07, 07:39 PM

On Jun 26, 7:04 pm, Marc Ramsey > wrote:
> Sally W wrote:
> > But surely only the ones with winch experience teach
> > winch launching? So it's not an issue? And surely
> > no-one goes from aerotow to winching without getting
> > some instruction?
>
> Correction:
>
> You probably haven't spent much time in the United States 8^)

If you are telling me that there are instructors teaching winch
launching in the US who don't know what they are doing, and people
trying it with no prior instruction, you are putting me off ever
flying in the US big time. Surely you folks over there have a better-
developed sense of self-preservation?

Cats

June 26th 07, 07:44 PM

On Jun 26, 5:54 pm, Ian > wrote:
> On 26 Jun, 17:29, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>
> > I spend a lot of time doing winch training. One of the big
> > misunderstandings I encounter is the assumption that all winch launches are
> > made with full-up elevator. That's why I reacted to the earlier post.
>
> There is at least one large club in England which teaches this as the
> right way to winch launch. They aren't worried about spins, because
> their gliders are unspinnable and they aren't worried about cable
> breaks because they chaneg the cables regularly. So that's all right
> then.
>
> Ian

Then if they are still doing that, I suspect they are not following
the latest BGA advice:

http://www.gliding.co.uk/bgainfo/documents/safewinchlaunching.pdf

"A stall and possible spin/flick roll during rotation results from a
low airspeed combined with a
rapid rate of rotation. Accidents of this kind are rare but often
fatal."

"· Do not take off with the stick held back."

(but read the full PDF)

BTW there has been some debate about the full launch angle being 35
degrees, and we seemed to reach the conclusion that was the path the
CoG took, not the attitude of the glider.

Bill Daniels

June 26th 07, 08:57 PM

"Sally W" > wrote in message
...
> But surely only the ones with winch experience teach
> winch launching? So it's not an issue? And surely
> no-one goes from aerotow to winching without getting
> some instruction?
>

I'm sure that it's a rare situation. Fortunately, there is a lot of good
guidance on the web about winch proceedures from various national aero clubs
and quite a few instructors who read this guidance.

Bill Daniels

Cats

June 26th 07, 09:24 PM

On Jun 26, 8:57 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> "Sally W" > wrote in message
>
> ...
>
> > But surely only the ones with winch experience teach
> > winch launching? So it's not an issue? And surely
> > no-one goes from aerotow to winching without getting
> > some instruction?
>
> I'm sure that it's a rare situation.

I hope it's as rare as flying pigs.

> Fortunately, there is a lot of good
> guidance on the web about winch proceedures from various national aero clubs
> and quite a few instructors who read this guidance.

And I'd hope the instructors have been doing a bit more than reading
the Internet for guidance.

Marc Ramsey

June 26th 07, 09:27 PM

Bill Daniels wrote:
> "Sally W" > wrote in message
> ...
>> But surely only the ones with winch experience teach
>> winch launching? So it's not an issue? And surely
>> no-one goes from aerotow to winching without getting
>> some instruction?
>>
>
> I'm sure that it's a rare situation. Fortunately, there is a lot of good
> guidance on the web about winch proceedures from various national aero clubs
> and quite a few instructors who read this guidance.

As you know, the training of the majority of winch qualified pilots
(i.e., those with a ground launch endorsement) here in the US consisted
of pulling a rusty underpowered Gerhlein out from behind a hangar,
plopping the transitioning pilot in the front seat of a nose hook
equipped 2-33, then three flights: pilot follows instructor on controls,
instructor follows pilot on controls, instructor signs off pilot, pilot
flies a solo launch.

There are several clubs that now use winches as their primary launch
method, and they take instruction (and safety) much more seriously.
But, much of the resistance to increased use of winches in the US comes
as a reaction to these past (for the most part) "training" activities...

Marc

Ian

June 26th 07, 10:10 PM

On 26 Jun, 19:44, Cats > wrote:
> On Jun 26, 5:54 pm, Ian > wrote:

> > There is at least one large club in England which teaches this as the
> > right way to winch launch.

> Then if they are still doing that, I suspect they are not following
> the latest BGA advice:
>
> http://www.gliding.co.uk/bgainfo/documents/safewinchlaunching.pdf

A document which I saw for the first time a couple of weeks ago. I was
rather struck by this

"There is no case of an airworthy glider being damaged by excessive
airspeed on a winch launch which is why it is not listed as a hazard."

which makes me wonder why it is imediately followed by this

"If the speed is excessive near the ground, climb gently to several
hundred feet and release, or signal if the excess speed is now
moderate."

If it's not a hazard, why do anything about it?

Ian

Andreas Maurer[_1_]

June 26th 07, 10:40 PM

On Tue, 26 Jun 2007 14:10:57 -0700, Ian >
wrote:

>If it's not a hazard, why do anything about it?

To avoid breaking the cable?

Bye
Andreas

Bill Daniels

June 26th 07, 10:42 PM

"Ian" > wrote in message
ups.com...
> On 26 Jun, 19:44, Cats > wrote:
>> On Jun 26, 5:54 pm, Ian > wrote:
>
>> > There is at least one large club in England which teaches this as the
>> > right way to winch launch.
>
>> Then if they are still doing that, I suspect they are not following
>> the latest BGA advice:
>>
>> http://www.gliding.co.uk/bgainfo/documents/safewinchlaunching.pdf
>
> A document which I saw for the first time a couple of weeks ago. I was
> rather struck by this
>
> "There is no case of an airworthy glider being damaged by excessive
> airspeed on a winch launch which is why it is not listed as a hazard."
>
> which makes me wonder why it is imediately followed by this
>
> "If the speed is excessive near the ground, climb gently to several
> hundred feet and release, or signal if the excess speed is now
> moderate."
>
> If it's not a hazard, why do anything about it?
>
> Ian
>

The "no case" statement just means don't take precipitous action if the
airspeed is too high. Accidents have occured from pilot actions that were
unwarranted. None have occured simply due to exceeding Vw by a small
margin.

Excessive speed near the ground means that acceleration and therefore the
winch power is way too high. The pilot is advised to release and land ahead.

However, both statements lead one to think that the winch is controlling
airspeed which is difficult since the winch driver has no idea what the
glilder airspeed is. If the winch is producing the right power, the pilot
can, and should, control airspeed with pitch.

The relationship of power and airspeed is exactly like an airplane. With
fixed power, raising the nose will reduce airspeed, lowering it will cause
airspeed to increase. The relationship between pilot and winch driver is
exactly like that between a pilot and flight engineer where the engineer
controls power and the pilot flies the airplane.

Bill Daniels

Dan G

June 26th 07, 10:48 PM

On Jun 26, 10:10 pm, Ian > wrote:
> On 26 Jun, 19:44, Cats > wrote:
>
> > On Jun 26, 5:54 pm, Ian > wrote:
> > > There is at least one large club in England which teaches this as the
> > > right way to winch launch.
> > Then if they are still doing that, I suspect they are not following
> > the latest BGA advice:
>
> >http://www.gliding.co.uk/bgainfo/documents/safewinchlaunching.pdf
>
> A document which I saw for the first time a couple of weeks ago. I was
> rather struck by this
>
> "There is no case of an airworthy glider being damaged by excessive
> airspeed on a winch launch which is why it is not listed as a hazard."
>
> which makes me wonder why it is imediately followed by this
>
> "If the speed is excessive near the ground, climb gently to several
> hundred feet and release, or signal if the excess speed is now
> moderate."
>
> If it's not a hazard, why do anything about it?
>
> Ian

Because if you don't release the weak link is going to break, which
leaves you in a launch failure situation rather than a releasing at a
more moderate angle, which is preferable. A high-speed link break is
not very comfortable (I had one last weekend, when the winch driver
inexplicably floored the winch half way up a launch). Breaking the
weak link is also a major PITA for those on the ground (we lost the
strop+rings, which I believe is £££).

RE the club we're not naming - amazingly I understand they've not had
a winch launch accident, at least not recently. Other clubs have
though.

Dan

Chris Reed[_1_]

June 26th 07, 10:49 PM

Ian wrote:
>> http://www.gliding.co.uk/bgainfo/documents/safewinchlaunching.pdf
>
> A document which I saw for the first time a couple of weeks ago. I was
> rather struck by this
>
> "There is no case of an airworthy glider being damaged by excessive
> airspeed on a winch launch which is why it is not listed as a hazard."
>
> which makes me wonder why it is imediately followed by this
>
> "If the speed is excessive near the ground, climb gently to several
> hundred feet and release, or signal if the excess speed is now
> moderate."
>
> If it's not a hazard, why do anything about it?
>
> Ian

I think the point being made is that no-one has yet proved it to be a
hazard in practice by pulling the wings off, or more likely causing the
tailplane to fail.

However, if you read "Gliding" by Steve Longland (which is the book-form
advanced BGA manual plus), you will see that flying beyond the max winch
speed at some point takes the glider outside its design limits. Outside
the limits no-one knows what will happen to the airframe. Maybe it'll be
fine, maybe not (and the parts of the book about repeated stresses
outside design limits leading to gradual though invisible deterioration,
followed by catastrophic failure, give pause for thought).

As I read the advice, if your only choice is to accept excessive speed
or to accept something worse, then excessive speed is the safer choice.
If you can do something safe rather than overspeed, then do the other thing!

For example, from my experience driving a winch, I've seen numerous
pilots rotate and then immediately start wagging the glider's tail (the
UK signal for "too fast"). If you read about the physics of the launch,
at this stage the loads on the glider are low, and overspeeding presents
little or no hazard. The consequence is often (especially if the glider
is climbing through a wind gradient) that if the driver reduces the
speed, a few seconds later the glider is too slow - now that *is* proved
to be dangerous.

Experienced winch-launching pilots who I know are content to accept
overspeeding in the first part (say 1/3) of the launch and wait for the
speed to settle to the correct figure. If not (in the second 1/3 where
the loads are increasing) they signal to slow down. If speed is too high
in the top 1/3 (where the forces start to approach or exceed design
limits) then it's goodbye to the cable - but at that point you have
enough height to make a safe circuit so it's only an argument with the
driver about your wasted launch fee and not a case of recovering your
remains from the runway.

If the speed is madly excessive (and I've had this happen to me a couple
of times) then even signalling can be a problem. In that case, allowing
the glider to "float" up to circuit height with little or no load on the
airframe is the safest way of coping, followed by forcible re-education
of the winch driver.

Ian

June 27th 07, 09:07 AM

On 26 Jun, 22:40, Andreas Maurer > wrote:
> On Tue, 26 Jun 2007 14:10:57 -0700, Ian >
> wrote:
>
> >If it's not a hazard, why do anything about it?
>
> To avoid breaking the cable?

Then it would be a hazard!

Ian

Ian

June 27th 07, 09:10 AM

On 26 Jun, 22:42, "Bill Daniels" <bildan@comcast-dot-net> wrote:

> The relationship of power and airspeed is exactly like an airplane. With
> fixed power, raising the nose will reduce airspeed, lowering it will cause
> airspeed to increase.

It's not alwaysthat simple, and depends a lot on the construction of
the winch. It makes a big difference, for example, if it has a torque
convertor as opposed to a fxed ratio gearbox or a fluid flywheel. You
need to take account of the tension-speed relationships for both the
winch and the glider.

Ian (one time winch instructor)

Ian

June 27th 07, 09:13 AM

On 26 Jun, 22:48, Dan G > wrote:
> On Jun 26, 10:10 pm, Ian > wrote:

> > If it's not a hazard, why do anything about it?

> Because if you don't release the weak link is going to break, which
> leaves you in a launch failure situation rather than a releasing at a
> more moderate angle, which is preferable.

Ah. So it is a hazard, then?

> RE the club we're not naming - amazingly I understand they've not had
> a winch launch accident, at least not recently. Other clubs have
> though.

You know who I mean, then? Their members are said to be rather prone
to accidents at other sites ...

Ian

Ian

June 27th 07, 09:21 AM

On 26 Jun, 22:49, Chris Reed > wrote

> I think the point being made is that no-one has yet proved it to be a
> hazard in practice by pulling the wings off, or more likely causing the
> tailplane to fail.

What about the Oly which clapped its wings as a result of an overspeed
winch launch at - iirc - Sutton Bank?

> Experienced winch-launching pilots who I know are content to accept
> overspeeding in the first part (say 1/3) of the launch and wait for the
> speed to settle to the correct figure.

I sort of agree. I will never rotate into the full climb if the speed
is excessive, and I will give the driver a few seconds to sort things
out. If I have the slightest doubt, though, I will pull off and
perform some ...

> ... forcible re-education of the winch driver.

Since an overspeed at the early part of thelaunch is a) entirely
preventable and b) entirely the winch driver's fault. When I'm
driving, by the way, I expect to be treated the same way. I make a
point of regularly asking experienced pilots (normally instructors)
how the launch was, particularly at the start of my stint, as it helps
to picture wind gradients and so on.

Ian

Chris Reed[_1_]

June 27th 07, 09:47 AM

Ian wrote:
>
> What about the Oly which clapped its wings as a result of an overspeed
> winch launch at - iirc - Sutton Bank?
>
The accident report put the cause as severe corrosion of the spar end
metal fittings.

Ian

June 27th 07, 10:37 AM

On 27 Jun, 09:47, Chris Reed > wrote:
> Ian wrote:
>
> > What about the Oly which clapped its wings as a result of an overspeed
> > winch launch at - iirc - Sutton Bank?
>
> The accident report put the cause as severe corrosion of the spar end
> metal fittings.

Certainly a factor, but if it hadn't oversped (overspeeded?) on
launch, it wouldn't have failed. Well, not then, anyway.

I knew of a Ka6 which pushed over so violently after a cable break
that it landed afterwards - for the last time - with significant
anhedral. OK, nothing to do with overspeeding, but a salutory tale
illustrating something or other.

Ian

Bert Willing

June 27th 07, 12:57 PM

"Ian" > wrote in message
oups.com...
> On 27 Jun, 09:47, Chris Reed > wrote:
>> Ian wrote:
>>
>> > What about the Oly which clapped its wings as a result of an overspeed
>> > winch launch at - iirc - Sutton Bank?
>>
>> The accident report put the cause as severe corrosion of the spar end
>> metal fittings.
>
> Certainly a factor, but if it hadn't oversped (overspeeded?) on
> launch, it wouldn't have failed. Well, not then, anyway.

Well, that is pure speculation, isn't it ?

Andreas Maurer[_1_]

June 27th 07, 01:55 PM

On Wed, 27 Jun 2007 01:07:44 -0700, Ian >
wrote:

>On 26 Jun, 22:40, Andreas Maurer > wrote:
>> On Tue, 26 Jun 2007 14:10:57 -0700, Ian >
>> wrote:
>>
>> >If it's not a hazard, why do anything about it?
>>
>> To avoid breaking the cable?
>
>Then it would be a hazard!

That's why something needs to be done. :)

Bye
Andreas

Ian

June 27th 07, 03:34 PM

On 27 Jun, 12:57, "Bert Willing" <willing_no_spam_ple...@ir-
microsystems.com> wrote:
> "Ian" > wrote in message

> > Certainly a factor, but if it hadn't oversped (overspeeded?) on
> > launch, it wouldn't have failed. Well, not then, anyway.
>
> Well, that is pure speculation, isn't it ?

My understanding was that the failure which occurred was deemed to be
a result of structural problems triggered by overspeed. I am happy to
be corrected if I am misremembering - I can't find accident reports on
the BGA website any more to check.

A friend of mine has an Oly which has been grounded for ever for this
reason - the glue in the aluminium/wood/aluminium sandwich spar has
seriously deteriorated and is beyond economic repair. He was winching
it quite happily until the accident happened.

Ian

Ian

June 27th 07, 03:36 PM

On 27 Jun, 13:55, Andreas Maurer > wrote:
> On Wed, 27 Jun 2007 01:07:44 -0700, Ian >
> wrote:
>
> >On 26 Jun, 22:40, Andreas Maurer > wrote:
> >> On Tue, 26 Jun 2007 14:10:57 -0700, Ian >
> >> wrote:
>
> >> >If it's not a hazard, why do anything about it?
>
> >> To avoid breaking the cable?
>
> >Then it would be a hazard!
>
> That's why something needs to be done. :)

The normal reason why things need to be done in the UK is that Lasham
has a new CFI who wants to make his mark ... nobody ever got famous by
saying "everything is going pretty well at the moment."

Ian

Mike Lindsay

June 27th 07, 03:40 PM

In article om>, Ian
> wri
> That's why the BGA has every ab initio in the UK religiously
>checking the flaps on a K13 every time they launch.
>
My God! (that's the religious bit)

I don't think I've ever seen a K13 with flaps.
--
Mike Lindsay

Bruce

June 27th 07, 04:46 PM

Mike Lindsay wrote:
> In article om>, Ian
> > wri
>> That's why the BGA has every ab initio in the UK religiously
>> checking the flaps on a K13 every time they launch.
>>
> My God! (that's the religious bit)
>
> I don't think I've ever seen a K13 with flaps.
True, but they check them just in case...

Sandro Rodriguez

June 27th 07, 05:09 PM

Mike Lindsay schrieb:

>> That's why the BGA has every ab initio in the UK religiously
>> checking the flaps on a K13 every time they launch.

> I don't think I've ever seen a K13 with flaps.

That was exactly his point.

Chris Reed[_1_]

June 27th 07, 06:49 PM

Ian,

Looks like we both recall correctly but incompletely. The AAIB report of
the 1996 accident, at
http://www.aaib.dft.gov.uk/cms_resources/dft_avsafety_pdf_502118.pdf states:

"Several witnesses formed the opinion that this launch was faster and
less steep than normal, the launches already being considered, by
several witnesses, as being fast that day. One witness reported the
presence of a strong wind gradient, the surface wind being 5/10 kt. At a
height variously estimated by witnesses of between 600 and 700 feet the
glider was seen to 'speed- up' and its climb angle reduce. At about this
time, and whilst still in a nose high attitude and connected to the
cable, several relatively rapid oscillations in pitch occurred. One
witness estimated these to be as much as 15°, with the wings being seen
to 'flex' correspondingly an abnormal amount. At about this point,
the airbrakes were seen to briefly deploy. Almost immediately, they
deployed again, this time coincident with the right wing failing in an
upwards and rearwards direction, pivoting about its root end and
releasing a cloud of debris."

A doubled weak link was used, which could have allowed excessive loads
on the airframe in previous launches and in this one. Part of the
conclusion was:

"In view of the fact that the corrosion had developed over a long period
of time, during which the glider had been launched and flown without
incident, and that the aircraft had been launched by winch earlier on
the same day in similar conditions by the same pilot, it is considered
probable that excessive loads were induced on this occasion. This, in
turn, exploited the degraded strength of the wing spar, resulting in the
upper spar boom collapse in the right wing."

I read this as saying that continued overstressing on a weakened
structure led to the failure, with that days's overstress being the
final straw. The report says that other gliders flying from the same
airfield had probably been overloaded. Only this one failed
structurally, because of the corrosion.

As I wrote before, flying outside the envelope takes one into uncharted
territory. However, overspeeding on its own does not necessarily do so -
it depends on how the pilot flies the launch and when the launch is
abandoned.

To summarise how I understand the UK training:

1. If overspeed is clearly excessive from the outset, release and land
ahead if possible. If not possible to land ahead, see (3).

2. If moderately excessive in the lower 1/3 of the launch, give a chance
for it to settle down and if not, signal too fast.

3. If it doesn't settle down, reduce the load on the airframe through a
shallow rate of climb and release once a safe height is achieved.

4. Overspeed in the top 1/3 of the launch is potentially dangerous as
the glider is under its highest load at that point, and cumulative
overstress can lead to failure particularly if the structure is already
weakened.

5. Too slow is more dangerous than too fast, provided you fly the fast
launch so as not to overstress the airframe.

I'd add that all suspicions of corrosion, overstress through excessive
g, etc. need to be checked out by a qualified person.

Sally W

June 28th 07, 08:37 AM

At 15:54 27 June 2007, Bruce wrote:
>Mike Lindsay wrote:
>> In article , Ian
>> wri
>>> That's why the BGA has every ab initio in the UK religiously
>>> checking the flaps on a K13 every time they launch.
>>>
>> My God! (that's the religious bit)
>>
>> I don't think I've ever seen a K13 with flaps.
>True, but they check them just in case...
>
And they are checked in a K21...

Dan G

June 28th 07, 09:23 PM

On Jun 27, 6:49 pm, Chris Reed > wrote:
> Ian,
>
> Looks like we both recall correctly but incompletely. The AAIB report of
> the 1996 accident, athttp://www.aaib.dft.gov.uk/cms_resources/dft_avsafety_pdf_502118.pd fstates...

Sorry folks, I've just repeated some of what Chris posted, didn't
notice that the conversation had "gone over the page".

However, Chris does seem to be intimating that it's possible to
structurally damage a glider during a winch launch from overspeeding.
Providing the correct weak is used, that is not possible. Old myths
die hard though.

Dan

Chris Reed[_1_]

June 29th 07, 09:49 AM

Dan G wrote:
> However, Chris does seem to be intimating that it's possible to
> structurally damage a glider during a winch launch from overspeeding.
> Providing the correct weak is used, that is not possible. Old myths
> die hard though.
>
Apologies - didn't mean to intimate that.

All I was trying to say is that overspeeding is not dangerous per se,
but might become so depending on the condition of your glider, where you
are in the launch and how you fly it. So far as structural damage is
concerned, the only example we have is from an already damaged glider,
so you may well be right that with the correct weak link you're
protected from structural damage.

However, I still refuse to accept overspeeding in the top 1/3 of the
launch because (a) the glider is not designed for it, even if it won't
fall apart, (b) I don't know whether my glider's structure has been
invisibly weakened by past overspeeding, groundloops, etc, and (c) I can
safely do something about it (bye bye cable).

Below that, I'm prepared to try to sort out the situation unless it's
clearly irredeemable.

Of course, much depends on what you mean by overspeeding. 2kt over max
winch is within the margin of error. 20kt over is far too much to live
with all the way to the top.

Colin Field[_2_]

June 29th 07, 12:31 PM

At 08:54 29 June 2007, Chris Reed wrote:

>Of course, much depends on what you mean by overspeeding.
>2kt over max
>winch is within the margin of error. 20kt over is far
>too much to live
>with all the way to the top.

Debatable safety considerations aside, there's no benefit
in fast winch launches anyway- there's just increased
drag and therefore reduced final height, along with
the possible distraction and discomfort of excessive
acceleration at the beginning.

Martin Gregorie[_1_]

June 29th 07, 03:35 PM

Sally W wrote:
> At 15:54 27 June 2007, Bruce wrote:
>> Mike Lindsay wrote:
>>> In article , Ian
>>> wri
>>>> That's why the BGA has every ab initio in the UK religiously
>>>> checking the flaps on a K13 every time they launch.
>>>>
>>> My God! (that's the religious bit)
>>>
>>> I don't think I've ever seen a K13 with flaps.
>> True, but they check them just in case...
>>
> And they are checked in a K21...
>
....and in an SZD Junior, Discus and Pegasus at my club, at least
by me - and in my Standard Libelle.

I see no reason to deviate from the standard CBSIFTCBE checklist,
so "Flaps: not fitted" accompanied by a glance to see that there
is indeed no flap handle is part of my checklist for a non-flapped
glider.

This has the benefit of keeping instructors happy on check rides
without straining my brain to remember what checklist is expected as
compared with what I might do or say when no instructor is present.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Ian

June 29th 07, 07:55 PM

On 28 Jun, 21:23, Dan G > wrote:

> However, Chris does seem to be intimating that it's possible to
> structurally damage a glider during a winch launch from overspeeding.
> Providing the correct weak is used, that is not possible. Old myths
> die hard though.

Why, then, is the winch launch maximum speed not Vne?

Ian

brtlmj

June 29th 07, 08:20 PM

> > structurally damage a glider during a winch launch from overspeeding.
> > Providing the correct weak is used, that is not possible. Old myths
> > die hard though.
> Why, then, is the winch launch maximum speed not Vne?

If I understand it correctly, flying at maximum winch speed or below
ensures that you won't lose your wings even if you use a wrong weak
link or no weak link at all.

Bartek

Vaughn Simon

June 29th 07, 11:26 PM

"Martin Gregorie" > wrote in message
...
> Sally W wrote:
> I see no reason to deviate from the standard CBSIFTCBE checklist,
> so "Flaps: not fitted" accompanied by a glance to see that there
> is indeed no flap handle is part of my checklist for a non-flapped
> glider.
>
> This has the benefit of keeping instructors happy on check rides
> without straining my brain to remember what checklist is expected as compared
> with what I might do or say when no instructor is present.

Perhaps it is just the way that my mind works, but I have to respectfully
disagree.

If you fly something with fixed gear for your first 1000 flights, each time
dutifully reciting something unnecessary like "UNDERCARRIAGE" and each time
DOING NOTHING but just skipping on to the next item, then when you finally get
in something with retractable gear, you are liable to do the same thing you have
always done and land gear up as a result. I believe that checklists should be
ideally posted in the cockpit and should be made specific to each aircraft so
that each step on the list has real meaning each and every time.

Vaughn

Paul Hanson

June 29th 07, 11:56 PM

At 19:24 29 June 2007, Brtlmj wrote:
>> > structurally damage a glider during a winch launch
>>>from overspeeding.
>> > Providing the correct weak is used, that is not possible.
>>>Old myths
>> > die hard though.
>> Why, then, is the winch launch maximum speed not Vne?
>
>If I understand it correctly, flying at maximum winch
>speed or below
>ensures that you won't lose your wings even if you
>use a wrong weak
>link or no weak link at all.
>
>Bartek
>
VNE in free air is determined by the amount of lift
a wing can generate vs. it's load strength; ie the
wings can only generate as much lift as the spar/structure
can safely handle.--During a winch launch there is
significantly more stress for a given airspeed due
to the downward force being applied to it by the winch
pulling it, counteracting some the lift the wings are
generating. The wings generate the same amount of lift
at any given airspeed, whether on or off the cable,
but while it is attached to the cable a lot more of
the force is being directed into the airframe, since
the hook/cable is keeping it from being able to zoom
in it's normal path physics would otherwise dictate,
were it not attached at that speed; and naturally the
forces increase with increases in speed.
I have a novel idea--how about a new thread about winching,
so this one can remain on the subject: New Trainer
from SZD Bielsko. I personally ca not wait to fly one
of these beautiful new aircraft. I think it is about
time that an alternative to the K-21, 1000, Duo, and
Fox be available. It seems like it will make a great
trainer for XC, acro, or maybe even beginners that
show aptitude. All this and for much less money than
the other options (OK, priced similar to the Fox, but
the Fox is not really an XC ship). Not knocking any
of the other ships, they all have their ups and downs.
I still say hats off to SZD!!

Paul Hanson
"Do the usual, unusually well"--Len Niemi

Martin Gregorie[_1_]

June 30th 07, 08:00 PM

Paul Hanson wrote:
> VNE in free air is determined by the amount of lift
> a wing can generate vs. it's load strength; ie the
> wings can only generate as much lift as the spar/structure
> can safely handle.
>
With respect, this is entirely wrong. In straight free flight the wings
generate exactly enough life to counter the weight of the airframe and
its contents. If the wings generate more lift than that the aircraft
will loop: if they generate less its called a "stall".

I suspect that Vne is more often determined by the torsional resistance
of the wing. That's certainly the case for an ASW-20.

>--During a winch launch there is
> significantly more stress for a given airspeed.
>
Correct. The minimum amount of lift needed must counter the weight of
the airframe and contents plus the weight of the cable plus the vertical
component of the tension in the cable.

The upper maximum amount of lift is the point at which the wings fail in
bending unless other factors such as elevator power or the wing's
accelerated stalling performance intervene to set a lower limit.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Martin Gregorie[_1_]

June 30th 07, 08:13 PM

Vaughn Simon wrote:
> "Martin Gregorie" > wrote in message
> ...
>> Sally W wrote:
>> I see no reason to deviate from the standard CBSIFTCBE checklist,
>> so "Flaps: not fitted" accompanied by a glance to see that there
>> is indeed no flap handle is part of my checklist for a non-flapped
>> glider.
>>
>> This has the benefit of keeping instructors happy on check rides
>> without straining my brain to remember what checklist is expected as compared
>> with what I might do or say when no instructor is present.
>
> Perhaps it is just the way that my mind works, but I have to respectfully
> disagree.
>
> If you fly something with fixed gear for your first 1000 flights, each time
> dutifully reciting something unnecessary like "UNDERCARRIAGE" and each time
> DOING NOTHING but just skipping on to the next item, then when you finally get
> in something with retractable gear, you are liable to do the same thing you have
> always done and land gear up as a result. I believe that checklists should be
> ideally posted in the cockpit and should be made specific to each aircraft so
> that each step on the list has real meaning each and every time.
>
Isn't that a different situation?

I regard it as different because, unlike the pre-landing checks, its
done on the ground and without anything like the same time pressure to
complete it and without competing claims on your attention.

I was never taught a pre-landing checklist for just the reasons you
give. When I was flying an ASW-20 I taught myself to use WUF (Water,
u/c, flaps) as a pre-landing check. Now I have an early Std Libelle (not
B series, so no water) I've reverted to no mnemonic checklist because U
seems a bit silly. In any case the club flying orders now say that the
u/c should be lowered and a radio call made as soon as you decide to
join the circuit, which is much too early for the only other checklist
item (trimming for the approach). A second radio call is made at high
key and trim for landing toward the end of the downwind leg, so there's
really no point when a more formal checklist should be run.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Paul Hanson

June 30th 07, 11:29 PM

At 19:06 30 June 2007, Martin Gregorie wrote:
>Paul Hanson wrote:
>> VNE in free air is determined by the amount of lift
>> a wing can generate vs. it's load strength; ie the
>> wings can only generate as much lift as the spar/structure
>> can safely handle.
> >
>With respect, this is entirely wrong. In straight free
>flight the wings
>generate exactly enough life to counter the weight
>of the airframe and
>its contents. If the wings generate more lift than
>that the aircraft
>will loop: if they generate less its called a 'stall'.
>
>I suspect that Vne is more often determined by the
>torsional resistance
>of the wing. That's certainly the case for an ASW-20.
>

You suspect incorrectly. The faster you fly, the more
lift the wing is generating, until it can no longer
safely bear the bending (compression) loads, or in
some cases I suppose can no longer be countered by
the other flight control surfaces, but certainly not
as a function of parasite drag (especially on a 20).
Perhaps some gliders wings twist (torsional load) a
bit more than others, but most bend upwards more than
they twist. I'm sure this varies with washout as well,
but just watch a high speed finish or any high speed
flying, particularly on a long wing. You can see them
bending upwards (not backwards or twisting) due to
the excessive (excessive in this case meaning more
than is needed to simply offset the glider against
gravity) lift being generated at higher speeds, and
it most certainly increases as a function of speed.

By the very same phenomenon, the outboard wing generates
more lift in turning flight, since the outboard wing
is moving faster through the air--hence the over banking
tendency. This is why when once established in a bank
, it usually requires somewhere between neutral stick
and top aileron to maintain the same bank angle without
increasing (not on all gliders though). Of course while
turning other forces are at play too, like increased
drag creating adverse yaw, diving tendency etc, but
that is a different subject.
I stand by my statement. The wing can only take so
much stress from EXCESS LIFT generated at higher speeds,
and that usually determines a glider's VNE. Other
factors (besides the center of lift usually closely
coinciding with the center of gravity) keeping the
glider form 'looping' at higher speeds are being applied
by other flight control surfaces, like the elevator
for instance. There may be some specific cases where
VNE is determined by the speed at which the other flight
controls are no longer effective enough to counter
the lift the wings generate, but no examples I can
site off hand. The generation of lift is in direct
mathematical relation to the speed of the relative
wind, period.
BTW, a stall only in the simplest sense is from the
wing generating 'not enough lift'. It is from exceeding
the critical angle of attack for any given loading
condition, and can happen at any airspeed, any gross
weight. It happens when the airflow over the wing becomes
too turbulent to provide the needed aerodynamic reaction
to offset it's current load requirement, any angle,
any speed.

Paul Hanson
"Do the usual, unusually well"--Len Niemi

Andreas Maurer[_1_]

July 1st 07, 12:37 AM

On 29 Jun 2007 22:56:02 GMT, Paul Hanson
> wrote:

>VNE in free air is determined by the amount of lift
>a wing can generate vs. it's load strength; ie the
>wings can only generate as much lift as the spar/structure
>can safely handle.

Close, but no cigar... ;)

The above is basically the definition of Va (maneuver speed).

Bye
Andreas

brtlmj

July 1st 07, 02:21 AM

> >I suspect that Vne is more often determined by the
> >torsional resistance
> >of the wing. That's certainly the case for an ASW-20.
> You suspect incorrectly. The faster you fly, the more
> lift the wing is generating,

...._at_a_constant_angle_of_attack_. Fortunately, we have this nice
device called "elevator" and can change angle of attack.

Vne is limited by flutter speed. I am not entirely sure, but I think
there is strict dependence between Vne and the theoretical speed when
flutter should occur.

Bartek

Paul Hanson

July 1st 07, 02:56 AM

At 01:24 01 July 2007, Brtlmj wrote:
>> >I suspect that Vne is more often determined by the
>> >torsional resistance
>> >of the wing. That's certainly the case for an ASW-20.
>> You suspect incorrectly. The faster you fly, the more
>> lift the wing is generating,
>
>...._at_a_constant_angle_of_attack_. Fortunately, we
>have this nice
>device called 'elevator' and can change angle of attack.
>
Ahh yes, the elevator. so thats what thats for :-)
You CAN stall an aircraft at any angle of attack though,
it is a matter of exceeding the CRITICAL AOA, which
can happen at any speed, AOA, or load condition. Like
an accelerated stall for entry of snap maneuvers for
instance. This occurs at much higher than normal stall
speed, by intentionally exceeding the critical AOA,
meaning the AOA in which creates too much turbulence
on the top of the wing to keep it from stalling. Add
full rudder next and whala, you just did a snap roll,
great fun BTW.

>Vne is limited by flutter speed. I am not entirely
>sure, but I think
>there is strict dependence between Vne and the theoretical
>speed when
>flutter should occur.
>
>Bartek
>
With this statement you are correct for some gliders,
but not all. The same goes for the aerodynamic loading
I have been hammering on, for too long now--some gliders
but not all. VNE is usually based on aerodynamic loading,
and if well designed, flutter should not occur until
much higher speeds than that. Not always the case though.

Paul Hanson
"Do the usual, unusually well"--Len Niemi

Paul Hanson

July 1st 07, 02:57 AM

At 23:42 30 June 2007, Andreas Maurer wrote:
>On 29 Jun 2007 22:56:02 GMT, Paul Hanson
> wrote:
>
>
>>VNE in free air is determined by the amount of lift
>>a wing can generate vs. it's load strength; ie the
>>wings can only generate as much lift as the spar/structure
>>can safely handle.
>
>Close, but no cigar... ;)
>
>The above is basically the definition of Va (maneuver
>speed).
>
>
>Bye
>Andreas

Not at all, my rough explanation of deriving VNE is
correct (but possibly not complete) for straight and
level flight, at sea level, in free air. BTW, by 'Safely
handle' I mean with a safety factor of 1.5 of course.
Va on the other hand, is the maximum speed at which
you can fly and still make abrupt and full control
deflections without overloading any part of the airframe
and is primarily associated with imposing G-loads as
opposed to imposing aerodynamic loads, again at sea
level with a safety margin of 1.5. This means the wings
are still generating little enough lift at Va that
you can make a full abrupt elevator pull back and still
not overload them with the additional G's you will
pull. If flying at VNE on the other hand, you are
right at at 1.5 times below the actual load limit,
but this being aerodynamically imposed as a function
of lift generation. At these speeds a strong gust has
the potential provide the overload (I think it has
to be stronger than 15 m/s for JAR 22, but I am not
positive), and a full abrupt pull back on the stick
would most certainly snap any ordinary wings due to
adding the G-loads to the inherent aerodynamic loads
already being imposed on the wings, from increased
lift being generated at those speeds.
There is more to this equation though, although is
not generally often considered to apply towards sailplanes
(but has definitely come into play in the past) due
to the average altitude bands we normally operate in.
It comes with increasing in altitude. The higher you
go, the lower your VNE (IAS) gets, although not due
to increased aerodynamic loads ( again meaning increased
lift generation), but rather due to G-load considerations
due to increased TAS. As you get higher in altitude
the air thins and your TAS vs IAS is increasing, and
TAS is responsible for imposing G-loads due to control
inputs, as it represents your true velocity. VNE (IAS)
and Va (TAS) eventually cross each other in whic case
you should stick with the lower figure to fly safely,
and if you go high enough, VNE (TAS) and stall speed
(always a function of IAS) cross each other. That's
called the 'Coffin Corner'.

Back to the point though, and from a different angle,
if lift does not increase as a function of speed, why
then do you need to fly faster when flying wet, or
turning, or with passengers? Increasing the load increases
the minimum lift requirements, meaning stall speed
increases, no? The extra lift needed is generated by
flying faster, no? This increase in lift generation
continues on up throughout the speed range, until you
achieve catastrophic failure, usually from generating
more lift than the spar/structure can endure, since
the wing roots are attached at the fuse and can not
continue to rise as the tips can while the speed increases.
Again, this is why the wings bend up higher, the faster
you fly. This is really pronounced on open class ships
with flexible wings. You can only bend the wings so
far...

You can still keep the cigar though ;-), although I
do miss them a bit since I quit smoking.

Paul Hanson

"Do the usual, unusually well"--Len Niemi

brtlmj

July 1st 07, 03:47 AM

> Ahh yes, the elevator. so thats what thats for :-)
> You CAN stall an aircraft at any angle of attack though,

A given airfoil stalls at constant AOA, regardless of airspeed. You
can't stall at smaller AOA. Or did you mean to say "at any speed"?

> I have been hammering on, for too long now--some gliders
> but not all. VNE is usually based on aerodynamic loading,

Do you really think that when you fly at 100 knots, straight and
level, your wings produce four times more lift than when You fly at 50
knots, straight and level?

Bartek

Bob Whelan

July 1st 07, 06:07 AM

Paul Hanson wrote:
> At 19:06 30 June 2007, Martin Gregorie wrote:
>
>>Paul Hanson wrote:
>>
>>>VNE in free air is determined by the amount of lift
>>>a wing can generate vs. it's load strength; ie the
>>>wings can only generate as much lift as the spar/structure
>>>can safely handle.
>>>
>>
>>With respect, this is entirely wrong. In straight free
>>flight the wings
>>generate exactly enough life to counter the weight
>>of the airframe and
>>its contents. If the wings generate more lift than
>>that the aircraft
>>will loop: if they generate less its called a 'stall'.
>>
>>I suspect that Vne is more often determined by the
>>torsional resistance
>>of the wing. That's certainly the case for an ASW-20.
>>
>
>
> You suspect incorrectly. The faster you fly, the more
> lift the wing is generating,
<stuff snipped...>

"Not quite."

Writing as a non-practicing aerospace engineer (that's what they called
aeronautical engineering in the 1960's in the U.S.), a dormant teacher
gene compels me to comment. I'd have written "Agreed," IF the words
"capable of" were inserted between "is" and "generating."

As has been pointed out, in steady state flight, pure speed has
esentially zero to do with the amount of lift a wing generates. It
generates an amount essentially equal to the glider's weight *if in
steady state flight*! Why no excess? That pesky elevator, which allows
the whole flying system to reduce the main wing's angle of attack (AOA),
in conjunction with an increasingly descending flight path. Not unless
a gust, or elevator use changes AOA will momentarily excess lift appear
(or, disappear).
- - - - - -

> but just watch a high speed finish or any high speed
> flying, particularly on a long wing. You can see them
> bending upwards (not backwards or twisting) due to
> the excessive (excessive in this case meaning more
> than is needed to simply offset the glider against
> gravity) lift being generated at higher speeds, and
> it most certainly increases as a function of speed.
>
"It" (i.e. lift) does not directly increase as a function of speed.
(Just the *capability* of momentarily creating it does.) Considering
steady state high speed finishes of long wing birds (for the sake of
discussion...note that these principles hold true for any wing, with or
without flaps or spoilers), given the likelihood (either aerodynamic or
geometrical) washout does exist, the lift distribution DOES change for a
fixed trailing edge configuration with reduced/changing AOA (imagine
reducing it to the point of inverted flight). Decambering the trailing
edge with negative flap will of course further affect lift distribution.
The presence of wing bending may be due merely to the normal
(washout-affected) lift distribution of high speed flight, or it could
be increased by spoiler use or the presence of aft stick, but it is
incorrect to conclude it is entirely due to "excess lift due to speed."
So long as Joe Pilot does not create (or encounter a gust that
creates) excess lift, in what used to be steady state flight, note that:
Speed alone will NOT overstress the wing in bending.
- - - - - -

<more snips>
> I stand by my statement. The wing can only take so
> much stress from EXCESS LIFT generated at higher speeds,
Agreed, as stated. But see below...

> and that usually determines a glider's VNE.

Um...unless I was the designer, I'd be loath to be so dogmatic.
Especially when enthusiastic elevator use above maneuvering speed
definitionally implies capability to generate lift generating G
exceeding design factors (which may or may not be the spar, incidentally).
- - - - - -

Other
> factors (besides the center of lift usually closely
> coinciding with the center of gravity) keeping the
> glider form 'looping' at higher speeds are being applied
> by other flight control surfaces, like the elevator
> for instance. There may be some specific cases where
> VNE is determined by the speed at which the other flight
> controls are no longer effective enough to counter
> the lift the wings generate, but no examples I can
> site off hand. The generation of lift is in direct
> mathematical relation to the speed of the relative
> wind, period.
Um...With respect to the last sentence, I could have sworn AOA enters
the picture somewhere. An equation for a symmetrical airfoil comes to
mind...

CL = Lift/(0.5*air density*free stream velocity[squared]* wing area

For a wing SECTION (beloved of mathematical types), replace wing area
with wing chord, and (as way too many college teachers told me) "It can
be shown that" the section lift coefficient of a thin, low-speed,
symmetrical airfoil solves to 2*pi*AOA. Camber (which gliders obviously
have), changes the *location* of a lift curve when plotted vs. AOA
graph, but not the linear relationship with AOA.

So, "Agreed," speed has a BIG impact on (potential) lift for any given
airframe/glider. That pesky velocity squared term.

But it isn't speed that directly affects lift, rather it is AOA. This
(obviously!) isn't obvious, but further research and thought should
clarify things for you. The way I think of it is speed *depends* on
AOA, as does the potential for "excess lift." But (always assuming
steady state flight for ease of our thought experiment) speed by itself
is NOT the driver of things, it's merely along for the AOA ride.
_ _ _ _ _ _

> BTW, a stall only in the simplest sense is from the
> wing generating 'not enough lift'. It is from exceeding
> the critical angle of attack for any given loading
> condition,
Agreed.
and can happen at any airspeed, any gross
> weight.
Agreed, despite what Tom Knauff semantically preaches (for
understandable if arguable reasons).
It happens when the airflow over the wing becomes
> too turbulent to provide the needed aerodynamic reaction
> to offset it's current load requirement, any angle,
> any speed.

Discussion of the 3rd sentence of this paragraph is probably better left
for a real conversation. I'd need to hear more to decide if I agreed or
not. I've never heard, or thought, of the degree of turbulence being a
factor in where definitional stall separation occurs. (Let's ignore
laminar airfoils during our thought experiments.)
>
> Paul Hanson
> "Do the usual, unusually well"--Len Niemi

Len Niemi (whom I never met) was one of my heroes.

Regards,
Bob - pedantically apologetic - W.

Ian

July 1st 07, 06:42 AM

On 1 Jul, 02:56, Paul Hanson
> wrote:

> Ahh yes, the elevator. so thats what thats for :-)
> You CAN stall an aircraft at any angle of attack though,

I find that very hard to believe.

> it is a matter of exceeding the CRITICAL AOA, which
> can happen at any speed, AOA, or load condition.

Care to expand on that a bit? Given that most wings stall at an AOA of
about 18 degrees, how would you go about getting one to stall at, say,
5 degrees?

Ian

Paul Hanson

July 1st 07, 08:35 AM

At 05:12 01 July 2007, Bob Whelan wrote:
>Paul Hanson wrote:
>> At 19:06 30 June 2007, Martin Gregorie wrote:
>>
>>>Paul Hanson wrote:
>>>
>>>>VNE in free air is determined by the amount of lift
>>>>a wing can generate vs. it's load strength; ie the
>>>>wings can only generate as much lift as the spar/structure
>>>>can safely handle.
>>>>
>>>
>>>With respect, this is entirely wrong. In straight free
>>>flight the wings
>>>generate exactly enough life to counter the weight
>>>of the airframe and
>>>its contents. If the wings generate more lift than
>>>that the aircraft
>>>will loop: if they generate less its called a 'stall'.
>>>
>>>I suspect that Vne is more often determined by the
>>>torsional resistance
>>>of the wing. That's certainly the case for an ASW-20.
>>>
>>
>>
>> You suspect incorrectly. The faster you fly, the more
>> lift the wing is generating,
>
>
>'Not quite.'
>
>Writing as a non-practicing aerospace engineer (that's
>what they called
>aeronautical engineering in the 1960's in the U.S.),
>a dormant teacher
>gene compels me to comment. I'd have written 'Agreed,'
>IF the words
>'capable of' were inserted between 'is' and 'generating.'
>
>As has been pointed out, in steady state flight, pure
>speed has
>esentially zero to do with the amount of lift a wing
>generates. It
>generates an amount essentially equal to the glider's
>weight *if in
>steady state flight*! Why no excess? That pesky elevator,
>which allows
>the whole flying system to reduce the main wing's angle
>of attack (AOA),
>in conjunction with an increasingly descending flight
>path. Not unless
>a gust, or elevator use changes AOA will momentarily
>excess lift appear
>(or, disappear).
>- - - - - -
>
>> but just watch a high speed finish or any high speed
>> flying, particularly on a long wing. You can see them
>> bending upwards (not backwards or twisting) due to
>> the excessive (excessive in this case meaning more
>> than is needed to simply offset the glider against
>> gravity) lift being generated at higher speeds, and
>> it most certainly increases as a function of speed.
>>
>'It' (i.e. lift) does not directly increase as a function
>of speed.
>(Just the *capability* of momentarily creating it does.)
> Considering
>steady state high speed finishes of long wing birds
>(for the sake of
>discussion...note that these principles hold true for
>any wing, with or
>without flaps or spoilers), given the likelihood (either
>aerodynamic or
>geometrical) washout does exist, the lift distribution
>DOES change for a
>fixed trailing edge configuration with reduced/changing
>AOA (imagine
>reducing it to the point of inverted flight). Decambering
>the trailing
>edge with negative flap will of course further affect
>lift distribution.
> The presence of wing bending may be due merely to
>the normal
>(washout-affected) lift distribution of high speed
>flight, or it could
>be increased by spoiler use or the presence of aft
>stick, but it is
>incorrect to conclude it is entirely due to 'excess
>lift due to speed.'
> So long as Joe Pilot does not create (or encounter
>a gust that
>creates) excess lift, in what used to be steady state
>flight, note that:
>Speed alone will NOT overstress the wing in bending.
>- - - - - -
>
>
>> I stand by my statement. The wing can only take so
>> much stress from EXCESS LIFT generated at higher speeds,
>Agreed, as stated. But see below...
>
>> and that usually determines a glider's VNE.
>
>Um...unless I was the designer, I'd be loath to be
>so dogmatic.
>Especially when enthusiastic elevator use above maneuvering
>speed
>definitionally implies capability to generate lift
>generating G
>exceeding design factors (which may or may not be the
>spar, incidentally).
>- - - - - -
>
> Other
>> factors (besides the center of lift usually closely
>> coinciding with the center of gravity) keeping the
>> glider form 'looping' at higher speeds are being applied
>> by other flight control surfaces, like the elevator
>> for instance. There may be some specific cases where
>> VNE is determined by the speed at which the other
>>flight
>> controls are no longer effective enough to counter
>> the lift the wings generate, but no examples I can
>> site off hand. The generation of lift is in direct
>> mathematical relation to the speed of the relative
>> wind, period.
>Um...With respect to the last sentence, I could have
>sworn AOA enters
>the picture somewhere. An equation for a symmetrical
>airfoil comes to
>mind...
>
>CL = Lift/(0.5*air density*free stream velocity[squared]*
>wing area
>
>For a wing SECTION (beloved of mathematical types),
>replace wing area
>with wing chord, and (as way too many college teachers
>told me) 'It can
>be shown that' the section lift coefficient of a thin,
>low-speed,
>symmetrical airfoil solves to 2*pi*AOA. Camber (which
>gliders obviously
>have), changes the *location* of a lift curve when
>plotted vs. AOA
>graph, but not the linear relationship with AOA.
>
>So, 'Agreed,' speed has a BIG impact on (potential)
>lift for any given
>airframe/glider. That pesky velocity squared term.
>
>But it isn't speed that directly affects lift, rather
>it is AOA. This
>(obviously!) isn't obvious, but further research and
>thought should
>clarify things for you. The way I think of it is speed
>*depends* on
>AOA, as does the potential for 'excess lift.' But
>(always assuming
>steady state flight for ease of our thought experiment)
>speed by itself
>is NOT the driver of things, it's merely along for
>the AOA ride.
>_ _ _ _ _ _
>
>
>> BTW, a stall only in the simplest sense is from the
>> wing generating 'not enough lift'. It is from exceeding
>> the critical angle of attack for any given loading
>> condition,
>Agreed.
> and can happen at any airspeed, any gross
>> weight.
>Agreed, despite what Tom Knauff semantically preaches
>(for
>understandable if arguable reasons).
> It happens when the airflow over the wing becomes
>> too turbulent to provide the needed aerodynamic reaction
>> to offset it's current load requirement, any angle,
>> any speed.
>
>Discussion of the 3rd sentence of this paragraph is
>probably better left
>for a real conversation. I'd need to hear more to
>decide if I agreed or
>not. I've never heard, or thought, of the degree of
>turbulence being a
>factor in where definitional stall separation occurs.
> (Let's ignore
>laminar airfoils during our thought experiments.)
>>
>> Paul Hanson
>> 'Do the usual, unusually well'--Len Niemi
>
>Len Niemi (whom I never met) was one of my heroes.
>
>Regards,
>Bob - pedantically apologetic - W.
>
Thanks Bob, it is nice to be corrected with correct
information. It all makes sense now (for the moment...),
and I will now use this new and corrected view on the
subject to get back to a point from earlier. VNE is
more often determined by the speed at which the aerodynamic
loads are too great for the spar/structure to handle
(most gliders), but not due to 'excess lift'. Rather
is it due to the bending loads being imposed on the
spars/structure (or elsewhere in the airframe of course)
by the downward force from the elevator conflicting
with the lift the wings are generating, and THAT load
increases as a function of speed due to the additional
downward elevator forces required to bring this mode
about, while the lift the wings generate remains basically
constant (steady state of course). Additionally, increasing
the angle of attack at high speeds WILL most certainly
affect the generation of lift, which also comes into
play for VNE considerations due to increased loading
from lift potential being converted into lift kinetic,
during these transitions.
Being a Sisu driver, I too am am a big Niemi fan, but
also was not fortunate enough to meet him before he
left us. Bummer he wasn't inducted into the Hall of
Fame sooner...

PS. Love your books, will you be at Albuquerque to
scribe in them?

Paul Hanson
"Do the usual, unusually well"--Len Niemi

Bob Whelan

July 1st 07, 06:23 PM

Paul Hanson wrote:

<A bunch of intervening stuff snipped...>
> Thanks Bob, it is nice to be corrected with correct
> information. It all makes sense now (for the moment...),
I consider that an encouraging qualification there! This stuff is worth
thinking about if it interests a person, both because it's
fun/satisfying to learn stuff, and, because the knowledge may keep a
person alive longer when they're flying near the margins of a plane's
envelope (be those margins structural or aerodynamic [e.g. flutter]).

> and I will now use this new and corrected view on the
> subject to get back to a point from earlier. VNE is
> more often determined by the speed at which the aerodynamic
> loads are too great for the spar/structure to handle
> (most gliders), but not due to 'excess lift'. Rather
> is it due to the bending loads being imposed on the
> spars/structure (or elsewhere in the airframe of course)
> by the downward force from the elevator conflicting
> with the lift the wings are generating, and THAT load
> increases as a function of speed due to the additional
> downward elevator forces required to bring this mode
> about, while the lift the wings generate remains basically
> constant (steady state of course). Additionally, increasing
> the angle of attack at high speeds WILL most certainly
> affect the generation of lift, which also comes into
> play for VNE considerations due to increased loading
> from lift potential being converted into lift kinetic,
> during these transitions.
I think what you write here is exactly correct for most airframes
available to the GA pilot. Where uncertainty enters the picture in my
mind is in knowing the weak link on any given ship (impossible to know
without access to the designer's calculations, or, accident data...more
than a few earlier-production-run V-tailed Bonanza tails were ripped off
due to excessive downloads at higher speeds after 'continued VFR flight
into IMC conditions').

Another category of ship where what you write likely isn't true is the
first generation of 'pure fiberglass' gliders (as distinct from those
with carbon spar caps/skins, etc.). VNE on some (all?) of those ships
is more likely set by aerodynamic/flutter, or perhaps, control-run
mounting considerations than primary structure limitations. As a
general rule of thumb, glider spars absent carbon reinforcement are
'overstrong' in comparison to (say) metal glider spars, or (probably)
carbon-fiber-reinforced spars of a ship of equal span. As I recall,
ASW-12 spars were tested to at least 12 (20?) G without failure,
possibly the Open Cirrus, as well. Understandably, German bureaucracy
was cautious certifying fiberglass technology when it upset the
sailplane applecart in the 50's and 60's; they were almost undoubtedly
reinforced in their conservatism by the sad loss of Bjorn Stender in his
prototype BS-1 (which E. Hanle/Glasflugel re-engineered prior to
ultimately producing).

Perhaps someone (Bert Willing?) could shed more light on more current
sailplane spar structural testing now required by the LBA.

> Being a Sisu driver, I too am am a big Niemi fan, but
> also was not fortunate enough to meet him before he
> left us. Bummer he wasn't inducted into the Hall of
> Fame sooner...

"Roger that!"

>
> PS. Love your books,
All feedback appreciated...some more than others! I'm gratified your
reading time wasn't wasted.

will you be at Albuquerque to
> scribe in them?
I'd like to waste the rest of my youth perpetually bumming around the
glider world, but reality too often intrudes. It's too early to tell
about Albuquerque, but I'd *like* to attend...

>
> Paul Hanson
> "Do the usual, unusually well"--Len Niemi
>
>

Regards,
Bob W.

Chris Reed[_1_]

July 2nd 07, 10:41 AM

Bob Whelan wrote:
<large snip>

> Another category of ship where what you write likely isn't true is the
> first generation of 'pure fiberglass' gliders (as distinct from those
> with carbon spar caps/skins, etc.). VNE on some (all?) of those ships
> is more likely set by aerodynamic/flutter, or perhaps, control-run
> mounting considerations than primary structure limitations. As a
> general rule of thumb, glider spars absent carbon reinforcement are
> 'overstrong' in comparison to (say) metal glider spars, or (probably)
> carbon-fiber-reinforced spars of a ship of equal span. As I recall,
> ASW-12 spars were tested to at least 12 (20?) G without failure,
> possibly the Open Cirrus, as well. Understandably, German bureaucracy
> was cautious certifying fiberglass technology when it upset the
> sailplane applecart in the 50's and 60's; they were almost undoubtedly
> reinforced in their conservatism by the sad loss of Bjorn Stender in his
> prototype BS-1 (which E. Hanle/Glasflugel re-engineered prior to
> ultimately producing).

I've read that the Open Cirrus spar was tested to 15g (after which they
gave up, having failed to break it). When I rig mine I can believe this,
as the spars are as solid as a K21's.

Vne for the Open Cirrus was set on the basis of flutter, as you write
above. A damper (from a VW Variant/Squareback) was added to the rudder
circuit, following high speed flutter in some early competitions. I
believe the pilots were exceeding Vne and the damper may be unnecessary,
but I'd hate to find out the contrary - thus my damper was replaced
recently.

Ian

July 2nd 07, 12:59 PM

On 1 Jul, 08:35, Paul Hanson
> wrote:

> Rather
> is it due to the bending loads being imposed on the
> spars/structure (or elsewhere in the airframe of course)
> by the downward force from the elevator conflicting
> with the lift the wings are generating, and THAT load
> increases as a function of speed due to the additional
> downward elevator forces required to bring this mode
> about, while the lift the wings generate remains basically
> constant (steady state of course).

If the downforce on the tail has increased, and you're in a steady
state, then the upforce on the wing must also have increased to
balance it.

Ian

Frank Whiteley

July 2nd 07, 03:05 PM

On Jul 2, 3:41 am, Chris Reed > wrote:
> Bob Whelan wrote:
>
> <large snip>
>
> > Another category of ship where what you write likely isn't true is the
> > first generation of 'pure fiberglass' gliders (as distinct from those
> > with carbon spar caps/skins, etc.). VNE on some (all?) of those ships
> > is more likely set by aerodynamic/flutter, or perhaps, control-run
> > mounting considerations than primary structure limitations. As a
> > general rule of thumb, glider spars absent carbon reinforcement are
> > 'overstrong' in comparison to (say) metal glider spars, or (probably)
> > carbon-fiber-reinforced spars of a ship of equal span. As I recall,
> > ASW-12 spars were tested to at least 12 (20?) G without failure,
> > possibly the Open Cirrus, as well. Understandably, German bureaucracy
> > was cautious certifying fiberglass technology when it upset the
> > sailplane applecart in the 50's and 60's; they were almost undoubtedly
> > reinforced in their conservatism by the sad loss of Bjorn Stender in his
> > prototype BS-1 (which E. Hanle/Glasflugel re-engineered prior to
> > ultimately producing).
>
> I've read that the Open Cirrus spar was tested to 15g (after which they
> gave up, having failed to break it). When I rig mine I can believe this,
> as the spars are as solid as a K21's.
>
> VNe for the Open Cirrus was set on the basis of flutter, as you write
> above. A damper (from a VW Variant/Squareback) was added to the rudder
> circuit, following high speed flutter in some early competitions. I
> believe the pilots were exceeding Vne and the damper may be unnecessary,
> but I'd hate to find out the contrary - thus my damper was replaced
> recently.

My Open Cirrus didn't have the damper under after I sold it.
Inspectors never picked up on it until some major work was done.
Never a hint of flutter. I only got it 'really' fast once as it was
unnecessary in the UK.

IIRC, VNe was something like 15% under the flutter speed for that
generation of gliders. I've read it was common for competition pilots
to go through the gate at VNe+15%. I believe later glider design uses
6000m for an optimized altitude. Spar placement to accommodate
ballast and allow wider load ranges resulted in the true airspeed
tables for reducing VNe at altitude to prevent the onset of the
elastic mode of flutter as the center of pressure changed. Stiffening
against this would add weight and expense for the few that want to fly
faster a high altitudes. There was an OSTIV presentation on this
several years ago published in Technical Soaring. Several RAS threads
http://tinyurl.com/26nbu2

Frank Whiteley

Michael Ash

July 2nd 07, 03:44 PM

Ian > wrote:
> On 1 Jul, 08:35, Paul Hanson
> > wrote:
>
>> Rather
>> is it due to the bending loads being imposed on the
>> spars/structure (or elsewhere in the airframe of course)
>> by the downward force from the elevator conflicting
>> with the lift the wings are generating, and THAT load
>> increases as a function of speed due to the additional
>> downward elevator forces required to bring this mode
>> about, while the lift the wings generate remains basically
>> constant (steady state of course).
>
> If the downforce on the tail has increased, and you're in a steady
> state, then the upforce on the wing must also have increased to
> balance it.

If you're in a steady state, then the forces on all the surfaces will be
the same.

Your proposed balance doesn't work out because the wing and the elevator
aren't in the same horizontal position. An increased downforce on the tail
and upforce on the wing creates a twisting motion, which will raise the
nose.

As you go faster, the angle of attack needed to generate the required
amount of lift decreases, so the relative wind comes from a higher and
higher angle. This gives you a lower AoA on the wing, and also on the
elevator, which requires you to push the stick forward to compensate. But
the end result is the same vertical forces on the wing and elevator at all
speeds.

--
Michael Ash
Rogue Amoeba Software

Ian

July 2nd 07, 06:03 PM

On 2 Jul, 15:44, Michael Ash > wrote:
> Ian > wrote:

> > If the downforce on the tail has increased, and you're in a steady
> > state, then the upforce on the wing must also have increased to
> > balance it.
>
> If you're in a steady state, then the forces on all the surfaces will be
> the same.

Almost. Both the forces and the moments will sum to zero, so there are
six equilibrium conditions to satisfy. The force on the wing isn't
equal to teh force on the tail, since they have (jointly) to balance
gravity as well.

> Your proposed balance doesn't work out because the wing and the elevator
> aren't in the same horizontal position. An increased downforce on the tail
> and upforce on the wing creates a twisting motion, which will raise the
> nose.

Ah. Do you know why a downforce on the tail is needed for a dive?

> But
> the end result is the same vertical forces on the wing and elevator at all
> speeds.

Have you ever compared the size of wing and tailplane fittings?

Ian

Michael Ash

July 2nd 07, 07:20 PM

Ian > wrote:
> On 2 Jul, 15:44, Michael Ash > wrote:
>> Ian > wrote:
>
>> > If the downforce on the tail has increased, and you're in a steady
>> > state, then the upforce on the wing must also have increased to
>> > balance it.
>>
>> If you're in a steady state, then the forces on all the surfaces will be
>> the same.
>
> Almost. Both the forces and the moments will sum to zero, so there are
> six equilibrium conditions to satisfy. The force on the wing isn't
> equal to teh force on the tail, since they have (jointly) to balance
> gravity as well.

My apologies, my wording was ambiguous. What I meant was that the net
(vertical) force on the wing at 50kts is the same as at 100kts, and the
net (vertical) force on the elevator at 50kts is the same as at 100kts. I
didn't mean to imply that the force on the elevator was the same as the
force on the wing, but I can see how it would read that way.

>> Your proposed balance doesn't work out because the wing and the elevator
>> aren't in the same horizontal position. An increased downforce on the tail
>> and upforce on the wing creates a twisting motion, which will raise the
>> nose.
>
> Ah. Do you know why a downforce on the tail is needed for a dive?

I'm not sure which downforce you're referring to here. If you mean the
need to keep the stick forward, that's to compensate for the changed angle
of attack on the elevator.

>> But
>> the end result is the same vertical forces on the wing and elevator at all
>> speeds.
>
> Have you ever compared the size of wing and tailplane fittings?

Presumably the same misunderstanding as above.

I should note that my background in all of this is just a couple of
semesters of college physics combined with not a whole lot of flying
experience and some inquisitiveness.

--
Michael Ash
Rogue Amoeba Software

Ian

July 2nd 07, 07:49 PM

On 2 Jul, 19:20, Michael Ash > wrote:
> Ian > wrote:

> > Almost. Both the forces and the moments will sum to zero, so there are
> > six equilibrium conditions to satisfy. The force on the wing isn't
> > equal to teh force on the tail, since they have (jointly) to balance
> > gravity as well.
>
> My apologies, my wording was ambiguous. What I meant was that the net
> (vertical) force on the wing at 50kts is the same as at 100kts, and the
> net (vertical) force on the elevator at 50kts is the same as at 100kts. I
> didn't mean to imply that the force on the elevator was the same as the
> force on the wing, but I can see how it would read that way.

OK. However, you are still mistaken, I fear. In general, the downwards
force on the tail increases with speed, so the upwards force on the
wing increases to keep the weight balanced.

> > Ah. Do you know why a downforce on the tail is needed for a dive?
>
> I'm not sure which downforce you're referring to here. If you mean the
> need to keep the stick forward, that's to compensate for the changed angle
> of attack on the elevator.

Just because the glider is diving doesn't mean there's a changed angle
of attack.

What you're forgetting - or perhaps what nobody told you - is that
it's the motion of the centre of pressure which really matters.
Basically, as the AOA increases the net lift force on the wing appears
to move forwards, and as the AOA decreases it moves back.

This is unstable, since - all other things being equal: nose up ->
increased AOA -> cop moves forwards -> nose up moment -> nose up. So
what you do is stick a tail on the back. Now nose up -> positive AOA
on tail -> lift at tail and, if you get the sums and moment arms
right, this balances the pitching moment caused by the cop moving
forwards.

Similarly, diving involves a downwards force on the tail. Many people
find this counterintuitive - it seems far more likely that moving the
tail up should mean an upwards force, but it doesn't. Effectively you
are just using the tail to exploit the instability of the wing.
Incidentally, since the elevator goes down for a dive, when the tail
needs to produce a downforce, the tail is always working with camber
in the wrong direction. This is horribly inefficient and explains why
all-flying tailplanes work so well.

> I should note that my background in all of this is just a couple of
> semesters of college physics combined with not a whole lot of flying
> experience and some inquisitiveness.

As you'll have guessed, this is an enthusiasm of mine. I think a lot
of people would fly better, and find it easier, if they understood the
physics better. I include instructors, I'm afraid - hardly any of them
know why you need back stick in a turn, for example.

Ian

PS Lots of simplification in the above!