FAA PTS "Slips to Landing" requirement vs No-spoiler landings

[kirk.stant]

The past few weekends I've been watching some our our club students
being instructed on and practicing slips to a landing (i.e."no spoiler
landings") in preparation for their Private check rides. Gliders used
were our 2-33 and Blanik. I've also seen no-spoiler landings being
demonstrated in our G-103 - some quite nicely judged, I might add!

But I've been wondering about the utility and safety of this practice,
and whether it's taught in other countries - and if so, how it's
taught.

I realize that a no-spoiler approach is always an eventuality, and our
club even had one several years ago in a G-102 that left the glider in
the cornfield off the far end of the field, but it seems to me that
the skill learned in a slipped approach in a 2-33 may not really
transfer to a Discus 2 or other slippery glass ship, and that
conversely, realistic training - slipping all the way to touchdown, no
spoilers allowed - in a glass 2-seater (unless one has the luxury of a
really big field) could be somewhat hazardous.

It kind of reminds me of the old multi-engine requirement to
demonstrate Vmc at low altitudes, which was finally changed when the
authorities realized that they were killing more pilots in training
than in actual engine failures!

On the other hand, I've tried them in glass, including my Ls6 (which
does not recommend slips to a landing), and concluded that they are a
serious emergency that needs to be carefully thought out ahead of
time, and can only be safely practiced by breaking down into two
segments: First, no spoilers, slip to aim for the middle of the
field, then recover and land normally with spoilers as required; and
second, position the glider so as to be approaching the threshold at a
safe speed and altitude, then close spoilers, establish a slip, and
continue with the no-spoiler landing.

Comments? I'm especially interested in hearing how this is handled in
other countries.

Kirk
66

[Andy[_1_]]

On Sep 10, 3:07*pm, "kirk.stant" > wrote:

> Comments? *I'm especially interested in hearing how this is handled in
> other countries.
>
> Kirk
> 66

I remember teaching brakes jammed open and brakes jammed closed in my
brief period of instructing in UK. That was a while ago so don't
know what is required now.

I practice full rudder slips in every glider I fly but usually in
combination with full airbrake. It's amazing how much faster even a
modern glass bird will come down if a full slip is added to full
brakes. I have more than once been very glad I knew how to do it, and
in particular how the airspeed indicator would behave.

Andy

[Mike the Strike]

Both scenarios were part of my training in South Africa. I have never
personally come across a situation where spoilers failed to open,
although I can certainly think of a number of scenarios where this
could happen. I do know of one where the spoiler handle on a Grob 103
broke after they had been deployed and jammed full open, resulting in
an off-field landing.

I was always taught to deploy spoilers close enough to the field that
you could make it if they jammed open and to make a longer circuit
with a moderate slip to landing if they jammed closed.

The Discus 2 slips very nicely - perhaps the double dihedral helps?

Mike

[bildan]

On Sep 10, 5:24*pm, Mike the Strike > wrote:
> Both scenarios were part of my training in South Africa. *I have never
> personally come across a situation where spoilers failed to open,
> although I can certainly think of a number of scenarios where this
> could happen. *I do know of one where the spoiler handle on a Grob 103
> broke after they had been deployed and jammed full open, resulting in
> an off-field landing.
>
> I was always taught to deploy spoilers close enough to the field that
> you could make it if they jammed open and to make a longer circuit
> with a moderate slip to landing if they jammed closed.
>
> The Discus 2 slips very nicely - perhaps the double dihedral helps?
>
> Mike

Several years ago I was checking out a visiting pilot in the Boulder
wave flying a G103 Twin III. The sky was overcast with heavy cirrus
and there were lenticulars and roll clouds. There was a lot of
moisture in the air and 4" snow on the ground. Surface temperatures
were around -4C.

He was doing great so I was just idly looking out the side when I
noticed the rectangle of the spoiler box as it faded away to smooth
white perfectly matching the rest of the wing. Quickly looking around
I saw that in addition to the ice filigree of frozen breath on the
inside of the canopy, there was ice forming on the outside too. Water
vapor in the air was freezing directly on the glider without passing
through a liquid state. We were icing up fast!

Calling this to the attention of the pilot, I asked for his judgment
as to how to deal with clear air icing. Get down! he shouted. Good
thought!

But when we pulled on the spoiler handle, it wouldn't move. They were
literally frozen shut. OK, I thought, now it gets interesting. Gusty
west wind day, a slick, snow covered runway and no spoilers - plus a
thinly frozen over lake at the far end.

Fortunately, as is often the case along the Rocky Mountain foothills
in Winter, there was a warm layer of +3C air between 2000 and 500 feet
AGL. That was enough to thaw the spoilers. I wasn't looking forward
to that landing without spoilers.

Once we stopped rolling in the -4C surface temperature, the spoilers
refroze - this time open. The visiting pilot got a better wave
checkout than either of us intended.

[Eric Greenwell]

bildan wrote:
I wasn't looking forward
> to that landing without spoilers.
>
> Once we stopped rolling in the -4C surface temperature, the spoilers
> refroze - this time open. The visiting pilot got a better wave
> checkout than either of us intended.

It occurs to me that spoilers frozen shut provide two problems for a lot
of gliders: 1) getting the glider down safely on the ground by slipping,
and 2) stopping the glider on the ground without the wheel brake.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[vaughn[_2_]]

"Mike the Strike" > wrote in message
...
> I do know of one where the spoiler handle on a Grob 103
> broke after they had been deployed and jammed full open, resulting in
> an off-field landing.
>
And I know of a case where just one spoiler deployed on a glider. Causes a
nasty uncommanded roll. The only solution (once you figure out what is
going on) is to close the spoilers and proceed without them.

Vaughn

[bildan]

On Sep 10, 8:02*pm, "vaughn" >
wrote:
> "Mike the Strike" > wrote in ...> I do know of one where the spoiler handle on a Grob 103
> > broke after they had been deployed and jammed full open, resulting in
> > an off-field landing.
>
> And I know of a case where just one spoiler deployed on a glider. *Causes a
> nasty uncommanded roll. *The only solution (once you figure out what is
> going on) is to close the spoilers and proceed without them.
>
> Vaughn

Nah, you can do a really cool slip with one spoiler.

[bildan]

On Sep 10, 7:31*pm, Eric Greenwell > wrote:
> bildan wrote:
>
> * *I wasn't looking forward
>
> > to that landing without spoilers.
>
> > Once we stopped rolling in the -4C surface temperature, the spoilers
> > refroze - this time open. *The visiting pilot got a better wave
> > checkout than either of us intended.
>
> It occurs to me that spoilers frozen shut provide two problems for a lot
> of gliders: 1) getting the glider down safely on the ground by slipping,
> and 2) stopping the glider on the ground without the wheel brake.
>
> --
> Eric Greenwell - Washington State, USA
> * Change "netto" to "net" to email me directly
>
> * "Transponders in Sailplanes"http://tinyurl.com/y739x4
> * * * Sections on Mode S, TPAS, ADS-B, Flarm, more
>
> * "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

No kidding!

I had flown IFR in the area for many years and knew to be on the
lookout for a low altitude warm layer. We just flew around at min
sink in the warm air until the ice melted, then entered the landing
pattern.

Someone with less experience might have missed that and rushed to a
spoilerless landing. Good thing Grobs have OAT gauges.

[Bruce]

vaughn wrote:
> "Mike the Strike" > wrote in message
> ...
>> I do know of one where the spoiler handle on a Grob 103
>> broke after they had been deployed and jammed full open, resulting in
>> an off-field landing.
>>
> And I know of a case where just one spoiler deployed on a glider. Causes a
> nasty uncommanded roll. The only solution (once you figure out what is
> going on) is to close the spoilers and proceed without them.
>
> Vaughn
>
>
>
>
>
Single spoiler deployment has caused at least one fatal accident.

If a linkage fails resulting in asymmetric airbrake deployment it is
possible to run out of options very quickly.

My thoughts are that you need to open the brakes to balance the drag and
lift asymmetry. Then you can fly the aircraft through the resulting
descending roll and recover. Depending on your height and speed it may
be quite pressing to land, it may also be quite pressing to reduce speed...
However - if this happens in a high energy state (where else?) you may
already have a lot of yaw and roll inertia by the time you get the other
airbrake open. Especially on a long winged open class ship there may
just not be enough control authority left, and if you are very fast
and/or very close to the ground the options are limited.

To overcome the differential lift caused by the yaw you may need full
rudder.
To limit the speed and avoid terrain you may need large elevator deflection.
To reverse the roll and return to level flight you almost certainly will
need full aileron.

You are unlikely to find such a high G, rolling pull up close to , or
over Vne with airbrakes deployed in the manual.

There is a reason for that "max manoeuvre speed" entry...

A little math says that at 250km/h and 300m (~1000")AGL a 30 degree
descent angle will give you less than 8 seconds to avoid terrain.

[Derek Copeland[_2_]]

I once had one spoiler fully out due to a failure of a diecast aluminium
bracket in a Grob Astir. This broke in flight, with a loud bang as the
left airbrake suddenly sucked open and stayed there. I then found that I
needed almost full right aileron and rudder to conteract the roll and yaw
to the left. I was only about 900ft AGL at the time.

The solution I worked out was to open the the other airbrake, which still
worked, and then make the best more or less straight ahead landing that I
could into a field. I had to sideslip the glider to get in, but walked
away from it and didn't further damage the glider.

BTW, this and another case is why many Grob Astirs have a little perspex
inspection window under the wing, so that you can see the offending
bracket.

Getting back to the original subject, we do teach no airbrake approaches
in the UK as a post solo exercise, just in case the airbrake mechanism
fails, or the brakes freeze shut while wave soaring. I have made a video
of such an exercise, but you float an awfully long way in ground effect,
which is why I eventually told the student to open the brakes, as it was
the last flight of the day and we wanted to stop somewhere near to the
hangar. See:

http://www.youtube.com/watch?v=5t7xnls2w5k

This was done in a K13, which sideslips very nicely and very much more
effectively than most glass gliders. With a lot of slip on, the ASI will
usually totally misread.

Derek Copeland

P.S. I know the Yanks call a sideslip a 'forward slip' before someone
pulls me up on that!


At 02:02 11 September 2009, vaughn wrote:
>
>"Mike the Strike" wrote in message
...
>> I do know of one where the spoiler handle on a Grob 103
>> broke after they had been deployed and jammed full open, resulting in
>> an off-field landing.
>>
>And I know of a case where just one spoiler deployed on a glider.
Causes
>a
>nasty uncommanded roll. The only solution (once you figure out what is
>going on) is to close the spoilers and proceed without them.
>
>Vaughn
>

[[email protected]]

On Sep 10, 6:07*pm, "kirk.stant" > wrote:
> The past few weekends I've been watching some our our club students
> being instructed on and practicing slips to a landing (i.e."no spoiler
> landings") in preparation for their Private check rides. *Gliders used
> were our 2-33 and Blanik. *I've also seen no-spoiler landings being
> demonstrated in our G-103 *- some quite nicely judged, I might add!
>
> But I've been wondering about the utility and safety of this practice,
> and whether it's taught in other countries - and if so, how it's
> taught.
>
> I realize that a no-spoiler approach is always an eventuality, and our
> club even had one several years ago in a G-102 that left the glider in
> the cornfield off the far end of the field, but it seems to me that
> the skill learned in a slipped approach in a 2-33 may not really
> transfer to a Discus 2 or other slippery glass ship, and that
> conversely, realistic training - slipping all the way to touchdown, no
> spoilers allowed - in a glass 2-seater (unless one has the luxury of a
> really big field) could be somewhat hazardous.
>
> It kind of reminds me of the old multi-engine requirement to
> demonstrate Vmc at low altitudes, which was finally changed when the
> authorities realized that they were killing more pilots in training
> than in actual engine failures!
>
> On the other hand, I've tried them in glass, including my Ls6 (which
> does not recommend slips to a landing), and concluded that they are a
> serious emergency that needs to be carefully thought out ahead of
> time, and can only be safely practiced by breaking down into two
> segments: *First, no spoilers, slip to aim for the middle of the
> field, then recover and land normally with spoilers as required; and
> second, position the glider so as to be approaching the threshold at a
> safe speed and altitude, then close spoilers, establish a slip, and
> continue with the no-spoiler landing.
>
> Comments? *I'm especially interested in hearing how this is handled in
> other countries.
>
> Kirk
> 66

Realistic requirement for a number of reasons.
1) It is useful for additional sink rate in many ships- makes my '28
come down much faster.
2) Spoilers do freeze shut - we see it in the Winter in the East.
3) Equipment does fail.
4) It is a useful exercise in aircraft control
5) Folks we are training may fly ships that don't have the really good
dive brakes of the modern ships.
6) It's kinda fun. No spoiler- no brake spot landings are a challange.
FWIW
UH

[vaughn[_2_]]

"Bruce" > wrote in message
...
>
> My thoughts are that you need to open the brakes to balance the drag and
> lift asymmetry. Then you can fly the aircraft through the resulting
> descending roll and recover.

In the case I am talking about, that option was not available. One spoiler
stayed connected to the linkage and fully operable while a broken bracket
had effectively disconnected the other one, leaving it closed. The only was
to return the glider to balance flight was to close the spoilers. (Yes, a
1-spoiler slip may have been possible, but that is a lot to figure out when
you are on downwind and are suddenly presented with a strange control
situation).

Vaughn

[vaughn[_2_]]

"bildan" > wrote in message
...>
wrote:

>Nah, you can do a really cool slip with one spoiler.

That would depend on the glider.

Vaughn

[Maurizio Cocchi]

In Italy we have to practice during instruction the side "wing" slip
landing, for license examination, but the main reason is to be able to
do it but in case you are too high, when you are final in landing and
want to create your final glide even more steep
Maurizio

On Sep 11, 12:07*am, "kirk.stant" > wrote:
> The past few weekends I've been watching some our our club students
> being instructed on and practicing slips to a landing (i.e."no spoiler
> landings") in preparation for their Private check rides. *Gliders used
> were our 2-33 and Blanik. *I've also seen no-spoiler landings being
> demonstrated in our G-103 *- some quite nicely judged, I might add!
>
> But I've been wondering about the utility and safety of this practice,
> and whether it's taught in other countries - and if so, how it's
> taught.
>
> I realize that a no-spoiler approach is always an eventuality, and our
> club even had one several years ago in a G-102 that left the glider in
> the cornfield off the far end of the field, but it seems to me that
> the skill learned in a slipped approach in a 2-33 may not really
> transfer to a Discus 2 or other slippery glass ship, and that
> conversely, realistic training - slipping all the way to touchdown, no
> spoilers allowed - in a glass 2-seater (unless one has the luxury of a
> really big field) could be somewhat hazardous.
>
> It kind of reminds me of the old multi-engine requirement to
> demonstrate Vmc at low altitudes, which was finally changed when the
> authorities realized that they were killing more pilots in training
> than in actual engine failures!
>
> On the other hand, I've tried them in glass, including my Ls6 (which
> does not recommend slips to a landing), and concluded that they are a
> serious emergency that needs to be carefully thought out ahead of
> time, and can only be safely practiced by breaking down into two
> segments: *First, no spoilers, slip to aim for the middle of the
> field, then recover and land normally with spoilers as required; and
> second, position the glider so as to be approaching the threshold at a
> safe speed and altitude, then close spoilers, establish a slip, and
> continue with the no-spoiler landing.
>
> Comments? *I'm especially interested in hearing how this is handled in
> other countries.
>
> Kirk
> 66

[bildan]

On Sep 11, 12:01*am, Bruce > wrote:
> vaughn wrote:
> > "Mike the Strike" > wrote in message
> ....
> >> I do know of one where the spoiler handle on a Grob 103
> >> broke after they had been deployed and jammed full open, resulting in
> >> an off-field landing.
>
> > And I know of a case where just one spoiler deployed on a glider. *Causes a
> > nasty uncommanded roll. *The only solution (once you figure out what is
> > going on) is to close the spoilers and proceed without them.
>
> > Vaughn
>
> Single spoiler deployment has caused at least one fatal accident.
>
> If a linkage fails resulting in asymmetric airbrake deployment it is
> possible to run out of options very quickly.
>
> My thoughts are that you need to open the brakes to balance the drag and
> lift asymmetry. Then you can fly the aircraft through the resulting
> descending roll and recover. Depending on your height and speed it may
> be quite pressing to land, it may also be quite pressing to reduce speed....
> However - if this happens in a high energy state (where else?) you may
> already have a lot of yaw and roll inertia by the time you get the other
> airbrake open. Especially on a long winged open class ship there may
> just not be enough control authority left, and if you are very fast
> and/or very close to the ground the options are limited.
>
> To overcome the differential lift caused by the yaw you may need full
> rudder.
> To limit the speed and avoid terrain you may need large elevator deflection.
> To reverse the roll and return to level flight you almost certainly will
> need full aileron.
>
> You are unlikely to find such a high G, rolling pull up close to , or
> over Vne with airbrakes deployed in the manual.
>
> There is a reason for that "max manoeuvre speed" entry...
>
> A little math says that at 250km/h and 300m (~1000")AGL a 30 degree
> descent angle will give you less than 8 seconds to avoid terrain.

40 years ago I was involved in building and testing a glider with
spoilers for roll control instead of ailerons. Preliminary flight
tests were done on normal gliders rigged to permit one spoiler to be
deployed at a time.

The first thing we learned is that spoilers don't do what they are
generally thought to do.

The results of asymmetrical spoiler deployment vary dramatically with
airspeed since drag increases with the square of airspeed but lift
which is 'spoiled' pretty much remains constant with airspeed. (Any
lift reduction is transient since the glider quickly re-establishes
equilibrium at one G flight where lift =weight.)

The bottom line was that below some airspeed like 50kts, weak roll
(~10% of aileron authority) was the dominate result and above that
powerful yaw was the dominate result. We found it best to regard
differential spoilers as yaw control devices. Thus the concept of
roll spoilers was a failure.

In one iteration, spoilers were rigged to the pedals with the normal
rudder fixed in neutral. With yaw spoilers, ailerons and elevator, we
had a remarkably agile glider - albeit not a particularly efficient
one.

So, the accidental deployment of one spoiler will result in powerful
yaw not roll which leads me to the subject of using one in a slip.

When slipping a glider one quickly finds the limit is available rudder
authority. With full rudder one can use only about 15 degrees of bank
while maintain a straight track. However, with one spoiler deployed,
the pilot has far more 'rudder' authority in the direction of the open
spoiler and a far steeper bank can be used. This results in an
incredibly steep approach.

This situation is 'dangerous' only to the extent the pilot doesn't
understand how to control his partially disabled aircraft.

[John Cochrane]

I think it's a useful maneuver in the same way that boxing the wake is
-- it tells the examiner you're really in charge of the aircraft and
pattern planning. We don't really do it for broken spoilers, that's a
once in a gazillion event. That's why the new PTS does not require an
actual landing with spoilers, only demonstration of glide path control
using spoilers alone.

The PTS should also require slips WITH spoilers not slips INSTEAD of
spoilers. That's the maneuver you will use, when too high, to get in
to a field, etc. Many pilots have no idea how steeply you can in fact
come down. We'll just have to train that on our own. I've been having
fun with students -- the challenge is, set up a landing so that you
will use full slip and full spoiler on final. If you have to back off,
you buy the beer (after flying)

John Cochrane

[Ron Ogden]

At 07:00 11 September 2009, Derek Copeland wrote:
>I once had one spoiler fully out due to a failure of a diecast aluminium
>bracket in a Grob Astir. This broke in flight, with a loud bang as the
>left airbrake suddenly sucked open and stayed there. I then found that I
>needed almost full right aileron and rudder to conteract the roll and
yaw
>to the left. I was only about 900ft AGL at the time.
>
>The solution I worked out was to open the the other airbrake, which
still
>worked, and then make the best more or less straight ahead landing that
I
>could into a field. I had to sideslip the glider to get in, but walked
>away from it and didn't further damage the glider.
>
>BTW, this and another case is why many Grob Astirs have a little perspex
>inspection window under the wing, so that you can see the offending
>bracket.
>
>Getting back to the original subject, we do teach no airbrake approaches
>in the UK as a post solo exercise, just in case the airbrake mechanism
>fails, or the brakes freeze shut while wave soaring. I have made a video
>of such an exercise, but you float an awfully long way in ground effect,
>which is why I eventually told the student to open the brakes, as it
was
>the last flight of the day and we wanted to stop somewhere near to the
>hangar. See:
>
>http://www.youtube.com/watch?v=5t7xnls2w5k
>
>This was done in a K13, which sideslips very nicely and very much more
>effectively than most glass gliders. With a lot of slip on, the ASI will
>usually totally misread.
>
>Derek Copeland
>
>P.S. I know the Yanks call a sideslip a 'forward slip' before someone
>pulls me up on that!
>
>
>At 02:02 11 September 2009, vaughn wrote:
>>
>>"Mike the Strike" wrote in message
...
>>> I do know of one where the spoiler handle on a Grob 103
>>> broke after they had been deployed and jammed full open, resulting in
>>> an off-field landing.
>>>
>>And I know of a case where just one spoiler deployed on a glider.
>Causes
>>a
>>nasty uncommanded roll. The only solution (once you figure out what is

>>going on) is to close the spoilers and proceed without them.
>>
>>Vaughn
>>
>P.S. I know the Yanks call a sideslip a 'forward slip' before someone
pulls me up on that

If the British call our "forward slip" a "sideslip" what do they call
a mild slip that you would use primarily to counteract a crosswind?
Thanks
>

[Martin Gregorie[_5_]]

On Fri, 11 Sep 2009 18:45:03 +0000, Ron Ogden wrote:

> If the British call our "forward slip" a "sideslip" what do they call a
> mild slip that you would use primarily to counteract a crosswind? Thanks
>>
Nothing - I was taught to fly a crabbed approach and to kick it straight
just before touchdown. AFAIK the crosswind countering slipped approach
isn't taught in the UK.


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

[Derek Copeland[_2_]]

At 18:45 11 September 2009, Ron Ogden wrote:
>
>If the British call our "forward slip" a "sideslip" what do they
call
>a mild slip that you would use primarily to counteract a crosswind?
>Thanks
>>
>
How about a crosswind landing? There are two ways of doing this - wing low
or crabbing.

Derek Copeland

[[email protected]]

I concur with Kirk. Spoilerless approaches in glass requires a major
rethink of the approach and hopefully lots of practice in similar
(glass) ships prior to the real-deal. I do not believe, based on lots
of real-world experience, and observation, that most pilots could get
their glass ships on the ground in less than 3-4000 ft of runway
"first pass" without significant prior training, thought, and
practice.

Other than for the practice and proficiency, I do not know why anyone
would slip a 2-33 or similar to get rid of altitude. Merely pushing
over to higher speeds is very effective in such a draggy ship.

In preparation for the first flight of my AS-W12, I slipped anything
that was available to a spoilerless landing: Caproni (bad idea), AS-
W20, AS-W17, K21, Grobs, LS-4, etc. After those, the 12 was no big
deal. This type of approach and landing needs a serious change in
your paradigms and pretty much freaks out everyone who might be
watching as it is distinctly "abnormal". As the PIC, it is a bit
distracting seeing your "friends" lining the runway and exchanging
wager $$ based on your next landing. Major kudos to Larry and Jane
Barrett for their faith in me during my practice phase.

Like others have said, and similar to the Landing On Tow, spoilerless
approaches improve pilot skill and awareness and make an otherwise
boring day quite a bit more exciting. All of this is Good. Mastery of
spoilerless approaches = better pilot!

[Bruce]

bildan wrote:
> On Sep 11, 12:01 am, Bruce > wrote:
>> vaughn wrote:
>>> "Mike the Strike" > wrote in message
>>> ...
>>>> I do know of one where the spoiler handle on a Grob 103
>>>> broke after they had been deployed and jammed full open, resulting in
>>>> an off-field landing.
>>> And I know of a case where just one spoiler deployed on a glider. Causes a
>>> nasty uncommanded roll. The only solution (once you figure out what is
>>> going on) is to close the spoilers and proceed without them.
>>> Vaughn
>> Single spoiler deployment has caused at least one fatal accident.
>>
>> If a linkage fails resulting in asymmetric airbrake deployment it is
>> possible to run out of options very quickly.
>>
>> My thoughts are that you need to open the brakes to balance the drag and
>> lift asymmetry. Then you can fly the aircraft through the resulting
>> descending roll and recover. Depending on your height and speed it may
>> be quite pressing to land, it may also be quite pressing to reduce speed...
>> However - if this happens in a high energy state (where else?) you may
>> already have a lot of yaw and roll inertia by the time you get the other
>> airbrake open. Especially on a long winged open class ship there may
>> just not be enough control authority left, and if you are very fast
>> and/or very close to the ground the options are limited.
>>
>> To overcome the differential lift caused by the yaw you may need full
>> rudder.
>> To limit the speed and avoid terrain you may need large elevator deflection.
>> To reverse the roll and return to level flight you almost certainly will
>> need full aileron.
>>
>> You are unlikely to find such a high G, rolling pull up close to , or
>> over Vne with airbrakes deployed in the manual.
>>
>> There is a reason for that "max manoeuvre speed" entry...
>>
>> A little math says that at 250km/h and 300m (~1000")AGL a 30 degree
>> descent angle will give you less than 8 seconds to avoid terrain.
>
> 40 years ago I was involved in building and testing a glider with
> spoilers for roll control instead of ailerons. Preliminary flight
> tests were done on normal gliders rigged to permit one spoiler to be
> deployed at a time.
>
> The first thing we learned is that spoilers don't do what they are
> generally thought to do.
>
> The results of asymmetrical spoiler deployment vary dramatically with
> airspeed since drag increases with the square of airspeed but lift
> which is 'spoiled' pretty much remains constant with airspeed. (Any
> lift reduction is transient since the glider quickly re-establishes
> equilibrium at one G flight where lift =weight.)
>
> The bottom line was that below some airspeed like 50kts, weak roll
> (~10% of aileron authority) was the dominate result and above that
> powerful yaw was the dominate result. We found it best to regard
> differential spoilers as yaw control devices. Thus the concept of
> roll spoilers was a failure.
>
> In one iteration, spoilers were rigged to the pedals with the normal
> rudder fixed in neutral. With yaw spoilers, ailerons and elevator, we
> had a remarkably agile glider - albeit not a particularly efficient
> one.
>
> So, the accidental deployment of one spoiler will result in powerful
> yaw not roll which leads me to the subject of using one in a slip.
>
Al relatively low speed I would expect this to be reasonably controllable.

It would be interesting to test this at high speed - the yaw will be
severe at full open, the secondary effect of that yaw will be a roll in
the direction of the open spoiler. The uncoordinated flight is going to
increase drag significantly, and the glider will start to descend.
In the case of an open class/long winged glider the roll may exceed
aileron authority if this happens at high speed.
Even with 15m wingspan you are going to need significant control input
on the ailerons.

a glider one quickly finds the limit is available rudder
> authority. With full rudder one can use only about 15 degrees of bank
> while maintain a straight track. However, with one spoiler deployed,
> the pilot has far more 'rudder' authority in the direction of the open
> spoiler and a far steeper bank can be used. This results in an
> incredibly steep approach.
>
> This situation is 'dangerous' only to the extent the pilot doesn't
> understand how to control his partially disabled aircraft.

Full control input on an already stressed airframe at speeds above max
manoeuvring speed is not advisable - but may be the only option available.

The only incident I know of the glider ended up in tiny pieces of carbon.

[bildan]

On Sep 13, 1:21*am, Bruce > wrote:
> bildan wrote:
> > On Sep 11, 12:01 am, Bruce > wrote:
> >> vaughn wrote:
> >>> "Mike the Strike" > wrote in message
> ....
> >>>> I do know of one where the spoiler handle on a Grob 103
> >>>> broke after they had been deployed and jammed full open, resulting in
> >>>> an off-field landing.
> >>> And I know of a case where just one spoiler deployed on a glider. *Causes a
> >>> nasty uncommanded roll. *The only solution (once you figure out what is
> >>> going on) is to close the spoilers and proceed without them.
> >>> Vaughn
> >> Single spoiler deployment has caused at least one fatal accident.
>
> >> If a linkage fails resulting in asymmetric airbrake deployment it is
> >> possible to run out of options very quickly.
>
> >> My thoughts are that you need to open the brakes to balance the drag and
> >> lift asymmetry. Then you can fly the aircraft through the resulting
> >> descending roll and recover. Depending on your height and speed it may
> >> be quite pressing to land, it may also be quite pressing to reduce speed...
> >> However - if this happens in a high energy state (where else?) you may
> >> already have a lot of yaw and roll inertia by the time you get the other
> >> airbrake open. Especially on a long winged open class ship there may
> >> just not be enough control authority left, and if you are very fast
> >> and/or very close to the ground the options are limited.
>
> >> To overcome the differential lift caused by the yaw you may need full
> >> rudder.
> >> To limit the speed and avoid terrain you may need large elevator deflection.
> >> To reverse the roll and return to level flight you almost certainly will
> >> need full aileron.
>
> >> You are unlikely to find such a high G, rolling pull up close to , or
> >> over Vne with airbrakes deployed in the manual.
>
> >> There is a reason for that "max manoeuvre speed" entry...
>
> >> A little math says that at 250km/h and 300m (~1000")AGL a 30 degree
> >> descent angle will give you less than 8 seconds to avoid terrain.
>
> > 40 years ago I was involved in building *and testing a glider with
> > spoilers for roll control instead of ailerons. *Preliminary flight
> > tests were done on normal gliders rigged to permit one spoiler to be
> > deployed at a time.
>
> > The first thing we learned is that spoilers don't do what they are
> > generally thought to do.
>
> > The results of asymmetrical spoiler deployment vary dramatically with
> > airspeed since drag increases with the square of airspeed but lift
> > which is 'spoiled' pretty much remains constant with airspeed. *(Any
> > lift reduction is transient since the glider quickly re-establishes
> > equilibrium at one G flight where lift =weight.)
>
> > The bottom line was that below some airspeed like 50kts, weak roll
> > (~10% of aileron authority) was the dominate result and above that
> > powerful yaw was the dominate result. *We found it best to regard
> > differential spoilers as yaw control devices. *Thus the concept of
> > roll spoilers was a failure.
>
> > In one iteration, spoilers were rigged to the pedals with the normal
> > rudder fixed in neutral. *With yaw spoilers, ailerons and elevator, we
> > had a remarkably agile glider - albeit not a particularly efficient
> > one.
>
> > So, the accidental deployment of one spoiler will result in powerful
> > yaw not roll which leads me to the subject of using one in a slip.
>
> Al relatively low speed I would expect this to be reasonably controllable..
>
> It would be interesting to test this at high speed - the yaw will be
> severe at full open, the secondary effect of that yaw will be a roll in
> the direction of the open spoiler. The uncoordinated flight is going to
> increase drag significantly, and the glider will start to descend.
> In the case of an open class/long winged glider the roll may exceed
> aileron authority if this happens at high speed.
> Even with 15m wingspan you are going to need significant control input
> on the ailerons.
>
> * a glider one quickly finds the limit is available rudder
>
> > authority. *With full rudder one can use only about 15 degrees of bank
> > while maintain a straight track. *However, with one spoiler deployed,
> > the pilot has far more 'rudder' authority in the direction of the open
> > spoiler and a far steeper bank can be used. *This results in an
> > incredibly steep approach.
>
> > This situation is 'dangerous' only to the extent the pilot doesn't
> > understand how to control his partially disabled aircraft.
>
> Full control input on an already stressed airframe at speeds above max
> manoeuvring speed is not advisable - but may be the only option available..
>
> The only incident I know of the glider ended up in tiny pieces of carbon.

A little fuzzy. We did try full deployment of one spoiler at high
speed and the results were not pretty.

The roll 'effect' produced by asymmetric spoilers is fairly constant
with changing airspeed but aileron authority increases with increasing
speed. At no time is the roll effect of an open spoiler greater than
the aileron roll effect.

However, and this is the big one, the yaw effect produced by
asymmetric spoilers increases with the square of airspeed and will
quickly overwhelm rudder authority at higher speeds. Further, if the
pilot applies aileron to oppose 'spoiler roll', adverse yaw will add
to that produced by the open spoiler making matters worse.

The situation is not unlike dealing with a engine out in a light twin
airplane where the open spoiler is analogous to the dead engine. It's
difficult but doable. Banking away from the open spoiler makes
maintaining control easier just as banking away from a dead engine
does.

[Eric Greenwell]

bildan wrote:

>
> A little fuzzy. We did try full deployment of one spoiler at high
> speed and the results were not pretty.
>
> The roll 'effect' produced by asymmetric spoilers is fairly constant
> with changing airspeed but aileron authority increases with increasing
> speed. At no time is the roll effect of an open spoiler greater than
> the aileron roll effect.
>
> However, and this is the big one, the yaw effect produced by
> asymmetric spoilers increases with the square of airspeed and will
> quickly overwhelm rudder authority at higher speeds.

Is this what you experienced? I'd expect the rudder authority to also
increase with the square of the airspeed, just as lift does for the same
angle of attack.


--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[bildan]

On Sep 13, 4:47*pm, Eric Greenwell > wrote:
> bildan wrote:
>
> > A little fuzzy. *We did try full deployment of one spoiler at high
> > speed and the results were not pretty.
>
> > The roll 'effect' produced by asymmetric spoilers is fairly constant
> > with changing airspeed but aileron authority increases with increasing
> > speed. *At no time is the roll effect of an open spoiler greater than
> > the aileron roll effect.
>
> > However, and this is the big one, the yaw effect produced by
> > asymmetric spoilers increases with the square of airspeed and will
> > quickly overwhelm rudder authority at higher speeds.
>
> Is this what you experienced? I'd expect the rudder authority to also
> increase with the square of the airspeed, just as lift does for the same
> angle of attack.
>
> --
> Eric Greenwell - Washington State, USA
> * Change "netto" to "net" to email me directly
>
> * "Transponders in Sailplanes"http://tinyurl.com/y739x4
> * * * Sections on Mode S, TPAS, ADS-B, Flarm, more
>
> * "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Yep, to the point of flying sideways.

Bill D

[Joe]

The Practical Test Standard was clarified regarding "Slips to Landing"
that an actual slip to landing was not required. I have not
instructed in a few years and maybe this had been clarified in the PTS
but in the "Designee Update" of Jan.2000 this was clarified after an
instructor in MN brought up the question to the FAA. I quote it
below:

AFS-600 Regulatory Support Division,
Designee Update
Vol.12, No.1 January 2000

“GLIDER SLIPS”
For you folks who operate in the glider community,
the April 1999 Private and Commercial Pilot-Glider
Practical Test Standards include a landing TASK
entitled “Slips to Landing.” In the objective, the
applicant is required to “establish a slip without the
use of drag devices” and then complete a landing.
We have had questions on whether the applicant
should complete the landing, with or without the
use of drag devices.
There was never any intent to require an applicant to
complete the landing without the use of drag
devices. The applicant is only required to
demonstrate a slip (forward or side) without using
drag devices, to position the glider for a safe
landing. Element 6 of the TASK states; “make
smooth, proper, and positive control applications
during recovery from the slip.” Once this has been
accomplished, the maneuver being evaluated is
over. The applicant then lands the glider within the
designated landing area, using drag devices as
appropriate.
Most important for examiner standardization, the
examiner should not add or decrease elements to
this task, or any other task, by asking the applicant
to do
more or less than is required.




On Fri, 11 Sep 2009 10:16:07 -0700 (PDT), John Cochrane
> wrote:

>I think it's a useful maneuver in the same way that boxing the wake is
>-- it tells the examiner you're really in charge of the aircraft and
>pattern planning. We don't really do it for broken spoilers, that's a
>once in a gazillion event. That's why the new PTS does not require an
>actual landing with spoilers, only demonstration of glide path control
>using spoilers alone.
>
>The PTS should also require slips WITH spoilers not slips INSTEAD of
>spoilers. That's the maneuver you will use, when too high, to get in
>to a field, etc. Many pilots have no idea how steeply you can in fact
>come down. We'll just have to train that on our own. I've been having
>fun with students -- the challenge is, set up a landing so that you
>will use full slip and full spoiler on final. If you have to back off,
>you buy the beer (after flying)
>
>John Cochrane