Flat Spin

[JJ Sinclair]

I'm surprised this spin thread hasn't produced more discussion of the flat
spin. One poster told us about getting into a flat spin after several
revolutions of a "normal" spin" at Minden when the Puch went flat (nose on
horizon). The poster thought it was kind of thrilling, until he applied spin
recovery controls (opposite rudder & forward stick) The Puch continued to flat
spin for another 5 or 6 revolutions. This spin started at 12,000 feet. Had it
been initiated at a much lower altitude, we might be investigating yet another
Puch-in. Has anyone else had the Puch go into a flat spin?

Perhaps those who have are no longer with us?
JJ Sinclair

[BTIZ]

I wonder where the CG was for the "Puch Flat Spin"

BT

"JJ Sinclair" > wrote in message
...
> I'm surprised this spin thread hasn't produced more discussion of the flat
> spin. One poster told us about getting into a flat spin after several
> revolutions of a "normal" spin" at Minden when the Puch went flat (nose on
> horizon). The poster thought it was kind of thrilling, until he applied
spin
> recovery controls (opposite rudder & forward stick) The Puch continued to
flat
> spin for another 5 or 6 revolutions. This spin started at 12,000 feet. Had
it
> been initiated at a much lower altitude, we might be investigating yet
another
> Puch-in. Has anyone else had the Puch go into a flat spin?
>
> Perhaps those who have are no longer with us?
> JJ Sinclair

[Gus Rasch]

(JJ Sinclair) wrote in message >...
> I'm surprised this spin thread hasn't produced more discussion of the flat
> spin. One poster told us about getting into a flat spin after several
> revolutions of a "normal" spin" at Minden when the Puch went flat (nose on
> horizon). The poster thought it was kind of thrilling, until he applied spin
> recovery controls (opposite rudder & forward stick) The Puch continued to flat
> spin for another 5 or 6 revolutions. This spin started at 12,000 feet. Had it
> been initiated at a much lower altitude, we might be investigating yet another
> Puch-in. Has anyone else had the Puch go into a flat spin?
>
> Perhaps those who have are no longer with us?
> JJ Sinclair



Group,

As a Pitts owner and pilot who flies a LOT of aerobatics I thought I
would chime in on a possible reason for the Puchs' delayed recovery
from the flat spin.

The quickest and most assured method of exiting a flat spin is to
first convert it to a conventional spin and then exit that spin mode.

In a Pitts you get the spin to go flat by adding opposite aileron.
Take away the the opposite aileron and it returns to a conventional
spin. The puch most likely flatens out the same way.

More than one Pitts pilot has pounded in while trying to exit a flat
spin before first converting it to a conventional spin. This delay in
recovery from a flat spin could find you establishing a new bottom to
the aerobatic box.

It is therefore imperative to not add opposite aileron while spinning
(in an attempt to pick up the low wing) or risk having it go flat. If
you do find yourself in a developed flat spin you need to confirm that
you have not added opposite aileron and/or add a little pro-spin
aileron to assist in returning the aircraft to a conventional spin and
then recover from that spin mode.

All that said, I must also add that I have never flown the Puch. All
the above is based on aerobatics in a Pitts. I am not a CFIG or the
current world aerobatic champ. This is information that my CFIG has
instilled in me and is supported by many books on aerobatics that I
have read. It has also been proven to myself time and time again in
practical application.

Anybody up for a discussion on inverted accelerated flat spins?!

Gus Rasch
Pitts S1S
N21JF

[John Smith]

"The Puch continued to flat
> spin for another 5 or 6 revolutions. This spin started at 12,000 feet. =
Had it
> been initiated at a much lower altitude, we might be investigating yet =
another
> Puch-in."
Rather unlkely scenario as you are not taking account of air =
density/Reynolds number.
My experience of extensive spinning in the SZD30 Puchacz is that at =
altitudes in excess of 8,000 feet the spin recovery is prolonged =
regardless of spin characteristics. If "out spin" aileron is applied the =
spin tends to go flat and the rotation apparently decreases. If "in =
spin" aileron is applied the spin goes nose down and appears to increase =
in rate of rotation. Standard recovery action results in both types of =
spin stopping after three to 5 turns - remember that part of the =
recovery procedure is "centralise ailerons".
Below 5,000 feet the SZD30 tends to cease spinning if the back pressure =
on the stick is simply relaxed, i.e. without application of out spin =
rudder.
The difference is nothing to do with C of G position or aircraft =
configuration - it is simple aerodynamics connected to the air density =
decreasing with increasing altitude.=20
When considering the various reports of spinning on this forum how many =
actually take into consideration the altitude at which the exercise was =
undertaken.
Admittedly this does not explain the high?? accident rate but there is =
currently a lack of suitable training gliders in which to undertake spin =
training. The ASK21 has been designed as supposedly unspinnable - try it =
at 10,000 feet - you might be surprised. As said elsewhere how does the =
accident rate in the Puchacz compare to say the Bocian which was another =
excellent aircraft for spin recovery training. The DG505 is one of the =
newer German aircraft that also exhibits good characteristics for spin =
training although be aware of spinning close to the aft C of G.
I have to admit to deliberately spinnIng any aircraft (subject to its =
Cof A limitations) so that I am thoroughly aware of any peculiarites in =
respect of its handling. I would be amiss in not doing so as I would =
then be unable to thoroughly brief any pupils for their first flight in =
these aircraft. I also want to know what the characteristics of the =
aircraft are from a self preservation aspect - at least I will not be =
caught out by inadvertant departure from normal flight due to gusts, =
rotor, etc.

[Jon Meyer]

I haven't flown a puch, but I have been in a flat spin
in an SF34 with an instructor some years ago. The instructor
had decided to see how many turns we could manage in
a spin (note that after 3 you become a test pilot).
We were at 6500ft when we entered the spin. After 10
turns he decided to recover, but the spin was already
completely flat, with the nose gently nodding above
and below the horizon as we turned. Upon application
of the recovery control inputs, the spin continued
for another 3 turns (which gave plenty of time to start
worrying and thinking about the parachute) before we
eventually recovered. Unfortunately I never noted down
accurate start and finish heights in my log book, but
I think that we recovered at about 3500'. Needless
to say we never tried that again, and I wouldn't recommend
anyone prolonging a spin beyond 3 turns.

[Kevin Neave]

... and then you wonder why the back end fell off that
particular glider!


At 11:18 06 February 2004, Jon Meyer wrote:
>I haven't flown a puch, but I have been in a flat spin
>in an SF34 with an instructor some years ago. The instructor
>had decided to see how many turns we could manage in
>a spin (note that after 3 you become a test pilot).
>We were at 6500ft when we entered the spin. After 10
>turns he decided to recover, but the spin was already
>completely flat, with the nose gently nodding above
>and below the horizon as we turned. Upon application
>of the recovery control inputs, the spin continued
>for another 3 turns (which gave plenty of time to start
>worrying and thinking about the parachute) before we
>eventually recovered. Unfortunately I never noted down
>accurate start and finish heights in my log book, but
>I think that we recovered at about 3500'. Needless
>to say we never tried that again, and I wouldn't recommend
>anyone prolonging a spin beyond 3 turns.
>
>
>
>
>
>

[Stefan]

Jon Meyer wrote:

> had decided to see how many turns we could manage in
> a spin (note that after 3 you become a test pilot).

JAR requires 5 turns.


JAR 22.221

(b) The sailplane must be able to recover
from spins of at least five turns or such lesser
number at which the spin changes into a spiral
dive, by applying the controls in a manner
normal for recovery ...

etc.


Stefan

[Kevin Neave]

At 14:48 06 February 2004, Jon Meyer wrote:
>French engineering at its best!

That would be 'Scheibe' , makers of 'Le Moteur Falke'
?

:-)

[[email protected]]

Jon Meyer > wrote:
> The thought had occured to me Kevin, but I suspect
> that a flat spin puts very little strain on the airframe
> compared with other manouvres.....provided it doesnt
> continue all the way to ground level that is.

> I think that thing was just never glued together properly
> at the back end, considering the fact that after the
> accident you mention, they found that none of the frames
> in the tail section were bonded to the fuselage skins.
> French engineering at its best!
> Considering the way that thing was built I think all
> of us who flew it should just be glad that it didnt
> break when we were flying it and that, when it did
> break, nobody was hurt.

By the way, could you explain us what French engeneering has to do with the
Puch or the SF34 ? I have seen particularly badly engeneered French gliders,
notably the Bijave and the Javelot, but here i am really wondering about
what glider you are speaking. Incidentally we have heard recently discussions
about poorly glued wings from the most prestigious German factory, while
this did not occur, up to my knowledge, with the *much* cheaper Pegase.






--
Michel Talon

[Jon Meyer]

Sorry my mistake, got confused by the fact that the
Alliance 34 is made by Pegase (a copy of the SF34).

I know all about the quality of french construction
though, I fly an ASW20F and drive a Peugeot......neither
is as well made as their german equivalents :-)

[Robert John]

And having flown both, I can say they were pretty unimpressive
machines.
BTW Jon, you must have a fair amount of faith in French
engineering to fly your ASW20f at 130kts 6inches above
an undulating field while waving at the club safety
officer! ;-}
Rob
PS I've forgotten, was that YOUR Peugeot that mated
with a tree at the end of the field at NYM?

At 17:54 06 February 2004, Jon Meyer wrote:
>
>Sorry my mistake, got confused by the fact that the
>Alliance 34 is made by Pegase (a copy of the SF34).
>
>I know all about the quality of french construction
>though, I fly an ASW20F and drive a Peugeot......neither
>is as well made as their german equivalents :-)
>
>
>
>
>

[[email protected]]

Jon Meyer > wrote:

> Sorry my mistake, got confused by the fact that the
> Alliance 34 is made by Pegase (a copy of the SF34).

> I know all about the quality of french construction
> though, I fly an ASW20F and drive a Peugeot......neither
> is as well made as their german equivalents :-)


For the ASW20F i cannot comment, i have seen some which were in apparent good
state. Anyways, at the time Centrair had little experience of building
gliders, and the ASW20 were built under German license. After that they did
the Pegase, which is, in my opinion, a great success. The wings were designed
by the French office Onera, and this is a glider which has basically the same
performances as the German LS4, is more fun or less fun than the LS4 according
to personal taste, but was surely much cheaper.
As far as cars are concerned, Peugeot cannot be compared fairly with Mercedes
and BMW which are in a completly different category for a lot of reasons.
First and foremost, prices are in a completly different range, second these German
cars are propulsions while Peugeot are tractions, meaning that they don't
address the same problems. The aim of Peugeot is to produce cars that people
can afford (with European salaries), are comfortable and secure (good secure
dynamical qualities). With some bad faith i could say exactly the opposite of
the above German ones. Now compare Peugeot cars with VWs or Opel cars, which
are in the same category, and deciding the best is very debatable. To say the
truth, all the European constructors buy parts in the same pool (Bosch being a
well known example), use same technics, etc. Frequently the so called German
car or French car is built in Spain or whatever. What is obviously true is
that German firms do considerably better research and work in the motor
department. Clearly Porsche, BMW, and Mercedes develop fantastic motors, Japan
firms do the same, and French firms don't. I suppose that the strict speed
limitations in France explain a lot about that, but this is sad nonetheless.



--
Michel Talon

[Shawn Curry]

wrote:

> Jon Meyer > wrote:
>
>>The thought had occured to me Kevin, but I suspect
>>that a flat spin puts very little strain on the airframe
>>compared with other manouvres.....provided it doesnt
>>continue all the way to ground level that is.
>
>
>>I think that thing was just never glued together properly
>>at the back end, considering the fact that after the
>>accident you mention, they found that none of the frames
>>in the tail section were bonded to the fuselage skins.
>>French engineering at its best!
>>Considering the way that thing was built I think all
>>of us who flew it should just be glad that it didnt
>>break when we were flying it and that, when it did
>>break, nobody was hurt.
>
>
> By the way, could you explain us what French engeneering has to do with the
> Puch or the SF34 ? I have seen particularly badly engeneered French gliders,
> notably the Bijave and the Javelot, but here i am really wondering about
> what glider you are speaking. Incidentally we have heard recently discussions
> about poorly glued wings from the most prestigious German factory, while
> this did not occur, up to my knowledge, with the *much* cheaper Pegase.

French engineering? Never heard of it. ;-)

Shawn

P.S. Those bad wings came out of a Czech factory. They were engineered
in Germany, not made there. IIRC the Pegase and ASW-20F were german
designs as well.

[[email protected]]

Shawn Curry > wrote:
> Shawn

> P.S. Those bad wings came out of a Czech factory. They were engineered
> in Germany, not made there. IIRC the Pegase and ASW-20F were german
> designs as well.

Not the Pegase.

--
Michel Talon

[Chris OCallaghan]

Great information, Gus!

Many models of sailplane require holding opposite aileron to maintain
the spin, otherwise it transitions into a spiral dive. It is very
possible that Puchacz pilots are doing exactly this, then returning
the ailerons to neutral to perform a normal recovery after the spin
goes flat. Your suggestion, then, is to put the the stick into the
inside wing (raise the aileron on the higher drag wingtip) and pause
as a precursor to initiating normal spin recovery?

Another question for you...

Do your aerobatics texts discuss the suitability of different
types/models of aircraft for aerobatics? Are there models that are
suitably stressed, but not ideal because of control issues (too
little, too much...)?

(Gus Rasch) wrote in message >...
> (JJ Sinclair) wrote in message >...
> > I'm surprised this spin thread hasn't produced more discussion of the flat
> > spin. One poster told us about getting into a flat spin after several
> > revolutions of a "normal" spin" at Minden when the Puch went flat (nose on
> > horizon). The poster thought it was kind of thrilling, until he applied spin
> > recovery controls (opposite rudder & forward stick) The Puch continued to flat
> > spin for another 5 or 6 revolutions. This spin started at 12,000 feet. Had it
> > been initiated at a much lower altitude, we might be investigating yet another
> > Puch-in. Has anyone else had the Puch go into a flat spin?
> >
> > Perhaps those who have are no longer with us?
> > JJ Sinclair
>
>
>
> Group,
>
> As a Pitts owner and pilot who flies a LOT of aerobatics I thought I
> would chime in on a possible reason for the Puchs' delayed recovery
> from the flat spin.
>
> The quickest and most assured method of exiting a flat spin is to
> first convert it to a conventional spin and then exit that spin mode.
>
> In a Pitts you get the spin to go flat by adding opposite aileron.
> Take away the the opposite aileron and it returns to a conventional
> spin. The puch most likely flatens out the same way.
>
> More than one Pitts pilot has pounded in while trying to exit a flat
> spin before first converting it to a conventional spin. This delay in
> recovery from a flat spin could find you establishing a new bottom to
> the aerobatic box.
>
> It is therefore imperative to not add opposite aileron while spinning
> (in an attempt to pick up the low wing) or risk having it go flat. If
> you do find yourself in a developed flat spin you need to confirm that
> you have not added opposite aileron and/or add a little pro-spin
> aileron to assist in returning the aircraft to a conventional spin and
> then recover from that spin mode.
>
> All that said, I must also add that I have never flown the Puch. All
> the above is based on aerobatics in a Pitts. I am not a CFIG or the
> current world aerobatic champ. This is information that my CFIG has
> instilled in me and is supported by many books on aerobatics that I
> have read. It has also been proven to myself time and time again in
> practical application.
>
> Anybody up for a discussion on inverted accelerated flat spins?!
>
> Gus Rasch
> Pitts S1S
> N21JF

[Papa3]

Don't know if it's the French per se. Maybe it's just socialism. I
remember the Peugot 404 my parents bought in 1965 or so. That car was
indestructible. Ran for 12 years without a single repair, other than
replacing parts of the muffler system that rusted out. The 504 they bought
in the late 70s couldn't get out if its own way - engine rebuild after
10,000 miles, electrics that would randomly short out, etc.

Flame shields set to max :-))




"Jon Meyer" > wrote in message
...
>
> Sorry my mistake, got confused by the fact that the
> Alliance 34 is made by Pegase (a copy of the SF34).
>
> I know all about the quality of french construction
> though, I fly an ASW20F and drive a Peugeot......neither
> is as well made as their german equivalents :-)
>
>
>
>

[Mike Borgelt]

On 5 Feb 2004 18:57:40 -0800, (Gus Rasch)
wrote:

(JJ Sinclair) wrote in message >...
>> I'm surprised this spin thread hasn't produced more discussion of the flat
>> spin. One poster told us about getting into a flat spin after several
>> revolutions of a "normal" spin" at Minden when the Puch went flat (nose on
>> horizon). The poster thought it was kind of thrilling, until he applied spin
>> recovery controls (opposite rudder & forward stick) The Puch continued to flat
>> spin for another 5 or 6 revolutions. This spin started at 12,000 feet. Had it
>> been initiated at a much lower altitude, we might be investigating yet another
>> Puch-in. Has anyone else had the Puch go into a flat spin?
>>
>> Perhaps those who have are no longer with us?
>> JJ Sinclair
>
>
>
>Group,
>
>As a Pitts owner and pilot who flies a LOT of aerobatics I thought I
>would chime in on a possible reason for the Puchs' delayed recovery
>from the flat spin.
>
>The quickest and most assured method of exiting a flat spin is to
>first convert it to a conventional spin and then exit that spin mode.
>
>In a Pitts you get the spin to go flat by adding opposite aileron.
>Take away the the opposite aileron and it returns to a conventional
>spin. The puch most likely flatens out the same way.
>
>More than one Pitts pilot has pounded in while trying to exit a flat
>spin before first converting it to a conventional spin. This delay in
>recovery from a flat spin could find you establishing a new bottom to
>the aerobatic box.
>
>It is therefore imperative to not add opposite aileron while spinning
>(in an attempt to pick up the low wing) or risk having it go flat. If
>you do find yourself in a developed flat spin you need to confirm that
>you have not added opposite aileron and/or add a little pro-spin
>aileron to assist in returning the aircraft to a conventional spin and
>then recover from that spin mode.
>
>All that said, I must also add that I have never flown the Puch. All
>the above is based on aerobatics in a Pitts. I am not a CFIG or the
>current world aerobatic champ. This is information that my CFIG has
>instilled in me and is supported by many books on aerobatics that I
>have read. It has also been proven to myself time and time again in
>practical application.
>
>Anybody up for a discussion on inverted accelerated flat spins?!
>
>Gus Rasch
>Pitts S1S
>N21JF


On my spin flight in the S2A we got to accelerated flat spins upright.
I thought that was thrilling enough.
Your point about the in and out spin aleron is well made and this is
something that you can demonstrate easily in a Pitts and which I had
never seen in a glider althoght knew about it.

Had an interesting discussion with that instructor yesterday about all
this spinning stuff. He has a lot of time in gliders too. We are both
of the opinion that full spin training is best done in powered
aircraft with professional instructor.

Mike Borgelt

[Bert Willing]

Well, the airfoil of the Pégase is French, the rest is a copy of German
design...

--
Bert Willing

ASW20 "TW"


> a écrit dans le message de
...
> Shawn Curry > wrote:
> > Shawn
>
> > P.S. Those bad wings came out of a Czech factory. They were engineered
> > in Germany, not made there. IIRC the Pegase and ASW-20F were german
> > designs as well.
>
> Not the Pegase.
>
> --
> Michel Talon

[W.J. \(Bill\) Dean \(U.K.\).]

I have often wondered whether the Pegase airfoil is an entirely different
design to the ASW20, or whether it is basically a fixed flap version of the
ASW20 wing.

I understand that the LS8 wing is a fixed flap version of the LS6 wing,
and the LS8 does seem to work rather well.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Bert Willing" > wrote in
> message ...
>
> Well, the airfoil of the Pégase is French, the rest is a copy of German
> design...
>
> Bert Willing
>

[Michel Talon]

Bert Willing > wrote:
> Well, the airfoil of the Pégase is French, the rest is a copy of German
> design...
>

Of course, the rest is not "unrelated" to the ASW20 that Centrair used
to build under German licence :-) But i maintain that the design of the
wing is extremely important for a glider, and that in the case of the
Pegase, this design was original, and a great success. Until appearance
of the Discus and its quite novel wing, the Pegase was in par with other
similar gliders. If you want me to say that the different German firms
have produced the most beautiful and fine gliders of our epoch, this is
obviously true. They have failed however to keep the prices reasonable,
and this is, in my opinion an extremely grave failure, which is killing
the sport.

--

Michel TALON

[Bert Willing]

No, the Pégase airfoil is a completely new airfoil designed by the French
ONERA. You would need to compare the Pégase to the ASW19 standard class, and
it must be stated the the performance of the Pégase is significantly better
than an ASW19.
Actually, flying an ASW20 against a Pégase in competition is quite a pain -
they climb very well, glide fairly well and have a much lower handicap
coefficient...

--
Bert Willing

ASW20 "TW"


"W.J. (Bill) Dean (U.K.)." > a écrit dans le message
de ...
> I have often wondered whether the Pegase airfoil is an entirely different
> design to the ASW20, or whether it is basically a fixed flap version of
the
> ASW20 wing.
>
> I understand that the LS8 wing is a fixed flap version of the LS6 wing,
> and the LS8 does seem to work rather well.
>
> W.J. (Bill) Dean (U.K.).
> Remove "ic" to reply.
>
> >
> > "Bert Willing" > wrote in
> > message ...
> >
> > Well, the airfoil of the Pégase is French, the rest is a copy of German
> > design...
> >
> > Bert Willing
> >
>
>
>

[Bert Willing]

Well, it's easy to say that German gliders are much more expensive than
French ones... Centrair didn't have to pay the development of the ASW20,
neither of the Pégase airframe, neither of the Alliance 34 (which, as SF34
was a complete flop in Germany, so I still don't see the reason that
Centrair took it up...).
Development cost of a glider makes for a significant part of the selling
price as you have to get the amortization from somewhere.
And sorry, if I look at the fleet of club ships in Germany and France - it's
not the price of a new sailplane which kills the activity.

--
Bert Willing

ASW20 "TW"


"Michel Talon" > a écrit dans le message de
...
> Bert Willing > wrote:
> > Well, the airfoil of the Pégase is French, the rest is a copy of German
> > design...
> >
>
> Of course, the rest is not "unrelated" to the ASW20 that Centrair used
> to build under German licence :-) But i maintain that the design of the
> wing is extremely important for a glider, and that in the case of the
> Pegase, this design was original, and a great success. Until appearance
> of the Discus and its quite novel wing, the Pegase was in par with other
> similar gliders. If you want me to say that the different German firms
> have produced the most beautiful and fine gliders of our epoch, this is
> obviously true. They have failed however to keep the prices reasonable,
> and this is, in my opinion an extremely grave failure, which is killing
> the sport.
>
> --
>
> Michel TALON
>

[Michel Talon]

Bert Willing > wrote:
> Well, it's easy to say that German gliders are much more expensive than
> French ones... Centrair didn't have to pay the development of the ASW20,
> neither of the Pégase airframe,

Let us stick with the Pegase, since the ASW20F was an unmodified copy
of the ASW20, and the other Centrair productions are crap. The Pegase
had at least a new wing, hence needed all sorts of development and testing
expenses, new certification process, etc. When you take that into
account, and notably the certification process is said to be very
expensive, you see that your argument is far from being conclusive.

>neither of the Alliance 34 (which, as SF34
> was a complete flop in Germany, so I still don't see the reason that
> Centrair took it up...).
> Development cost of a glider makes for a significant part of the selling
> price as you have to get the amortization from somewhere.
> And sorry, if I look at the fleet of club ships in Germany and France - it's
> not the price of a new sailplane which kills the activity.
>

Yes of course, it is. I know tons of people who have stopped flying
because it was too expensive, and even many more who dream of flying
but cannot afford. When something as simple as a glider, that is
something vastly simpler than a car, costs the price of a house,
something is utterly wrong. You can argue as much as you want about
research and development involved in this industry, i think it doesn't
explain squat about this failure. Completely inefficient production
processes is surely a more convincing explanation. This being said, it
is true that French and German clubs have considerable fleet, because
they have accumulated gliders for many years, and in particular, at
least in France, they have bought a lot of Pegase which were relatively
cheap. However they need to renew fleet, and regularly buy new models
to avoid erosion of their capital. And due to the insane actual prices,
this means they have to charge higher memberships or worse rent their
gliders higher. Sorry to say that, but my salary is strictly aligned on
the official inflation, that is to say, it stays fixed ... and i am not
alone in this situation, by far. Hence when glider prices double in a
few years, a lot of people get expelled out of the activity, and you
observe what i can see around me, glider clubs are becoming old people
clubs.



--

Michel TALON

[Jon Meyer]

>something vastly simpler than a car, costs the price
>of a house,

I think you are ignoring economies of scale. If the
Peugeot 306 had a total production run of only 500
over a period of several years as opposed to (at a
guess) 500 a day, then I think your little peugeot
runabout would probably cost about £1,000,000. Gliders
are handmade because that is the most cost effective
method of composite construction for a production run
that does not extend into the 10,000's. It is not highly
inefficient, it is the most efficient economical means
available. Do you not think that Schleicher and Schempp
would be using a cheaper means if it were available?
After all, the cheaper the glider is to make, the higher
their profit margins.

It is just a sad fact that gliders will always be expensive,
it is the nature of the market.

[Bert Willing]

I don't see this price argument as valid. My salary hasn't gone up for a
long time neither... But of course, if you insist on always flying the very
last gimmick, or if you insist on buying 0h gliders, you will end up paying
a lot if you go for your private glider.
On the club side, I can tell you that many clubs in Germany have fees which
didn't even follow inflation over the last 20 years, and they were still
able to renew their fleet. French clubs have been a bit stuck with the
Pégase capital-wise: sure it's a lot of glider for little money, but the
value of a used Pégase goes down rapidly - whereas I had to pay about the
same amount of money for my ASW20 like the first owner who bought it 20
years ago (of course, that doesn't take into account inflation). One reason
for the Pégase going down in value is probably that the French market is
swamped by them, and that you can't sell them in Germany (where the market
is about 3 times larger).

As to inefficient production methods - building a couple of hundred gliders
from negative moulds is handcrafting, nothing else. If you want to have more
performant production tools, you need *much* higher numbers to be able to
compensate the tooling investment. The only way to reduce cost is either
cutting down on the finish (has been done successfully by Grob), or going to
do the production in countries with low wages (as done by SH and DG).
Still with the high prices for last generation gliders, companies like LS go
belly up...

--
Bert Willing

ASW20 "TW"


"Michel Talon" > a écrit dans le message de
...
> Bert Willing > wrote:
> > Well, it's easy to say that German gliders are much more expensive than
> > French ones... Centrair didn't have to pay the development of the ASW20,
> > neither of the Pégase airframe,
>
> Let us stick with the Pegase, since the ASW20F was an unmodified copy
> of the ASW20, and the other Centrair productions are crap. The Pegase
> had at least a new wing, hence needed all sorts of development and testing
> expenses, new certification process, etc. When you take that into
> account, and notably the certification process is said to be very
> expensive, you see that your argument is far from being conclusive.
>
> >neither of the Alliance 34 (which, as SF34
> > was a complete flop in Germany, so I still don't see the reason that
> > Centrair took it up...).
> > Development cost of a glider makes for a significant part of the selling
> > price as you have to get the amortization from somewhere.
> > And sorry, if I look at the fleet of club ships in Germany and France -
it's
> > not the price of a new sailplane which kills the activity.
> >
>
> Yes of course, it is. I know tons of people who have stopped flying
> because it was too expensive, and even many more who dream of flying
> but cannot afford. When something as simple as a glider, that is
> something vastly simpler than a car, costs the price of a house,
> something is utterly wrong. You can argue as much as you want about
> research and development involved in this industry, i think it doesn't
> explain squat about this failure. Completely inefficient production
> processes is surely a more convincing explanation. This being said, it
> is true that French and German clubs have considerable fleet, because
> they have accumulated gliders for many years, and in particular, at
> least in France, they have bought a lot of Pegase which were relatively
> cheap. However they need to renew fleet, and regularly buy new models
> to avoid erosion of their capital. And due to the insane actual prices,
> this means they have to charge higher memberships or worse rent their
> gliders higher. Sorry to say that, but my salary is strictly aligned on
> the official inflation, that is to say, it stays fixed ... and i am not
> alone in this situation, by far. Hence when glider prices double in a
> few years, a lot of people get expelled out of the activity, and you
> observe what i can see around me, glider clubs are becoming old people
> clubs.
>
>
>
> --
>
> Michel TALON
>

[Michel Talon]

Bert Willing > wrote:

> As to inefficient production methods - building a couple of hundred gliders
> from negative moulds is handcrafting, nothing else. If you want to have more
> performant production tools, you need *much* higher numbers to be able to
> compensate the tooling investment. The only way to reduce cost is either
> cutting down on the finish (has been done successfully by Grob), or going to
> do the production in countries with low wages (as done by SH and DG).
> Still with the high prices for last generation gliders, companies like LS go
> belly up...
>

Shure, and this is really a pity. Still i am convinced that it is
absolutely essential to cut radically on prices. After all, other
industries succeed perfectly in cutting prices by a factor of two
in a couple of years to survive in a competitive market. I see many
examples of industries where there is a constant effort
to augment productivity, diminish prices, etc. I am convinced that
the glider factories have never done this reflexion effort
and content themselves to augment their tarifs each year.
This destroys the sport, destroys their market, and will ultimately lead
to their disparition. Gliding is by nature a sport for young people,
not for rich people. You will have hard time recruiting guys who
are both rich, have a lot of free time, good reflexes, etc. At the
end of the day it remains only a crew of retirees to animate the clubs.



--

Michel TALON

[W.J. \(Bill\) Dean \(U.K.\).]

I have always understood that the first ASW20F was an exact copy of the
Schleicher built machine, but built under licence by Centrair.

I also heard that the ASW20FL was not covered by the licence, but was an
unauthorised copy of the Schleicher ASW20L; and that it did not incorporate
certain modifications incorporated into the German machine; and that as a
result they are not strong enough and use of the tips is now forbidden.

It is obvious to anyone who looks at it that the fuselage and tail feathers
of the Pegase are pure ASW20. I also heard that the unflapped wing uses
the ASW20 wing main spar.

I like flying the Pegase, I had a share in one for a while. But then I
have always liked Schleicher gliders.

I don't recall that Centrair have produced any successful gliders which are
not essentially Schleicher.

I have owned several Peugeot cars, I have one now. Build quality has never
been their strong point, not after the 403 anyway.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

>
> "Michel Talon" > wrote in message
> ...
>
> >
> > Bert Willing > wrote:
> >
> > Well, the airfoil of the Pégase is French, the rest is a copy of German
> > design...
> >
>
> Of course, the rest is not "unrelated" to the ASW20 that Centrair used
> to build under German licence :-) But I maintain that the design of the
> wing is extremely important for a glider, and that in the case of the
> Pegase, this design was original, and a great success. Until appearance
> of the Discus and its quite novel wing, the Pegase was in par with other
> similar gliders. If you want me to say that the different German firms
> have produced the most beautiful and fine gliders of our epoch, this is
> obviously true. They have failed however to keep the prices reasonable,
> and this is, in my opinion an extremely grave failure, which is killing
> the sport.
>
> Michel TALON
>

[Bill Daniels]

"Michel Talon" > wrote in message
...
> Bert Willing > wrote:
>
> > As to inefficient production methods - building a couple of hundred
gliders
> > from negative moulds is handcrafting, nothing else. If you want to have
more
> > performant production tools, you need *much* higher numbers to be able
to
> > compensate the tooling investment. The only way to reduce cost is either
> > cutting down on the finish (has been done successfully by Grob), or
going to
> > do the production in countries with low wages (as done by SH and DG).
> > Still with the high prices for last generation gliders, companies like
LS go
> > belly up...
> >
>
> Shure, and this is really a pity. Still i am convinced that it is
> absolutely essential to cut radically on prices. After all, other
> industries succeed perfectly in cutting prices by a factor of two
> in a couple of years to survive in a competitive market. I see many
> examples of industries where there is a constant effort
> to augment productivity, diminish prices, etc. I am convinced that
> the glider factories have never done this reflexion effort
> and content themselves to augment their tarifs each year.
> This destroys the sport, destroys their market, and will ultimately lead
> to their disparition. Gliding is by nature a sport for young people,
> not for rich people. You will have hard time recruiting guys who
> are both rich, have a lot of free time, good reflexes, etc. At the
> end of the day it remains only a crew of retirees to animate the clubs.
>
> Michel TALON
>

I agree Michel. There HAS to be a way to reduce production costs. There
are thousands of people that will tell you that "it can't be done". My
experience tells me that these are "negative experts" who always know
exactly, to the Nth decimal place, why whatever you want to do can't be
done, but are totally silent when asked how something CAN be done.

I tend to view the problem as an engineering one rather than an economic
one. Worse finishes by cheaper labor is not a rewarding way to go. I call
this a "negative compromise" where you end up paying a little less (or maybe
the same) for a much worse product.

So, how might it be done? Start with computers, materials and processes.
Large CNC milling machines can produce extremely accurate plugs or even
finished molds. If the process of making the flying part accurately
replicates these CNC generated mold surfaces, little post molding work
should be needed. The fact that a lot of post molding work IS needed today
says a lot about the materials and methods used.

A very promising area the homebuilders are playing with is "Vacuum assisted
resin Infusion" which reduces the labor of wet layup by 75%. Lay the dry
fiber in place on the mold and vacuum bag it. Then, inject resin at
strategic places so it flows through the whole part. The resin content
drops to around 25% instead of the 40 -50% typical of wet layup and voids
are almost completely eliminated. The result is a lighter, stronger, more
accurate and cheaper part.

It would be very economical if the resin saturated part could be heat cured
while in the mold. If the mold is fiberglass, it will warp with repeated
temperature cycles (PIC 20D). Making the mold out of aluminum is expensive,
but you only have to pay for it once. The payback is fast cycle times
because you can heat the part in the mold so it cures in minimum time. You
may get three parts per day instead of only one and the part will be far
more temperature tolerant.

There must be thousands of tricks like this that drive up quality while
cutting costs. That's the way to go. Think outside the box.

Bill Daniels

[Eric Greenwell]

Bill Daniels wrote:

> So, how might it be done? Start with computers, materials and processes.
> Large CNC milling machines can produce extremely accurate plugs or even
> finished molds. If the process of making the flying part accurately
> replicates these CNC generated mold surfaces, little post molding work
> should be needed. The fact that a lot of post molding work IS needed today
> says a lot about the materials and methods used.

The German manufacturers are already doing this. Still, there are
joining lines that must be dealt with.

> A very promising area the homebuilders are playing with is "Vacuum assisted
> resin Infusion" which reduces the labor of wet layup by 75%. Lay the dry
> fiber in place on the mold and vacuum bag it. Then, inject resin at
> strategic places so it flows through the whole part. The resin content
> drops to around 25% instead of the 40 -50% typical of wet layup and voids
> are almost completely eliminated. The result is a lighter, stronger, more
> accurate and cheaper part.

Another method, used in SparrowHawk production, is pre-impregnated
carbon fiber cloth and rovings. Resin content is precisely controlled,
the cloth easily cut, layup is dry.
>
> It would be very economical if the resin saturated part could be heat cured
> while in the mold.

The laid up SparrowHawk parts are cured in an oven to 225 deg F,
yielding a stronger material than wet layup, and it doesn't have to be
painted white, either. I don't know why the German factories don't use
this material.

If the mold is fiberglass, it will warp with repeated
> temperature cycles (PIC 20D). Making the mold out of aluminum is expensive,
> but you only have to pay for it once.

The SparrowHawk uses carbon fiber molds, but the major components (wing,
fuselage, tail surfaces) are _assembled_ in aluminum jigs, so the
accuracy of the molds are not critical. It's more expensive to set up
production, but you are assured of accurate parts.

The payback is fast cycle times
> because you can heat the part in the mold so it cures in minimum time. You
> may get three parts per day instead of only one and the part will be far
> more temperature tolerant.

Ah, here's the rub: unless you are making more than one glider a day,
this has no value.

>
> There must be thousands of tricks like this that drive up quality while
> cutting costs. That's the way to go. Think outside the box.

After watching the SparrowHawk in various stages of completion, I can
tell there are far more pieces in a glider than you can imagine! Each
one has it own mold and must be laid up then cured, it must be glued or
bolted in by hand, then the halves of major components mated, glued, and
cured, canopy fitted, filling and painting, wiring and instruments
installed. It just goes on and on.

Also, the materials are expensive. The urethane paint on the SparrowHawk
varies from $160 to $400 a gallon, depending on the color, and it takes
more than a gallon. It's a small glider, too.

I'm sure improvements in glider manufacturing will continue, but I don't
see any thing dramatic coming along. To build a cheap glider now can be
done: make it small, make it light, and build 3 a week so the molds are
always busy and the factory space is all in use.

How cheap would this 11-12 meter, 35:1 glider have to be so they could
sell that many? Already, I can hear people saying "That is silly! for
only a little extra you make a 15 meter glider!" and "That is silly! for
the same price you can buy a used glider with more performance!".

I think we could build a good, cheap glider, but I don't think we could
sell it.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Bert Willing]

Great thinking outside the box, but it shows that both of you have never
been involved in the economics of small and medium series production of
composite parts.

--
Bert Willing

ASW20 "TW"


"Bill Daniels" > a écrit dans le message de
...
>
> "Michel Talon" > wrote in message
> ...
> > Bert Willing > wrote:
> >
> > > As to inefficient production methods - building a couple of hundred
> gliders
> > > from negative moulds is handcrafting, nothing else. If you want to
have
> more
> > > performant production tools, you need *much* higher numbers to be able
> to
> > > compensate the tooling investment. The only way to reduce cost is
either
> > > cutting down on the finish (has been done successfully by Grob), or
> going to
> > > do the production in countries with low wages (as done by SH and DG).
> > > Still with the high prices for last generation gliders, companies like
> LS go
> > > belly up...
> > >
> >
> > Shure, and this is really a pity. Still i am convinced that it is
> > absolutely essential to cut radically on prices. After all, other
> > industries succeed perfectly in cutting prices by a factor of two
> > in a couple of years to survive in a competitive market. I see many
> > examples of industries where there is a constant effort
> > to augment productivity, diminish prices, etc. I am convinced that
> > the glider factories have never done this reflexion effort
> > and content themselves to augment their tarifs each year.
> > This destroys the sport, destroys their market, and will ultimately lead
> > to their disparition. Gliding is by nature a sport for young people,
> > not for rich people. You will have hard time recruiting guys who
> > are both rich, have a lot of free time, good reflexes, etc. At the
> > end of the day it remains only a crew of retirees to animate the clubs.
> >
> > Michel TALON
> >
>
> I agree Michel. There HAS to be a way to reduce production costs. There
> are thousands of people that will tell you that "it can't be done". My
> experience tells me that these are "negative experts" who always know
> exactly, to the Nth decimal place, why whatever you want to do can't be
> done, but are totally silent when asked how something CAN be done.
>
> I tend to view the problem as an engineering one rather than an economic
> one. Worse finishes by cheaper labor is not a rewarding way to go. I
call
> this a "negative compromise" where you end up paying a little less (or
maybe
> the same) for a much worse product.
>
> So, how might it be done? Start with computers, materials and processes.
> Large CNC milling machines can produce extremely accurate plugs or even
> finished molds. If the process of making the flying part accurately
> replicates these CNC generated mold surfaces, little post molding work
> should be needed. The fact that a lot of post molding work IS needed
today
> says a lot about the materials and methods used.
>
> A very promising area the homebuilders are playing with is "Vacuum
assisted
> resin Infusion" which reduces the labor of wet layup by 75%. Lay the dry
> fiber in place on the mold and vacuum bag it. Then, inject resin at
> strategic places so it flows through the whole part. The resin content
> drops to around 25% instead of the 40 -50% typical of wet layup and voids
> are almost completely eliminated. The result is a lighter, stronger, more
> accurate and cheaper part.
>
> It would be very economical if the resin saturated part could be heat
cured
> while in the mold. If the mold is fiberglass, it will warp with repeated
> temperature cycles (PIC 20D). Making the mold out of aluminum is
expensive,
> but you only have to pay for it once. The payback is fast cycle times
> because you can heat the part in the mold so it cures in minimum time.
You
> may get three parts per day instead of only one and the part will be far
> more temperature tolerant.
>
> There must be thousands of tricks like this that drive up quality while
> cutting costs. That's the way to go. Think outside the box.
>
> Bill Daniels
>

[nafod40]

Eric Greenwell wrote:
> I'm sure improvements in glider manufacturing will continue, but I don't
> see any thing dramatic coming along. To build a cheap glider now can be
> done: make it small, make it light, and build 3 a week so the molds are
> always busy and the factory space is all in use.
>
> How cheap would this 11-12 meter, 35:1 glider have to be so they could
> sell that many? Already, I can hear people saying "That is silly! for
> only a little extra you make a 15 meter glider!" and "That is silly! for
> the same price you can buy a used glider with more performance!".
>
> I think we could build a good, cheap glider, but I don't think we could
> sell it.

I'll toss out my idea again. With airplanes, cost very closely
correlates with mass, and goes down rapidly with the number of
gliders/cars/toasters produced. Setting up racing and record classes
based on mass rather than wingspan would create a motivation for low
mass gliders, which would be lower cost. The ultralight class is too
light, I think, but has the right idea. There's records to be set all
over the place in that class.

Maybe to avoid the race for exotic materials, have a kind of standard
material class (Al, glass) and an exotics class (carbon fibre).

[Bill Daniels]

"nafod40" > wrote in message
...

> Maybe to avoid the race for exotic materials, have a kind of standard
> material class (Al, glass) and an exotics class (carbon fibre).
>

Materials cost is tiny in comparison to the labor cost. Use exotic
materials if they cut labor or improve performance.

I remember an engineer who responded to the suggestion that gliders use
carbon fiber. "You can't use that stuff, he said, "it costs $100 a pound".
"How may pounds do you plan to use?", I asked.

Bill Daniels

[nafod40]

Bill Daniels wrote:
> "nafod40" > wrote in message
> ...
>
>
>>Maybe to avoid the race for exotic materials, have a kind of standard
>>material class (Al, glass) and an exotics class (carbon fibre).
>>
>
>
> Materials cost is tiny in comparison to the labor cost. Use exotic
> materials if they cut labor or improve performance.

Ah, good point.

[Bill Daniels]

"nafod40" > wrote in message
...
> Bill Daniels wrote:
> > "nafod40" > wrote in message
> > ...
> >
> >
> >>Maybe to avoid the race for exotic materials, have a kind of standard
> >>material class (Al, glass) and an exotics class (carbon fibre).
> >>
> >
> >
> > Materials cost is tiny in comparison to the labor cost. Use exotic
> > materials if they cut labor or improve performance.
>
> Ah, good point.
>

There's a great example in the Space Shuttle. The bean counters at NASA
(and the US Congress) insisted that it be built of ordinary aircraft
aluminum - "Because it's cheaper". There are more than a few engineers who
think that Columbia might have survived the breach in the heat shield if the
basic airframe had been titanium. I wonder how much they think the choice
of aluminum saved them now?

Bill Daniels

[Robert Ehrlich]

Papa3 wrote:
>
> Don't know if it's the French per se. Maybe it's just socialism. I
> remember the Peugot 404 my parents bought in 1965 or so. That car was
> indestructible. Ran for 12 years without a single repair, other than
> replacing parts of the muffler system that rusted out.

The first car I bought in 1963 was a Peugeot (notice the 2nd "e") 203.
When i bought it, it was 12 years old. Had it not been destroyed in an
accident, maybe it could be always running.