Several years ago, we made templates along the leading edge of a
popular standard class sailplane . The particular sailplane was a
winner. It was shocking to compare the left and right wing contours
with these templated. Close? Not at all. But the sailplane went very
well.
Then we did the same on another sailplane by another manufacturer.
The templates were identical left and right. Mirror image. As made in
a machine. Perfect. This particular sailplane never did well. Not a
winner.
Conclusion?
set the flame on low,
Thanks,
GA

> *Conclusion?

Ship #1 had 2 slightly imperfect copies of a good wing design.
Ship #2 had 2 perfect copies of a poorer wing design.

Simple, no flames required! ;-)

Bob

I've had the same experience exactly. Goes like stink, flies arrow
straight, best in class glider, and you'd think the right and left
wings came from different types. That's when I knew I should have
spent more on TLAs, buzzwords, and smoke and mirrors.

Bob K.

On Aug 22, 4:25*pm, glider > wrote:
> Several years ago, we made templates along the leading edge of a
> popular standard class sailplane . The particular sailplane was a
> winner. It was shocking to compare the left and right wing contours
> with these templated. Close? Not at all. But the sailplane went very
> well.
> *Then we did the same on another sailplane by another manufacturer.
> The templates were identical left and right. Mirror image. As made in
> a machine. Perfect. This particular sailplane *never did well. Not a
> winner.
> *Conclusion?
> *set the flame on low,
> *Thanks,
> *GA

On Aug 22, 7:25*pm, glider > wrote:
> Several years ago, we made templates along the leading edge of a
> popular standard class sailplane . The particular sailplane was a
> winner. It was shocking to compare the left and right wing contours
> with these templated. Close? Not at all. But the sailplane went very
> well.
> *Then we did the same on another sailplane by another manufacturer.
> The templates were identical left and right. Mirror image. As made in
> a machine. Perfect. This particular sailplane *never did well. Not a
> winner.
> *Conclusion?
> *set the flame on low,
> *Thanks,
> *GA

So you don't think the pilot had ANYTHING to do with it?

Put me in a JS1 and WE in my LS1. He'd still whip me...

With me in the JS1, I would just land out further away from home....

Ray Lovinggood
Carrboro, North Carolina, USA

On Aug 22, 7:25*pm, glider > wrote:
> Several years ago, we made templates along the leading edge of a
> popular standard class sailplane . The particular sailplane was a
> winner. It was shocking to compare the left and right wing contours
> with these templated. Close? Not at all. But the sailplane went very
> well.
> *Then we did the same on another sailplane by another manufacturer.
> The templates were identical left and right. Mirror image. As made in
> a machine. Perfect. This particular sailplane *never did well. Not a
> winner.
> *Conclusion?
> *set the flame on low,
> *Thanks,
> *GA

I have seen the same thing.
Obviously some airfoils ars more sensitive to manufacturing errors
than others. Std Cirrus seems to be one of those. When carefully
perfected they seem to improve a good bit. Revised handicaps used in
WGC reflets this, I suspect.
UH

On Aug 22, 7:25*pm, glider > wrote:
> Several years ago, we made templates along the leading edge of a
> popular standard class sailplane . The particular sailplane was a
> winner. It was shocking to compare the left and right wing contours
> with these templated. Close? Not at all. But the sailplane went very
> well.
> *Then we did the same on another sailplane by another manufacturer.
> The templates were identical left and right. Mirror image. As made in
> a machine. Perfect. This particular sailplane *never did well. Not a
> winner.
> *Conclusion?
> *set the flame on low,
> *Thanks,
> *GA

Aw, come on, we want dirt! Bring it on!

There was a similar story about a certain 15m sailplane that was "the
ship to fly" 20 odd years ago and a templates and t/c measurements
taken from what was believed to be a particularly good example. The
results were, uh, distressing. But the ship in question flew real
well.

There's a lot to be said for profiles that are forgiving of
manufacturing tolerance.

-T8

> There's a lot to be said for profiles that are forgiving of
> manufacturing tolerance.
>
And of aging, both of the wing itself and the molds. Some gliders are
great right out of newish molds. Then after a few years, the molds
aren't the same. Nor are the wings. Nor is the performance. Some are
more susceptible than others. Of course, left and right wings/molds
SHOULD age/distort similarly but don't apparently.

I'd say distortion caused by aging was more a problem in the past than
now but some recent models have been notorius, too. Conversely, other
models (my own glider being a good example, to my immense relief),
appear to be "timeless" when holding their contours. Is it hard tanks
vs. bags? Spar/spar cap design? Glass vs. carbon vs. aramid? Layers
and weaves and orientation? Epoxies? Manufacturing methods?

All this stuff can be fixed in a specific glider, but for what a new
glider costs, it seems like the manufacturers should get it right
every time.

Chip Bearden
ASW 24 "JB"
USA