Short Wings Gliders

wrote:
One thing that may not have been covered is cost. I see in "Gliding
International" concern about the increasing cost of material and
labour ("exploding"). If a shorter wing were used, there would be
less of both.


There is not a single proof that this is true. The difference of cost
between 14 m span and 15 m is presumably totally insignificant.
One has to chase economies elsewhere.


--

Michel TALON

One thing that may not have been covered is cost. I see in
"Gliding
International" concern about the increasing cost of material
and
labour ("exploding"). If a shorter wing were used, there
would be
less of both.


There is not a single proof that this is true. The difference of
cost
between 14 m span and 15 m is presumably totally
insignificant.
One has to chase economies elsewhere.


I have a Russia and an ASW20. I've been through both of them
pretty thoroughly, and I am amazed at the complexity of the
ASW20 and the simplicity of the Russia.

The Russia weighs 300 pounds. The ASW20 weighs almost twice
as much. I'll agree that just a few feet more wing probably does
not add that much to the cost, but all the complexity involved in
getting 40:1 or better sure does. Both ships were done by
brilliant designers, each shooting at a different target. If you
want performance, the 20's got it. Still going strong after all
these years. If you want a ship that assembles by one person in
10 minutes, is super easy to manufacture, has a really low parts
count and still has enough performance to go X/C, then the
Russia is hard to beat. I don't think anyone has discovered how
to do both. It will take the discovery of a new material that
lends itself to automated molding to get there.

One thing that I noticed last year is that it is hard to go
backwards in L/D. After flying a borrowed Libelle on a few
X/C's, I could hardly get myself back in the Russia. From this
point of view I understand the low opinions of the shortwings. It
does not alter the fact that I learned on it, loved it and it
provided a springboard to better opportunities. It is also cheap
and easy to fly. This is where the World Class can beat all other
classes. New blood can get into affordable, easy to fly, easy to
assemble ships and have huge fun. If they stick with it and want
to move up, they will find a way.

Brian

The ASW20 is complicated and heavy, because it is fitted with flaps and was
designed to win the 15 metre class world championship.

The original concept of the Standard Class was for a simple 15 metre
sailpane that would gave the best compromise between performance and cost.
I can't really see that anything has changed, apart from the use of exotic
high tech materials in the latest models. Just ban these to keep the costs
down.

I note that even the fairly old tech. Libelle (Standard Class?) gave Brian
noticeably better performance than the Russia. I have flown an example of
the latter when it was called the ME7. Although I didn't make any
measurements, it seemed to have about the same performance as a wooden K6,
maybe a bit better at higher speeds, but not exactly inspiring.

Derek Copeland


At 15:30 01 February 2009, Brian Bange wrote:
One thing that may not have been covered is cost. I see in
"Gliding
International" concern about the increasing cost of material
and
labour ("exploding"). If a shorter wing were used, there
would be
less of both.


There is not a single proof that this is true. The difference of
cost
between 14 m span and 15 m is presumably totally
insignificant.
One has to chase economies elsewhere.


I have a Russia and an ASW20. I've been through both of them
pretty thoroughly, and I am amazed at the complexity of the
ASW20 and the simplicity of the Russia.

The Russia weighs 300 pounds. The ASW20 weighs almost twice
as much. I'll agree that just a few feet more wing probably does
not add that much to the cost, but all the complexity involved in
getting 40:1 or better sure does. Both ships were done by
brilliant designers, each shooting at a different target. If you
want performance, the 20's got it. Still going strong after all
these years. If you want a ship that assembles by one person in
10 minutes, is super easy to manufacture, has a really low parts
count and still has enough performance to go X/C, then the
Russia is hard to beat. I don't think anyone has discovered how
to do both. It will take the discovery of a new material that
lends itself to automated molding to get there.

One thing that I noticed last year is that it is hard to go
backwards in L/D. After flying a borrowed Libelle on a few
X/C's, I could hardly get myself back in the Russia. From this
point of view I understand the low opinions of the shortwings. It
does not alter the fact that I learned on it, loved it and it
provided a springboard to better opportunities. It is also cheap
and easy to fly. This is where the World Class can beat all other
classes. New blood can get into affordable, easy to fly, easy to
assemble ships and have huge fun. If they stick with it and want
to move up, they will find a way.

Brian

Maybe, since the 18m and over, classes are becoming very popular, by
default the 15m wingspan will become the new and accepted shortwing
class.

Now the trick will be for a clever designer to combine modern
materials and manufacturing methods to design and build that 38-40:1
ship. And with an eye towards "affordability", it can be engineered
with the simplicity that went in to the Russia and Apis line of
sailplanes.

My HP-24 is being built along those lines; I expect to get at least
40:1, it will be under 500 pounds. Has the sleek sexy lines and
retractable gear we all want and should be a solid recreational
sailplane.

Brad

On Feb 1, 5:50*am, (Michel Talon) wrote:

There is not a single proof that this is true...

Any of several public domain wing weight estimators will show you
nearly exactly what the difference in structural weight is between 14m
and 15m. It's not to be sneezed at.

The difference of cost between 14 m span and 15 m is
presumably totally insignificant....

No, not true. As I've written elsewhere the manufacturing cost seems
to scale exponentially with span. A lot of that is due to the larger
tools required to make larger wings, the larger buildings required to
store and use the tools, the greater amount of energy and other area
and volume costs and business expenses associated with larger
buildings. It goes to worms in a right hurry, it does.

One has to chase economies elsewhere.

One must chase economies everywhere.

Thanks, Bob K.

Bob Kuykendall wrote:
No, not true. As I've written elsewhere the manufacturing cost seems
to scale exponentially with span.

I don't pretend to be as knowledgeable as you about gliders, but
i know that exp(15/14) is not very different from 15/14.

One has to chase economies elsewhere.

One must chase economies everywhere.

Mostly in the hourly cost of manpower, e.g. by building in China,
not paying horrendous fees to some university departments to do the
computations when it is certainly possible to get them for free,
and so on. Probably everything else is negligible.


--

Michel TALON

On Feb 1, 2:06*pm, (Michel Talon) wrote:
Bob Kuykendall wrote:
No, not true. As I've written elsewhere the manufacturing cost seems
to scale exponentially with span.

I don't pretend to be as knowledgeable as you about gliders, but
i know that exp(15/14) is not very different from 15/14.

One has to chase economies elsewhere.

One must chase economies everywhere.

Mostly in the hourly cost of manpower, e.g. by building in China,
not paying horrendous fees to some university departments to do the
computations when it is certainly possible to get them for free,
and so on. Probably everything else is negligible.

--

Michel TALON

Not so fast, if you want to argue with pseudo-math lets get it right.
15/14 is ~1.071, e^1.071 is 2.91 which *is* very different. But what
you should be asking is what is e^15/e^14 which is a ratio of 2.72,
since Bob said the cost scales exponentially with span, not
exponentially with the span ratio. Not that 2.7 is far from 2.9, but
at different span ratios the difference in calculations becomes, ah
exponential. Not that this means anything, since Bob was just likely
making a point with a hyperbole.

I'm curious who pays "horrendous fees" to universities. My impression
is many European manufactures get pretty sweet deals via relationships
with different University research groups and Akafliegs.


Darryl

Darryl Ramm wrote:
On Feb 1, 2:06*pm, (Michel Talon) wrote:
Bob Kuykendall wrote:
No, not true. As I've written elsewhere the manufacturing cost seems
to scale exponentially with span.

I don't pretend to be as knowledgeable as you about gliders, but
i know that exp(15/14) is not very different from 15/14.

One has to chase economies elsewhere.

One must chase economies everywhere.

Mostly in the hourly cost of manpower, e.g. by building in China,
not paying horrendous fees to some university departments to do the
computations when it is certainly possible to get them for free,
and so on. Probably everything else is negligible.

--

Michel TALON

Not so fast, if you want to argue with pseudo-math lets get it right.
15/14 is ~1.071, e^1.071 is 2.91 which *is* very different. But what
you should be asking is what is e^15/e^14 which is a ratio of 2.72,
since Bob said the cost scales exponentially with span, not

I expressed myself very poorly, my idea was that the increase in cost is
exp(15/14) *compared to* the case where there is no increase, exp(14/14)
so the net increase is exp(1/14) which is very close to 1/14 (the second
order term being 1/2 (1/14)^2, negligible). Hence, even if the increase
in cost is exponential, you will pay (15/14) x (cost of a 14 m glider)
for a 15 m glider. The factor 2.7.. = exp(1) above is bogus.


exponentially with the span ratio. Not that 2.7 is far from 2.9, but
at different span ratios the difference in calculations becomes, ah
exponential. Not that this means anything, since Bob was just likely
making a point with a hyperbole.

I agree completely with that. But i remark that the cost of gliders has
indeed increased exponentially the last twenty years, for reasons which
have nothing to do with concrete factors, but everything to do with
hourly cost of workers, and total lack of will of controlling the costs.
The glider factories seem to think that glider buyers are like Ferrari
buyers, who will accept to pay any price for their toys. The problem
with that is the category of people interested in flying has no
intersection with the category of people interested in showing their
external signs of richness to bimbos.



I'm curious who pays "horrendous fees" to universities. My impression
is many European manufactures get pretty sweet deals via relationships
with different University research groups and Akafliegs.

A closely previous post mentioned that Schleicher was paying heavy fees
to Delft University to get his computations done. Compare this to the
Pegase which was computed at ONERA for free. I have the impression that
the Pegase was the last glider whose aim was allowing a lot of people to
fly. And incidentally, it shows that one can build a 15m glider of
reasonable simplicity, with performances not that different from the more
complex ASW 20, easier to fly, and much cheaper. The LS4 also fits the
bill, but already in its time it was 3/2 more expensive.



Darryl


--

Michel TALON

One of the reasons the PW5 never caught on in the UK, apart from its
appearance, is that you could buy a secondhand Standard Cirrus, Libelle,
Pegasus, ASW19, or any any other first/second generation glass Std Class
15 metre span glider, more cheaply and with much better performance. These
gliders compete in our 'Club Class' competitions, which are normally
oversubscribed. There is not enough interest in the 'World Class' to
make it worthwhile to organise a National Comp.

Derek Copeland

At 10:14 02 February 2009, Michel Talon wrote:
Darryl Ramm wrote:
On Feb 1, 2:06*pm, (Michel Talon) wrote:
Bob Kuykendall wrote:
No, not true. As I've written elsewhere the manufacturing cost
seems
to scale exponentially with span.

I don't pretend to be as knowledgeable as you about gliders, but
i know that exp(15/14) is not very different from 15/14.

One has to chase economies elsewhere.

One must chase economies everywhere.

Mostly in the hourly cost of manpower, e.g. by building in China,
not paying horrendous fees to some university departments to do the
computations when it is certainly possible to get them for free,
and so on. Probably everything else is negligible.

--

Michel TALON

Not so fast, if you want to argue with pseudo-math lets get it right.
15/14 is ~1.071, e^1.071 is 2.91 which *is* very different. But what
you should be asking is what is e^15/e^14 which is a ratio of 2.72,
since Bob said the cost scales exponentially with span, not

I expressed myself very poorly, my idea was that the increase in cost is
exp(15/14) *compared to* the case where there is no increase, exp(14/14)
so the net increase is exp(1/14) which is very close to 1/14 (the second
order term being 1/2 (1/14)^2, negligible). Hence, even if the increase
in cost is exponential, you will pay (15/14) x (cost of a 14 m glider)
for a 15 m glider. The factor 2.7.. = exp(1) above is bogus.


exponentially with the span ratio. Not that 2.7 is far from 2.9, but
at different span ratios the difference in calculations becomes, ah
exponential. Not that this means anything, since Bob was just likely
making a point with a hyperbole.

I agree completely with that. But i remark that the cost of gliders has
indeed increased exponentially the last twenty years, for reasons which
have nothing to do with concrete factors, but everything to do with
hourly cost of workers, and total lack of will of controlling the costs.
The glider factories seem to think that glider buyers are like Ferrari
buyers, who will accept to pay any price for their toys. The problem
with that is the category of people interested in flying has no
intersection with the category of people interested in showing their
external signs of richness to bimbos.



I'm curious who pays "horrendous fees" to universities. My
impression
is many European manufactures get pretty sweet deals via relationships
with different University research groups and Akafliegs.

A closely previous post mentioned that Schleicher was paying heavy fees
to Delft University to get his computations done. Compare this to the
Pegase which was computed at ONERA for free. I have the impression that
the Pegase was the last glider whose aim was allowing a lot of people to
fly. And incidentally, it shows that one can build a 15m glider of
reasonable simplicity, with performances not that different from the
more
complex ASW 20, easier to fly, and much cheaper. The LS4 also fits the
bill, but already in its time it was 3/2 more expensive.



Darryl


--

Michel TALON

On 2 Feb 2009 12:30:05 GMT, Derek Copeland
wrote:

There is not enough interest in the 'World Class' to
make it worthwhile to organise a National Comp.

In the years back when the World Class concept was being introduced, I
remember having read a very serious, very academic marketing study
that forecsted the production of thousands of World Class one-design
gliders 'round the world within a few years.

Go trust the experts...

Aldo