Short Wings Gliders

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

At 12:50 01 February 2009, wrote:

I think the world class was a great idea,
but the PW's 32:1 reach just wasn't enough.
It's 15 years later, let's see what the designers can do!

40:1 with 13.3 meters wingspan is he
http://en.wikipedia.org/wiki/Alisport_Silent_2_Targa

Mike Hostage kit built one in less then 12 months!!!!

ALSO SPRACHT HERR HOSTAGE:
"The Silent 2 Targa is a fine flying machine and the kit is very straight
forward. I built mine in just under one year.
However, the Euro/Dollar rate is a killer!
Mike"

(msg 33 of many)

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

In article ,
Dan Silent wrote:

At 12:50 01 February 2009, wrote:

I think the world class was a great idea,
but the PW's 32:1 reach just wasn't enough.
It's 15 years later, let's see what the designers can do!

40:1 with 13.3 meters wingspan is he
http://en.wikipedia.org/wiki/Alisport_Silent_2_Targa

Mike Hostage kit built one in less then 12 months!!!!

ALSO SPRACHT HERR HOSTAGE:
"The Silent 2 Targa is a fine flying machine and the kit is very straight
forward. I built mine in just under one year.
However, the Euro/Dollar rate is a killer!
Mike"

(msg 33 of many)

Can't imagine why anyone slams one type of glider over another. All of
our ships have their advantages and shortcomings. Each type has it's
place. Short wing gliders seem to fit best in situations where there are
other short wings, such as in a one-design racing class, or when several
are present in one club and can fly together. Or, when you are the only
glider driver and you fly alone. Fly a short wing with a bunch of
"normal" span gliders and you may find yourself with a case of "span
envy".

Similar principle applies if you fly, oh, say an old Libelle, with a
bunch of those obscene -27's and Ventus 2's ;-).

On Feb 1, 2:30*pm, Dan Silent wrote:

40:1 with 13.3 meters wingspan is here...

With all due respect, I'll believe that when it's validated by an
independent third party. In the meantime, I remain convinced that the
shortest-span glider that will carry a normal-sized person at 40:1 is
about 14.3m, and that's predicated on a much higher aspect ratio than
the Silent.

Thanks, Bob K.

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

At 15:27 01 February 2009, Papa3 wrote:

So, I do believe a lot of it comes back to land. Specifically, the
fact that land use policy (or lack thereof) in the US means that a
flat piece of land within say 90 minutes drive of most major
metropolitan areas is going to run into the several $milions. For
instance, a 30 acre property in a place equidistant from say NYC and
Philadelphia would set you back about $1M minimum...

Do you happen to know how taxes affect US clubs that own their own fields?
I suppose it varies from state to state, but some of these clubs have
pretty valuable pieces of land. Being set up as a non-profit organization
might help some, but I don't know if it would exempt the group from
taxes.

On the other hand, the way to save money is to be a church. Any club that
could set itself up as a religion would have it made. Maybe the Reverend
Charlie Spratt (or should I say Father Charlie?) would be interested in
consecrating a few bishops around the country to establish branches of the
Church of the Rising Air. Yeah, that's the way to go. It worked great
for L. Ron Hubbard.

Jim Beckman (Rev.-to-be)

cernauta wrote:

.....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.


And so it might have been if the selection had been, say, an LS4. No
doubt you've heard this before.

Tony V.