US Dollar sinks to new low against Euro

He is the fellow who was suing DG over the LS purchase? Maybe the
resolution was that he got the LS-4, and DG got everything else?

In what country will the LS-4 be produced?


Andreas Maurer wrote:
On Wed, 10 Nov 2004 23:06:18 GMT, "Paul Remde" wrote:


Hi,

Does anyone have the name of the person or company that is planning to
produce the LS-4s?


Walter Eisele.



Bye
Andreas

I would think that if the aspect ratio is the same, and the
wing is shorter, the wing must be thinner too.

Beyond that, if one makes a much lighter glider with the same stall speed,
one can use less wing.

Glider Span A/R Area sq ft Vs in mph

LS-4 15.0 21.4 113.0 40
AC-4 12.6 20.5 82.9 39
Sparwhwk 11.0 18.6 70.0 37
G-102 15.0 18.2 133.5 38

So one would need to add 36% more wing area to make an AC-4 into an LS-4.
And one would need to almost double the wing area to make a Sparrowhawk
into a G-102.

And this is just in two dimensions. I won't get into whether the
wing material is thinner (as I don't know).

Does adding 36% or doubling the wing area add significantly to
cost of building? I don't know. What I do know is that statements
claiming that lopping off 2-3 meters result in less than a 10% reduction
in wing area seem to not hold up to high school math applied to some common
gliders...

There are other factors here, though. Retract weighs a bit, and
so maybe justifies more span, to give the slightly improved polar.
Cockpit size is another factor: sure it's easy to make a light glider
with a midget cockpit.

So there are things other than just the wing to consider. I suspect that
builders spend a LOT more time with the detail finish work (and the
associated $$$ cost) on the fuselage/cockpit/empennage than on the wings...
So perhaps even halving the amount of material or work on wings
really has little effect on the total cost of the aircraft.

Other practical considerations:

Tow vehicle: Mazda Protege vs. Toyota 4 runner
Shipping from BFE: Two gliders vs. one in a container
Push it: Just me on rough ground vs. two of us

etc...

I think the most compelling reasons for 15m have less to do
with apples to apples comparisons, and more to do with
ballast, overbuilding, heavy pilots, and girth ;P


In article ,
Pete Reinhart wrote:
Lighter wings?
Cain't lif' that heavy glass no more.
Cheers?


"Erik mann" wrote in message
. com...
Eric Greenwell wrote in message
...
Bob Kuykendall wrote:

Many people say they would be delighted to have a glider with the
performance of an LS4. This performance can now be achieved with a
smaller span glider of 13 M or less. Can you guess at the cost reduction
that would be possible with a 12 or 13 meter glider compared to the 15M
LS4? Smaller factory, less materials, less labor (especially if hand
finishing is needed), smaller trailer, lower shipping costs (RO-RO is by
volume, I think).

Eric,

I wonder about this cost issue. Having done some re-profiling and
re-finishing myself, I have to believe that the decrement in labor and
materials involved in a 2 meter reduction in span is insignifiant.
For instance, once you have the 600 grit on the sanding bar and you're
moving right along, the last one meter of a given wing is lost in the
overall effort of setup and cleanup. Although the materials are
clearly incremental, the percentage of material is certainly less than
10 percent since the surface area of the last two meters is likely
less than 10 percent of a modern wing (e.g. 115ft2 for a modern glass
bird vs about 15 ft2 for the outboard 1 meter on each side [3 feet x 2
feet mean chord]). So, maybe we could optimistically see a 5-7%
reduction in per unit construction cost. Throw in tooling and
development costs, and what's the real savings? That's at least how I
would view the numbers if I were setting up shop...

I think 13M is a legacy of the "build it in your garage" movement.
In that case, there was a very practical reason for a 13M span; the
half-span would fit in an average garage (aka "workshop"). But, since
the homebuilders movement is pretty much moribund except for a few
hearty soles, what's the magic about 13M?

Erik




--

------------+
Mark J. Boyd

Eric Greenwell wrote:
Bob Kuykendall wrote:

This performance can now be achieved with
a smaller span glider of 13 M or less.

Theoretically so. But in order to bring that 13m ship closer to your
goal of 15m-type performance, you have to make it lighter per unit of
area than a 15m ship. And that means more costly materials and
processes. That's one of the reasons why Sparrowhawks go for $193 per
pound versus about $100 per pound for a new-run LS-4.

But, at 150 pounds versus 500 pounds, the SparrowHawk would still be
cheaper! I don't know what the economic comparison of pre-preg carbon

Aren't you glad we don't buy gliders like lettuce, by the pound?
I'd pay $20k for a one pound glider is a heartbeat if it had a
polar better than the AC-4 and provided all the other amenities!
Hehe. C'mon Bob, per pound costs don't seem to mean much...


--

------------+
Mark J. Boyd

Earlier, (Jacek Kobiesa) wrote:

... Also, most the european manufacturers
will see a big impact, affecting their
production, because individuals in the
U.S.A. were buying more new gliders then
any other countries...

My understanding is that the US market typically accounts for about
15% of manufactured soaring articles including sailplanes. I haven't
heard of anything about that changing lately.

Bob K.

Earlier, Eric Greenwell wrote:

...Nothing magic about the 13 meters, except it's
big enough that I think a modern design can match
the LS4 in performance (it IS a 24 year old
design, after all!), which has become the de
facto "minimum acceptable performance" for the
more vocal on the newsgroup...

If you think that a modern 13m design can match the LS4 in
performance, then by all means I think you should go on out there and
develop that glider! I know that it can be done; I'm just somewhat
skeptical that the result would be a viable commercial product.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

Bob Kuykendall wrote:
Earlier, Eric Greenwell wrote:


...Nothing magic about the 13 meters, except it's
big enough that I think a modern design can match
the LS4 in performance (it IS a 24 year old
design, after all!), which has become the de
facto "minimum acceptable performance" for the
more vocal on the newsgroup...


If you think that a modern 13m design can match the LS4 in
performance, then by all means I think you should go on out there and
develop that glider! I know that it can be done; I'm just somewhat
skeptical that the result would be a viable commercial product.

Me, too, but not because it couldn't match the LS4 in performance. While
it's per-unit costs would be lower, the start-up costs wouldn't be, and
it would have to compete with all the used gliders plus, apparently, new
LS4s. Currency risks, and a market that seems to be growing slowly (if
at all), and all those skeptics that think 15 meters is a absolute
requirement, regardless of the performance, and it'd take a brave
manufacturer to risk it.

But here's question: we know a modern glider can be smaller than the 24
year old LS4 design and have the same performance. I suggest 13 meters
would do it without heroic efforts by the designer, but what do the
citizens of RAS think is the minimum?


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

Eric Greenwell
Washington State
USA

Looks to me like an APIS 15 polar is pretty much identical to the LS4. The
APIS 13 has a slightly better L/D at lower speeds and slightly worse in the
60-100 mph range. So the 13 is awfully close, but the cost is not much less
than a 15, i.e. 8% less.

Don't know how the price compares to a new or used LS4 or how the APIS
actually flies, but on paper it looks very good. Polar is waay better than
the SparrowHawk, based on the info I've seen.
Wad.


If you think that a modern 13m design can match the LS4 in
performance, then by all means I think you should go on out there and
develop that glider! I know that it can be done; I'm just somewhat
skeptical that the result would be a viable commercial product.

On Wed, 10 Nov 2004 16:17:01 -0800, Greg Arnold
wrote:

He is the fellow who was suing DG over the LS purchase? Maybe the
resolution was that he got the LS-4, and DG got everything else?

I think so... but I'm not the one to answer this question.


In what country will the LS-4 be produced?
I think it's going to be produced by AMS in Slowenia.. This is the
company that has produced the DG gliders in the past and that also
produces and markets the DG-303 and 505 now.

Here's the website: http://www.ams-flight.si/





Bye
Andreas

On Wed, 10 Nov 2004 22:57:27 -0800, Eric Greenwell
wrote:


But here's question: we know a modern glider can be smaller than the 24
year old LS4 design and have the same performance.

Do we really know that?

I believe it when I see one. Frankly spoken, I doubt that this is
possible without major compromises concerning cockpit size and crash
protection.

I need a certain cockpit cross-section to be able to sit comfortably,
so the cross-section of the fuselage (which defines most of its drag)
is fixed, independent of the wing span. Fuselage surface area is also
fixed (apart from the fact that the fuselage will be a little
shorter), so there is very little potential to reduce the fuselage
weight compared to a current glider (say, ASW-28). Proof is the PW-5
which is only slightly lighter than an ASW-28 despite the fact that it
has much lower Vne and maximum weight.


Fixed fuselage cross-section with a smaller wing means that the
fraction of fuselage drag on total drag is going to be greater. As a
consequence the wing needs to save drag - and the only chance to do
this is increased aspect ratio... which will lead to wing loading
problems.

One solution could be to build the whole glider extremely light (like
the Apis or Sparrowhawk) to get normal wing loadings of about 33
kg/m^2 at a high aspect ratio, but this is going to result in the
inability to carry water, low Vne (hence the comparably bad
penetration of the Apis compared to club class gliders with similar
L/D and wing loading) and questionable crash protection.

The Sparrowhawk and Apis look really good and are definitely state of
the art - but to be honest, I would not like to rely on their cockpit
shell strength when I impact at 50 kts or above.



I suggest 13 meters
would do it without heroic efforts by the designer, but what do the
citizens of RAS think is the minimum?

It's not the wing span or weight, its acceptance. And I think history
has shown what kind of glider will be accepted (and bought) and which
not.
How many LS-4 have been sold? 1.400?


Let's face it:
At the moment the Sparrowhaw is sold for $33,950, the LS-4 for 39.500
EUR (VAT not included).
The Sparrowhawk is not that much cheaper, especially if we consider
the fact that it is much smaller and much simpler (no retractable
gear). And, of course, it's not certified (the certification alone is
the major part of the development costs - this is what makes an
aircraft so expensive). Shall we bet that if it was certified the
Sparrowhawk would be at least as expensive as an LS-4?


If we had an exchange rate of 1:1 as we had two years ago, you'd get a
lot more bang per buck with an LS-4, wouldn't you?







Bye
Andreas

Earlier, Eric Greenwell wrote:

But here's question: we know a modern glider can be smaller than the 24
year old LS4 design and have the same performance. I suggest 13 meters
would do it without heroic efforts by the designer, but what do the
citizens of RAS think is the minimum?

I dunno about the others, but I'm betting on the range of about 14.3m
to 14.6m for normal sized US pilots. And that the very first guy who
buys one will ask "So, when will I be able to get 15m tips for it?"

I tend to believe that the legacy of span-limited competition classes
is such that sailplane buyers will tend to gravitate towards
competition spans, even those with very weak inclination to ever
compete. That's one of the reasons I'd like to see a distinct
competition class for sub-15m ships; and I think that 13m would be a
perfectly good place to draw the line.

A 13-meter class would collect all the Russias, Apii (Apia?), PW5s,
and Sparrowhawks, though sadly leave the 14m L33 (TG-10D for
USAFAians) out in the cold. It would give people at least a plausable
excuse to buy these little gliders, and give developers an economic
basis for developing them. And I think that it would be a kick-ass fun
class to fly in, since I'm just the right size for it and I'm used to
flying a few points short of a Libelle.

Thanks again, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24