52/1 Performance in a 15M ship at half the weight.

....and since we're spinning a bit off-topic, here's an update on the
whole "new battery technology" front:

http://gas2.org/2009/01/21/silicon-n...hell-approach/

Having batteries store 3x the current charge of the Antares (or the
same charge for 1/3rd of the weight) sounds nice! Peering into my
(cludy, amateur) crystal ball, I'd bet money that these cells are on
the market in 3 years. The global economic climate isn't favorable
for new entreprenurial investments; but at the same time there's
plenty of excess factory capacity around the world right now, lots of
unemployed people to work in the factories, and batteries are going to
be in high demand for the foreseeable future.

Take care,

--Noel

On Feb 27, 2:59*pm, "noel.wade" wrote:
...and since we're spinning a bit off-topic, here's an update on the
whole "new battery technology" front:

http://gas2.org/2009/01/21/silicon-n...ake-two-the-co...

Having batteries store 3x the current charge of the Antares (or the
same charge for 1/3rd of the weight) sounds nice! *Peering into my
(cludy, amateur) crystal ball, I'd bet money that these cells are on
the market in 3 years. *The global economic climate isn't favorable
for new entreprenurial investments; but at the same time there's
plenty of excess factory capacity around the world right now, lots of
unemployed people to work in the factories, and batteries are going to
be in high demand for the foreseeable future.

Take care,

--Noel

Along those lines, I'm very excited about Eestor. I hope they can
produce what they say they can. The power-to-weight ratio would be a
huge advantage for electric aircraft.

snip it's probably not where the real action is going to be in the
future /snip

Certainly not the near future!

2009 Nationals registration counts as of 27 Feb --

15M: 49
18M: 12

And I'd go to the 15M nats too (I have a glider that will do both)
were it not on the east coast!

..02NO

On Feb 27, 4:15*pm, Tuno wrote:
snip it's probably not where the real action is going to be in the
future /snip

Certainly not the near future!

2009 Nationals registration counts as of 27 Feb --

* * 15M: 49
* * 18M: 12

And I'd go to the 15M nats too (I have a glider that will do both)
were it not on the east coast!

.02NO

Agreed! That's why I'm smack in the middle of those 49 15Ms!

But look at what is being built right now, and project that forward a
few years....

Of course, that just means it'll be more fun to beat the snotty-nosed
18m ships with a ratty old 15m, winglets (draglets) be damned!

Is this a great sport or what!

Kirk
66

wrote:

It would seem that the Duckhawk would have more international appeal
as a Standard class (15m no flaps) ship - wonder how it would perform
without flaps?

It sure wouldn't need that 200 knot Vne, would it? Flaps are essential
to get the wide speed range that makes the the 200 knot Vne useful. My
understanding is the airfoil is optimized for climbing and very high
speed flight.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Feb 27, 8:55*pm, Eric Greenwell wrote:

My understanding is the airfoil is optimized for climbing and very high
speed flight.

Eric, that kinda stretches the meaning of the word "optimize" a bit.

Thanks, Bob K.

Bob Kuykendall wrote:
On Feb 27, 8:55 pm, Eric Greenwell wrote:

My understanding is the airfoil is optimized for climbing and very high
speed flight.

Eric, that kinda stretches the meaning of the word "optimize" a bit.

Thanks, Bob K.


It is an optimized compromise.

The DuckHawk wing IS optimised for high speed and low speed flight. A
tremendous amount of effort went into creating a wing that would work
well at slow speeds with the flaps down, and also work very well at
high speeds with flaps up.

Additionally, Greg did a lot of analysis of how to maximize the cross
country speed. To simplify greatly, the result was to climb really
fast and run really fast. That actually simplified things a little
with the flaps. Basically, one would fly with flaps down while
climbing and then transition directly to flaps up and run fast to find
the next thermal. Intermediate speeds and flap positions were not
that necessary. So, the flaps up/high speed case and the flaps down/
low speed point were optimized. Of course, in the real world, there
might be times when you don't want to do exactly what the theory says,
so last I heard, the flaps will just have 3 positions: up, zero, and
down (a landing position was discussed, but I don't know if it is
incorporated). Quite a lot of effort was also made to give a fairly
wide performance range to each position. So, while it is optimized
for run and climb, there won't be a big hole in the middle of the
polar.

Doug T.

On Feb 28, 6:46*am, Bob Kuykendall wrote:
On Feb 27, 8:55*pm, Eric Greenwell wrote:

My understanding is the airfoil is optimized for climbing and very high
speed flight.

Eric, that kinda stretches the meaning of the word "optimize" a bit.

Thanks, Bob K.

On Feb 27, 11:55*pm, Eric Greenwell wrote:
wrote:
It would seem that the Duckhawk would have more international appeal
as a Standard class (15m no flaps) ship - wonder how it would perform
without flaps?

It sure wouldn't need that 200 knot Vne, would it? Flaps are essential
to get the wide speed range that makes the the 200 knot Vne useful. My
understanding is the airfoil is optimized for climbing and very high
speed flight.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes"http://tinyurl.com/y739x4
* * * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Climb and glide scenario has been going out of favor as optimum
strategy for many years now in favor of extended glide techniques that
optomise cross country speed by minimizing circling and using long
periods of time in the mid to high range to maximize speed made good.
This requires a glider with excellent performance through the whole
speed range which likely will mean that very low speed and or very
high speed are less favored.
Optomising for really high speeds is great for ridge and wave, but not
much use other than final glide in most soaring environments.
It is good to see guys like Gred and Bob giving it a shot.
FWIW
UH

On Feb 28, 12:43*pm, wrote:
On Feb 27, 11:55*pm, Eric Greenwell wrote:



wrote:
It would seem that the Duckhawk would have more international appeal
as a Standard class (15m no flaps) ship - wonder how it would perform
without flaps?

It sure wouldn't need that 200 knot Vne, would it? Flaps are essential
to get the wide speed range that makes the the 200 knot Vne useful. My
understanding is the airfoil is optimized for climbing and very high
speed flight.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes"http://tinyurl.com/y739x4
* * * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Climb and glide scenario has been going out of favor as optimum
strategy for many years now in favor of extended glide techniques that
optomise cross country speed by minimizing circling and using long
periods of time in the mid to high range to maximize speed made good.
This requires a glider with excellent performance through the whole
speed range which likely will mean that very low speed and or very
high speed are less favored.
Optomising for really high speeds is great for ridge and wave, but not
much use other than final glide in most soaring environments.
It is good to see guys like Gred and Bob giving it a shot.
FWIW
UH

Good point Hank. Cruise speeds have been coming down, though an
analogous set of principles apply. Still a lighter, smaller airframe
should be able to add a 5-10 knots in cruise speed and you'd think
they could design around that.

9B

9B