question: delta winged boost gliders
doug holverson
for figuring out the elevon/elevator deflection for a delta winged boost
glider?
-DGH-
IDT407
Doug,
About the only formula that applies in this case is TLAR . Once the model
is flight ready, you go into the yard and apply the TLAR (That Looks About
Right) principle to the elavators. There really isn't any true way to test this
except take it out and glide test it . I've built and flown many B/G's of
different kinds and it's what ya gotta do. There are just too many varibles to
figure it any other way.
Even after getting a good glide by hand testing it, you still cannot be sure
until its launched. I've beautiful gliding birds nose dive or porpoise badly
when launched.
Wish I had better news for you.
Mike - launchin since ' 65
BULLPUPP
>Mike - launchin since ' 65
>
>
atronmike incognito????
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The Silent Observer
Only one I can think off offhand; if you need more than about 30 degrees
deflection to do the job, you don't have enough area. Beyond 30
degrees, while you still get rotation, you also get a "reverse flap
effect" that reduces the lift of the whole surface even as it rotates --
this can lead to a stall.
That said, if you're talking about a boost glider instead of an R/C
rocket glider, you can probably get away with a strip along the entire
trailing edge comprising around 10% of the total delta area.
--
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Donald Qualls, aka The Silent Observer NAR # 70141-SR Insured
Rocket Pages http://members.aol.com/silntobsvr/launches.htm
Opinions expressed are my own -- take them for what they're worth
and don't expect them to be perfect.
doug holverson
----------
In article <3605A857...@ix.netcom.com>, The Silent Observer
<sil...@ix.netcom.com> wrote:
>doug holverson wrote:
>>
>> Does anybody know any formula, software, spread sheet, rule of thumb, etc.
>> for figuring out the elevon/elevator deflection for a delta winged boost
>> glider?
>
>Only one I can think off offhand; if you need more than about 30 degrees
>deflection to do the job, you don't have enough area. Beyond 30
>degrees, while you still get rotation, you also get a "reverse flap
>effect" that reduces the lift of the whole surface even as it rotates --
>this can lead to a stall.
>
>That said, if you're talking about a boost glider instead of an R/C
>rocket glider, you can probably get away with a strip along the entire
>trailing edge comprising around 10% of the total delta area.
>
Actually, this is a rocket glider. It's sort of an Astron Space Plane
updated so the engine doesn't eject with an Yitah Wu style sliding engine
device to shift the CG and trip the elevons. It has a 15" span, 4" root, 2"
tips, and .75" wide elevons. Anyway, I launched it today and the CG wasn't
quite far enough ahead for boost and it then flat-stalled on glide. The next
one will have twice the CG shift and 5° of elevons instead of 10°.
I'm playing around with Glider Design 1.2.1 (old cheeseware for the Mac),
which doesn't do deltas but I'm trying to kludge it my treating the main
part of the delta as the wing and the elevons as the tail and then
positioning the tail so it has 1/3 the span (and area) and three times the
moment arm to cancel each other out. It spits out deflection results in the
1-3° range.
-DGH-
Bill Standing
"Basics of R/C Model Aircraft Design" by Andy Lennon. You might be able
to find it in your local hobby shop.
Bill Standing
doug holverson wrote:
>
> Does anybody know any formula, software, spread sheet, rule of thumb, etc.
> for figuring out the elevon/elevator deflection for a delta winged boost
> glider?
>
> -DGH-