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Old Feb 22, 2002, 05:14 AM
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United States, CA
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Spoilerons on Flying Wing

Hi all,

Need some advice. This might get fuzzy; maybe too many variables involved for a simple answer, but here goes.

Id like to use spoilerons on a flying wing glider having planform similar to a Zagi, but bigger overall.

Given a FW's pitch sensitivity, will spoilerons create a strong (relative to a conventional glider) pitching moment? If so, is there an optimum chordwise location to install spoilerons in order to offset pitching, and is it possible to accomplish this over a broad speed band?

I'm envisioning spoilers deployed at something like 45 degrees, instead of 90, in order to create a downward force where, if the center of this downward force is strategically positioned per above, would negate the pitching moment created by the spoilers' drag (horizontal) component. Or just forget all this and mix-in elevator compensation?

Re roll authority at low speed (spoilers deployed) - I plan to have ballast compartments located fairly far outboard to dampen roll sensitivity to wind buffeting. Any rules of thumb (specific to FWs) as to spanwise location of spoilerons to achieve good balance of lift dumping vs. roll authority? >>> Or just a bad idea?, i.e. should just use plain spoilers and rely only on elevons for roll control?
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Old Feb 22, 2002, 09:25 AM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
Erm.. I'm a little confused .. you have elevons - two control surfaces (total) that with mixing to control roll and pitch by acting as ailerons and elevator. Spoilerons are when you use ailerons as spoilers, raising both ailerons together to kill lift. On a model without a tail, however, this is your pitch control. i.e. elevator, so it is not possible to use your ailerons as spoilerons, except in that at ultra low airspeed, more 'up' elevator is required to maintain altitude..
..a
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Old Feb 22, 2002, 09:38 AM
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I should have clarified - The "spoilerons" would be physically identical to regular spoilers, i.e. flat panels popping out of the wing, so I'd actually have 4 surfaces. Rather than ailerons used as spoilers, I'm considering spoilers (partially-deflecting) used as ailerons, in addition to the elevons.
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Old Feb 22, 2002, 01:36 PM
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Steve Fehr's Avatar
Chesapeake, VA
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There are other spoilerons- the P-61, for example, has full-wing flaps and no ailerons. It steers entirely by spoilerons which are otherwise conventional spoilers (at about 2/3 chord) deployed differentially to impart roll. I believe Ziroli P-61s use them successully in model aircraft... I wouldn't even venture to guess the effect on a wing, tho!
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Old Feb 22, 2002, 03:20 PM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
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Now I understand. Sorry, I have never heard of or seen this, but it's obviously been done with some success in the past.

Does seem like a rather complex way to approach it, however - plain old spoilers to kill lift and elevons for the rest seems like a simpler approach. If we wanted a simpler life, however, we wouldn't be here, right!!
..a
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Old Feb 22, 2002, 05:12 PM
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Olathe, KS (next to the Castle)
Joined Jun 2001
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Rigid wing hang gliders use spoilerons for turn control. One spoileron deployed not only kills lift lowering than wing, but also creates drag which yaws the wing. If done right the wing will do coordinated turns with the spoilers. The hitch is these wings use weight shift for pitch not moving surfaces.

Spoilelerons are usually place on or behind the highest camber point on the top of the wing along the pitching access. To achieve this you need to have a wing with low sweep.

You mentioned a Zagi as a comparison. With spoilelerons you won't have an aerobatics wing because you will not be able to roll with them.

Check out http://www.hang-gliding.com/atos.html
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Old Feb 22, 2002, 05:13 PM
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It's supposed to provide excellent low-speed control and reduce tendancy to tip-stall; might be worth playing with if you've got a computer radio and a flaperon equipped sailplane with discrete spoilers? EG, with flaps and spoilers fully deployed for landing, aileron control would be mixed into the spoilers...
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Old Feb 22, 2002, 06:30 PM
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rpage53's Avatar
Victoria, BC, Canada
Joined Apr 2001
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Re: Spoilerons on Flying Wing

Quote:
Originally posted by green66
Id like to use spoilerons on a flying wing glider having planform similar to a Zagi, but bigger overall.
Spoilers on flying wings are fairly common starting with the Horten German planes of the '40's.
http://www.geocities.com/nedu537/go229/
They can be used for pitch and roll control or just to reduce lift. Sounds like you just want to reduce lift, but the specific locations and pitch effects really depends on all the rest of your design.
The short answer is that yes they can be made to work.
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