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Old Jun 27, 2008, 07:01 PM
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Build Log

2008 SSDC - Oblique Dynamic Soaring


Name: Geode
Category: open/crunchy
Project Name: Oblique Dynamic Soaring
Build Thread: here
Design Goals:

To answer following questions about oblique flying wing (OFW)

- Can OFW soar on the slope without motor?
- Can OFW fly with 2~3 control surfaces?
- Does OFW preserve the benefits at subsonic speed?
- Is there any benefit for dynamic soaring with OFW?

Be the first ODSing flying wing ..... I hope
Last edited by Geode; Jun 13, 2009 at 10:26 AM.
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Old Jun 27, 2008, 07:07 PM
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Background Information


Oblique Wing (from Wikipedia, the free encyclopedia)

An Oblique wing is a variable geometry wing concept. On an aircraft so equipped, the wing is designed to rotate on center pivot, so that one tip is swept forward while the opposite tip is swept aft. By changing its sweep angle in this way, drag can be reduced at high speed (with the wing swept) without sacrificing low speed performance (with the wing perpendicular).

DARPA oblique flying wing ..... this is cool

DARPA Oblique Flying Wing (0 min 26 sec)
Old Jun 27, 2008, 08:16 PM
Cory is offline
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I DS slower than I build!
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Are you putting a SAS in that? (Stability Augmentation System) It'll sure be cool if you get it to work.
Old Jun 27, 2008, 08:39 PM
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Really really really cool. Thoughts on control surfaces? If you had two "elevons" the more aft one would be an elevon/elevator and the one on the side that is more front (possibly even partly in front of the cg) would be just an aileron? Hmmmm. Maybe 3 control surfaces? Hmmm... Thin wing with fuse or thicker wing with no fuse?
Old Jun 27, 2008, 09:36 PM
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The problem that NASA had with their oblique wing project is that when the wing is at high angles to the fuse, the ailerons begin to have a pitch effect as well as roll so it kind of mixes weirdly. It was because the ailerons suddenly became placed in between the pitch and the roll axes instead of being directly on the roll axis.

I'd like to see this working. Are you going to have it be variable geometry or fixed?
Old Jun 28, 2008, 01:00 AM
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Not really sure what to do on control surface at this moment (that's what I'm trying to find out through this build thread. Don't be surprised if I dropped out half way ). A few thoughts, basically follwiing Dr. Jones' prior work.

Oblique Flying Wing on CNN (2 min 56 sec)


I'll keep the control surface as flexible as possible on the prototype (could be 3~4 control surfaces) and count on my EVO Tx to trim it right. Once set, I hope I could reduce the number of servos.

I also plan to start with a few "fixed" flying modes (such as normal, 30 deg and 60 deg modes) with manual adjustment on vertical tail. Once set/trimmed for each fly mode, I plan to add one servo controling a full flying vertical tail and use "fly mode switch" to change oblique angles. No fuse planned at this momnent to make the building simple.

As for SAS, looks like I need to count on my two thumbs and EVO Tx .

Geode
Last edited by Geode; Jun 28, 2008 at 01:29 AM.
Old Jun 28, 2008, 06:05 AM
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hmmm wont the ailerons work like an elevator? ooh its giving me a headache just thinking about it!
Old Jun 28, 2008, 06:13 AM
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Why not try the AD-1? At least you've got a tail group.

NASA's Ames Dryden AD-1 Pivoting (Oblique) Wing plane (1 min 7 sec)


Last edited by mr_editor; Jun 28, 2008 at 06:14 AM. Reason: Image size
Old Jun 28, 2008, 11:41 AM
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That's a good ideal. If ODS flying wing doesn't work, I'll just add a tail group and go ODS AD1 .

Here is a draft version of ODS flying wing at 45 degree oblique angle. Vertical tail is removable with plug-in CF tube/rod.

Now the question is .... should I turn left or turn right for ODS'ing (i.e., the vertical tail should be on the R- or L-hand side)?

Geode
Old Jun 28, 2008, 11:46 AM
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That does look sweet. Better get my SSDC design drafted.
Old Jun 28, 2008, 11:50 AM
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One additional question, forget the aileron/elevator problem, what happens to the CG when you shift the wing? Is the perceived chord longer so the CG position is less critical? And forward swept wings have structural twist issues, so what happens there? And what about washout.

i must go lie down. My head hurts.
Old Jun 28, 2008, 12:11 PM
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My head hurts too.

CG - Will do some free-flight model to check it out.

Washout - will do zero washout. But like to add some transitional airfoil for aerodynamic washout.

Wing twist - I do not have a fuse. Should not be as bad as conventional configuration. This is also part of the planform/airfoil optimization to minimize the twist.

BTW, I'm not sure if OFW is swept forward or backward .
Last edited by Geode; Jun 28, 2008 at 12:29 PM.
Old Jun 28, 2008, 01:20 PM
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Quote:
Originally Posted by mr_editor
One additional question, forget the aileron/elevator problem, what happens to the CG when you shift the wing?

i must go lie down. My head hurts.
I think that if you pivot the wing on it's CG then there should be no issues concerning the CG of the aircraft. However, I'm not sure where the wing would have to pivot - either on the CG or on the center of lift.

Quote:
Originally Posted by Geode
BTW, I'm not sure if OFW is swept forward or backward
It's both!
Old Jun 28, 2008, 07:02 PM
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That looks more like a surfboard than a wing
Old Jun 28, 2008, 08:32 PM
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Good idea.

Here is where I fly. Once done with front side ODS'ing, just flip it and go surfing, I mean "OS'ing" .
Last edited by Geode; Jun 28, 2008 at 09:20 PM.


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