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Old Dec 08, 2010, 10:44 AM
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Phil Davy's Avatar
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F3B & F3F rules on airfiol shape shifting! Sceptics welcome!

Ok, I am just a dork when it comes to rules of competition, but... What if we changed the airfoil in flight? Servos that change the aspect ratio or camber or any other thing we want of the wing at the precise time we need speed or to manage effiency of the airfoil? It can be done. It was outlawed in F1 (Formula1 competition) but it can be done in a number of ways! Check out this vid and see for yourself. Call it Frightfull technology from the master herself! This is a 2LB bird!

High-Velocity Falcon (2 min 59 sec)


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Old Dec 08, 2010, 12:16 PM
Eggcellent...
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Originally Posted by Phil Davy View Post
What if we changed the airfoil in flight? Servos that change the aspect ratio or camber or any other thing we want of the wing at the precise time we need speed or to manage effiency of the airfoil?
I kinda thought we had camber changing now. The variable span/aspect ratio thing was actually built as an F3B plane about 20 years ago. Didn't catch on.

Tom
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Old Dec 08, 2010, 12:44 PM
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QUOTE=tewatson;16767446]I kind of thought we had camber changing now. The variable span/aspect ratio thing was actually built as an F3B plane about 20 years ago. Didn't catch on.

Tom[/QUOTE]

Camber changing yes but not in tandem with airfoil changing Tom. Explain what you know. Even with my limited experience it is not hard to understand that one shape can do everything all the time! I grew up with the Gurney Family (Dan Gurney, the only Man to ever design build and race a F1 car to victory in history), his Son’s where best friends of mine since my young days, I spent some time with aerodynamics and access to Hiro's full circle wind tunnel. There are only a couple of those in the whole country. Have you ever seen one? It can be done. But at what cost in weight? That is the question. And when we figure it out if will it be accepted in competition? Look at the bird! Hyper streamline flight. A 2LB bird going 242MPH! Doesn’t that raise your eyebrow? You are an engineer right? Thanks for the spirited reply! No offense dude, but we have to look at the obvious. Shape shifting!

Phil
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Old Dec 08, 2010, 01:26 PM
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Structural integrity

It is an interesting concept, but in model aircraft we need to maintain structural integrity for the whole flight, and with the small and thin airfoils we utilize, it seems mechanically impossible with a typical sized glider....if you look at what the bird was doing in the dive (which was amazing!), it is reminicent of a swing wing fighter...but the bird is flesh and muscle, ie: lots of "servos" to shape shift each surface (feather)....my 2 cents
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Old Dec 08, 2010, 01:43 PM
yyz
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One of the new approaches in full-scale soaring is to use suction to manage the airfoil's boundary layer (eg, drawing air into the wing near/before the separation point). There is some research being done at Delft right now if I remember correctly.

Blowing air to trip the airflow early has been done for 20 years. Acoustics have also been tried to manage flow.

Not sure how laminar the state-of-the-art F3B airfoils are but I would imagine well past the aileron/flap hinge line. Would be interesting to see what some of folks with aero/fluids expertise have to say.

Interesting topic,

Mike
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Old Dec 08, 2010, 01:52 PM
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Impossible?

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Originally Posted by ScottCondon View Post
It is an interesting concept, but in model aircraft we need to maintain structural integrity for the whole flight, and with the small and thin airfoils we utilize, it seems mechanically impossible with a typical sized glider....if you look at what the bird was doing in the dive (which was amazing!), it is reminicent of a swing wing fighter...but the bird is flesh and muscle, ie: lots of "servos" to shape shift each surface (feather)....my 2 cents
Is that what you say Scott My freind in big wind? (And He rips). Servos can be 1/10 of an OZ, little servos for little movements! Maybe it is not worth it? (Winning within the rules in F1 was banned because of increases in technology)? Don't cut yourself short! Smart always wins, (unless rules slow you down). But ask the F1 Teams how that slows them down! The Euros will go forward without U.S.!
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Old Dec 08, 2010, 03:08 PM
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The Euros will go forward without U.S.!
...And then we will buy the good stuff from them like we do now
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Old Dec 08, 2010, 04:21 PM
F3B and F3K
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I just quickly mention what to my best knowledge has been tried in F3B in that respect:

-variable wingspan: Tele F

-moulded plane with variable wing thickness (don't remember the name, but it could withstand a winch launch, but pneumatic mechanism was a bit heavy and slow)

-wing with two hingelines for flaps and ailerons, Shark, Logo Team. It worked excellent, but the conventional linkage was a pain in the ass. They could make the overall chord of the two segmented flap much deeper than on wings with only one hingeline.
DC 10 and MD 11 have multi-hingeline rudder to enhance efficiency.

-all moving tailplane with hinged elevator surface: idea: camber change via hinged elevator for high cl, all moving tailplane to adjust "best" angle of attack of the tailplane while flying a turn radius.

-Wing with slats (Daryl can tell you more, his wing had 12 servos)

Among these planes, some concepts are still highly interesting.

*With RDS, one could re-visit multihingeline surfaces. This would allow much smoother camber changes of the airfoil. The RDS rod would have multiple bents instead of one.

*Slats should enable massively increased AOA and higher CL for winch launch. The wing might not even stall in this configuration.
Daryl knew that a long time ago, so not all innovations come from Europe.

*If one would find a simple kinematic for the all moving tailplane with an additional hinged elevator surface, this would be worth a try.

Reto
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Old Dec 08, 2010, 05:12 PM
yyz
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*If one would find a simple kinematic for the all moving tailplane with an additional hinged elevator surface, this would be worth a try.
Reto
Didn't the Altus have a very clean, all-flying stabilizer? Seems like you could redesign the stab to also have elevator surfaces driving them with RDS on each side. Then it's "just" a matter of mixing the three servos to get the action you want.

I did something like this on a large scale ship and it's "doable" but have yet to prove the real worth vs flat-out nerd factor,

Mike
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Old Dec 08, 2010, 05:21 PM
Deniable plausibility
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I'm not sure that at model scale, we can achieve variable profile geometry AND adequate strength to weight ratio. However, it could be possible to achieve something like that which was fitted to the full-size Sigma sailplane (see attached). Maybe this could help with [at the very least] launches at high weight?
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Old Dec 08, 2010, 05:21 PM
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Man you smart guys are on it!

Sounds like Greek to me (sorry Grecians) but that is why I spoke up! I saw this video and it seemed like it could happen!

Hey Reto, again, great constuctive comments...

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Old Dec 08, 2010, 05:25 PM
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Shed, nice dude!

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Originally Posted by Shedofdread View Post
I'm not sure that at model scale, we can achieve variable profile geometry AND adequate strength to weight ratio. However, it could be possible to achieve something like that which was fitted to the full-size Sigma sailplane (see attached). Maybe this could help with [at the very least] launches at high weight?
That is interesting! You Guys are smart! See what a question can do!

Hmn...

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Old Dec 08, 2010, 06:51 PM
F3B and F3K
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Originally Posted by yyz View Post
Didn't the Altus have a very clean, all-flying stabilizer? Seems like you could redesign the stab to also have elevator surfaces driving them with RDS on each side. Then it's "just" a matter of mixing the three servos to get the action you want.
Mike
Of course you want to keep the elevator servo (s) in the nose. There are kinematics with one or two bellcranks using one or two servos.

I made two sketches. The first one should be obvious, you use either two servos or if you use one, you adjust the leverage between bellcranks and servoarm.

The second one would work with only one bellcrank, which is offset to the rotation point of the tailplane. Owing to the offset, the elevator surface will be cambered when the incidence angle is changed.

I would need to write a little Mathematica file to optimize the geometry, but it would be doable.

Reto
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Old Dec 08, 2010, 07:00 PM
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Control inputs, snap flap, reflex are all "shape shifting" The idea is to get shape shifting without a lot of complex, heavy structure.
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Old Dec 08, 2010, 07:54 PM
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Tele-F collapsable/extendable wing in action
http://www.rcgroups.com/forums/showthread.php?t=1315244
see the video in first post - amazing stuff

Phil.
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