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Aerowerx

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I figure elliptical in close to perfect..bell shape is normal to a flying wing.
Well, sort of. Maybe. Perhaps. It depends.

If you design a flying wing (with no vertical surfaces) and then optimize it for yaw damping and to eliminate adverse yaw you will end up with something that looks a lot like a bell-shaped distribution. So in that respect bell-shaped could be thought of as "normal" for a flying wing! Knowing this, why not start out planning on the bell-shape? It will save A LOT of trial and error.

And elliptical IS NOT close to perfect. It puts too much lift near the wing tips, which can cause a problem with wing tip stall, which can lead to spins. It also requires a heavier spar to handle the bending moment at the root. Remember bending moment = force x distance. Reduce the force at the wing tip and you reduce the bending moment at the wing root---->lighter spar required.
 
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Speedboat100

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Well, sort of. Maybe. Perhaps. It depends.

If you design a flying wing (with no vertical surfaces) and then optimize it for yaw damping and to eliminate adverse yaw you will end up with something that looks a lot like a bell-shaped distribution. So in that respect bell-shaped could be thought of as "normal" for a flying wing! Knowing this, why not start out planning on the bell-shape? It will save A LOT of trial and error.

And elliptical IS NOT close to perfect. It puts too much lift near the wing tips, which can cause a problem with wing tip stall, which can lead to spins. It also requires a heavier spar to handle the bending moment at the root. Remember bending moment = force x distance. Reduce the force at the wing tip and you reduce the bending moment at the wing root---->lighter spar required.

Very good point Aerowerx.

Wing will fly:
 
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Speedboat100

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Me with silk gloves? lmao...that's great.

Red,

Explain us all the negative aspect of the flying wing the mittel effekt (or mittleren effekt as Reimar Horten put it) and how we can get rid of it in a good flying wing design !
 
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Aerowerx

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Red,

Explain us all the negative aspect of the flying wing the mittel effekt (or mittleren effekt as Reimar Horten put it) and how we can get rid of it in a good flying wing design !
From post #7 in this RC forum:
The forces on a wing are focused on the 25% chord line of each wing panel. In the case of a swept back flying wing, where the 25% chord lines meet at an angle at the center line, the flow associated with one panel interferes with the flow from the other panel producing additional drag due to this "middle effect." The Horton brothers mitigated the middle effect by giving the planform a bat tail which caused the 25% chord line to bend around gracefully from one panel to the other rather than meeting at a sharp angle. You can also see this in commercial jets which have a sharp increase in chord near the wing center by increasing the chord at the trailing edge rather than interrupting the sweep angle of the leading edge.
And I don't think you can get rid of it. Besides, you want the stall (that is, maximum cl) to occur at about 30%-40% of the half span from the root.

I also like this statement from post #4 of the same thread:
So, washout, sweep back, taper, airfoil selection, aspect ratio and CG location all have to be harmonized in a tailless model to achieve stable, trimmed flight. Harmonizing all six aspects of the design which are built into the model makes the successful design of a flying wing configuration more difficult than for a conventional, tailed configuration.
 

Speedboat100

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From post #7 in this RC forum:


And I don't think you can get rid of it. Besides, you want the stall (that is, maximum cl) to occur at about 30%-40% of the half span from the root.

I also like this statement from post #4 of the same thread:

Now you spoiled all the fun of studying from Red.
 

Urquiola

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Speedboat100

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The book by Horten indicated the bell shaped distribution of lift remains their choice and their secret, but there is a recent 'Aviation Week' article about: 'High efficiency wing moves to next test stage', by Guy Norris, Mon 2016-05-02, that indicates this concept was developed by German engineer Ludwig Prandtl. Salut +
http://aviationweek.com/commercial-aviation/high-efficiency-wing-moves-next-test-stage
Ludwig Prandtl was a busy man: https://www.kitplanes.com/prandtl-wing-goldschmied-fuselage/

Red is here too: https://amablog.modelaircraft.org/amaeducation/2017/05/08/manned-prandtl/

Dunne and Lippisch used a rudder: https://en.wikipedia.org/wiki/Tailless_aircraft
 

Red Jensen

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Yes Red could have become the head of my wind turbine teams aerodynamical division...had he answered correctly.
As amazing and prestigious as this sounds, I think I'll pass. :rolleyes: You will be happy to know however that we are doing some prop research as well.....
 

Speedboat100

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As amazing and prestigious as this sounds, I think I'll pass. :rolleyes: You will be happy to know however that we are doing some prop research as well.....
You might be surprised that scientists have discovered that a prop is very inefficient in a wind turbine...a H-Darreus type wind turbine can reach Cp 12% past Betz limit !

My innovation based pitch controlled HD ( H-Darreius ) actually rews faster than anything in the history books so far...but it also endures more Gs than anyone has ever measured in a similar wind turbine before.

Red...you could have become multi billionaire in this project.

https://iopscience.iop.org/article/10.1088/1742-6596/753/2/022056/pdf

Maybe you could shed this light into the wind turbine communities: Using the optimized pitch angle curve depicted in Figure 4a a converged power output, which is ≈12% higher than that of the Betz limit, is determined.

I will do my doctorate degree about this..in the field of fluid dynamics.
 
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Speedboat100

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What is the thing made of? So it can stand those G forces. Carbon fibre?

I figure there happens something else ( that sorta compensates the G forces )...what I am going to find out. This contraption is entirely outa wood..except some bolts, tubes and generator.
 

pictsidhe

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12% past theoretically possible?

Somebody has screwed up somewhere, I somewhow doubt that it was Betz. His limit has been around a long time, and nobody has shown it to be wrong yet.

Ye cannae change the laws of physics, Jim!
 
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