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Sig Wonder planform

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cluttonfred

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This post came from the Flying wing as cheap and simple option for basic fun flying. thread, but since that is now up to 78 pages and over 1,500 posts, I thought I'd start a new thread. I'd really like to explore this planform, not changing it to a delta or a pure plank or anything else.

What are the pros and cons of this planform and how might this work at full human scale? It would be short-coupled (but not as bad as a plank) and you'd have to pay special attention to stall behavior and the transition from the long-chord center section to to short-chord outer panels. Would wing fences from the leading edge to the vertical fins be a useful addition? Vortex generators on the outer panels? Stall strips on the inner panels? I don't know, but my gut tells me this planform has some real potential for a sport plane.

Cheers,

Matthew

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For those like me that had to look up the Sig Wonder:

wonder plan.jpgwonder 1.jpgwonder 2.jpgwonder 3.jpg

It's a very interesting design. From the point of view of a homebuilt aircraft project, it could be easily broken down into a number of smaller parts for easy assembly, transport, and storage. Imagine a fuselage pod with engine and landing gear that ends at the projected trailing edge of the the ailerons, a long-chord wing center section mounting the elevator, fins, and rudders, and two outer wing panels. The canopy would actually be mounted on the center section which in turn sits on top of the pod.

Thinking of the planform as four squares arranged in a T, if those outer panels were 7' chord and 7' span each, and the center section 7' span and 14' chord, you'd have 196 ft of wing area on 21 ft span for an aspect ratio of 2.25. That's a lot of wing area in a small package so you can use low wing loading to make up for high induced drag. At 750 lb gross weight with a basic 55 hp VW conversion I get 33 mph stall, 82 mph 75% cruise, 91 mph 100% max, 1100 fpm climb, and 700 fpm power off sink rate.

Take the exact same exterior shape and crank it up to full LSA gross weight of 1320 lb and you have a stall speed of under 44 mph but you need a lot more power to make it work. 100 hp gives you 111 mph max and 100 mph cruise and a climb rate over 900 fpm but a power off sink rate also over 900 fpm.

Keep in mind that all these numbers assume a max CL of 1.4 and do not properly account for special behavior of low aspect ratios. Still, my takeaway is that something like this could make a great single-seat fun flyer but is less attractive once you move up to LSA weights.

While not the purest form of a flying wing, how would a human-carrying Sig Wonder work out? One wouldn’t easily fit in a container but you could probably pack a whole bunch of them in a club hangar
 
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