Verhees Delta brain fart

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Topaz

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what airfoil would be appropiate?' A zero negativ pitch foil?
As always, the one that best matches the needs of your particular design. If you're going to use trailing-edge control surfaces on a tailless design like the Verhees Delta, then a positive pitching-moment airfoil will be necessary. How much positive will depend on the particulars of your specific configuration and the mission profile.
 

Aircar

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Auto- that foam indoor electric CriCri is fabulous !-reminds me of the FESTO flapping bird --this could be a way of investigating some characteristics of weird configurations without a wind tunnel or needing still air outside --even with a control line phase indoor at higher speeds perhaps . Now, where is there a big empty building close handy....

The photo of the Dyke Delta showing wrinkling of the wing skins is probably caused by the bending moment buckling the thin unsupported glass sheeting --it was very noticeable on Sander Ve Enstra's ultralights with a tubular aluminium spar and the ribs going around it with the skin furtherest out --not visible from below the wing (the cockpit in flight) but even just lifting a bit from the tips created enormous waves ---why the underside is buckling on the Dyke is possibly due to torsion or even just dynamic pressure (even to thermal shrinkage of the steel substructure as a possibility )
 

Dannz

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Perhaps he would sell the prototype, we could then remodel and refine it's structure and surface to produce a more aerodynamic craft. Are Mr. Verhees's contact details available?
 

Sockmonkey

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I'm kind of stuck on the notion of a prone pilot electric pusher delta like so. The proportions are a bit off since this was just a quick and dirty design but it gets the idea across.
 

Head in the clouds

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I'm kind of stuck on the notion of a prone pilot electric pusher delta like so. The proportions are a bit off since this was just a quick and dirty design but it gets the idea across.
Full-scale pusher deltas are fraught with problems unfortunately.

As shown in your illustration the props would be subject to large amounts of FOD from debris thrown up by the main wheels AND you'd have to have impossibly tall landing gear legs to prevent prop-strikes when taking off or landing.

The tendency then, is to move the thrustline up and keep the props entirely above the wing but that has its own set of problems because it causes a nose down pitching effect which has to be overcome by the elevons which, even power-off, are already hugely decreasing the lift of the mainplane when reflexed sufficiently to raise the nose i.e. the elevons reduce the CL of the wing just at the time when you most want the CL to be at its highest. That's where a canard or fin mounted elevators come into their own.

I've spent a lot of time looking at possible configurations for deltas and for my money I'd stick with a tractor propeller in the nose and that's easily done if you're considering electric. Alternatively you could have a pair of electric motors mounted on the leading edge of the wing like the image below.

Don't be fooled by what models can do with high thrustlines, they have far greater power-to-weight ratios than full-scale sport aircraft can achieve.

DeltaRay.jpg
 

Sockmonkey

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Yeah, the issues with a high thrust-line seemed worse than the landing gear issues and I intended tandem wheels to minimize the FOD in the props.
This is about how it would be with tractors.

I really want to stick with a prone pilot both for streamlining and to improve the landing visibility that tends to be an issue with deltas. That means stick with twin props though at that point it may be better to stick with this.

I probably went way overboard with the beefy-ness of the landing gear. Still torn as to if this should use fixed gear or not.
If STOL isn't vital the props could be about half that size, and yes I'm still thinking electric.
 

Riggerrob

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Fixed versus folding undercarriage is mainly determined by cruise speed. Cirrus, Lancair 4/Cessna Columbia and RV- series has proven that if you plan to cruise less than 200 knots, fixed gear is good enough.
Otherwise folding gear just increases complexity, weight and the risk of landing wheels up.
 

Aesquire

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I want that mini XF5U.

2 questions.

Prop arc will be in front of the canopy, right? Definitely in front of your head. ... ?

How do you plan egress? Crawl over the top and close a canopy? Bomb bay doors, and crawl up and strap in?
 

Sockmonkey

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1:The props don't stick past the canopy. They have plenty of side clearance though, and if it's a significant safety issue the shafts could be made a little longer.
2:Top entry with a canopy seems most practical. Also easy to get out in case of a hard landing causing gear failure.

Regarding the gear, this is an alternate design based on the Horton wingless.

This one doesn't rely on the prop-wingtip interactions that the XF4U does, instead the fixed gear housings double as endplates for the low-aspect straight wing.
 
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