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J.L. Frusha

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Been fiddling with an ultralight design, figured it's time to get a bit more serious...

Wing Calc. puts CG ~3/4 in ahead of the V.
Expect to use the 1/2 VW engine w/~32 in prop.

Wing calculation does not include the Junkers Control Surfaces.

Mechanical mix Flaperons, Leading edge Slats, 2 x 2 Aluminum Fuselage with welded reinforcement,.
Wing construction loosely based on the Chotia Woodhopper and Gypsy design, using Foam-filled Carbon Fiber Spars
and possibly Tensegrity ribs and reinforcement, with struts as necessary, perhaps vacuum-infused CF skins.

Initial design:

1642762723793.png
 

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J.L. Frusha

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Can't read the small print. Confirm it is a flying wing, no horizontal stab.
Yes, it is a Flying Wing design, with the elevators as part of the wing. There is no horizontal stabilizer.

The design is basically a modified gyrocopter. with a flying wing in place of the rotary wing.
 

J.L. Frusha

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Have you considered mounting the wing on a pivot (AKA Sprat Control Wing) like the gyro gimbal for the rotor head on the gyro?
Not really. My main goal is for STOL capabilities. I'm not certain that the planned features are compatible, but I will look into it.
 

jedi

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From the Flying Plank thread:

Just one opinion on how to work with the narrow CG range of the plank flying wing.

The Spratt control wing hangs the variable payload below the wing on a fixed pivot point. It adds a tail defeating the simplicity of the plank but the pilot needs some place to put the body regardless and this allows the pilot compartment more freedom to fit the needs of the pilot. It also allows a lifting tail without destroying the stability of the aircraft.

Combining the pendular pitch control of a hang glider with the tail of the Sprat Control Wing may be a good hybrid solution. My preference is to use the weight shift for trim and the tail for aerodynamic pitch control and additional lifting surface for a low speed landing.

I think this would work well for your configuration. You have the tail for the vertical stab why not mount a horizontal surface also. The gyro people discovered this advantage long ago.

The wing pivot idea may require a repositioning of the engine for proper CG of the free wing but this is a good thing if you can work out the prop clearance issues.
 

jedi

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A search wth the HBA search function found this as a reference:

 

J.L. Frusha

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@jedi

The Pratt Control Wing negates at least half of my high lift 'devices'... The Junkers 'Flaps' control surfaces. Spratt isn't going to do what I want to do.
 
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My main goal is for STOL capabilities.
STOL and flying wings are generally considered mutually exclusive parameters. However.................................
With forward swept flying wings the 2 parameters may be able to be more closely aligned. Keep in mind that forward sweep introduces aeroelastic twist that is backwards for good/safe stall progression with normal ailerons. You may be able to 'cheat' a little with the Junkers.

Think of a forward swept wing as "We just hide the canard" rather than "We just hide the tail"

You may have started with a Gyro frame but the result looks very Marske-ish.

Yes, Spratt can do what you want, and very effectively. Doing so requires a rather complex control system.
 

J.L. Frusha

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@Hot Wings

Marske Monarch was a big, initial influence. I couldn't work out the wing/CG and make it look right. Didn't like the single wheel too much, either.

Looking more for stick-n-rudder, than hang glider 'weight-shift' style controls.

By and large, I'm looking to make it able to use a high angle of attack at both take-off and landing (something approaching 45*. I'll take all I can get), which is why I chose the combination of Forward Swept Wings, LE Slats/Slots and Junkers 'Flaps' for control surfaces (swiped from Stuka). Breaking the 100sq ft mark helps assure that Part 103 UL stall speed.

Probably make the LE Slats like a smaller wing and install in a notch, if I stay with this wing design. If I hang them right, I can 'tune' them, somewhat, rather than make a static copy that needs more work.

Going to need a fuel pump, due to engine location. 5 Gallon fuel-tank/seat will help put the variable weight (including pilot) at the CG. I can put a sliding battery tray on the boom for the rudder pedals, to adjust the CG, since th engine and prop are behind the CG.
 

J.L. Frusha

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Control wing is how you can get the high angle of attack. With a fixed wing the gear legs get very extreme.
The tires (Port and Starboard) are 15-16 in diameter. In straight and level, the seat is no more than 2 ft above the bottom of the tires. That isn't extreme, by any measurement. Hell, my @$$ is higher than that.
 

Victor Bravo

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This is the perfect case for 3 foot R/C "foam and tape" test models. Make as many wacky configurations as you like, using the same materials, same motor/battery/servos, the same span or wing area, ballast them to the same weight... and see which ones perform better. Seriously, that will give you better and more useful information than tens of thousands of dollars' worth of CAD, engineering time, CFD, wind tunnel, having a seance with Dr. Wortmann and Max Munk, etc.
 

J.L. Frusha

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This is the perfect case for 3 foot R/C "foam and tape" test models. Make as many wacky configurations as you like, using the same materials, same motor/battery/servos, the same span or wing area, ballast them to the same weight... and see which ones perform better. Seriously, that will give you better and more useful information than tens of thousands of dollars' worth of CAD, engineering time, CFD, wind tunnel, having a seance with Dr. Wortmann and Max Munk, etc.
I have 1 sheet of foam-board, no rc equipment whatsoever and a very limited income.

If I do the 1/2 wing glued on top of the main wing, I can make 1 glider with about a 2 ft span... 1 in : 1 ft is as close as I can get.
 

TFF

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Chinese RC equipment is very budget friendly. I would make 5-6 ft span. As much as I love small models, they hide a lot of sins. Make it fly without the slats first.
 

Tiger Tim

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I have 1 sheet of foam-board, no rc equipment whatsoever and a very limited income.
One hundred foam board RC models will be cheaper than finishing your full-scale, finding you’ve made a terrible mistake, and having to start over. Because you’re combining things that really haven’t been done before (versus drawing up yet another Cub-like airplane) it’s fair to expect a learning curve and some changes along the way.
 
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