Flying wing as cheap and simple option for basic fun flying.

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jedi

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You're welcome to think that.

Personally, working with low to intermediate aspect ratios, I know the data from xfoil doesn't appear correct. I tried, hired an aero eng to figure my garbage in/out issue - it wasn't me/my data. He did a reasonably optimized tip using xfoil - it was worse than square tips.

1/3 scale and swapping asymmetric tips gives a decent data point with trim settings. Let's one quickly see better / worse. Swapping out to pairs for stall/max speed testing is more accessible than wind tunnel time.

A commercial airliner wing vs a homebuilt wing are vastly different in optimization - ones designed already to limit losses ones designed mostly for ease of construction.

I'll get some data points hopefully soon - new datalogger and pitot has been in transit for months. You'd hope it would come in soon...
Agree low aspect ratio may be the exception, particularly for crude tips. Just a caution that you may not see the fine results. Also note that non-symmetric weight needs to be accounted for.
 

Hephaestus

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What I've been playing with I'm holding the square footage and wing loading as a constant. Right now most of its locked in other than the last 2 inches of wingtip.

Question will be what's the next step, I need bigger to get a better tuft test information. I was thinking 50%, but at that point - why not just go 100% and start to work on the Briggs and construction methods properly? Wouldn't be the biggest wingspan at the club field, though I'm moving away from using that. Gotta sit down and understand the regulation changes they've put in the last few years. Might end up needing a drone license...
 

Steve C

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One thing I'm certain they didn't do with that 747 was go stall it to see which side gives up first. If testing a model you'd certainly want to do that.
 

cluttonfred

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Personally, I would argue for span as the constant rather than area because workshop size and/or hangar size are more likely to be real world constraints for a homebuilt. Thats the problem with the interchangeable wingtip resting method unless you’ve designed the tips for constant span.

What I've been playing with I'm holding the square footage and wing loading as a constant. Right now most of its locked in other than the last 2 inches of wingtip.
 

Hephaestus

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Personally, I would argue for span as the constant rather than area because workshop size and/or hangar size are more likely to be real world constraints for a homebuilt. Thats the problem with the interchangeable wingtip resting method unless you’ve designed the tips for constant span.
2" of wingtip mounted to a fixed base wing is constant :) as long as the tips are always kept at 2"...

What I'm talking about and sockmonkey are talking about are low aspect ratio designs. So building space is less of an issue as a design choice.
 

Sockmonkey

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Yeah, storage space is one of the reasons for going LAR. I'm only torn on the wingtips because while Hoener tips are probably less draggy, using endplates makes it easy to use a junkers flap which provides a big safety factor in that you have full pitch authority even if the wing is fully stalled.
 

Hephaestus

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Yeah, storage space is one of the reasons for going LAR. I'm only torn on the wingtips because while Hoener tips are probably less draggy, using endplates makes it easy to use a junkers flap which provides a big safety factor in that you have full pitch authority even if the wing is fully stalled.
I have never seen a flying wing or plank with junkers separated elevons/flaperons - has it ever been done?

Generally your wing doesn't stall in its entirety, thus you still have control function as long as controls aren't exclusively in the stalled areas.
 

Sockmonkey

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I have never seen a flying wing or plank with junkers separated elevons/flaperons - has it ever been done?

Generally your wing doesn't stall in its entirety, thus you still have control function as long as controls aren't exclusively in the stalled areas.
In this application, the flap is functioning as your elevator so the wing wash won't blanket your pitch control surfaces.
 
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Norman

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The Soviets, BOK and Cheranovsky, also used external airfoil stabilators AKA "Junkers flaps" on several tailless designs. It's reasonabl to think of them as slotted reflexed airfoils with the slot at the point on the airfoil where the mean line crosses the chord line.
 

rotax618

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From my experimental models the improvement in performance that tip fins, endplates and winglets make is related to the aspect ratio. Aspect ratios > about 2.5, effective span is probably increased and so is performance - for lower aspect ratios the tip fins seem to interfere with the formation of a stable vortex at high alpha and the craft becomes less stable and likely looses lift.
 

thjakits

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....exactly! Today you could do that or e-glide it. Look at the plans, recalculate - maybe just a little bigger to accomodate a bigger pilot and a some kind of gear and off you go!

thjakits
 

erkki67

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The main drawback with the Horten is the fact, that you need to built approx 30 different wing ribs, and having complicated designed wingspars. Herewith we are very far away from a cheap flying wing option.
 

jedi

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One thing I'm certain they didn't do with that 747 was go stall it to see which side gives up first. If testing a model you'd certainly want to do that.
The stall happens at the root of the wing. I doubt the winglet versus no winglet wing tip would have a significant effect on stall characteristics. The winglet is optimized for the cruise AOA. That is where it should have the largest effect on performance.
 

nestofdragons

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The main drawback with the Horten is the fact, that you need to built approx 30 different wing ribs, and having complicated designed wingspars. Herewith we are very far away from a cheap flying wing option.
I was creating a full scale Horten inspired hangglider. The DragonWing. My design had a straight front spar. That part in the rear is not a rear spar but a hinge line for the triangular shaped elevon.
2020-07-06 DW 01.jpg
 
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