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

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nestofdragons

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Ok, we are still looking for a cheap and simple layou, its not going to be much simpler than this, most difficult part are the wing tips on this bird of Sockmonke, all ribs have the same size, the wing spars are straight, the landing gear could be straight, the engine mount could be made like on the Fritz round wing.View attachment 106548
I once made these wingtips. Wing had only one rib type. Tip created some small dihedral in wing.f_openpou_01.jpg
 

BJC

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Most smart people say build a model first they don't say it but the implication is, if you don't you are retarded.
Before CFD and FEA, the big guys went to great lengths to build wind tunnel models for aero analysis. I enjoyed watching the Lockheed C5A model flutter testing being done, under the leadership of a homebuilder that I knew, in the 9 foot tunnel at GT.


BJC
 

Vigilant1

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The "car top wind tunnels" used by Rutan and others also worked pretty well. You can put a small scale version of a whole plane up there, or a full scale version of a small bit (wing section, cooling duct and radiator, etc). The car/truck/flatbed trailer provides a lot of real estate for manometer tubes, cameras (for tuft or dye drip testing), force sensors so you don't have to guess about what is going on, etc. And, it is unlikely to crash--unless you crash, too.
An RC model is good for a lot of things, but can require a lot of trial and error to determine the "why” that accompanies a "what.' If the "what" results in a crash, then another model will need to be built. So, computers, low budget wind tunnels, and RC models are complementary.
 
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TFF

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Most build test RC models too small and light for testing. Something like that runabout, needs to weigh about ten pounds with a five foot wing. Yes you could build it to five pounds and it will fly fine. It will not be a good test. At ten pounds, it’s not stretching physics a whole bunch, but it will tell you if it is really working. It will give a hint of real handling. Usually if you go full dynamic scale it will be a mess that small. Most will say about building a test model, it’s small for budget, or it’s not my hobby, so I’m not putting money in. Usually that makes the testing is an automatic invalidation. You’re not trying to test a better model or one guaranteed to fly well. Thrust line, weight under the wing, landing gear qualities will show fast.
 

Speedboat100

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Most build test RC models too small and light for testing. Something like that runabout, needs to weigh about ten pounds with a five foot wing. Yes you could build it to five pounds and it will fly fine. It will not be a good test. At ten pounds, it’s not stretching physics a whole bunch, but it will tell you if it is really working. It will give a hint of real handling. Usually if you go full dynamic scale it will be a mess that small. Most will say about building a test model, it’s small for budget, or it’s not my hobby, so I’m not putting money in. Usually that makes the testing is an automatic invalidation. You’re not trying to test a better model or one guaranteed to fly well. Thrust line, weight under the wing, landing gear qualities will show fast.

How about the air foil qualities ?
 

Victor Bravo

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Trikes are pretty short coupled nose gear birds, right?! They don’t have stability issues for ground handling. So if we take this in mind, the flying of the plank is the only mystery to solve.
OK, show me one of those "trikes" that is a tailwheel model. Main gear in front of the CG, tailwheel behind. Go ahead, no rush....
 

Aerowerx

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Most build test RC models too small and light for testing. Something like that runabout, needs to weigh about ten pounds with a five foot wing. ....
I remember 5 or 10 years ago there was a discussion here on Dynamic Scaling. It should turn up in a search.

Or Google "Dynamic Scaling". There is info out there on how to do it. Somewhere around here I have a pdf that gives details, like for an 'X' scale model, the weight is scaled by 'A', the power by 'B', scale speed by 'C', etc.
 

Mike W

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I remember 5 or 10 years ago there was a discussion here on Dynamic Scaling. It should turn up in a search.

Or Google "Dynamic Scaling". There is info out there on how to do it. Somewhere around here I have a pdf that gives details, like for an 'X' scale model, the weight is scaled by 'A', the power by 'B', scale speed by 'C', etc.
Is this the one?

Mike
 

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Hephaestus

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This is the other one you want to pay attention to.


Scale models aren't a cost, they're a cost saver, reworking a wing / canard profile at a small scale is infinitely cheaper than doing it once it's built as an EAB.

Poke around a bit and you'll find fully 3d printed RC planes - which yes means there might not be a 3 month building project to validate - also means you might be able to power through a bunch of iterative design changes in a day.
 

TFF

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You can go the full dynamic scaling, but it can be too small, it’s just not going to be valid. You want the scale to be at a point where you are not forcing it to fly. You pick one where it accepts flying. Airfoils may or may not scale and be valid. It doesn’t mean it will not fly with a custom airfoil; the problem is a model will fly with just about any airfoil. What generally is valid is layout. Moments in relationship to thrust and wing; gear type, general handling. Something with a 3 ft span will fly like a model. Fun but it has characteristics of small that you will not get out. 5 ft span will control reasonably like a real plane, it will shake out much of modelness. 8 ft will usually be a decent analog.
 

Vigilant1

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Is this the one?

Mike
Here is the second of Stan Hall's articles to complement the one that Mike W. already posted.
Thanks to both of you for those great Sport Aviation articles by Stan Hall. He covered a lot of ground very concisely, and clearly. Those old Sport Aviations had fantastic content. It would be super if someone wrote modern companion pieces, they could use Stan's work as-is as a foundation and then add some spreadsheet tools that readers could get at the EAA site.

FWIW, Hall writes that a flying model should be at a minimum of Reynolds number 120,000 to give useful information. He also describes other reasons to go bigger, if practical.

Hephaestus, thanks for the NASA pdf, there's lots there to chew on.

Mark
 
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Pops

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You can go the full dynamic scaling, but it can be too small, it’s just not going to be valid. You want the scale to be at a point where you are not forcing it to fly. You pick one where it accepts flying. Airfoils may or may not scale and be valid. It doesn’t mean it will not fly with a custom airfoil; the problem is a model will fly with just about any airfoil. What generally is valid is layout. Moments in relationship to thrust and wing; gear type, general handling. Something with a 3 ft span will fly like a model. Fun but it has characteristics of small that you will not get out. 5 ft span will control reasonably like a real plane, it will shake out much of modelness. 8 ft will usually be a decent analog.
I agree. The larger the better. 8' is a nice compromise. Removable 4' wing panels makes the transporting easy. I have a 8.5' wing span glider design and its much more efficient than making the same design smaller. The larger size starts handling like a full size glider
 
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