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

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Norman

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Disregard all previous comments about twist. When you said it would be similar to the AV-44 I assumed you meant a low AR tapered plank with little or no sweep of the 1/4 chord. This drawing shows substantial forward sweep. BSLD hasn't been tried with forward sweep because it probably won't work.
 
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BSLD hasn't been tried with forward sweep because it probably won't work.
Wasn't Bowers working in integrating the math for that? Or am I remembering someone else? Been a while since I watched the videos.............

Structure could be a problem trying to keep the twist where desired on a full size plane but I'm not seeing any reason why it wouldn't, in theory, work with forward sweep?
 

Norman

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I haven't heard of anybody working on BSLD+forward sweep. I was a bit surprised by Marko Staminovic's FVT models because I had assumed that taper alone wouldn't provide enough induced AoA. Clearly I was wrong about that. But... On a yawed wing the aft tip has a higher effective angle of attack than the forward tip and this induced AoA is what allows a camber change to produce thrust at the tip of a swept and washed out wing. Since it's the aft part that can produce thrust [and therefor yaw] sweep forward doesn't seem too promising.
 
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Topaz

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Wasn't Bowers working in integrating the math for that? Or am I remembering someone else? Been a while since I watched the videos.............

Structure could be a problem trying to keep the twist where desired on a full size plane but I'm not seeing any reason why it wouldn't, in theory, work with forward sweep?
It was Don Crawford that was working on the math for applying lifting-line theory to wings with sweep and dihedral. He wasn't done yet, and the math was... daunting.



Back on to the case of a FSW with BSLD, building a precise, accurate, and constantly-varying twist across the span seems a lot to expect of the usual garage shop. It wouldn't be a simple geometric twist root to tip, that's for sure, not without a really funky chord length distribution.
 

Victor Bravo

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Attempting to return this a little closer to the original intent (and title) of the thread... I'm no expert but it seems that a lot of the more advanced concepts in flying wings (sweep one way or another, Al's brilliant but exotic twisting, and PhD's argiung the merits of lifting lines) would negate the original intent.

Correct me if I'm mistaken, but I'm figuring that any flying wing involving "cheap and simple" is kinda gonna have to be a straight unswept plank or straight spar Fauvel derivative, or at the most exotic a Marske derivative with a straight spar and Marske's wide-root tapered planform.

Or, in other words... "Objection, Your Honor, cost and complexity!"

You expert folks can disagree, but IMHO wing sweep (forward or rearward) complicates this entire exercise when you compare it to the achievements of Backstrom, Debreyer, Mike Whittaker, and Scott Winton.

It seems to me that the more efficient flying wings (the ones that achieve proverse yaw, the ones that can theoretically out-run or out-L/D a conventional plank or straight-spar Fauvel) should be in a newly dedicated "high performance flying wing" thread.

The uneducated, lowbrow neanderthals like myself can use this thread to find solace in the idea of... "a cheap and simple option for basic fun flying" that someone can build more easily.
 
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jedi

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Attempting to return tis a little closer to the original intent (and title) of the thread... I'm no expert but it seems that a lot of the more advanced concepts in flying wings (sweep one way or another, Al's brilliant but exotic twisting, and PhD's argiung the merits of lifting lines) would negate the original intent.

Correct me if I'm mistaken, but I'm figuring that any flying wing involving "cheap and simple" is kinda gonna have to be a straight unswept plank or straight spar Fauvel derivative, or at the most exotic a Marske derivative with a straight spar and Marske's wide-root tapered planform.

Or, in other words... "Objection, Your Honor, cost and complexity!"

You expert folks can disagree, but IMHO wing sweep (forward or rearward) complicates this entire exercise when you compare it to the achievements of Backstrom, Debreyer, Mike Whittaker, and Scott Winton.

It seems to me that the more efficient flying wings (the ones that achieve proverse yaw, the ones that can theoretically out-run or out-L/D a conventional plank or straight-spar Fauvel) should be in a newly dedicated "high performance flying wing" thread.

The uneducated, lowbrow neanderthals like myself can use this thread to find solace in the idea of... "a cheap and simple option for basic fun flying" that someone can build more easily.

VB: I will respectfully disagree.

It Cost me about $75 to build my first Rogollo style hang glider in about 1974.

I wasn’t concerned with BSLD at the time and although it had a lot of sweep and plenty of wash out it was less of each than typical for the day.

I would not be surprised to find that the lift distribution was much closer to a BSLD than the Cherokee 140 wing that was very popular at the time.

What is needed in this thread is more thinking outside the box.

VB said “The uneducated, lowbrow neanderthals like myself can use this thread to find solace in the idea of... "a cheap and simple option for basic fun flying" that someone can build more easily.”

I would very much like to convert the “neanderthals” to my way of thinking.

Can we (you and I) steer this conversation in that direction, please?
 
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The uneducated, lowbrow neanderthals like myself can use this thread to find solace in the idea of... "a cheap and simple option for basic fun flying" that someone can build more easily.
I kind of put myself in that group...........

IMHO using the BSLD for the class of plane we are thinking about would not be contrary to the intent but would still be a poor choice. This is not due to building/design complexity but due to the fact that I think one of the 'set in stone' design parameters to meet the goal of 'cheap' is a tow it home plane that fits in a single stall garage bay. This leads to short spans or multi piece wing panels. Multi piece wing panels (more than 3 total) are just too much work to build and assemble.
Since the efficiency of the Prandtl-D lift distribution is based on increasing the span to retain the same lift, drag and build weight there is no reason to choose this route if the overall design is span limited due to factors such as trailer-ability or stuffing int in a 20 foot shipping container. If span is limited the old simple elliptical lift distribution is still the best?

The Debryer Pelican clone - essentially a shortened version of the untwisted Fauvel AV-36/361 - is where I'm headed. Ironical, other than my personal situation, the thing holding me back from starting building is not the wing, but the fuselage. It is actually more complex to design and build than the wing if I eliminate the mold-less composite path.
 

Martin R.

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..... What is needed in this thread is more thinking outside the box. .....
Exactly!

But that's difficult here :(. I tried in another thread* to show ideas as described in the paper: "An inflatable wing using the principle of Tensairity"


.... and somewhere else technologies, used for other "toys": TRIPSTIX Clustair technology for demanding water sports

But the comments* following my posting have shown me that you can hardly leave the "box" you are talking about. (At least now I know the meaning of "Pop goes the weasel")

PS I have repeated these "wing ideas" here because this thread should also deal with a new wing that is as simple as possible.

* Is there a cheapest/lightest/simplest wing structure other than aluminium tube and fabric?
 
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Aesquire

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I don't think a "rear/regular" swept wing is that hard a build problem.

The "different ribs" complexity is no different from an elliptical or tapered wing.
Conical curvature of leading edge sheeting is the same as tapered, and much easier than elliptical. ( Spitfire, Ellipse )
Washout doesn't have to be as complex as in BSLD design. Simple geometric washout on a flat table is reasonable for most of the builders, imho. ( If I can do it with wire bracing on a sloped driveway with garden hose water levels, & thousands of conventional homebuilts do it on a flat table, it's doable. )
And there's a sweet spot/area on the sweep/AR chart that is where benign stall characteristics live. So AR from 6-8+ is "safe" from the nasty backflipping stall if everything else is designed right.

I don't expect most builders to go much past an AR of, 9? For the many reasons listed by others, above. ( storage, multi part wings, build difficulty, structural weight )

Is the additional complexity worth the broader CG range, or longer lever arm/pitch damping? That answer varies with designers and application.

Almost every current weight shift flex wing/hang glider uses a swept wing, but that's an evolution over decades and the folding wing with ribs removed and inserted isn't a rigid wing solution. Ditto the hinged ribs etc. on wings like the SWIFT. Doesn't translate well to sheet metal.

So the construction may be irrelevant, but the Aerodynamics is. They work. And a "swept Hershey Bar" wing works too.

OTOH, just because it's a Plank doesn't mean it's Simple.

I've been following the development of paragliders, lately. I quit paying attention shortly after they began, as I didn't like the flight characteristics and failure modes. ( yes, I have flown the earliest ones ) But they've worked a lot of bugs out of the things, including stuff I argued for in the 1980s, but can't take any credit for, since I thought they were obvious. ;)

And if you want COMPLEXITY?!
PHANTOM
Over a hundred "ribs" and many angled, bracing, webs, almost all different shapes and sizes. ( other than pairs for symmetry )
And other designs especially for PPG, using "reflexed" airfoils, and complex mixer systems in the controls, that makes a V tail seem simplistic.

Lack of notable sweep sure doesn't make a paraglider a plank. :)
 

Tiger Tim

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Attempting to return tis a little closer to the original intent (and title) of the thread...
The uneducated, lowbrow neanderthals like myself can use this thread to find solace in the idea of... "a cheap and simple option for basic fun flying" that someone can build more easily.
Yeah, that was my read of the intent as well. A sort of “Quest for the Volks-Plank,” if you will.
 

jedi

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Exactly!

But that's difficult here :(. I tried in another thread* to show ideas as described in the paper: "An inflatable wing using the principle of Tensairity"


.... and somewhere else technologies, used for other "toys": TRIPSTIX Clustair technology for demanding water sports

But the comments* following my posting have shown me that you can hardly leave the "box" you are talking about. (At least now I know the meaning of "Pop goes the weasel")

PS I have repeated these "wing ideas" here because this thread should also deal with a new wing that is as simple as possible.

* Is there a cheapest/lightest/simplest wing structure other than aluminium tube and fabric?

And I will reference my page 12 post number 225 of that thread that reference revising the old for new ways of improving/reviving stale/stalled technologies.

I think the proposal was to look for new ideas. Then when one is proposed we get comments like post #221 of the referenced link that I will quote the pertinent statement here.

“Trying to reinvent the wheel is futile. Still it is like reading the classics. There is so much that has been done that is always worth to look to the past in quest for inspiration.”

Well I am impressed with the “Shark Wheel”* that does claim to reinvent the wheel. While not nearly as revolutionary as the inventors claim it is an interesting concept that takes the traditional two dimensional wheel into three dimensional design concepts.

* Google “Shark Wheel” or go to “shark wheel shark tank”

Edit: I would like to post a URL but can’t. You will have to muddle through. The three year old Shark Tank videos give a good explanation.
 
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Riggerrob

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Dear Hot Wings,
Who says that you need a multi-piece wing?
A 20 foot span is enough for a light single-seater with limited horsepower (say 40 hp.). 20 feet is small enough to slide into an ISO 40 container without hinges or disconnecting panels.
Then the challenge is building a fuselage less than 8 feet long.
Folding the rudder 90 degrees sideways is a start.
It is easier to fold the nose if it only contains a pilot. You could hinge the nose and canopy at the leading edge and just install enough slow-collapse foam to reduce crash injuries. Fold the rudder pedals up so that they lay within the silhouette of the leading edge.
Folding a nose that contains a small electric motor is doable.
Folding a nose that contains a petrol motor is the most complex.

I am thinking about Junkers external ailerons and elevator to simplify construction and - slightly - lengthen the tail moment arm. Folding them sideways 90 degrees will reduce silhouette.
 
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Then the challenge is building a fuselage less than 8 feet long.
Just as I noted. ;) 👍
The AV-36/361 with the rudders folded and the nose cone removed pretty much get you there. I've not figured out a way to fold the nose yet and an easily detachable one presents problems maintaining reasonable crash protection.

Once we decide to fold/remove the nose for a sideways road tow then span becomes a little less constrained, but still needs to be enough for low stall speeds. I'm also trying to stay part 103 legal and that means a span in the range of 24+ feet, with a minimum length chord to contain the pilot forward of the spar. A span of 26 folds to an overall span of 14 with no overlap of the tips on the fuselage section. 34 foot span can be similarly folded to fit in the 20 foot container.


I too like the Junkers. They have the added advantage of still being effective if the wing in that area is stalled. But they tend to take longer to build (more parts then the Fauvel method) and are a little more sensitive to hangar rash type damage.

This thread has gone on too long.
I've made my decision(s) several chapters back - but we can still keep going around in circles to take the longest thread crown from VP-21/Raptor/???
 

Victor Bravo

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But that's difficult here :(. I tried in another thread* to show ideas

But the comments* following my posting have shown me that you can hardly leave the "box" you are talking about.
Many of us could make the very same complaint from the opposite direction - when we wish to make a modest but realistic improvement on the status quo, so many people immediately push the discussion out to the border of fantasy, taking the position that any useful improvement must completely abandon everything that has been the "status quo".

So it also gets difficult here to discuss a slight alteration to the status quo, because the science fiction futurists and the "clean sheet is the only sheet" proponents reduce any modest discussions to rubble.

How woud you suggest a fair and useful discussion thread for "cheap and simple flying wings" that is not prejudiced against modest improvements to existing Backstrom and Fauvel designs... and that is also not prejudiced against the Tripstix inflatable surfboard discussed in your post... and that is also not prejudiced against a vacuum molded and resin-infused carbon Prandtl-Bowers-Horten wing?

The only answer that I can offer/suggest is to keep status quo and clean-sheet in separate dedicated areas so silly people like myself cannot spoil a game-changing exotic approach.
 
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