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

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rotax618

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The premise was for a “Cheap and Simple Flying Wing”, the more curves, taper, bling you add increases the complexity and cost, take for example Bud Evan’s Volksplane, it is square and boxy but has been popular - I have built a Volksplane and the only change I made was to make it lighter and substitute unobtanium parts.
The Aussie Plank could be made a little better looking by tapering the nose, I’m not sure what effect that would make to the flying characteristics - the report from the owner is that it showed no vices, had no discernible stall (only assumed a higher descent and flew on when power was applied.
I visited the designers home in Brisbane many years ago and spoke to him at length, the aircraft also appears on a video “Australian Ultralight Aircraft and their Pilots” I have a copy of the video, my aircraft the Boorabee is described in it, unfortunately it is copyrighted so I am unable to reproduce it for you.
 

nestofdragons

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Ok, guys, i just was imspired by the Pneumagic hangglider. Now ... would this idea be possible. Why not mix the old Delka, the Pneumagic with a low aspect ratio motorized ultralight?
For those who cannot recall the Delka. It was mainly a tube that was inserted in the leading edge and pulled into a curve to create a nice curved front. Well, my latest low aspect ratio thoughts with straight trailing edge and parabol leading edge might have such a tube at the front.
Delka-xc-top.jpg Delkas.jpg
This is the Delka.
Combine it with one of these ideas.
113619-0c063120da241bb8c007a3bfc05747e9.png
114547-e07f4a70f1a72c80cdaa6c91c1fbc974.png
Make that tube be the leading edge. Use a triangle with struss in it to create kind of spar going from ...lets say the front point of the last rib in the last draft to the middle of the root rib. It creates the needed tension on the front tube to get that curce. It might be rather ridig already. The rest of the airplane might be fabric with Pneumagic kind of ribs. The trailing edge might be a tube that can be pulled up and down to create a full half wing elevon.
This is just a veeeery primary thought. Hmmm ... would it create something that can fit INSIDE a regular car? Who needs a hangar? ;)
 

addaon

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Careful, if you continue too far that way you'll re-invent the paraglider. Fits inside a regular backpack inside a regular trunk of a regular car.

Or on a less good day, you'll re-invent the Woopy-Fly.

1660914345993.png
 

ypsilon

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The Delka was a really bad design (in almost every respect I can think of). It killed Didier Favre. Kalbermatten built rather questionable paragliders before, and the Woopys are something I personally wouldn't use to fly any higher than I'm willing to fall.
I think it's good that Kalbermatten now concentrates on building sails for boats.

Talking about the pneumagick glider: Great idea - never flew. Prospective Concepts had it manufactured in Eastern Europe (all the cross stitches were done manually, which made it extremely expensive).

There are examples of inflatable planes (McDaniel Glider, Reluctant Phoenix, and of course the Inflatoplane), but high aspect ratio wings without struts don't lend themselves to this concept, really.
 

Aesquire

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The Bowsprit hang gliders had fewer aluminum tubes and used wire bracing for a strong, light, structure.

This one is discontinued, but I would love one. The downside is drag from the wires. But dang, they are light.

 

erkki67

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The Delka was a really bad design (in almost every respect I can think of). It killed Didier Favre. Kalbermatten built rather questionable paragliders before, and the Woopys are something I personally wouldn't use to fly any higher than I'm willing to fall.
I think it's good that Kalbermatten now concentrates on building sails for boats.

Talking about the pneumagick glider: Great idea - never flew. Prospective Concepts had it manufactured in Eastern Europe (all the cross stitches were done manually, which made it extremely expensive).

There are examples of inflatable planes (McDaniel Glider, Reluctant Phoenix, and of course the Inflatoplane), but high aspect ratio wings without struts don't lend themselves to this concept, really.

What was wrong with the Delka, Woopy and the Genair, Trilair and and so on?
 

erkki67

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Laurent de Kalbermatten is the designer of the Whoopy Fly and Delka inflatable wings. The test pilot of the Delka died while testing in the mountains, work on the Delka design was abandoned for the lower aspect Woopy Fly.
Yes, Laurent de Kalbermatten did suspend the development of the Delka after the deadly accident of his friend Didier Favre. But there wasn’t anything very wrong with the wing itself. The Delka was only roll and speed controlled. The pilot was sitting in the CG. The accident report showed what went wrong. The Woopy Fly and Woopy Jump are a complete deifferent story. The Jump version is more a glide streching wing, not really for flying, just a slope glider. The Woopy Fly was a wing to fly, for hours if the conditions did allow it. I’ve no idea why the production ceased, only Mr. Kalbermatten will know the answer. Mr.Kalbermatten was in the early stages of the Paraglider movement the biggest manufacturer of paraglider wings beginning with the maxi and randoneuse. The designs of the genair and trilair where top notch gliders of their time, had some flaws, but led to the wings of today.
 

ypsilon

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What was wrong with the Delka, Woopy and the Genair, Trilair and and so on?
The Genair and the Prisair were state of the art paragliders back then and built the foundation of Ailes de K's success. State of the Art didn't mean all that much in the 1980s when it comes to building paragliders, though. The whole industry was still a bunch of young enthusiasts trying to improve parachutes, without much insight in the (admittedly complex) aerodynamic and aeroelastic problems. Kalbermatten was one of them, and one of the most successful in the very beginning. In my view (and hindsight) the Trilair was already trying to improve performance by optimising the wrong things. It was frankly a dangerous wing and losing ground to the competition (eg. the Nova Comet (CX(C), Falhawk Apex etc.). Kalbermatten responded with more of the same (namely trying to force performance, without really understanding what was going on aerodynamically) and created outright dangerous (yet not very high performing wings) culminating in the development of the "Magistrair". The German DHV didn't certify the wing (for good reason).
Kalbermatten pre-produced way to many gliders and didn't expect the industry to develop that quickly, which eventually led to the collapse of his company.

Now the Delka:

In the paragliding craze of the early 90s, it was very hard for a radically new hang glider design to be successful. I agree that the idea of having a light, neatly fold-able hang glider is good in principle, but that's about all I find reasonable about this wing. The pretensioning of the spar that not only has to counteract bending loads but also torsional loads weakened the whole system. IIRC it was built from fibreglass, and was pretty soft. So the interaction of aerodynamics and structure (i.e. aeroelastic effects) were hardly controllable, and I doubt that he did any kind of simulation back then.
Weightshift steering has it's limits (that is true for all hang gliders) and those limits are exacerbated by placing the pilot in the wing (and still simply trying to tilt the wing). Having very little sweep doesn't help the situation either.

The layout of the wing was obviously inspired by the suggestions of Wohlfahrt and Nickel. Their book (Schwanzlose Flugzeuge) was the Bible in hang gliding industries, but if you look at their suggestions (specifically for hang gliders): They come with a big grain of salt, and were never tested. We now know, that they overestimated the effects that lead them to this specific wing layout. In practice you end up with a pretty large k-factor (thus a lot of induce drag). Also the stall progression in not favourable and (due to the soft structure) hardly forseeable.

the accident report showed what went wrong
Do you have this report available? I'd be very much interested!

The Woopys are aerodynmically sound, but I doubt that the structure can withstand the loads posed by an even moderately turbulent day in the alps (I would say that a minimum of 4g ultimate is required). Its improvement over the delka is, that the torsional loads on the spar are reduced significantly, the pilot moved below the wing, and there are wires to support the spar. However sleeving in one tube into another with vastly different diameters is not a good idea (notch effect).

The Woopy concept may work in a small niche of low-aspect ratio wings combined with a pretty fat cross section. I don't see the advantage over a paraglider, though.
 
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Aesquire

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don't see the advantage over a paraglider, though.
Other than the rigid connection to the wing...

That's not trivial. But there's been very little development in the concept for years, afaik.

There's an ongoing Evolution in paragliders. Ozone & the Sharknose, ( now almost universal ) using CFD to realign ribs, stiffeners, less lines/more internal structures, New steering rigging, etc.

Some crossover tech from the specialized PPG wings, and increasingly from the kite surfing / snow & buggy kiting worlds, which often are divisions of the same company.

My Opinion, aka Guess, is the one way air intake system used in kites intended for water use, will increasingly change the resistance to frontal collapse, and that will force changes to the Certification process. Already some newer designs can only be forced into failure modes that are part of the testing process, by tricks, like adding extra lines to induce failure for the testing, not needed or wanted on the production models.

Certification in paragliding is very oriented toward Recovery from failure to hold wing shape. If the particular failure no longer happens, there isn't recovery, either. A wing may fail a test by not having a failure to test! ( insert German Engineering joke here )

I'll shorten the rant on regulation stalling innovation, to pointing out that a canard designed to not have a conventional stall, couldn't pass a mandatory test for full stall recovery.

I'm not knocking the organizations that do the testing! Nor the good they do for the sport. Just pointing out the need for evolutionary rule making along with evolutionary designs.

In hang gliders an early failure mode in "standard Rogallo wings" was the "full luff dive", where flying at too low an AOA might collapse the sail, and it "flagging" flutter failure to hold airfoil shape and stability. That got cured, years before the Hang Glider Manufacturers Association ( in the U.S. ) created standards for testing. They don't "test" for Full Luff Dives per se. They do an extensive test for pitch stability at different AOA, including negative AOA that may have induced a Luff condition in the older, obsolete gliders. The purpose of the test is aimed at recovery from Unusual Attitudes an old Rogallo probably couldn't achieve, and almost certainly wouldn't easily recover from, so ultimately it's a valid test in multiple ways.
 

Aesquire

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Irony! As we discuss BDSM lift curves ( no, hold it, that can't be right ) and proverse yaw, I notice that paraglider steering in normal mode uses one way down elevon control, aka brakes. Apply brake on the right side of the wing, and increased drag causes a right ( yaw ) turn. There's complex coupling to roll going on too. Right brake also increases camber on that side, increasing lift. It's "adverse roll". But in practice, that adverse roll counteracts yaw/roll coupling leading to a flatter, more efficient soaring turn.

Meanwhile, one way elevon/camber input affects pitch. And lift, directly.

Like many subtleties in piloting, it's not easily seen from outside. Probably easier to see in PPG take offs, where "brake" application on take off run increases lift to break ground, then is eased off to accelerate to climb speed.

The next generation of AOA & camber controls is going to change a lot.

How we translate these controls to a rigid aluminum or carbon fiber wing is going to take some work.
 

MR101005

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....... 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.

I absolutely agree.

But: why not describe a new idea for a simple wing in this thread? If enough people are interested we will open a new thread. But only in this case! Because if you start a new thread for every single new idea or question, the index of threads overflows and the overview of the whole forum is lost.

By the way: The thread "Flying wing as cheap and simple option for basic fun flying" was opened 5 1/2 years ago and counts almost 3400 postings. That's why an additional idea ("outside the box") will certainly not completely change our thread.

The paper I indicated* contains numerous considerations and calculations that are interesting for someone who deals with this technique for the first time. And it's certainly no coincidence that Delft University of Technology and Swiss Federal Laboratories for Materials Science & Technology (EMPA) are looking into the matter.

Here is the very first sentence of the investigation:

"The paper describes the new concept Tensairity which can be used
to significantly improve the load bearing capacity of inflatable wings."


Does something like this really have no place in our thread?

* https://repository.tudelft.nl/islan...378-a145-75905c83efa7/datastream/OBJ/download
 
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jedi

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the one way air intake system used in kites intended for water use, will increasingly change the resistance to frontal collapse, and that will force changes to the Certification process.
Is this a valve (flap of fabric) to limit/ eliminate outflow thru the leading edge opening?

From post # 2412 “BDSM lift curves“ explain BDSM please.

Thought you might be referring to the Big Dumb Stupid Models I made long ago.

Plan view of BDSM flex wing hang glider, cheep and simple flying wing built 1974.

417C55D2-00EE-4F5B-8E73-0686BF6D358A.jpeg

40 foot span 8 foot cord tension bent leading edge of 1 1/2 inch OD x .052 wall 6061 T6 IIRC. Cost < $100
 
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MR101005

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Still looking for it
I can't find a report at the moment either. Don't forget: The institutions that investigate flight accidents in Switzerland (especially those in the paragliding and trike sector) changed in the last 22 years (the accident happened in 1994)!

But if I remember correctly, the paper was written in French and the accident did not happen during a test flight but during a flight for a planned commercial. Every flight movement was precisely prescribed. But it seems that the pilot ended up performing some maneuvers that were not forseen for the film and never tested before. And during such a maneuver the accident happened.

Apparently he had too much faith in the machine. Definitely more than those who wrote the script and more than the machine earned.
 

jedi

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BDSM Translation. I still need help here. Reference post 2518. “From post # 2412 “BDSM lift curves“ explain BDSM please.” If I were to post the internet/Google replies I would expect to be banned.

Definition of BDSM​


: sexual activity involving such practices as the use of physical restraints, the granting and relinquishing of control, and the infliction of pain.

This kind of sounds like something the FAA would be involved with.
 
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Aesquire

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BDSM was a joke mocking the aviation/military use of TLAs. ( three letter acronyms )

I mean, sure, gravity is a harsh mistress, so that's a connection not often made...

Yes, the intake "valves" on the kites are simple light fabric tubes sewn to the inlets, that collapse when internal pressure exceeds the inflow. Often referred to as open ended tube socks.

Here's an example.


Crashing the kite while kite boarding on water would otherwise immediately fill it with water and leave a Deadly submerged jellyfish like mess of thin high strength lines and fabric. With the valves, th wing holds shape, & floats, making relaunch much easier.

In a paraglider context, the airflow through the wing is complicated. Openings in the trailing edge are small, to drain dirt/water, so basically the internal pressure has to escape out the nose inlets. The internal ribs have weight reduction holes that also allow cross flow of air to reinflate collapses.

But the collapse, the distortion of the wing, is possible because air escapes. Pressurized by ram air, but not sealed! Parachute, not air mattress.

The Whoopy Fly is air mattress type, with fan/pump, with ram air assistance in flight.

This my speculation that a hybrid ram air inflatable wing that didn't allow air to freely flow out the ram air intakes, would reduce the current failure modes in paragliding. And introduce new ones. TANSTAAFL.

Like several things in my hang glider past, it's likely that by the time I actually build my better mouse trap that a much more talented company will have a better version on sale.

I've considered simply buying a 27 sq. Meter (water surfing ) kite and re-rigging it to a paragliding harness control system, and testing it with ground handling and short hops on small slopes. But by the time I've tuned it ( with my limited experience and knowledge ) to be safe enough to fly it high enough to test any imagined improvement, I bet I'll be able to just order one from a company that has the expertise and experience to certify one.

In the context of our flying wings, I suspect few here want to deal with the long lines and pendulum swings and soft connection to the wing that paraglider pilots do. True, I can carry a powered trike in my minivan with wings in a bag the size of a back pack, or 3 PPG power units and wings, but that's a specialized niche, well supported by retail sales, not homebuilder territory, normally.

However... A modern version of the Woopy, with an internal aluminum or carbon fiber spar, and hard connection to the pilot/engine pod/trike/fuselage would allow a reasonable AR of 7 or better, a surprisingly efficient wing that folds into a duffle bag plus a rigid spar and pod frame. And the main wing spar would be a multi part, tapered tube, that just slides and locks together, that you slip through the wing on assembly into a fabric tube that is sewn to the internal structures. Like the Woopy. Faster setup than a hang glider like trike with battens, ( 20 minutes ) by a little, and more compact storage. A bit. Be pretty easy to meet the Sub70 kilo standard class weight.

The major problem, from MY perspective, is the high sewing skill required and the very complex structure. Like many subtleties of aviation, it LOOKS simple, and the smooth exterior shapes conceal hidden complexity and skull sweat to analyze and optimize.

Much Like composite work, or welding, or multi thousand rivet metal construction, learned skills are required and possible to attain.

Personally I'm fine with the metal work, precision cutting, drilling, rivets and bolts... But am mediocre with sewing machines. :)
 
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