Aluminum Tube & Gusset Airbike / Legal Eagle / Parasol Thread

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TerryM76

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Please provide some more detailed information on the structure of these early aluminum tube and gusset airplanes - I for one would like to learn more about them. I clearly remember the DSK airplane advertisements in Soaring, PM, and other magazines, but have never seen one in person.
I’m hoping VB comes back from Tehachapi with a concept for a tube & gusset motor glider….
 

Victor Bravo

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I’m hoping VB comes back from Tehachapi with a concept for a tube & gusset motor glider….

Well, to be honest, I went to Tehachapi with concepts of tube and gusset motorgliders already haunting me.

For a "conventional sailplane layout" glider, my idea would be something the size of a Woodstock or even a Scheibe SF-27, built using fabric covered tube and gusset for the fuselage, tail, and rear/main wing ribs (with a traditional flush riveted sheet metal wing D-tube fwd of the spar). Two electric motors would be mounted on the wing trailing edges about three feet out from the fuselage. The battery would be mounted on top of the wing center section, restrained by a very serious Kevlar safety strap to keep it out of the pilot's skull in a hard landing. This would yield a somewhat high performance soaring glider with low drag (aft folding props) without having to do the engine retract and folding door mechanism. The SF-27 was listed as 34-1 L/D, this version with the motors faired in properly and the prop blades folded back could easily be 30.

Another perfectly good idea is the "airplane with long wings" layout like the Fournier RF-3, with a paramotor or other IC engine in the nose. Mark Calder's Robin uses this, and the only difference is that it might be able to be executed easier/cheaper in tube/gusset than wood or plastic.

Where build cost, parts count, build time, compactness, and weight is brought forward... the "straight spar flying wing" layout becomes more relevant to me... I would likely go with a Fauvel AV-36 derivative. There were several Fauvel motorgliders, but the larger ones would be pretty high parts count and a lot lot lot of different ribs. Using fairly light tube and gusset for the fuselage (think Graham Lee Nieuport), Kolb style tube and gusset wing ribs aft of the spar, and hammered ribs with lightening holes and .016 sheet for the D-tube - you might come in a fair bit lighter than the weight of the original wood Fauvels. A Polini or Simonini engine mounted at the top of the trailing edge would be balanced out by the battery in the nose, and the pilot moved fore-aft on seat rails to balance the airplane (on the wheel or nose skid) before each flight. So this would allow a more streamlined and modern looking nose, with a more comfortably reclined pilot than the original AV-36 with its bolt-upright seating.
 
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TerryM76

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Well, to be honest, I went to Tehachapi with concepts of a tube and gusset motorgliders already haunting me.

For a "conventional sailplane layout" glider, my idea would be something the size of a Woodstock or even a Scheibe SF-27, built using fabric covered tube and gusset for the fuselage, tail, and rear/main wing ribs (with a traditional flush riveted sheet metal wing D-tube fwd of the spar). Two electric motors would be mounted on the wing trailing edges about three feet out from the fuselage. The battery would be mounted on top of the wing center section, restrained by a very serious Kevlar safety strap to keep it out of the pilot's skull in a hard landing. This would yield a somewhat high performance soaring glider with low drag (aft folding props) without having to do the engine retract and folding door mechanism. The SF-27 was listed as 34-1 L/D, this version with the motors faired in properly and the probp blades folded back could easily be 30.

Another perfectly good idea is the "airplane with long wings" layout like the Fournier RF-3, with a paramotor or other IC engine in the nose. Mark Calder's Robin uses this, and the only difference is that it might be able to be executed easier/cheaper in tube/gusset than wood or plastic.

Where build cost, parts count, build time, compactness, and weight is brought forward... the "straight spar flying wing" layout becomes more relevant to me... I would likely go with a Fauvel AV-36 derivative. There were several Fauvel motorgliders, but the larger ones would be pretty high parts count and a lot lot lot of different ribs. Using fairly light tube and gusset for the fuselage (think Graham Lee Nieuport), Kolb style tube and gusset wing ribs aft of the spar, and hammered ribs with lightening holes and .016 sheet for the D-tube - you might come in a fair bit lighter than the weight of the original wood Fauvels. A Polini or Simonini engine mounted at the top of the trailing edge would be balanced out by the battery in the nose, and the pilot mounted moved fore-aft on seat rails to balance the airplane (on the wheel or nose skid) before each flight. So this would allow a more streamlined and modern looking nose, with a more comfortably reclined pilot than the original AV-36 with its bolt-upright seating.
I’ve always been a fan of the RF-3…..it might be a rather mediocre performer but it does have a certain attraction for me. If I recall correctly, Dan Armstrong was working on a simple to build glider design that was going to use a tube and gusset construction method but the years might have polluted my memory a bit on this one. I like the Fauvel designs and it would certainly be more economical in time and materials to fabricate from off the shelf aluminum materials than trying to source the wood and doing all the splicing and laminations needed to build the airframe.
 

Victor Bravo

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Dan had a design called the Wind-Dancer, which I cannot ever recall seeing a 3-view of. But it was an ultralight glider of some sort; I never heard the word engine or motorglider attached to it, but that means nothing because I was never involved or associated with it, and only heard it mentioned a few times. I had thought his spars were going to be carbon rods, but I have no idea what the reat of the airplane was made out of. Dan had a whole lot of "life gets in the way" that effectively shelved that project, and I have no idea if it will come off the shelf or not.
 

karmarepair

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Dan had a design called the Wind-Dancer, which I cannot ever recall seeing a 3-view of. But it was an ultralight glider of some sort...
Nest of Dragon has a page on it, looks like a forum post of e-mail from his wife. Nest of Dragons
"It will be conventional in appearance, with a T-tail. It will have a canopy (the soaring that is done here is frequently at 10,000-17,999 foot altitudes). It will be mostly carbon construction. The wing span is 40 feet, the area is 104 square feet, and the wing loading will be about 3.5 pounds per square foot."
 
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