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Doran Jaffas

Well-Known Member
Joined
Jun 25, 2019
Messages
428
You're still stuck with welding the sheets together, then in dealing with sheet thinning as it stretches, in areas that might not be convenient for structural strength. And subsequent heat-treating to regain the strength. Boats can afford to use thicker sheets of soft, weldable aluminum that doesn't need further heat-treating; they likely weld in internal frames to stiffen the structure. It won't be a lightweight monocoque hull, but it might still be lighter than a lot of fiberglass boats.

Fiberglass is not light stuff. I've worked on the Cirrus and Corvalis airplanes, and their empty weights are quite high, not the lightweight things we expected from the composite hype of the 1970s. The Cirrus SR20 has 200 HP and four seats and fixed gear, and an empty weight 400 pounds higher than a 180-hp four-seat fixed-gear Cessna 172SP. 70 pounds of that increase will be the BRS, another 20 the CS prop, maybe another 10 or 20 pounds in the engine. The rest is structure.
You bring up some very good points. I appreciate that. Always good to learn new things. I was wondering about the strength versus weight of the boat holes myself because I know that they are not as critical in the wait area. again it would have to be an extremely controlled environment and whether or not we even have the technology to do that right now would be in question if we do I'm sure the expense would be prohibitive. I intend to stick with tube and rag or wood and call it a day.
 

Mad MAC

Well-Known Member
Joined
Dec 9, 2004
Messages
729
Location
Hamilton New Zealand
Friction stir welding can get around the weldablity issue of 2024 (not simple jigging), other wise there are new high strength weldable alloys (6013 is one example).

Anyone got an article on the Questair Venture skin forming?
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
14,737
Location
Port Townsend WA
The Questair skins were stretch formed with hydraulic cylinders, as I recall, from the Sport Aviation article.
 

Bigshu

Well-Known Member
HBA Supporter
Joined
Jun 7, 2020
Messages
270
You bring up some very good points. I appreciate that. Always good to learn new things. I was wondering about the strength versus weight of the boat holes myself because I know that they are not as critical in the wait area. again it would have to be an extremely controlled environment and whether or not we even have the technology to do that right now would be in question if we do I'm sure the expense would be prohibitive. I intend to stick with tube and rag or wood and call it a day.
The video of parts being formed by the Ryan Aeronautical Company didn't look to be extremely controlled, or particularly expensive to replicate. The actual explosives might be hard to come by, but otherwise, it's just forms and water.
 
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