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Tiger Tim

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Came across this madness earlier today on YouTube:


Who’s going to be first to propose they build an airplane that way?
 

sming

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Apr 10, 2019
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ha! that's when you realize youtube is scary: it just show the same videos to everybody, as I've also watched them and thought 'you could probably shape a fuselage in one shot with this' ;)
 

Hephaestus

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YMM
Can you find me a nice step by step? 😂

Explosion formed wing ribs sound way better than press stamped wing ribs 🤠
 

Tiger Tim

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I was thinking flying saucers and other round-ish low aspect wings that get so much talk on this site could be blasted into shape as top and bottom shells.
 

Dan Thomas

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Came across this madness earlier today on YouTube:
Who’s going to be first to propose they build an airplane that way?
Madness? It's neat. Works well for some stuff. For airplanes you'd have to use a weldable alloy (which means one with less tensile strength, since alloys like 2024 aren't weldable) and it would have to be in a dead-soft condition for the explosion, then heat-treated to specified strength and hardness in a huge oven. Thin sheet would be more likely to tear, too, and thicker sheet would make a heavier airplane.

Interesting to see that boats might be returning to aluminum. I recently finished restoring a 45-year-old Springbok 16 foot aluminum runabout. I wanted aluminum because I can rivet and cut and form, and fiberglass is so messy. And most fiberglass boats available cheap have been sitting out in the weather and the water has gotten into the foam flotation under the floor and saturated it, and mold and mildew have set in. I even found moss and small plants growing along the edges of the floorboards in some boats. UV also degrades the polyester resin.
 

Riggerrob

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The guys over at "Myth Busters" build a lead balloon and flew it. They started with thin sheets of lead and cold-formed them into a sphere, then filled it with helium and flew it inside a warehouse.
 

Tiger Tim

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The guys over at "Myth Busters" build a lead balloon and flew it. They started with thin sheets of lead and cold-formed them into a sphere, then filled it with helium and flew it inside a warehouse.
IIRC the lead ballon was a cube, the shape being critical to the filling process to prevent tears. The sheets were assembled flat on the ground in a very specific way then opened like origami as they filled it.
 

Kiwi303

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En Zed. Aka The Shire.
And they revisited it several times since the first sheets were too thick. it took something like a year to stumble across a supplier in (I think) germany while checking out an unrelated matter who could supply thinner sheet than they found in the USA.

Now a GOLD balloon... that would be a sight to see... gold leaf lifter design anyone?
 

Riggerrob

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IIRC the lead ballon was a cube, the shape being critical to the filling process to prevent tears. The sheets were assembled flat on the ground in a very specific way then opened like origami as they filled it.
You are correct. Myth Busters built a square, cubic lead balloon.
 

Doran Jaffas

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Can you find me a nice step by step? 😂

Explosion formed wing ribs sound way better than press stamped wing ribs 🤠
I'm really not sure why people are soured about this. The technique obviously works for the boat hauls. Seems to have worked very well. The difference I can see being and this might be made up with a smaller charge of explosive, is the lightweight needed for aircraft and the material is not being as durable as what you would install on a boat frame. The other is if this would work with a smaller amount of explosive, a much smaller amount of explosive in a controlled environment with the money be compatible to other forms of manufacturing.? As much as gets bad at around on forums for aircraft this really doesn't seem like such an extreme possibility. The tried and true methods obviously work and that is what I would stick with but on a commercial scale of light aircraft in a much controlled environment this could become a part of the manufacturing process maybe.
 

Dan Thomas

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As much as gets bad at around on forums for aircraft this really doesn't seem like such an extreme possibility. The tried and true methods obviously work and that is what I would stick with but on a commercial scale of light aircraft in a much controlled environment this could become a part of the manufacturing process maybe.
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.
 

malte

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Who’s going to be first to propose they build an airplane that way?
You realise, you just did exactly that?

[...]
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.
It is more a question how exactly things are built and how high the mass penalty ist. FRP can be designed extremely light. On most aircraft not strength but buckling / stiffness is the main driver of mass with FRP, and, of course, process steps necessary. And if you don't have high penalties for structural mass (to a certain degree), you can allow for "some more"1617987880593.png
 

rv7charlie

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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.
I'm no authority on structure weights, but did you notice the Cirrus interior 'appointments'? I'd bet on 50 lbs extra just inside the cockpit. The angle valve 360 is at least 30 lbs heavier than the parallel valve version. There's also the fact that it's a cantelever wing instead of strut braced.

dealing with sheet thinning as it stretches, in areas that might not be convenient for structural strength.
Have you seen how the Questair Venture fuselage (compound curved aluminum) was formed? According to magazine articles back in the previous century, it was stretch formed by dropping a giant chunk of concrete in the shape of a male mold into the female mold. THUNK. Fuselage half...

The current owners are local to me; I need to ask if they got the molds along with all the other jigs/hardware.
 
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