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#21
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ORVAL FAIRBAIRN
sednews In article , Matt Whiting wrote: Fortunat1 wrote: "Cy Galley" sednews:4V41e.103754$r55.32258@attbi_s52: I would check with a Van's builder. RVs have aluminum riveted tanks with pro-seal. If you know a good tig welder, then a welded tank can be built. OK, thanks.There are two down the road from me, in fact! I'll probably try and weld it myself, though I've never welded aluminum before. Then again, most ofthe things I've done on this contraption I've never done before. I'm assuming baffles (and I think I'd need them in a long shallow wing tank) aren't welded, though. I'm supposing that the tank would be assembled, but the back left open until the baffles are all riveted, and then closed up and welded? I see no reason not to weld the baffles as well. Probably less messy than sealing the rivets. Matt that depends on the aluminum alloy used -- and, how much warping you can tolerate. Van's tanks are "wet" cells -- part of the wing and are 2024-T3, which is NOT weldable. The nice thing about wet cells is that they add only the weight of the ProSeal to the airframe weight, while separate tanks add their own weight to the plane. 6061 and 5052 are common weldable alloys, but you will get some distortions from the welding process. I still don't see how I would weld the baffles in place before the tank is closed up. This tank would be about 48" by 24" by 5" The top has a bevel at the back to conform to an airfoil shape. I reckon I'd need two baffles (strictly eyeball engineering here) to minimize sloshing from side to side. maybe just one. If I were to make the tank out of a single wrapped piece with ends stitched on afterwards, how would i go about welding the baffles in place? Put the ends on last? Presumably, the baffles would only need to be tacked as opposed to a continuous seam all the way around.. |
#22
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"Rich S."
: "Montblack" wrote in message ... Aluminum will weigh 5 x the mahogany? Wow. Specific gravity of Aluminum = 2.7 Specific gravity of Mahogany = ~.5 What's the cost difference between aluminum and wooden props? New Ed Sterba Birch prop ~ $600. New Sensenich Aluminum $2,000. These are rough figures. Why do people buy birch instead of mahogany? Birch has a specific gravity ~ .7 and is a lot stronger per pound than Mahogany when used for a prop. Might go to a wood prop if the one I have doesn't work out. But it is quite a good prop, and it's absolutely gorgeous, to boot! |
#23
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"Fortunat1" wrote I still don't see how I would weld the baffles in place before the tank is closed up. This tank would be about 48" by 24" by 5" The top has a bevel at the back to conform to an airfoil shape. I reckon I'd need two baffles (strictly eyeball engineering here) to minimize sloshing from side to side. maybe just one. If I were to make the tank out of a single wrapped piece with ends stitched on afterwards, how would i go about welding the baffles in place? Put the ends on last? Presumably, the baffles would only need to be tacked as opposed to a continuous seam all the way around.. Keep in mind that the baffle need not be attached to both the top and bottom. Its job is to slow the fuel, not be a perfect seal. -- Jim in NC |
#24
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Fortunat1 wrote:
I still don't see how I would weld the baffles in place before the tank is closed up. This tank would be about 48" by 24" by 5" The top has a bevel at the back to conform to an airfoil shape. I reckon I'd need two baffles (strictly eyeball engineering here) to minimize sloshing from side to side. maybe just one. If I were to make the tank out of a single wrapped piece with ends stitched on afterwards, how would i go about welding the baffles in place? Put the ends on last? Presumably, the baffles would only need to be tacked as opposed to a continuous seam all the way around.. Yes, you would wrap the sheet to form the overall tank shape, weld in a baffle or three working from the open ends and then weld on the ends to close things up. Matt |
#25
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"Morgans"
: "Fortunat1" wrote I still don't see how I would weld the baffles in place before the tank is closed up. This tank would be about 48" by 24" by 5" The top has a bevel at the back to conform to an airfoil shape. I reckon I'd need two baffles (strictly eyeball engineering here) to minimize sloshing from side to side. maybe just one. If I were to make the tank out of a single wrapped piece with ends stitched on afterwards, how would i go about welding the baffles in place? Put the ends on last? Presumably, the baffles would only need to be tacked as opposed to a continuous seam all the way around.. Keep in mind that the baffle need not be attached to both the top and bottom. Its job is to slow the fuel, not be a perfect seal. Mmm, OK. I had considered that, but figured that the baffle would flex if it weren't nailed to each of the four sides. I'm thinking now it might be possible to get in from either end of the tank. I'd only have to get in about 16" throug a 5"X24" opening and make a few tacks to the top. I know a guy who welds aluminum boats up. I'll ask him what the deal is with those. |
#26
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Matt Whiting
: Fortunat1 wrote: I still don't see how I would weld the baffles in place before the tank is closed up. This tank would be about 48" by 24" by 5" The top has a bevel at the back to conform to an airfoil shape. I reckon I'd need two baffles (strictly eyeball engineering here) to minimize sloshing from side to side. maybe just one. If I were to make the tank out of a single wrapped piece with ends stitched on afterwards, how would i go about welding the baffles in place? Put the ends on last? Presumably, the baffles would only need to be tacked as opposed to a continuous seam all the way around.. Yes, you would wrap the sheet to form the overall tank shape, weld in a baffle or three working from the open ends and then weld on the ends to close things up. 'Kay. makes sense. Al I have to do now is learn to weld aluminum! |
#27
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"Fortunat1" wrote in message ...
Yes, you would wrap the sheet to form the overall tank shape, weld in a baffle or three working from the open ends and then weld on the ends to close things up. 'Kay. makes sense. Al I have to do now is learn to weld aluminum! Or, you can drill holes in the outer skin where the baffle flanges are located and then weld them from the outside. It's a lot easier than trying to get a stinger in the tank. Learn how to weld Aluminum? After a couple thousand in dedicated equipment, and a hundred hours of practice, you'll certainly be qualified. It's a little easier than turning crankshafts, I suppose. If it was me, I'd spend my time doing fun things and leave the 20 minutes of welding to the pros. Rich S. |
#28
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"Rich S."
: "Fortunat1" wrote in message ... Yes, you would wrap the sheet to form the overall tank shape, weld in a baffle or three working from the open ends and then weld on the ends to close things up. 'Kay. makes sense. Al I have to do now is learn to weld aluminum! Or, you can drill holes in the outer skin where the baffle flanges are located and then weld them from the outside. It's a lot easier than trying to get a stinger in the tank. Learn how to weld Aluminum? After a couple thousand in dedicated equipment, and a hundred hours of practice, you'll certainly be qualified. It's a little easier than turning crankshafts, I suppose. If it was me, I'd spend my time doing fun things and leave the 20 minutes of welding to the pros. Mmm, maybe. Plan was to borow my buddie's TIG, though! I do know someone who can do it for me, alright. On the other hand, ACS have atank for this airplane. By the way, I'm hurt! I learned to weld steel and it only took me a few months! And it was fun, too.. |
#29
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"Fortunat1" wrote
Mmm, maybe. Plan was to borow my buddie's TIG, though! I do know someone who can do it for me, alright. On the other hand, ACS have atank for this airplane. By the way, I'm hurt! I learned to weld steel and it only took me a few months! And it was fun, too.. Welding Al is indeed much harder to master than welding steel. The melting point of the filler and the melting point of the filler is the same, or very close to it. Get it got enough to flow the puddle, and if you are just a little too hot, it blows through. And of course, a tank has to be perfect to not leak. Many pros still get a few leaks. Make sure that whoever does the welding does a pressure test, before any gas goes in it. -- Jim in NC |
#30
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Having just finished the tanks for my RV-7, I agree with Cy. If you're
in the USA, call Van's A/C & get the name of a builder near you & go look at the plans for the tank/leading edge to get an idea of how they go together. If you can handle cutting & fitting the aluminum, the rest is pretty simple & you can build with a drill & a cheap 'pop' rivet tool using closed end pulled rivets. AD41H aluminum body steel mandrel is what's used to attach the back baffle to the ribs. You'll need at least a couple of internal ribs to stiffen the 2x4 foot top & bottom panels. The hardest thing will be bending up the 'box' but a good sheet metal shop can do that for you. (Be sure to tell them to use the proper radius on the bends.) You will be amazed at how light it will be. Charlie Cy Galley wrote: I would check with a Van's builder. RVs have aluminum riveted tanks with pro-seal. If you know a good tig welder, then a welded tank can be built. "Fortunat1" wrote in message ... "Rich S." sednews:_fydnZvUOMpYONnfRVn- : "Fortunat1" wrote in message . . . so I'm going to have to learn to build an aluminum tank.. Anyone know of a resource to show me how? The books by Tony Bingelis have excellent tips on this. http://www.amtbooks.com/sport_plane_...on_techniq.htm Mm, have all of his books and I don't remember seeing an article about ali tank construction, but I did find this article from SA on the net.. http://members.eaa.org/home/homebuil...About%20An%20A luminum%20Fuel%20Tank_.html |
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