Hi Guys;
I have a few questions about working sheet aluminum. I'm deciding whether I want to build a replica Mustang, similar to the Titan-51, but more from scratch, not their kit.
I also should state that I searched this section first, and found some answers, but not all. Please respond to as many or as few of these questions as you wish, and thank you in advance for answers. This group of homebuilders (and wanna-be's) continues to amaze me with useful feedback.
First, I would mimic what Titan has done, a steel tube fuselage with aluminum skin to make it look real. I considered a semi-monocoque approach, but at the moment, there are reasons I'm liking the 4130 tube fuselage frame. I've been known to change my mind many times!
The wing would be fairly conventional, angle or 7075-T6+ aluminum spar caps, and 2024-T3 shear web, probably a 4130 1/8" tie plate to join the two spars in the center, possibly detachable outer wings, again like Titan for ease of storage/transport. The skins would be similar gauge to Titan's choices, as would the overall flight characteristics.
What would maybe be a bit different than the Titan approach, is that their fuselage skin actually takes a lot of shear load, and they don't use diagonals in the fuse tube frame, whereas I would add diagonal members. Bigger tubes too, if weight permits. One inch diameter round, maximum, but 7/8" or 3/4" diameter if it works out to enough. Titan uses 1/2" square tubes. Obviously, total weights of materials will be a big concern, but that's always the case.
The fuselage skin would be mounted onto aluminum fuselage frames, which are attached by tabs to the tube frame. I wouldn't use the hat sections that Titan uses. Overall, I'd want the skin to appear to be scale, with all the joints, rivets etc., in roughly the right spots compared to a P-51D.
Let's say I want pulled rivets, probably countersunk type, for construction in almost all areas of the fuse, wing and tail skins (the spar would be solid rivets and possibly bolts).
1. Drilling: I assume for alignment, that a wing skin would be drilled while located on top of the wing ribs? I mean drill, Cleco, then drill the next hole? I can't see the holes being drilled on a flat skin, while on the bench, then draped onto the internal structure. All your holes would be off.
2. Deburring: If you drill through 2 or more sheets of thin aluminum, do you actually deburr EACH side of EACH sheet? if you drill through 3 sheets with one hole, that would mean 6 surfaces to deburr. Or is it common practice to deburr only the outside of the top and bottom sheets, where the burrs are biggest? By the way, I'd use a hand-held countersink tool for gently deburring. I also understand that deburring is also crack-prevention "medicine" so again, I'd like to know if ALL surfaces are typically deburred. That would mean a lot of assembly/disassembly.
3. Dimpling: Let's say I'm using countersunk-type pull rivets, and installing a wing skin, working from the Leading Edge. Can the builder start at the LE, and work back towards the spar? I mean, let's say the skin is 4 feet length, spanwise, and covers 5 ribs. Would it work to drill, deburr, install rivets near the LE of all 5 ribs, then work aftwards with the next row of rivets, and carry on like that until reaching the spar? Or, would you drill and Cleco as you go, finishing EVERY hole, remove the whole wing skin from the wing, then deburr each hole? After, then Cleco re-assemble, replacing each Cleco with a rivet? I guess what I'm asking for is YOUR experience and what's the typical method for riveting on a large panel with a zillion holes?
4. Corrosion between dissimilar metals: If I use a tie plate of 1/8" thick 4130, to tie the spars together at the root end, and bolt or rivet this to the 2024-T3 shear webs of the spars, I'm possibly looking at corrosion. Is it typical practice to apply an anti-corrosion spray or sealant to this area, such as zinc chromate, or other sealant? What would you use? Are there different accepted ways of guarding against corrosion in areas like these?
Well, I know that's a mouthful, but if you're game, dive and, and again accept my thanks for helping. I did just order a book that AVI suggested from Ebay, "Working with Sheet Metal for Aircraft" so this is a good step, but I like this approach to learning as well. I get more ideas and choices.
Cheers all, Tom.
I have a few questions about working sheet aluminum. I'm deciding whether I want to build a replica Mustang, similar to the Titan-51, but more from scratch, not their kit.
I also should state that I searched this section first, and found some answers, but not all. Please respond to as many or as few of these questions as you wish, and thank you in advance for answers. This group of homebuilders (and wanna-be's) continues to amaze me with useful feedback.
First, I would mimic what Titan has done, a steel tube fuselage with aluminum skin to make it look real. I considered a semi-monocoque approach, but at the moment, there are reasons I'm liking the 4130 tube fuselage frame. I've been known to change my mind many times!
The wing would be fairly conventional, angle or 7075-T6+ aluminum spar caps, and 2024-T3 shear web, probably a 4130 1/8" tie plate to join the two spars in the center, possibly detachable outer wings, again like Titan for ease of storage/transport. The skins would be similar gauge to Titan's choices, as would the overall flight characteristics.
What would maybe be a bit different than the Titan approach, is that their fuselage skin actually takes a lot of shear load, and they don't use diagonals in the fuse tube frame, whereas I would add diagonal members. Bigger tubes too, if weight permits. One inch diameter round, maximum, but 7/8" or 3/4" diameter if it works out to enough. Titan uses 1/2" square tubes. Obviously, total weights of materials will be a big concern, but that's always the case.
The fuselage skin would be mounted onto aluminum fuselage frames, which are attached by tabs to the tube frame. I wouldn't use the hat sections that Titan uses. Overall, I'd want the skin to appear to be scale, with all the joints, rivets etc., in roughly the right spots compared to a P-51D.
Let's say I want pulled rivets, probably countersunk type, for construction in almost all areas of the fuse, wing and tail skins (the spar would be solid rivets and possibly bolts).
1. Drilling: I assume for alignment, that a wing skin would be drilled while located on top of the wing ribs? I mean drill, Cleco, then drill the next hole? I can't see the holes being drilled on a flat skin, while on the bench, then draped onto the internal structure. All your holes would be off.
2. Deburring: If you drill through 2 or more sheets of thin aluminum, do you actually deburr EACH side of EACH sheet? if you drill through 3 sheets with one hole, that would mean 6 surfaces to deburr. Or is it common practice to deburr only the outside of the top and bottom sheets, where the burrs are biggest? By the way, I'd use a hand-held countersink tool for gently deburring. I also understand that deburring is also crack-prevention "medicine" so again, I'd like to know if ALL surfaces are typically deburred. That would mean a lot of assembly/disassembly.
3. Dimpling: Let's say I'm using countersunk-type pull rivets, and installing a wing skin, working from the Leading Edge. Can the builder start at the LE, and work back towards the spar? I mean, let's say the skin is 4 feet length, spanwise, and covers 5 ribs. Would it work to drill, deburr, install rivets near the LE of all 5 ribs, then work aftwards with the next row of rivets, and carry on like that until reaching the spar? Or, would you drill and Cleco as you go, finishing EVERY hole, remove the whole wing skin from the wing, then deburr each hole? After, then Cleco re-assemble, replacing each Cleco with a rivet? I guess what I'm asking for is YOUR experience and what's the typical method for riveting on a large panel with a zillion holes?
4. Corrosion between dissimilar metals: If I use a tie plate of 1/8" thick 4130, to tie the spars together at the root end, and bolt or rivet this to the 2024-T3 shear webs of the spars, I'm possibly looking at corrosion. Is it typical practice to apply an anti-corrosion spray or sealant to this area, such as zinc chromate, or other sealant? What would you use? Are there different accepted ways of guarding against corrosion in areas like these?
Well, I know that's a mouthful, but if you're game, dive and, and again accept my thanks for helping. I did just order a book that AVI suggested from Ebay, "Working with Sheet Metal for Aircraft" so this is a good step, but I like this approach to learning as well. I get more ideas and choices.
Cheers all, Tom.
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