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Thread: Fuel tank design questions

  1. #1
    Marty57's Avatar
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    Fuel tank design questions

    Iím getting ready to build the tanks for my 2+2 wing; standard Super Cub set up. The wing has a shear plate under the tank bay and the cover will be attached with screws into nut plates. I canít find much in the way of specifications related to the sump in the tank. Main question is the location of the sump; is the rear most inboard corner the best I? What about dimpling the tank at the sump location, is it necessary and if so, how big and what is the best way to accomplish it? The tank will be made from welded 5052 aluminum, about 16 gallons. There arenít any control cables running through the tank so it is a pretty simple design. I will have two baffles and outlets at each corner of the tank with strainers and will be using a sight gauge. Any thoughts, drawings, or pictures of tanks would be a big help.
    Thanks,
    Marty57

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    algonquin's Avatar
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    I saw a sump made by taking a piece of tubing welding a plate on one end with a nut welded on for the drain. Then a hole cut in the tank and the tube welded in.

  3. #3
    skywagon8a's Avatar
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    Cut a 3" or 4" circle in a scrap of plywood. Place the 5052 over the circle where you want the sump. Tap the 5052 with the ball of a ball peen hammer around the circumference of the circle. This will make a flat bottomed bowl in the 5052. The bowl doesn't need to be very deep, 1/4" or so. The sides of the bowl will stiffen the area where the drain is located. This is a good thing. This should be done before you bend up the sides of the tank but will work afterwards with more difficulty. Cut a 2" or so diameter disc out of a piece of 3/8" or so thick aluminum. Weld around the circumference of the disc to the flat on the outside of the sump bowl. Drill and tap 3/8 pipe hole in center (or whatever size your quick drain is) for the quick drain. Some tanks don't have any sump since the outlet finger screen is normally above the bottom of the tank by some amount leaving the bottom of the tank as the sump. Sumps are good though since they provide a collection location for small drops of water and other contaminates.

    algonquin's method will also work with a lot more welding and more possibility of failure along the welds over time. It will also take more time to make.

    Try to bend up as many of the seams as possible to reduce welding joints. The tank can be made of one piece with the welded seams being the four vertical corners, the two top sides and the rear (or front) top edge. You can dress the lower corners before welding by tapping with a hammer without over stressing the material in the corners. Allow a little extra for this purpose when cutting the excess out of the corners before bending. Think before cutting.

    Design your baffles with stiffeners so that they can not flex due to vibration thus cracking themselves or their welds.

    Be careful not to make them too large. They are easier to install if slightly smaller than the hole into which they are being placed. It's better to have them 1/4" undersized than to have them 1/32" oversize.

    Take into consideration where the hold down straps tighten against the welded joints. If they are too tight they can concentrate loads on the welds which can cause cracks in the welds over time.

    Practice forming shapes out of aluminum with a hammer and a mold. Carve the mold out of a chunk of wood. Allow for the thickness of the aluminum when you make something which may be close fitting. Use a soft aluminum such as 5052-0, 5052-T3 or 2024-0. The part will get stiff when formed. You will find that there are lots of parts which you can make yourself. For example the streamlined cover which goes over the aileron pulley on the top of the wing.

    And by all means show us some pictures. Your wood work is a masterpiece.

    You can make a nice radius on the vertical corners if you plan ahead when cutting out the excess material. This may make the welding a bit easier. Think about it.
    Last edited by skywagon8a; 08-24-2016 at 05:49 AM.
    N1PA

  4. #4
    Marty57's Avatar
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    Skywagon,
    Thanks for the input on the tank; sounds good. I'll do some practice forming on some 5052 and see how it works. I have a weldable flange for the sump drain and could have that welded to the bottom of the tank after forming the bowel, would that work? I made a wood mock-up of the tank when I was building the tank bay and need to be pretty close to size for runs of cables but I think the one piece may be workable. My mock-up is exact on the sides but the tank will go out to each rib when finished. How much clearance is needed between the tank and rib for fittings, site gauges, etc?
    Thanks,
    Marty

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  5. #5
    algonquin's Avatar
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    I'd go with Skywagon over what I saw, I'm not the welder guy if you know what I'm saying,lol. When I'm welding there is no need to cut holes, I burn plenty. I do know that the 12 tanks have a design flaw the traps water, a good friend of mine crashed a 12 for this reason. He is a 18,000 hr guy and slumped before flight. I'll get him to chime in here and there is also a thread about the tanks on this site.

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    I've used tubing with a cap on one end and a boss for the quick drain. Especially in low dihedral angle wings put a quick drains and sumps on both the inboard and outboard ends of each tank. -----Read previous posts on pa-12 wing tanks.----With only an inboard drain, water will sit in the outboard end of the low wing. Happens often with low dihedral wings and every time you walk out on a float to check the sump your always checking a low wing and the only drainable water is that left in the sump. Most of the water will end up in the outboard end of the tank and without an outboard sump it is undrainable. It's easier to understand in a float plane but a small slope of ground is reflected by a large movement of the wing even in a wheel plane. In a cub a raised axel of .6 (six tenths of an inch) causes water to flow to the outboard end of the opposite wing tank. Uneven ground, stretched bungi, higher pressure in one tire ot tying one wing down first or more tightly all create this situation.

    Relevant to all wings but especially those with small dihedral angles. Put sump as far aft and as far outboard and inboard as possible. It makes the tank bottom stiffer to resist oil canning and catches more water. Be sure that the tank bottom will not oil can upward into the tank after prolonged pressure of pushing the quick drain up against the spring and tank bottom. Don't even consider not using sumps. The tank bottom will be even more likely to oil can inward leaving water sitting in a ring around the oil can and the drain. Be sure also when the sump is welded in place the weld does not create a high spot that will restrict waters flow into the sump

    If if you think your tank won't ever make water, keep in mind that you can't fool Mother Nature.

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    Fat Kid's Avatar
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    Fat Kid's Avatar
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  10. #10
    Marty57's Avatar
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    Fat Kid,
    That's what I wanted to see, thanks. It looks like the hole is flared out to accept the flange, thus creating the sump. Did you do one or two sumps?
    Marty
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  11. #11
    skywagon8a's Avatar
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    Quote Originally Posted by Marty57 View Post
    Skywagon,
    Thanks for the input on the tank; sounds good. I'll do some practice forming on some 5052 and see how it works. I have a weldable flange for the sump drain and could have that welded to the bottom of the tank after forming the bowl, would that work? I made a wood mock-up of the tank when I was building the tank bay and need to be pretty close to size for runs of cables but I think the one piece may be workable. My mock-up is exact on the sides but the tank will go out to each rib when finished. How much clearance is needed between the tank and rib for fittings, site gauges, etc?
    Thanks,
    Marty
    Your weldable flange is fine. Your mock-up will give you your "limit" dimensions for the finished product which will include the fitting flanges. The fittings can be screwed in after the tank is strapped in the wing. Be sure to allow for the welding bead around the edges. Make the holes in the butt rib and under the sumps large enough for a socket wrench with a little spare room for imprecise tolerances.

    Since the airplane is a tail dragger, I would place the lower fitting for the sight gauge as far aft as possible with the upper fitting forward. The stock Piper fuel gauge leaves a lot to be desired when on the ground and when low on fuel. The important fuel level to be cognizant of is when the level is low. You don't need the gauge to tell you that it is full.

    Cutting out the bottom of the bowl as in Fat Kid's picture would be optional. Leaving it in would (in my opinion) make the welding a bit easier. Thin aluminum moves a lot when being welded.

    Be cautious of making the sump too deep. If you have an upward opening door or window (even sometimes with a forward hinged door) there could be an interference problem with the quick drain.

    The idea of two sumps per tank at each rear corner is a good one for the reasons stated.

    Place the outlets to the engine as low as possible to reduce the unusable fuel quantity.

    Be certain to use a finger screen in the tank outlets to trap contaminates. (This is an FAA requirement for all certified airplanes and should apply to yours as well.)
    Available here: https://www.aircraftspruce.com/catal...clickkey=18612

    Also unless you are proficient at welding aluminum, find a good welder to help or do it for you. Aluminum is not as forgiving as steel. If you want to do it yourself, Practice, practice and more practice. Aluminum is fun once you get it accomplished but it does take a lot of practice. A small pin hole in the weld of a fuel tank can be a BIG pain in the derriere. It is worth while paying the guy with lots of practice to do the gas tanks.

    Make a fixture to hold the tank shape at least until it is tacked rigid. If it becomes distorted (easy to do) while welding it will not fit in the wing cavity.

    Your mock-up picture does not show the aft shape. It may be a good idea to make your one span wise weld seam at that lower forward edge. That edge appears in your photo to not have a strap pressuring against the welded seam. This will remove the concentrated stresses from the straps to the welded joint.

    After the tank is finished and before it is installed make sure that you remove any particles which always end up inside the tank during the build process. Even when you do this there always seems to be some particles show up in a quick drain somewhere when the tank is full of fuel.

    Make sure that the filler neck is tall enough to clear the top of the wing and that you can manipulate the cap.
    N1PA

  12. #12
    Marty57's Avatar
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    Skywagon,
    Great comments on the tank design, thanks. I didn't think about where to put the weld line based on the stress of the strap, great info. I think I'll try to build the tank in three pieces; the sides and one continuous skin all the way around with one seam. I can cut a 2" strip to do a practice bend to bet the skin the right length and the weld out of harms way. I do have the name of a good welder, old school who has been doing this kind of welding for a long time. I'll be calling him before I start fabricating the tank. I have all the flanges and strainers but I think I'll add another flange for a second sump. The span of my mock-up is shorter than the span of the well; I'll keep in mind the fitting. Great input. I'll post pictures as this comes together.
    Thanks,
    Marty
    Last edited by Marty57; 08-25-2016 at 11:03 AM. Reason: typo
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    skywagon8a's Avatar
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    For a thee piece tank make a form block from 3/4" or thicker plywood the shape of the side "rib" pieces. Cut this to the dimensions of the tank minus four times the thickness of the aluminum. Radius the edges about 1/8". Cut the end piece of 5052 to this dimension and shape plus 1/8"-5/16" all around. Dress down the edges to the shape of the block with a mallet. Make a left and a right part. This will give you a stiff end plate with a nice edge for the welder to attach the top piece. The aluminum also will not walk as much under the heat.

    For your baffles plan on attaching them to the bottom and front and back. The top can just be a bent over flange which is not attached to anything. This will make it easier to close up the tank and the rib will be supported.
    N1PA

  14. #14
    www.SkupTech.com mike mcs repair's Avatar
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    TRY to not have sump & outlet exactly inline, as finger screen and some deep quick drains will bend the finger screen...

  15. #15
    Fat Kid's Avatar
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    Marty I use one sump on the tanks i built. I located them in the aft inboard corner (lowest point in of the tank when installed on the aircraft). Some thing to keep in mined while your fabing up your tanks if your not a welder is the welds shrink when they cool. This shrinkage is what cause distortion. If you look at most aircraft fuel tanks you will find that very few use "butt" welds to joint material together to make a seam. Most tanks have an "edge" weld along flange to make a seam. The edge welded seam has less distortion and the use of a back up gas in tank is not as critical because the type of weld does not penetrate through to the inside of the tank. Your mock up looks very nice. Again from my experience don't get to crazy jigging and fixturing to try and hold it together for welding. I did that to start with and it did really help all that much. I had the best results just clamping the weld seam together and tacking as close to the clamp as possible then moving a half inch or so tacking and so on until the tank was completely tacked together. Starting your tack welds and final edge welds in the middle of the weld seam and working towards the corners helps a lot with minimizing distortion of the tank. I hope this is helpful and again I'm no expert this is just my experience.

    Ben K.

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    Square your tank front and rear. Will hold several gallons more fuel.

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    Marty57's Avatar
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    Lots of good points here, thanks. I was planning on bending over edges on the end pieces 3/8 for welding. This will allow me to weld the top on to the side flange. As for the shape of the tank, the rear will be square but the front will remain angled as in the mock up. The design takes into account the location of my control cables. the cables all run inside the wing and through the tank bay. I designed the tank so that I can remove it easily with out having to remove any cables. I know I will loose some capacity but I'm ok with the trade off. Mike, good tip on the outlet and the sump. They will be pretty close together but I can off set the sump a bit so it isn't lined up with the outlet. The fuel strainer only goes on the outlet, is that correct? As for welding, I plan on tack welding the tank together myself ........ maybe. I need to do a lot more practice as I am doing it old school and gas welding the aluminum. I'm pretty comfortable welding the .050 sheets together but haven't tried welding a thick flange to the relatively thin sheet. I may try that with an extra flange I have. Otherwise, I'll contact the welder who was recommended to me and see what his fabrication needs are. Anyone else out there ever gas welded aluminum? The trick is lots of tack welds, every inch. The tack welds help to distribute the heat easier when finishing up the seem. Any ideas or tricks to welding a thick flange to the .050? Last thing is to decide on one sump or two. I will be using a header tank if that makes any difference on the number of sumps.
    Thanks,
    Marty
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  18. #18
    skywagon8a's Avatar
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    Quote Originally Posted by Marty57 View Post
    ..The fuel strainer only goes on the outlet, is that correct?.I will be using a header tank if that makes any difference on the number of sumps.
    Thanks,
    Marty
    Yes the feed to the engine gets the strainer. There ought to be two outlets. One at the rear inboard corner and one at the forward inboard corner. This will ensure flow with a low fuel situation with the airplane nose low.

    A header tank has no bearing on the sump in the fuel tank.
    N1PA

  19. #19

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    I pro sealed and riveted my tanks on two different planes. Also riveted filler caps and fittings. Haven't been sorry.

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    Skywagon suggested a forward and aft feed from each tank. It's a great idea. This is what the CubCrafter header less fuel system uses. The header tanks are supposed to keep a continued fuel flow for a period of time during a turn where the low wing fuel pickup will port or during a nose low condition where an aft fuel pick up will port. The forward and aft fuel feeds cover this. However it requires that the feed be from both tanks simultaneously. There is a problem with this arrangement. Some pilots love it. Fly with fuel selector both tanks on and you don't have to think or pay attention.

    If your trying to fly light often times you carry minimum fuel. Hence partially full tanks and the increased likelihood of condensation. Also if your on both tanks when you get low on fuel the gauges are less acurate and you have your fuel divided between two tanks. I prefer to fly to the end of my right tank and have a larger quantity of fuel in my left tank for landing. If you are landing with minimal fuel you are better off having all that you have in one tank instead of devided between two tanks.

    A super cub with the standard header tank system is required to use the left tank for takeoff and landing. This should always be done especially when light on fuel except at times on slanted beaches with the left wing low or right dog legtakeoffs. I know of several accidents and incidents of engine failures caused by takeoffs during a low fuel conditions when feeding from the right tank. It can happen in a steep climb as well.

    When operating from both tanks simultaneously in the event of contaminated fuel, you have no way of knowing from which tank the contaminants came and switching tanks is a crap shoot, not necessarily a fresh source of fuel. Also if your timing your fuel burn and you should be, it is good to take off on your left, switch to the right and time your fuel burn and switch back to your left for landing. Simplifies the timing and measuring of fuel used.

  21. #21
    Marty57's Avatar
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    I'm not sold on the header tank; I didn't weld in the mounting straps in the fuselage for it before painting with the idea that I could add it latter. The Wag plans show a pretty simple system of a simple on/off fuel valve from the header tank to the gascolator. The idea of being able to better manage the fuel is good food for thought. I would then need a fuel valve rather than header tank. The header tank does give me a couple more gallons of fuel but it is inside the cockpit (so is the J3 so not a big deal). I'm for sure going to have the two outlets per tank. I guess I can decide on the header tank down the line. I would like to see how big these tanks come out. My best calculation is the tanks will be about 16 gallons each. The header would give me another 20 minutes of fuel. Hmmmmmmm; more to contemplate. Another issue that I'm am looking at is the filler neck and fuel cap. The neck has a bead around it but I will need to weld the neck higher due to the clearance of the straps from the cover. I am thinking of some how dishing out the area of the tank where the neck welds on. I assume that I want the cap pretty close to the cover but not touching it; am I right in that thinking?
    Marty
    Last edited by Marty57; 08-25-2016 at 11:56 PM. Reason: typo
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  22. #22
    Gordon Misch's Avatar
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    My stock -12 system had fore and aft outlets left tank only, and no header. The Atlee Dodge tanks are plumbed the same way. Factory valving was, and still is, a separate valve for each tank. It's placarded left tank for takeoff and landing. Never has been a problem in the 20+ years I've been flying the plane. I like simple.
    Gordon

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  23. #23
    Marty57's Avatar
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    I like the idea of two separate, simple fuel valves. My biggest challenge now is figuring out how to bend the skin to go around the tank. I don't have a slip roll so I may need to make the shape more with angles rather than curves like I have. I don't think I can make the skin in one piece, will need to go with two at least.
    Marty
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  24. #24
    Larry G's Avatar
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    Not sure if this will help you or not this is from Bill Rusk's photos. This is how Javron does there seams and end ribs.

  25. #25
    Gordon Misch's Avatar
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    Marty, I think if I were to do it over I'd consider a modern left-right-both-off valve. The plumbing would be a little simpler but the old brass plug valves do the job just fine!
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  26. #26
    skywagon8a's Avatar
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    Quote Originally Posted by Marty57 View Post
    My biggest challenge now is figuring out how to bend the skin to go around the tank. I don't have a slip roll so I may need to make the shape more with angles rather than curves like I have. I don't think I can make the skin in one piece, will need to go with two at least.
    Marty
    5052 bends easy. It can be bent by hand over a pipe or rounded piece of wood. I don't have a slip roll either and would not hesitate to bend it without. There is no need to make the top, front, bottom and rear from more than one piece particularly since you are making the sides separate.
    N1PA

  27. #27
    Cub junkie's Avatar
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    Here is a pic of my friends exp category cub. He uses two valves with no header, one on each side. I like the idea of a header tank but that's me.
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  28. #28
    Eddie Foy's Avatar
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    Here is the valving for mine. It has a valve for each wing. Off-Main-Aux.

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    "Put out my hand and touched the face of God!"

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    Marty57's Avatar
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    I guess I can decide on the valves after tanks are built; I'll use two feeds per tank regardless. One more question is thickness. The tank is basicly 28x28x6 and will have two internal baffles. I have .040 or .050 mentioned different places. With the size tank I am making any thoughts on thickness?
    Marty
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  30. #30
    skywagon8a's Avatar
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    Quote Originally Posted by Marty57 View Post
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    Quote Originally Posted by Marty57 View Post
    . One more question is thickness. The tank is basically 28x28x6 and will have two internal baffles. I have .040 or .050 mentioned different places. With the size tank I am making any thoughts on thickness?
    Marty
    If the tank is adequately supported either one will hold in the gasoline. Now consider a hard landing with full tanks or continuous flight in turbulent air, the gas will be sloshing around trying to deform the tank. One hard landing will make one deformation against the tank supports. Turbulent air will provide repeated impact loads against the tank supports and the welded joints. Repeated impact/bending loads on the welded joints can cause fatigue cracking along the weld. Consider this when designing and attaching the baffles. The fact that the tanks are located within the prop wash region places them subject to increased vibration induced cracking. Thin aluminum will bend and crack more easily than thick. I seem to recall that you had a discussion and showed pictures of making a plywood bottom to the fuel tank compartment. The above picture doesn't show this. If the tank will be resting directly on the plywood you could get away with thinner aluminum than if it were just hanging on two straps since the loads would be distributed over the entire tank bottom. .050" is easier to weld than .040". With all this in mind, it's your choice.

    Another thought to take into consideration when designing your baffles to back up my previous comment about the baffle not needing to attach to the top of the tank. When the tank is full there is no sloshing of the fuel since there is no air pocket for the fuel to flow into. The baffles need to reduce the sloshing when the tank is only partially full. As long as the baffle is shaped to resist bending along the top edge, it does not need to be attached to the top of the tank. It's your choice, four sided attachment means more work in the manufacturing process.

    Pressure test to 3 psi with soapy water along the welds when complete. One pin hole with a full gas tank will upset you.
    N1PA

  31. #31
    Marty57's Avatar
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    My tank bay has plywood as a shear plate but the tanks will be supported by straps; two top and two bottom. .050 makes sense based on loads and other factors as you mentioned. I'll need to locate or order .050. Thanks for the input.
    Marty
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
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  32. #32

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    Has anyone every considered "hydro-forming"? You would take two rectangular pieces (one with a water hose connection welded to it) of aluminum laid together, weld along the seams, maybe clamp pieces of wood say 3/4 inch in all around the edge and then attach your garden hose and inflate the "tank". Next cut off the welded edge so you could open it up to weld baffles in and then re weld the remaining flange edges. Perhaps you might need a wood form to inflate the "tank" into to limit travel in some directions? I have not tried this but some youtube videos showing making motorcycle exhaust pipes from steel suggest it's maybe one process that could do this?

    https://www.youtube.com/watch?v=llhcATrmsBg

    Do not use air for this!!! From testing steam boilers we learn liquid water does not compress so you can take it to a very high pressure and if it develops a small leak the pressure drops to a safe level almost immediately so you don't get the "big boom"!

  33. #33
    skywagon8a's Avatar
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    Quote Originally Posted by qsmx440 View Post
    Has anyone every considered "hydro-forming"?
    A friend of mine told me that he had visited the original Maule factory and that is how they formed their tanks. They had the whole process take place inside a big cage.
    N1PA

  34. #34
    Marty57's Avatar
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    Hydroforming seems like a lot of work for a short run; not something I would do for two tanks. I'll be trying some forming tomorrow using an oak form block. I will anneal the sheet first and cut some "darts" in the tight curves to see how it bends. I'm using remnant .040 for these first tests to see how it works. .050 will be here on Tuesday.
    Marty
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com

  35. #35
    skywagon8a's Avatar
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    Don't cut the darts. Work the metal down with your mallet. Make a backup block smaller than your form block. Perhaps chamfer the edges to allow room to swing the mallet. Clamp the aluminum between the two. This helps to control where the metal wants to buckle. If you anneal the alum it should flow around those tight radius corners. You will be stretching and shrinking the flange material. The portion under the backup block will remain unmodified. You can also make a rounded "chisel" out of a hard wood to help work the metal. Tap the chisel with the hammer while the other end pushes the metal. Start at the beginning of the bend working towards the edge.

    DARTS are for WHEN ALL ELSE FAILS.

    This is fun stuff. You may find that working metal is as much fun as your beautiful wood work.

    There are other tricks such as slapping the puckered edges with a lead strap smoothing out the puckers.
    Last edited by skywagon8a; 08-29-2016 at 04:53 AM.
    N1PA

  36. #36
    Marty57's Avatar
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    Well, that worked out very nicely. No cracking, no bumps, nice an smooth around all the curves. I didn't anneal the aluminum or anything; just cut, cleaned up the edge and formed it. I think I've discovered something else that I really enjoy doing. The forming process only took about a half hour. I talked to a welder who has been building tanks for 40+ years about my design. He gas welds the tanks and than heliarc welds the bushings for the sump, neck, etc. His method of building is to form the side with 1/2 the radius and than roll the same radius onto the top piece and cut it to half the radius. The pieces are fitted together and welded, making a nice continuous 1/4" corner at all seams. I've seen this done on custom hot rod's built from aluminum and gas welded together. When hammered and filed there is no sign of the welding at all. The pictured piece is my second side panel. The first came out just as nice but I didn't like the size as compared to my mock up so I made another form; only took about a hour to make the new form block. This one is exactly the size of my mock-up and I'm very happy with it. I'll be heading over to the welder next week to see about having him do final fabrication of the tank and welding. The price he gave me was about 1/2 the price of Dakota tanks without the shipping issue; he is about 30 miles from me. I found this fabricator from a world record holder at Bonneville; a neighbor of mine. The fabricator has been involved in racing and aviation for something like 40 years doing all forms of aluminum fabrication so I feel pretty fortunate to have found him. He prefers to build the tanks out of .060 3003 but can build it from .050 if I want; he has the .060 in his shop. The weight would be about 2 lbs more in the .060 and I know for many builders that is a huge amount of weight but I build such light wings (under 70 lbs) that I feel it would be ok to have that kind of strength and quality in a fuel tank for the extra weight. My design allows me to remove the tank without de-rigging the wing so I need to built the tanks to a pretty close tolerance for the cables to run across the front of the tanks. Pictures are attached of the side I formed from 5052 .050 to test my form block for size.
    Marty

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    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
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  37. #37
    skywagon8a's Avatar
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    I knew you could do it Marty, nice job.
    N1PA

  38. #38
    Marty57's Avatar
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    With the forms figured out, on to the next question. Where to put the fittings; specifically the for the sight tubes. I added to my mock up to see how the fittings interact with the braces inside the tank bay and came up with a location that works without any interference. Will this location work? I will likely just use tubing for sight tubes unless their is a compelling reason not to use it. Seems the tubing would be simple and less parts to leak. Suggestions?
    Thanks,
    Marty

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    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
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  39. #39
    Gordon Misch's Avatar
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    Marty, your craftsmanship, and ability to figure out new processes and implement them to very high standards is nothing short of amazing! Thank you for the ongoing inspiration!
    Gordon

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  40. #40
    Marty57's Avatar
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    Thanks Gordon; lots to learn. I do like building.

    Marty
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
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