Plastic jerry can for fuel tank

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Winginitt

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Joined
Apr 5, 2019
Messages
176
I may be overlooking something but the main points of concern here are to keep fuel contained in the event of a crash,and keeping fuel contained during normal operation (preventing leaks).
First you have to consider what works in normal operation, and a lot of things will function sufficiently to provide containment and leak free service. But, one must ask themselves not just what works in this situation, but what is "best", AND will it even be possibly sufficient in a crash.
Plastic can work well for fuel lines and even tanks in normal flight, but often doesn't have strong or even "any" provision for venting or securely attaching a fuel line. In those cases a builder must find ways to design and adapt something that could prove insufficiently strong or leak free. Often there are no mounting provisions, but that can be overcome with retaining straps. The restraining straps may not prevent vibration but should restrain major movement. In small ultralight aircraft, vibration can be more of a problem.
Aluminum tanks are available with mounts incorporated that will hold them securely and with rubber isolators, limit the effects of vibration. Add to them some lightweight nylon straps and it should be easy to prevent movement during a crash (within reason) that would pull the tank from the mounts or allow the gas mass to gain enough force to rupture the tank. Preventing movement of the tank should prevent fuel lines from being ripped out or suffering major damage. Yes there are unforseeable things that occur during an accident that may damage tanks or lines, but the basic scenario of damage caused by the fuel mass or inadequacy of the tank can be pretty much eliminated.Nylon restraining straps are light and strong and could offer much in the way of backup support to the solid mounts. If the tank doesn't move then the fuel lines are much more likely to survive without becoming severely damaged. Not sure why anyone would want a quick disconnect in an aircraft fuel system? Personally I would want connections that can only be disconnected by using a wrench or special tool.

Another thing that confuses me with the typical "fuel can" gas tank, is how someone draws fuel from it. In a normal gravity fed system, fuel is supplied from the lowest point in the tank. The very nature of the shape of a fuel can has no provision to drain fuel from the bottom and the only openings are well above the bottom. Am I missing something in how the tanks are mounted..........
 

SVSUSteve

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Joined
Aug 20, 2007
Messages
3,894
Location
Evansville, Indiana
Add to them some lightweight nylon straps and it should be easy to prevent movement during a crash (within reason) that would pull the tank from the mounts or allow the gas mass to gain enough force to rupture the tank. Preventing movement of the tank should prevent fuel lines from being ripped out or suffering major damage. Yes there are unforseeable things that occur during an accident that may damage tanks or lines, but the basic scenario of damage caused by the fuel mass or inadequacy of the tank can be pretty much eliminated.Nylon restraining straps are light and strong and could offer much in the way of backup support to the solid mounts. If the tank doesn't move then the fuel lines are much more likely to survive without becoming severely damaged. Not sure why anyone would want a quick disconnect in an aircraft fuel system? Personally I would want connections that can only be disconnected by using a wrench or special tool.
Quick disconnects are simply a design trade-off that is necessary in aircraft that have removable or folding wings. Honestly, there's not anymore of a safety concern in and of themselves than any other fuel line connection.

Frangible ("breakaway") connections are design to prevent spills when lines from tanks in wings, etc are loaded in a tensile direction. Having a secure tank in a situation where there are no non-spill breakaway is a BAD thing. For example: if the wing is sheared off or fails downward (in a high-wing aircraft), you're likely to either pull the line from the tank fitting or rip the line apart.

If you have breakaway valves, it's actually SAFER to have a wing-mounted tank come loose and either get tossed forward of the wreckage or be dragged back when the wing structure goes bye bye. As long as the tank isn't going to be thrown into the cockpit, it's something you want to get rid if you can as soon as possible. Remember that old joke about "when you're on fire" being one of the only times you can have too much fuel? Same also applies to a crash.
 

Charles_says

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HBA Supporter
Joined
May 26, 2019
Messages
137
Another thing that confuses me with the typical "fuel can" gas tank, is how someone draws fuel from it. In a normal gravity fed system, fuel is supplied from the lowest point in the tank. The very nature of the shape of a fuel can has no provision to drain fuel from the bottom and the only openings are well above the bottom. Am I missing something in how the tanks are mounted..........
Fuel would be drawn via fittings inserted in holes drilled in the lowest flat areas tank. Here is the one I originally used, before discarding the idea
https://www.amazon.com/Seasense-Thru-Bulk-Fitting-8-Inch-Brass/dp/B004XAFICS

They're sealed to the tank with fuel rated "Viton" :O: rings
https://www.amazon.com/Dorman-800-013-Viton-O-Rings/dp/B000CIV4OQ/ref=sr_1_5?crid=263XXQZ1IGOTV&keywords=viton+o+ring&qid=1565540053&s=automotive&sprefix=Viton+"O",sporting,208&sr=1-5
 
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