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External Tanks

mick

mick

Active Member
Trial fitting my new tanks. Extra 35Ltrs per tank. Not sure of the performance penalty but I think they look hot anyway. Only takes a few minutes to remove them for normal operations.
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Mick
 
Hard points

Ive often thought about those previous "a"model folks who have converted to tail wheel and how they could use the tricycle hard points to mount something external like a fuel tank or baggage compartment.

Your tanks look pretty real. I wonder what would happen if you accidently got close to a TFR here? The security over liberty mindset may not present a pleasant outcome.

By the way, they look cool and thinks for sharing!
 
Friggin' awesome!

I want to see a picture from the front, showing the overall plane with both external tanks, please.
 
Proceed with caution. That much mass on what looks like a ~12" arm may cause a significant change in wing torsional frequency.
 
DanH said:
Proceed with caution. That much mass on what looks like a ~12" arm may cause a significant change in wing torsional frequency.
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Just like wingtip tanks - each mod needs to be considered individually for those unintended consequences. Having said that, it's a cool looking mod!
 
They need fins on them. ;)

Very cool! How did you plumb them into your fuel system and how did you support the tank? Do you think this can be done as a retrofit to a flying aircraft?

Here is a picture of an RV-4 with external baggage pods. I would think they could be modified into fuel tanks rather easily.
rvpods.jpg
 
The center of gravity of the tank is just forward of the wing spar, about 1/4". The rear attachment is more for stability. This is just a test tank that has no plumbing installed and will be used for load testing only.
I will be plumbing the external tanks to the main tanks and transferring fuel with an electric fuel pump. My thoughts at the moment are that a line from the highest point on the main tank will return to the external tank so if the transfer pump is left on it will not over fill the mains and cause the fuel to be dumped out the vent lines. I would rather use the fuel from the external tanks first and this would allow me to run the fuel pumps until they are dry.

Mick
 
Mick, was it you that was playing around with a different nose wheel set up at one time. what happened to that project?, did you give up on that one.:)
 
PIN 37 said:
Mick, was it you that was playing around with a different nose wheel set up at one time. what happened to that project?, did you give up on that one.:)
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That was me.
I have gone with the antisplat brace in the end, nice and simple. The antisplat brace was not released when I did the nose gear. I do intend to refit the strut nose gear at a future date as the fast taxi tests showed great promise, and it was much smoother than the standard gear.

Mick
 
Carl J. Niedermeyer said:
As Dan alluded to, external stores, such as this fuel tank, reduce the speed at which the wing will flutter since they reduce the wing's torsion frequency, and the wing's torsion mode will couple with the wing's bending mode at a lower speed. (Classical flutter involves the coupling of two or more modes of vibration. For example, the wing bending mode and the wing torsion mode, or the aileron rotation mode and the wing bending mode.) It appears that the fore-aft center of gravity is slightly ahead of the wing's elastic axis, and that is beneficial and will offset some of the adverse effect mentioned above, but the overall result will be a lowering of the wing's flutter speed. I would strongly encourage an assessment/analysis, and possibly a ground vibration test, by a knowledgeable flutter engineer, and only then open up the flight envelope carefully using accepted flight flutter test techniques.
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I agree and do not intend to fly without some sort of assessment being done. I had an analysis done for the leading edge long range tanks that I build for RV's.
 
Remember that, with a partially full tank, the fuel will move forward in a dive and aft in a climb (unless you have a baffling system to hold it in place) which will change your CG with nose position.

-John

mick said:
The center of gravity of the tank is just forward of the wing spar, about 1/4". The rear attachment is more for stability. This is just a test tank that has no plumbing installed and will be used for load testing only.
Click to expand...
 
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