Item 0800

MAKE: Fuel - Tank - High Location

Drawing:

to come 

 

 Consider mounting fuel tank high, back of pilot's heat and partially between control rods. There may be enough space there now that seat has been moved forward 2". Might also allow for gravity flow; or at least gravity assist. Also consider passing inside lateral cyclic rods through tank as this will allow the tank's center of gravity to be closer to the helicopters center of gravity.

Mockup:

Allowable size under Far 103 is 5 gallons = 1155 cubic inches = .6684 cubic feet

_________________________

 

Cardboard cartons are 9" * 11" * 4.5" =

445.5"

 

3 cartons is 445.5 * 3 =

1336.5"

 

Less;

 

 

Cutout for inside lateral control rods (2.5" * 2.5" * 0.625 / 2) * 2 =

3.9"

 

More cutouts to be done.

 

 

Total size =

 

 

Vertical distance from bottom of mockup tank to carburetors is approximately 12".

Notes:

May not require fuel pump(s).

 ‘Polyesters have a lower moisture absorption and high chemical resistance which makes them well suited for fuel tanks.’

Does this mean that an epoxy fuel tank as part of the structural body may be a problem? Can inside of tank be coated, if necessary?

Consider having the fuel tank removable. This might be easier for filling and for inspection and adjustment of other components.

Consider using Eipper 5 gallon molded fuel tank. On the Gyrobee it is held on by a bungee chord and can be dismounted if it has to be used as a gas can for refueling

Re. mounting fuel tank high behind seat with gravity feed to engines. Potential problems:
    1. Leakage of fuel onto hot engine, particularly in a crash.
    2. Tanks will block some of the cooling air to the engines. Unless it has a pyramid shape and the base dimensions coincide with the frame.

Consider safe means of draining tank(s) to lighten load for emergency landing. Make sure tanks will not drain by them selves. Perhaps pulling flexible hose to engine will siphon off gas

Fuel tank(s) are connected to power train not fuselage.

Consider internal baffle(s) to control the effects of sloshing.

Consider lining the tanks with a crash resistant flexible blader.

Fuel Reserve (Safety)

1/ The fuel arrangement must be such that if one engine runs out of fuel there is still enough in the other for semi-autorotation and powered flare.

2/ An idea, for a fuel pump system only, would be to have a small 'bottle' located after the pump and in the fuel line to 1 engine ONLY. This bottle would be in an inverted position and located after a check valve. Should the main fuel tank go dry, then this one engine will stop say 30 seconds after the first because it was still receiving fuel from the pressurized bottle. The pressure would come from the air trapped in the inverted bottle. The 30 seconds would allow the pilot to setup for autorotation.

Make part of Power Train? September 17, 2000

If the fuel tank is part of the drive train then it can be larger (and/or) have a greater drop to the carbs. Plus it can also be part of the part train structure. It may not have to be lined or coated at it might have to be in the composite body. Shape: Once it is back of inside control rods it can widen out to the width of the current frame.

Lines to have compound shape so as to tie in with fuselage.

Note: If a weld breaks then fuel very well might pour down onto a hot engine.

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Last Revised: September 18, 2000