Thorp Air Command - T18.net

My O290G has an electric fuel pump and a mechanical fuel pump. I haven't had a need for the electric pump and was considering removing it. Like to keep things simple, any opinions?, thanks

I won’t recommend one way or the other. I don’t run any fuel pumps for my O-320 powered T-18. I gravity feed from the 29 gallon fuselage tank.

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

My 2 cents worth. If you have no pumps like Jeff and can achieve 150% of engine demand fuel flow with minimum fuel in the tank and maximum nose up attitude attainable in flight, then go for it. If you have a mechanical pump you generally need an electric back up pump (boost pump) because if the mechanical pump fails there is enough restriction and quite an amount more plumbing that may reduce the fuel flow to below what is demanded by the engine.

I have O-320 power and have both mechanical and electric pumps.

Tony Schischka
T18C
ZK-VMS

As stated above, I am not recommending one way or the other. That said, I am on my third T-18. None of them have had (a) fuel pump(s). No issues flying EXCEPT during a very high attitude takeoff with around a third of a tank. Engine lost power while I was showing off. Note: A fuel pump (or two) would not have made difference, IMO. What I did was unport the drain with the high nose. Fuel pump would have just pumped more air through the lines, waiting for me to lower the nose and let the blue stuff go down.
I lowered the nose to a more reasonable (normal) climb attitude, and up up and away I went.

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Philip Mandel
N118BC
S/N 957
Beaverton OR

5 cents this time
In the three point attitude I can drain all but about 500ml from the tank. If tank is built to the drawings it would be very difficult to un port the outlet unless in an extremely nose up attitude. Have a look at drawing K-584 (three view) put a ruler across the bottom of the tank to the carb inlet then rotate the drawing. You will see that with only a gallon or so fuel it doesn't take too much nose up for the fuel to have to run up hill to get to the carb. If you always fly with a minimum of 1/2 tank and no high pitch angles you will probably have no problems.
As said before the choice is yours but consider what type of missions you wish to fly and configure the system to suit.
Cheers

Tony Schischka
T18C
ZK-VMS

2 1/2 cents. Tony, good info, however, if the ball is not centered...

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Bob Highley
N711SH
SN 835
KLAL

Another reason to need a pump is if the fuel vent line fitting sticks down into the tank too far like mine does. As you fuel up, the fuel can cover the vent. The fuel is usually cold going into a warm plane. As it expands, it travels into the vent and blocks it. I would taxi out, run up, and take off and get about 20 feet in the air when the motor would quit...always with my wife in the right seat. I installed ticker pump to overcome the suction from a temporarily blocked vent.
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