EF

I want to use an OS 20FP in a small model.

Only tank size that fits realy comfortably is a 2 oz size.

Anyone have an estimate how long it can be expected to run on this (assuming some full and some partial throttle)?
(a 5-6 min. flight time is quite acceptable for me)

Dsegal

I think you will need a bigger tank. I am limited to a 2oz. tank with an OS.15LA on one model and I must set the timer to 4min. 30 seconds and land immediately when the buzzer sounds. Otherwise I risk a deadstick situation.

EF

Hmmm...well maybe I have found a suitable 3 oz tank that is still just within my 3" length limit.

Was hoping the fuel consumption was lower...[&o]

JohnBuckner

My Feedback: (1)

It depends entirely on the airplane type and the way in which it is flown. This airplane has a 20FP with a two ounce tank and easily reachs run times of fifteen minutes.

EF

I'm referring to a sport scale bipe - Gordon Whitehead's Hawker Demon.
Gordon used a .19 with a 2 oz tank, but does not mention how much time he got out of it.
It's a lightly loaded model, that wil probably cruise around on part throttle most of the time.

JohnBuckner

My Feedback: (1)

Then it should easily give you the target five to six minutes.

EF

Dave, looking at my tank I was wondering - are you using a clunk at the end of the fuel line inside the tank? it seems to me that if I leave the 1" long tube inside the tank with no clunk (that anyway doesn't do anything with such a short tube) then I can use more fuel otherwise the pick up hole is quite a distance above the tank floor.
Also, is your vent pipe reaching right up into that "bubble" at the top of the tank?

I'll probably bench run the engine with the same tank just to check operating time.