What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Inverted Fuel / Airflow Performance FI

HansR

Active Member
Hi

I will convert my O-360-A1A to FI with an Airflow Performance kit.

My big concern is that the manual clearly warns about air in the fuel. Seems difficult to avoid, without an acro-tank.
So, if it is possible with wing tank plz help me with below questions

  1. How do you arrange for constant fuel supply? A floppy in the wingtank? That would work in any constant attitude, but what happens when fuel is thrown around in the tank?
  2. Typically you would like to fly with very little fuel in the tank, how little does work?
  3. How dramatic is it when air enters the fuel line? A little rough running och a complete stall?
  4. I want to be able to run a tank completely dry, before switching to the other tank. Will the engine recover if I switch over when tank is empty (lets say in three seconds)?
 
No problems!

How do you arrange for constant fuel supply? A floppy in the wingtank? That would work in any constant attitude, but what happens when fuel is thrown around in the tank?

You can make a floppy tube that follows where the fuel goes - within limits. The sideways limits of the tube will determine how the fuel hose can work - like in a roll or a heavy slip.

Typically you would like to fly with very little fuel in the tank, how little does work?

It is a very small amount - maybe 4 ounces?

How dramatic is it when air enters the fuel line? A little rough running och a complete stall?

Rough running - not quite a complete stall. Believe me, your hand will move very quickly!

I want to be able to run a tank completely dry, before switching to the other tank. Will the engine recover if I switch over when tank is empty (lets say in three seconds)?

3 seconds might not be the number - more like 5-7 or so, then the stumbles will pass - mostly. You will also use the boost pump to get things going properly - maybe turn it on when the think you are almost out (at the empty tank).

I use all fuel when flying cross country, so I know what you are trying to do. Also I have done TWO rolls on a nearly empty tank - that is not a good idea; it takes a while to refill the system! Seems like an hour or so..:eek:
 
I dare to contradict anything in the AFP manual. I run tanks dry often. AFP pump has always recovered. Also the manual pump is clearly helping, or it may be doing most of the work. There is very little time difference between dry tank and recover on manual pump only, and dry tank with the AFP on.
Without the manual pump, I have no idea how long, or if the AFP pump would recover. It would be a pretty easy test on the ground to play with it. However a few ground tests on the AFP only would not necessarily mean it would be reliable in the air.
 
I use all fuel when flying cross country, so I know what you are trying to do. Also I have done TWO rolls on a nearly empty tank - that is not a good idea; it takes a while to refill the system! Seems like an hour or so..:eek:

Thanks Boss

Well typically I will do all reasonable RV-8 aerobatic maneuvers, basically whatever is in the sportsman scope. Choice of wingtank might be crucial - If I do a four point or slow roll to the right, it might work with a floppy in the right tank. I guess I could accept only to be able to do such maneuvers one way.
 
I dare to contradict anything in the AFP manual. I run tanks dry often. AFP pump has always recovered. Also the manual pump is clearly helping, or it may be doing most of the work. There is very little time difference between dry tank and recover on manual pump only, and dry tank with the AFP on.
Without the manual pump, I have no idea how long, or if the AFP pump would recover. It would be a pretty easy test on the ground to play with it. However a few ground tests on the AFP only would not necessarily mean it would be reliable in the air.

Thanks Kahuna.

Sounds its not a big deal. AFP warns also about running the pump dry, but I guess its a matter of how long time.
 
Back
Top