External fuel selection while on the ground

[_Spad_]

When external fuel was selected while sitting on the ground, the engine lasted about 20 seconds before cutting out. However, when I was airborne I selected the external fuel again and the engine ran fine.

[grafspee]

Correct as it is, external tanks often are pressurized by engine's supercharger, at low engine rpm you have no boost from supercharger so nothing is pushing fuel out of external tank.

Take off at Main tank, once you get to safe alt switch to external, if you have aux tank filled up bur it first, P-47 flies very unstable with aux tank full.

Edited July 10, 2021 by grafspee

[_Spad_]

1 hour ago, grafspee said:

Correct as it is, external tanks often are pressurized by engine's supercharger, at low engine rpm you have no boost from supercharger so nothing is pushing fuel out of external tank.

Take off at Main tank, once you get to safe alt switch to external, if you have aux tank filled up bur it first, P-47 flies very unstable with aux tank full.

 

Thanks for the explanation. I had no idea that's how the ext tanks worked.

 

Thanks!

Edited July 10, 2021 by _Spad_