P38 engines

[pinsog]

Please explain something to me.

I have read somewhere, maybe on this board about the P38 and a pilot trying to get into the fight when he had been bounced. It was telling all the things the pilot had to do to get the plane off of economical cruise and up to combat speed and it said the pilot had to

"switch from drop tanks to interal, turn on gun switches, ADVANCE THE THROTTLES, INCREASE RPM......."

I took it that this was 2 seperate acts. The pilot pushed the throttles forward and then did something else to increase rpm. Did I misread that? If so, tell me. If not, could someone else explain it for me?

 

[beaupower32]

Most WW2 aircraft had a seperate throttle control and RPM control.

A few aircraft (Bf-109 Fw-190) had automatice prop controls which adjusted the RPM to match the throttle setting without pilot input, but yet they could switch it to manual if needed to and adjust the prop pitch via a 2 way switch on the throttle grip.

 

[pinsog]

So in an aircraft without that feature, what happens when you push the throttle forward? Does the engine rpm increase?

 

[gumbyk]

Generally, the aircraft had was is termed a "constant speed" propeller. There is a small governor that maintains a constant speed by adjusting the pitch (angle) of the blades. the pilot could advance the throttle, and the propeller would keep the same RPM (within limits). The pilot could select the RPM of the engine, by adjusting the governor, and the governor would adjust the pitch of the blades to maintain the selected RPM.

Adjusting the RPM of the propeler is kind of like changing gear in a car; low gear (high RPM) to take-off and climb, high gear (low RPM) for higher speeds and cruise.

Hope this makes sense.