Hi Flyboy,
>in AH the only way to control prop pitch is throu changing the RPM.
>was it like that in real life? or was there a way to change the prop pitch directly?
It depended on the aircraft. In an attempt to free the pilot's attention from engine management tasks and for actual combat activities, more and more of the routine tasks were automated in later aircraft.
Most WW2 aircraft had constant speed propellers, which would maintain - obviously - a constant engine speed :-) However, others had direct pitch control, and the automatic control systems usually had way of controlling pitch instead of speed, too.
>i am not sure i fully understand how PP and RPM are related
is there a way to change RPM without changing the PP?
Yes, by changing airspeed or by changing engine boost.
As in combat, airspeed and engine boost changed as result of combat manoeuvres while the pilot wanted the engine to rev at its best speed anyway, that highlights why constant speed propellers were such a good idea :-)
Some aircraft, like Focke Wulf Fw 190, but also late-war Spitfires and early-war Dewoitines, took it one step further and combined boost and speed control in one single lever. The pilot would just push forward the now re-named "power" lever to the desired power setting, and an analogue (mechanical/hydraulical/pneumatical) computer would do the rest.
In the Spitfire, this worked optimally only for combat power settings, but in the Focke-Wulf it covered the entire power range. Only in dives, the Fw 190 pilot had to pull a second lever to prevent overspeeding, everything else was fully automatic.
(In the D.520, apparently such a control was missing, and the system seemed not to have worked very well if we believe the British test pilot Eric Brown. That's the trouble with new technology :-)
Regards,
Henning (HoHun)
