What am I doing wrong with the spitfire ?
 

In the campaign when you first get a spitfire and take her up for an initial practice, I notice that shortly after take off on full throttle the RPM falls sharply.

I do not have CEM selected. Also if I switch the auto pilot on, the rpm increases back immediately and then when I take over it immediately falls back.

Is there something I am doing wrong ?

Thats a bug mate..i have it too

That's not a bug: the AI (managing your engine) sets the prop pitch to coarse. Early Spits had a 2 position propeller, fine pitch for takeoff, landing and combat, and coarse for cruising. I guess you should enable CEM and do it yourself in order to be more efficient ;)

That doesnt explain why the AI then switches it back when the autopilot is selected. Essentially it means you can't fly the spitfire with CEM left to the AI.

...unless there is a key to change propeller position that I haven't found yet.Or perhaps the AI changes it when enemy planes are spotted.

I came here to find out why my RPMs were dropping too... this seems like bad AI. It definitely didn't change the prop pitch when enemy planes were spotted when I've tried.

It is not allowed to change pitch to fine during combat. The only situations where fine pitch is allowed is takeoff and landing with throttle back (to be able to go around).

Rubbish

So this plane is basically unplayable unless you use CEM, great.

AP 1590B Merlin II and III Aero-Engines:

There should be no problem provided that the rpm limits aren't exceeded; the engine doesn't know anything about the propeller; it only cares about boost, rpm and temperatures.

The chances are that for general flying, considering the 2600 rpm continuous limit, it would be difficult to operate in fine pitch other than at extremely low speed.

However, when using the combat concessions there should be no obstacle to using fine pitch provided that the combat limit of 3000 rpm is not exceeded. AP2095 is quite clear that in general limits are for the guidance, and may be disregarded in combat; it even starts going into some detail as to how far one might expect to push beyond them before really bad things happen.

It is also worth observing that the 3600 rpm dive concession was obviously provided for a reason.

I think that one of the biggest problems faced by a sim like this is that IRL the reason that you don't flog an engine beyond its book limits isn't for fear that it will fail on this sortie, but rather for fear that it will fail on the next one, or the one after that. A new engine with perhaps 100 hours of life assuming 50 sorties of 2 hours each with 5 minutes at combat power would have a safe life at combat power of at least 250 minutes, which is over 4 hours.

You'd probably run the tanks dry in less than an hour at combat power in most aeroplanes, so that means perhaps 4 sorties of rampant hooliganism, followed by substantial risk of failure from perhaps sortie 5 onwards.

Actually of course, early engines especially have takeoff power equal to or greater than combat power, so you probably get an extra minute per sortie built into the calculations, which would take you up to 5 hours of high power running.

Naturally exceeding the temperature limits could easily bring failure more rapidly, but the historical data suggests that cooling was probably less of a problem than our experience in the sim suggests, since the radiators of RAF aircraft at least were generally sized for the tropical climb case.

This means that if we combine realistic engine performance and reliability with the standard practice of giving people a brand new aeroplane each time they hit "refly", they really "should" be able to disregard the limits with reckless abandon.

For this reason, I think that it would be wonderful if an option to force people to fly a single aeroplane until it was either overhauled or shot down was provided, especially for online use (since I suppose it's probably already implemented offline in campaigns).

Otherwise the only way to make people treat their airframes and engines sensibly is to artificially reduce their tolerance of exceedances, which has the unfortunate side effect of making CEM much harder for novices than it would otherwise need to be.