Spitfire IIa prop pitch

[nakedsquirrel]

The Spitfire IIa prop pitch seems to behave differently than any of the other aircraft in game.

Most aircraft will gain some speed with a slightly coarse pitch, but the Spitfire IIa is fastest with the prop pitch set to fully fine.

Is this unintended, or is there something about the Spitfire IIa prop pitch that makes it different from the other aircraft? (IE is it supposed to be a version of auto-pitch?)

[41Sqn_Banks]

This is because the Spitfire II has a CSP (constant-speed propeller). The lever in the cockpit doesn't set the propeller pitch, it sets the desired engine RPM. The constant-speed unit/governor tries to keep the desired RPM by adjusting the propeller pitch. Of course the constant-speed unit/governor only allows to set RPM values that don't overstress the engine.

So if you set the RPM lever to the forward position the highest possible RPM is maintained. In combination with full throttle this will give you the highest possible engine output power and therefore the highest possible speed*.

*I assume the at highest possible engine RPM the propeller is spinning with an RPM where the propeller has the best efficiency. This is achieved by choosing a suitable propeller reduction gear.

Note that there are other aircraft that have a CSP, e.g. the Hurricane I Rotol and most (if not all) german bombers have a CSP.

[JG53Frankyboy]

flyable palnes with CSP units in the moment are:
-Spitfire II
-Hurricane I_Rotol
-G.50
-Br.20
-Ju87
-He111P&H
-Ju88

Manual pitch, in what you control the propeller anlge directly:
-Bf109
-Bf110

Two speed propeller, actually fixed propellers with two settings (fine and coarse):
-Hurricane I_DeHaviland
-Spitfire I and Ia (weird , but it still is this way ) , most propably the heartbreaker too, never flew it
-Blenheim

fixed propeller:
-Tiger Moth



lets hope in one of the future patches at least the Spitfire Ia gets a CSP and the Ju88 a manual one.

[Crumpp]

Spitfire IIa is fastest with the prop pitch set to fully fine.

Vmax occurs at maximum rpm and manifold pressure in any aircraft. Although it is called "course" and "fine" pitch, as the other posters have explained it is really maximum rpm.

The blade pitch will open as velocity increases and maintain rpm. In a selectable pitch propeller, the pilot must open the blade pitch to maintain maximum rpm as the aircraft speed increases.

This the reason for the VDM clock. It gave the pilot a measure of his blade pitch to set to achieve desired performance.

[Crumpp]

Manual pitch, in what you control the propeller anlge directly:
-Bf109
-Bf110

The VDM propellers are constant speed propellers with an electrical manual pitch that is used for emergencies.

I am not the Bf-109 expert but I believe only a small number of purely manual pitch propellers came into service early on in the 109 series development. IIRC, it was during the Battle of France that a handful were delivered "ohne automatik". It was then replaced with the "mit automatik" which is the VDM hydraulic-electric series used throughout the remainder of the war.

[JG53Frankyboy]

During BoB there were A LOT of Bf109s in active service still with manual pitch.

I cant count anymore how often we had this in the forums
here is just one example
http://forum.1cpublishing.eu/showthread.php?t=22204

So , its all do the decission of 1C what propeller system they will give the BoB time 109s - they cant decide wrong !