Have I been thinking incorrectly about adjusting the prop pitch with those planes having a constant speed prop?

[Uriah]

Have I been thinking incorrectly about adjusting the prop pitch with those planes having a constant speed prop? 

I may be confusing things as GB has the action 'Propeller RPM Control' rather than a term 'prop pitch'.  

I have been using the action 'Propeller RPM Control' for changing the prop pitch in the Spit V.  And I have been thinking that is what I am really doing.  But now I am thinking that what I am really doing is change the boost or something else.    Anyway, I am rather confused.

 

[Bobo]

It's prop pitch. 
I think the MkV has a two stage deal rather than a fully adjustable prop.  Either coarse or fine, something like that

[Uriah]

Google says...No, the Spitfire Mk V did not have a two-stage propeller pitch. Instead, it was equipped with a constant-speed propeller (which automatically and continuously adjusted the blade angles).

 

[BlitzPig_EL]

The early Spitfires had the two stage prop pitch adjustment.  The way that a constant speed prop works is that it will automatically adjust to keep the rpm that you select with the pitch lever, regardless (within reason) of where you set the throttle.  This makes your throttle the tool you use to set manifold pressure.  This is vital in planes with overly fragile engines, like the P40.  For most of my flying in the Warhawk I set rpm at 2600 and keep increasing manifold pressure as needed as altitude or combat circumstance dictates.  This make the P40 engine last a long time.  In difficult circumstances I will go to 2800+ rpm for very short periods only.

This flies in the face of how the V1710 was actually used in combat, but it's how it works in the sim.

[MaxPower]

Engine rpm has an effect on super charger rpm, which has an affect on boost pressure, but it is a secondary effect.  Boost pressure is primarily controlled by the boost lever, which throttles the supercharger.  Reducing boost until the engine doesn't have the horsepower to sustain the selected rpm can control rpm as well.  In at least some aircraft there is a backup propeller pitch control but I've never really used it.  Some aircraft like the Hs-129 have funky prop pitch control schemes that take some getting used to.

[Traffic]

59 minutes ago, BlitzPig_EL said:

The early Spitfires had the two stage prop pitch adjustment.  The way that a constant speed prop works is that it will automatically adjust to keep the rpm that you select with the pitch lever, regardless (within reason) of where you set the throttle.  This makes your throttle the tool you use to set manifold pressure.  This is vital in planes with overly fragile engines, like the P40.  For most of my flying in the Warhawk I set rpm at 2600 and keep increasing manifold pressure as needed as altitude or combat circumstance dictates.  This make the P40 engine last a long time.  In difficult circumstances I will go to 2800+ rpm for very short periods only.

This flies in the face of how the V1710 was actually used in combat, but it's how it works in the sim.

You can run 2800rpm at 49" for 17 minutes. I have hundreds of hours in it in multiplayer. You can definitely stretch its legs a bit. 

[kraut1]

11 hours ago, Uriah said:

Have I been thinking incorrectly about adjusting the prop pitch with those planes having a constant speed prop? 

I may be confusing things as GB has the action 'Propeller RPM Control' rather than a term 'prop pitch'.  

I have been using the action 'Propeller RPM Control' for changing the prop pitch in the Spit V.  And I have been thinking that is what I am really doing.  But now I am thinking that what I am really doing is change the boost or something else.    Anyway, I am rather confused.

 

It is for me sometimes a bit confusing too:

-for planes with total manual propeller control you have to adjust the propeller pitch during flight manually.

-for planes with constant speed propeller (most of the IL-2 GB planes) you can or have to adjust the RPM that is controlled by the constant speed unit (maybe the wrong word)

for example most planes with constant speed prop have at the mission begin the max. rpm that is good for take off or in combat for max. performance

e.g.: for the Ju88A4 2600rpm. After take off to avoid overheating the engine you could reduce the rpm to 2400rpm (at 1.25ATA) for 30minutes climbing. For cruise flight you have to reduce to 2250rpm (at 1.15ATA)...

-German Fighter Planes  (and maybe some advanced allied, I don't know) have since August 1940 (BF-109-E4) an automatic propeller controll unit, that is controlled by the pilot only by moving the throttle lever:

e.g.: BF109-F4 when the pilot moves the throttle forward for e.g.: 1.15ATA the rpm is automaticly controlled to ca. 2200rpm (unlimited time), at 1.3ATA to 2400rpm (30minutes climbing/combat) and at ca. 1.42 ATA to ca. 2600rpm (1 or 3 minutes).

(maybe this a bit simplified and  the exact numbers are a bit wrong, but altogether seen I think in this way it works)

[Uriah]

Is that a mistype Traffic?  49+ boost for 17 minnutes

[BlitzPig_EL]

I guess we need to know on what map, and what outlet cowl setting, etc...

I will test this soon.

[MaxPower]

8 hours ago, Uriah said:

Is that a mistype Traffic?  49+ boost for 17 minnutes

I think he was saying 49 inches of manifold pressure rather than +49 inches boost.  49 inches is + 19 inches boost, which translates into around + 9 psi if I'm correct.

[BlitzPig_EL]

I tested it tonight.  My P40 ran for just over 18 minutes @2800rpm and 49 inches of manifold. then the engine seized.

Edited June 6 by BlitzPig_EL

[Czech693]

I'm assuming you guys are using the upgraded engine on the P-40 to achieve those numbers.

[BlitzPig_EL]

Yes.  Not using the newer engine is just silly, it's the only way to get the P40 anywhere close to it's real world performance and durability.

[FeuerFliegen]

On 6/14/2026 at 11:33 AM, BlitzPig_EL said:

Yes.  Not using the newer engine is just silly, it's the only way to get the P40 anywhere close to it's real world performance and durability.

 

Of all the years I've played Great Battles, looking at all the different upgrades and changes the devs have made, some of my absolute favorite ones are how in the past couple years they gave us new engine timers, for many planes; P-40, P39, Bf109 F-4, G-2, G-4, G-6, Me410, Bf110 G-2, AM-38 engine on MiG-3.  These upgrades gave us a way to push these planes harder than we've ever been able to before and it made all the difference; especially on the P-39 and P-40 where you could only do max power for a minute or two, and most of us avoided ever using that, but now you can do max power for 5 minutes with confidence.

[kraut1]

The P40 engine is from my point of view one of the most complex to operate engines because the manifold pressure is not effectively automaticly limited and most importent the constant speed rpm control seems to be for me the worst of all IL-2 planes because it reacts so slowly. Because of this I am doing the same as mentioned here and set the rpm to only 2800 instead of 3000 for combat , in first line to avoid exessive rpm, especially during combat with sudden changes from level flight to diving...

[Traffic]

On 6/5/2026 at 8:31 PM, MaxPower said:

I think he was saying 49 inches of manifold pressure rather than +49 inches boost.  49 inches is + 19 inches boost, which translates into around + 9 psi if I'm correct.

Correct, 49" manifold pressure, at 2800 rpm seems to be the sweet spot for combat power. 

2700rpm / 49" = 17 minutes, 30 seconds before failure

2800rpm / 49" = 17 minutes combat power

2800rpm - 60" = ~7 minutes until failure

3000rpm at 68-75" manifold (temp dependent) = 3 minutes of full power, 4 minutes until failure. 

 

In multiplayer, all you have to do is be mindful of jamming the throttle up to full power. It'll burn. Run it up slowly, it can handle overboosting just fine. 

There is no need to throttle back when diving either. Like I said, I have hundreds of hours in it and those engine settings work just fine. 

There is also no set cowl flap setting because its outside temp dependent, but typically, when taking off, climbing, I keep it at ~25-30% open, but adjust as needed. 

Full power, you're definitely gonna need to open it up quite a bit to keep it cool. For take off and climbing, I set it at full rpm, and ~50" or so, go wheels up, back rpm down to 2800, set manifold to 49" and climb. As you climb, you'll need to keep pushing the throttle up until its wide open. Once at altitude, I throttle back to 40" at 2700 and cruise, to recharge engine timers and cool it off. 

 

Also, P38s can handle 2800rpmn at 55" for 30 hard minutes as well. Similar with Mustangs, 2700 / 60" for ~30 minutes+

[Uriah]

Lots to digest.  Thanks all.