General RPM Governor/Prop Settings

[CAFulcrum]

Sorry if this is a stupid question, but are there any rules of thumb when it comes to setting the governor? 

 

I've flown wwii sims before with a prop setting but they tended to model earlier planes with direct prop pitch control, so that's making things confusing for me (aside from coming from RoF which had fixed pitch).  I'm used to 'coarsing' the prop while diving, cruising and flying at higher altitudes, and 'fining' it at slow speeds and lower altitudes to maximize torque.  Does the governor do all of this, meaning I just slam it to 100% in all combat situations and control with the motor, or do I still need to make adjustments, for example when diving and extending?  What's the usual process?

 

I looked in the il2 manual and online but they didn't quite answer my question... 

[Jade_Monkey]

Each plane is different. Look at engine settings on the Specs tab in game (Press "O" and then click on specs).

 

I also posted a plane by plane guide in the guides section of the forum:

 

 

[[APAF]VR_Spartan85]

From my understanding, all the ships in this sim have constant speed props.. weather automatic or not.

 

but yes, stick to the specs of the plane provided and you’ll be safe    

[RedKestrel]

16 hours ago, CAFulcrum said:

Sorry if this is a stupid question, but are there any rules of thumb when it comes to setting the governor? 

 

I've flown wwii sims before with a prop setting but they tended to model earlier planes with direct prop pitch control, so that's making things confusing for me (aside from coming from RoF which had fixed pitch).  I'm used to 'coarsing' the prop while diving, cruising and flying at higher altitudes, and 'fining' it at slow speeds and lower altitudes to maximize torque.  Does the governor do all of this, meaning I just slam it to 100% in all combat situations and control with the motor, or do I still need to make adjustments, for example when diving and extending?  What's the usual process?

 

I looked in the il2 manual and online but they didn't quite answer my question... 

AFAIK all planes in game use constant speed propellers. In theory, the governor should be able to set the optimum propeller angle in most phases of flight and keep the same RPM. In practice, there are times when the governor can't keep up with the needs of the engine and propeller.

Every plane is modeled differently because the interaction between the governor, propeller and engine was unique to the plane. As an example, the Yak-1 s. 69 does not obtain top speed at low altitude on the max RPM setting. This is because the governor can't compensate properly for the propeller drag and you will actually get +/-10 kph more if you drop the RPM back down by about 150 or so (I forget the exact amount). The P-47 I believe has something similar, where a lower max RPM gives greater top speed at high altitude, once again because of prop drag.

Most of the axis fighters are fully automatic, in the sense that you just use the throttle to control the engine power, and the radiators, mixture, and RPM are all adjusted. In the 109s, you can actually choose to manually control prop pitch and some people use this to squeeze a bit more out of the aircraft, though I suspect the advantage is marginal compared to the workload required. The Spitfire IX is mostly automatic as well, though you can set it to independently control RPM and throttle. The P-47 allows you to 'link' Throttle, turbo and RPM, but in certain flight rare instances you need to have independent control of the Turbo. The soviet fighters are basically all 'manual' in the sense that you have to set the RPM and throttle independently. Most soviet planes (except the Yaks and the Pe-2s) do have a mixture setting that gives automatic mixture adjustment, and the lend-lease and bodenplatte planes have automatic mixture control at certain settings laid out in the tech specs (auto lean, auto rich, and full rich for most planes). 

The specs for each plane appear in the "Specifications" tab in the pre-mission briefing, and you can bring this up during the mission at any time by opening the map with "O" and clicking the specifications tab there as well. The specs indicate the maximums for different engine 'modes' (cruise, continuous, nominal, etc.) 

All that being said (I know, TL;DR), I have some rules of thumb I use for every plane:
1. For max (combat) climb, acceleration, and in combat, use max RPM.
2. When cruising and trying to save fuel and keep your engine cool, use a lower RPM setting. I use max continuous settings for non-combat climbs on planes that have more sensitive engines such as the P-39 to save my 'combat' time.
3. Before entering a dive, pull back throttle and RPM to avoid overspeeding the engine (especially in P-39, which seems really sensitive to that sort of thing). I think lower RPM should help you achieve higher top speed in a dive as well but I have not tested this and it may not be true.

 

[Mauf]

There is something that isn't mentioned often (and I think it isn't modelled in BoX but another sim):

Your RPM and boost/manifold pressure should stay within range of each other. You can't really go high RPM and low boost because the boost will limit how high the RPM can go effectively. Neither do you want to go high boost, low RPM as that will increase wear on the engine to the point it'll fail pretty quickly. The rule is:  When you increase power, you first increase the RPM, then increase the boost and when you reduce power, you first lower boost and then RPM.

 

While it isn't really necessary for BoX, it's a good idea to train that behaviour just in case (and because we want to sim)

[RedKestrel]

1 hour ago, Mauf said:

There is something that isn't mentioned often (and I think it isn't modelled in BoX but another sim):

Your RPM and boost/manifold pressure should stay within range of each other. You can't really go high RPM and low boost because the boost will limit how high the RPM can go effectively. Neither do you want to go high boost, low RPM as that will increase wear on the engine to the point it'll fail pretty quickly. The rule is:  When you increase power, you first increase the RPM, then increase the boost and when you reduce power, you first lower boost and then RPM.

 

While it isn't really necessary for BoX, it's a good idea to train that behaviour just in case (and because we want to sim)

I believe I've killed an engine by having high boost and low RPM when I throttled up and didn't realize my RPM was low. But it was in the P-39 so it might have just been that I pushed the throttle up too fast. 

It will depend on the engine a lot though. I seem to recall US P-38 pilots in WWII using a relatively high MP/low RPM setting to extend their range massively in the Pacific theatre. 

[Mauf]

Just now, RedKestrel said:

I believe I've killed an engine by having high boost and low RPM when I throttled up and didn't realize my RPM was low. But it was in the P-39 so it might have just been that I pushed the throttle up too fast. 

It will depend on the engine a lot though. I seem to recall US P-38 pilots in WWII using a relatively high MP/low RPM setting to extend their range massively in the Pacific theatre. 

Yes, the Charles Lindbergh hint. According to Wikipedia:

Quote

Lindbergh was instrumental in extending the range of the P-38 through improved throttle settings, or engine-leaning techniques, notably by reducing engine speed to 1,600 rpm, setting the carburetors for auto-lean and flying at 185 mph (298 km/h) indicated airspeed which reduced fuel consumption to 70 gal/h, about 2.6 mpg. This combination of settings had been considered dangerous and would upset the fuel mixture, causing an explosion

Doesn't mention what MAP was used. And as with everything, there is no hard "Too much boost" line I guess. I bet one of the better educated boffins on the forum will be able to illuminate us to this:)

[Finkeren]

19 hours ago, spartan85 said:

From my understanding, all the ships in this sim have constant speed props.. weather automatic or not.

 

The U-2 has a fixed pitch prop, the Ju 52 a variable pitch prop and I'm pretty sure the Kommandogerät on the Fw 190As controls a variable pitch prop and thus it isn't technically a csp, though for all intent and purpose it might as well be. 

[danielprates]

11 minutes ago, Finkeren said:

 

the Ju 52 a variable pitch prop 

 

Silly old me has been flying the ju52 like it had a fixed prop! What command is used to change the pitch, the same  'increase/decrease RPM' buttons? Can't believe I still hadn't noticed this.

 

How is it supposed to be operated? Like a bonanza, i.e., fine for takeoff and climb, and coarse for cruise?

[LukeFF]

The Ju 52 prop is fixed pitch. 

[-=PHX=-SuperEtendard]

There are also some planes which only have one or two specific RPM settings as governed ones, like the Hs 129 and MC 202. If you want a higher or lower RPM setting then you have to use manual prop pitch adjustments.

Edited May 11, 2019 by -=PHX=-SuperEtendard

[Finkeren]

9 hours ago, LukeFF said:

The Ju 52 prop is fixed pitch. 

Luke has his facts down as always. 

 

It has been some time since I last flew the Auntie. 

[CAFulcrum]

On 5/10/2019 at 7:37 AM, RedKestrel said:

AFAIK all planes in game use constant speed propellers. In theory, the governor should be able to set the optimum propeller angle in most phases of flight and keep the same RPM. In practice, there are times when the governor can't keep up with the needs of the engine and propeller.

Every plane is modeled differently because the interaction between the governor, propeller and engine was unique to the plane. As an example, the Yak-1 s. 69 does not obtain top speed at low altitude on the max RPM setting. This is because the governor can't compensate properly for the propeller drag and you will actually get +/-10 kph more if you drop the RPM back down by about 150 or so (I forget the exact amount). The P-47 I believe has something similar, where a lower max RPM gives greater top speed at high altitude, once again because of prop drag.

Most of the axis fighters are fully automatic, in the sense that you just use the throttle to control the engine power, and the radiators, mixture, and RPM are all adjusted. In the 109s, you can actually choose to manually control prop pitch and some people use this to squeeze a bit more out of the aircraft, though I suspect the advantage is marginal compared to the workload required. The Spitfire IX is mostly automatic as well, though you can set it to independently control RPM and throttle. The P-47 allows you to 'link' Throttle, turbo and RPM, but in certain flight rare instances you need to have independent control of the Turbo. The soviet fighters are basically all 'manual' in the sense that you have to set the RPM and throttle independently. Most soviet planes (except the Yaks and the Pe-2s) do have a mixture setting that gives automatic mixture adjustment, and the lend-lease and bodenplatte planes have automatic mixture control at certain settings laid out in the tech specs (auto lean, auto rich, and full rich for most planes). 

The specs for each plane appear in the "Specifications" tab in the pre-mission briefing, and you can bring this up during the mission at any time by opening the map with "O" and clicking the specifications tab there as well. The specs indicate the maximums for different engine 'modes' (cruise, continuous, nominal, etc.) 

All that being said (I know, TL;DR), I have some rules of thumb I use for every plane:
1. For max (combat) climb, acceleration, and in combat, use max RPM.
2. When cruising and trying to save fuel and keep your engine cool, use a lower RPM setting. I use max continuous settings for non-combat climbs on planes that have more sensitive engines such as the P-39 to save my 'combat' time.
3. Before entering a dive, pull back throttle and RPM to avoid overspeeding the engine (especially in P-39, which seems really sensitive to that sort of thing). I think lower RPM should help you achieve higher top speed in a dive as well but I have not tested this and it may not be true.

 

 

Thank you, super informative! 

Mixture controls are fairly easy to figure out, especially the ones with positions.  One question I have is do you have to be exactly at (for example in p40) 33%/66% or is there some wiggle room?

I can't figure out the spitIX, as it says 'automatic manifold pressure' but operating the throttle changes boost.  I think the in game manual says 'engine manifold pressure is automatically controlled above 1/3 throttle.'  It seems to just operate similar to any other manual-governor planes.

A number of planes have manual prop pitch settings (109 and p40 in my experience so far), for fining the prop while taxing to avoid prop wash and in case of governor malfunction, but they move slowly (I think all of them are toggle switch operated), does anyone actually use them in the game?

I've tried testing with maximum and minimum governor settings in a ~30 degreee dive in a p40 and the max setting produced about 10mph more, but it wasn't precise and didn't really seem to make much difference.  I don't know if it helps to go down by like 20-30%...

The difficulty I'm having 'groking' it is that when you change governor settings, the manifold pressure also reacts so it's very 'floaty' to get the values (prop pitch, engine speed and manifold power) in line with one another.  If you are simply always matching the manifold pressure to the prop setting I think that pretty much answers my questions.  I'm assuming there's no advantage to doing it manually vs having it done automatically, as in the 109s (which are super easy to manage).

[LukeFF]

2 hours ago, CAFulcrum said:

One question I have is do you have to be exactly at (for example in p40) 33%/66% or is there some wiggle room?

 

No, there's a range where a particular mixture setting will work in those instances - it's something like plus or minus 10 percent. 

Edited May 17, 2019 by LukeFF

[Mauf]

2 hours ago, CAFulcrum said:

I can't figure out the spitIX, as it says 'automatic manifold pressure' but operating the throttle changes boost.  I think the in game manual says 'engine manifold pressure is automatically controlled above 1/3 throttle.'  It seems to just operate similar to any other manual-governor planes.

 

Take the P40 for example: There you can overboost the engine because no automatic map regulator. So if you slam the throttle to 100% at SL, your engine will go pop in a matter of seconds. Do the same in a SpitIX. No popping because the needle will stop at 18 pounds. The magic of the regulator. That's what the term refers to. A quite clever thing as it avoids untimely engine death in hectic situations.

 

2 hours ago, CAFulcrum said:

A number of planes have manual prop pitch settings (109 and p40 in my experience so far), for fining the prop while taxing to avoid prop wash and in case of governor malfunction, but they move slowly (I think all of them are toggle switch operated), does anyone actually use them in the game?

I've tried testing with maximum and minimum governor settings in a ~30 degreee dive in a p40 and the max setting produced about 10mph more, but it wasn't precise and didn't really seem to make much difference.  I don't know if it helps to go down by like 20-30%...

The difficulty I'm having 'groking' it is that when you change governor settings, the manifold pressure also reacts so it's very 'floaty' to get the values (prop pitch, engine speed and manifold power) in line with one another.  If you are simply always matching the manifold pressure to the prop setting I think that pretty much answers my questions.  I'm assuming there's no advantage to doing it manually vs having it done automatically, as in the 109s (which are super easy to manage).

 

Yes, many use them because they either have to (P40) or the automatic is not pure optimum for example in some combat situations (109). Fine pitch is usually best when it comes to accelerating, so it's used in take-off and the vets use it in dogfight situations where you have to accelerate quickly (example: avoiding an overshoot and then accelerating again to chase a diver). Staying fine pitch gives you better response but the automatic prop governor will have coarsened the pitch a bit due to having throttled back.

 

About floatiness: usually that happens either in planes that lack regulators (e.g. P40) where you have to constantly readjust everything or in low settings you normally don't use in normal flight or combat (landing for example). As mentioned above, there are situations for a 109 where the automatic is not better than the manual (from a min-maxing perspective).

[danielprates]

8 hours ago, Mauf said:

Fine pitch is usually best when it comes to accelerating

 

It also responds faster. It's the main reason you are always supposed to set fine pitch, or high rpm in a constant speed propeller, during landing - if anything goes wrong and you quickly need to do that emergency go-around, or some other drastic thing, you will want quick engine response.