Prop pitch?

[Knarley-Bob]

Should one increase prop pitch with throttle or decrease it?

[migmadmarine]

It's a matter of what you're going for, if you want acceleration have the prop pitch set higher, if you want efficiency, set it lower, as I understand it. 

[69th_Mobile_BBQ]

If you're just looking for which to put up first, it goes like this:   Increase RPM then increase throttle.  Decrease throttle before decreasing RPM.   There is some space to work with and you don't need to be very far apart between one or the other.  You don't have to go full RPM to go full throttle but, going too low RPM at full throttle could be damaging.   If you notice some of the later Yaks have the RPM and throttle levers set up so both can be pushed up or brought down equally so, at least try to keep the motion even or the appropriate lever 2% or 3% ahead of the other. This should apply to any plane that requires manual RPM/Pitch control.

[Knarley-Bob]

2 hours ago, migmadmarine said:

It's a matter of what you're going for, if you want acceleration have the prop pitch set higher, if you want efficiency, set it lower, as I understand it. 

I thought I had it linked to the throttle but that isn't right.. Should it show on the info on the right side of the screen it's increasing?

1 hour ago, 69th_Mobile_BBQ said:

If you're just looking for which to put up first, it goes like this:   Increase RPM then increase throttle.  Decrease throttle before decreasing RPM.   There is some space to work with and you don't need to be very far apart between one or the other.  You don't have to go full RPM to go full throttle but, going too low RPM at full throttle could be damaging.   If you notice some of the later Yaks have the RPM and throttle levers set up so both can be pushed up or brought down equally so, at least try to keep the motion even or the appropriate lever 2% or 3% ahead of the other. This should apply to any plane that requires manual RPM/Pitch control.

I thought that increasing the throttle increased RPMs. I think we are going to learn something here.?

Edited March 3, 2023 by Knarley-Bob

[354thFG_Drewm3i-VR]

There is no real "prop pitch" control in IL2. Yes, you can disable the auto governor, but why would you? What you are actually referring to is "prop rpm," which sets a given rpm for a given boost setting in some plane. At a set rpm, pitch is automatically adjusted by the various constant speed mechanisms on the prop itself.

[69th_Mobile_BBQ]

1 hour ago, Knarley-Bob said:

 

I thought that increasing the throttle increased RPMs. I think we are going to learn something here.?

 

It's a bit of a balancing act.   Throttle/manifold pressure does affect engine RPM as does propeller pitch / propeller RPM speed.

 

The full playlist of CEM tutorials should help as there are a couple of different systems used to control both engine and propeller RPM. 

 

Engine RPM is the most important as overspeeding the engine's internals results in the most damage and/or critical failure.  Some systems use the propeller pitch control to directly adjust or limit the engine RPM. Others set a limit for the engine RPM and then adjust the propeller pitch automatically to keep the engine RPM speed from going beyond the limiter.  The latter is the case for almost all the planes available to fly, even the ones that have full-auto propeller management.

 

 

 

[Knarley-Bob]

More learning to do, thank you gentelmen.................

[kestrel79]

I want to say there's an aircraft or two (probably earlier war) where the Prop Pitch level actually does control the pitch. You can see the blades moving if the engine is turned off. Maybe the 109E model if you put it in manual mode?

 

I didn't really understand what prop pitch was either until visibly seeing it in this sim. 

[[CPT]Crunch]

Some are equipped with double systems like P-38, has electric feather motors in addition to its hydro mechanical control system, you can feather it on the ground without the engine running, don't think they're exactly modeled correctly, you can only get them moving once initiating the start procedure for that particular engine right before it cranks, should work once electrical power is applied especially with the opposing engine running, but not how its programmed. 

 

Some systems you only get a vote using the prop lever, the mechanical control system will take multiple inputs into consideration whether they be air speed via pitot static system, torque on the engine shaft, fly weight regulators on the prop governor, and the prop lever position itself to set the correct pitch angle for the particular phase of flight.  There's a lot of ways to build a prop control system, not all the same way getting to the desired end result.

[RyanR]

Prop pitch is a lot like the gears on a car transmission. The faster an engine goes, the more HP it generates... within reason.... and the more fuel it uses. Since the engine drives the supercharger directly, increasing engine speed increases supercharger speed, which will increase manifold pressure. This is why you should adjust prop before throttle.

 

At the end of the day, efficiency of an engine to produce power or run economically is dictated by the the valve train.... and the sweet spots for running an engine are sorted out in a lab on a dyno, so you should run with the engine set per the "manuals".

 

-Ryan

[69th_Mobile_BBQ]

4 hours ago, kestrel79 said:

I want to say there's an aircraft or two (probably earlier war) where the Prop Pitch level actually does control the pitch. You can see the blades moving if the engine is turned off. Maybe the 109E model if you put it in manual mode?

 

I didn't really understand what prop pitch was either until visibly seeing it in this sim. 

 

I could be wrong about this but, some (if not all) of the 109s have gauges for both engine RPM and prop pitch.  In the 'auto' mode, the prop auto-adjusts to keep things in the proper engine RPM range.  In manual mode, the propeller pitch directly affects the engine RPM with no limit.  This basically means that manual mode prop control can potentially blow the engine.   

In a plane such as the Yak, the propeller is always auto-adjusting to regulate the prop pitch to keep the engine RPM setting regulated and there is no direct control over the actual prop pitch except to throttle down or lower the engine RPM setting.

[Charon]

@kestrel79 I believe the Hs 129 is currently the only plane in the sim which is meant to be flown using prop pitch directly in normal operation. Switching it to auto is effectively combat mode.

[IckyATLAS]

The choice regarding the prop pitch has to do mainly with the speed of the airflow around your plane and use best the available engine power/torque. 

When you are at take off you will use minimum pitch. The reason is that you start from a still position and will start to slowly gain speed. You need maximum power and a propeller pitch adapted to the ambient airspeed which is minimal here or zero in non windy conditions. So to have a high RPM full power and high torque in the conditions of nearly still airspeed you need that the propeller blade turn without too much air resistance just what it needs to have the engine turn at optimal efficiency power/torque. The propeller will accelerate the air and push it behind the blades. This will start moving (accelerating) your plane forward and this means also that the airspeed relative to the aircraft will increase. You need to have these conditions until you take-off and have starting your climb at a set climb speed at which you will have a new intermediate higher pitch angle better adapted to the stabilized climb airspeed and then once you set in cruise conditions you will again increase the pitch for those conditions. As you go at higher altitude, air density goes down and so you can increase the pitch to keep a constant acceleration. There are also other counter effects, like for atmospheric engines non turbocharged, there is a loss of power with altitude, this is why the fighters were generally turbocharged (one stage or two stage) to keep enough volume of air in the engine intake to maintain the power rating up to a certain altitude. All this data is in the plane manuals. 

 

If you did not adapt your pitch and say kept it to minimum then there is a moment where your plane will stop accelerating and it will just compensate the drag of your plane, and you will find yourself at a slow speed with an engine that may overrev because the propeller will have very little effort to do, so you will have to reduce power and finally find yourself in a dangerous situation with stall risk if you have very high wing loadings due to combat loads.

 

The right combination of power/torque (you have in the manuals the graphics of the engine RPM and torque curve) and pitch settings is what makes for an efficient and fuel savvy flight until you enter the combat arena where things switch to survival mode. Knowing perfectly your plane its engine and its behavior allows you when you are in the heat of a combat to concentrate on the enemy and use (in a reflex mode, or say unconsciously) your plane the best way according to the combat conditions and what you are asking him. Otherwise you will find yourself in situations where you will ask to your plane/engine pair things that he can simply not do and you will be toast. This is why the newbies thrown into the combat arena after a few hours stood no chance against trained pilots. This is why countries that put the priority into keeping their pilots alive against countries that just did not care and used them as expandable, always won in the end.

 

 

Edited April 27, 2023 by IckyATLAS
won and not lost in the last phrase

[Jaws2002]

10 hours ago, Charon said:

@kestrel79 I believe the Hs 129 is currently the only plane in the sim which is meant to be flown using prop pitch directly in normal operation. Switching it to auto is effectively combat mode.

 

 I think that's the only one for now. The 109's we have in game have electric controls, but are meant to be used in emergency only.

 The IAR (same family of engine with Hs129) was also manual only. I don't know how it's going to be modelled, but in reality it didn't have an automatic setting. The pilot had to control the prop pitch directly to achieve and fine tune the required RPM.

 

 

[Skycat1969]

While this video is designed around a product for FSX and P3D, the explanation and demonstrations of how different propellers operate is outstanding:

 

Beyond the lesson, the takeaway is: know what type of propeller your aircraft is equipped with and study how to operate it properly and most efficiently. (I damaged a lot of Spitfire I engines in FSX before grasping this.)

[LukeFF]

13 hours ago, Charon said:

@kestrel79 I believe the Hs 129 is currently the only plane in the sim which is meant to be flown using prop pitch directly in normal operation. Switching it to auto is effectively combat mode.

 

Correct, it was meant to flown in manual pitch mode during taxi, takeoff, cruise, and landing. The automatic mode was only meant for combat.

[RossMarBow]

On 3/3/2023 at 10:58 AM, Knarley-Bob said:

Should one increase prop pitch with throttle or decrease it?

In-game it doesn't matter.

 

100% RPM/Pitch 100% pressure for max acceleration.
100% rpm 0% pressure to slow down.
100% pressure for speed. Anything less than 100% pressure will cost top speed.

 

If you want maximum speed all planes benefit from 100% pressure with reduced pitch/rpm.

 

Reducing pitch/rpm also greatly reduces heat output which allows for closing radiators and reducing drag.

 

Most planes have short timer limits close to 100% rpm or pressure.

 

Therefore, if you want to maximise the planes speed over a specified duration you need to use a combination to maximise this.

For example, the p47 can sustain a much higher speed for a far longer duration with rpm under 84% and pressure at 100%. ~30min duration.

The stang D can be flown optimally purely by adjusting RPM and leaving pressure at 100% setting, as reducing rpm reduces pressure.
In the super gap of the stang you need to increase rpm to 100% to counteract the huge loss of pressure output.

The Spit9s optimal combat cruise setting is something like 69% rpm 95% pressure. ~30min duration.

Yak9s optimal speed is 85% rpm 100% pressure. Unlimited duration.

 

With all these planes depending on elevation and temp more optimum setups can be found.
Generally at higher alts you need more RPM.
At lower temps you need less RPM.

 

Fuel savings at reduced RPM are minimal, but it might allow you to run in a hotter lean mix configuration and still be within you thermal-aerodynamic envelope. 

 

As far as I know no plane that benefits from having rpm/pressure throttle positions tied together.

 

 

Edited March 11, 2023 by RossMarBow

[Charon]

On 3/4/2023 at 7:33 AM, Jaws2002 said:

 

 I think that's the only one for now. The 109's we have in game have electric controls, but are meant to be used in emergency only.

 The IAR (same family of engine with Hs129) was also manual only. I don't know how it's going to be modelled, but in reality it didn't have an automatic setting. The pilot had to control the prop pitch directly to achieve and fine tune the required RPM.

 

 

Sounds fun, I'm looking forward to it. Do you know offhand if it had a manifold pressure regulator?

[Jaws2002]

11 hours ago, I./JG3_Charon said:

Sounds fun, I'm looking forward to it. Do you know offhand if it had a manifold pressure regulator?

Are you talking about the "boost regulator" on this page?:

 

 

 The manual shows it had automatic boost regulator. From what I see here the mixture is also automatically regulated, based on altitude, by the carburateur.

Edited March 17, 2023 by Jaws2002

[Strewth]

I think that maybe the easiest way to explain it to some is this:

And  forget about the actual speed.
Think about the throttle as the accelerator and thing about the prop pitch as the difference between level ground and a hill.
When driving a loaded vehicle on level ground, you can set the throttle to a speed and can overspeed if not careful.
When you reach an incline (hill), you can either keep your foot at the same position on the throttle, or you can increase the throttle to try to maintain speed. the hill (as the prop pitch) will ultimately dictate the efficiency of this action.
If the hill is a decent grade, you will increase manifold pressure and try to maintain the same shaft output.
At the same time if you level out again with the same throttle position, you will lose manifold pressure and start to rev higher, as the load on the output shaft has decreased.
If you want to maintain engine RPM on  steep hill, then you go back a gear (a finer pitch) which increases RPM and overall torque.
If you are on flat ground and you can select a higher gear (coarser pitch) and balance it with the throttle.
As you notice in your car, it is a balance between the gear (prop pitch) and your accelerator (throttle position).
There are points where it is more efficient at different gears and accelerator positions depending on the demand.

Well. To me it makes sense anyway.

 

[[SABRE]umkhunto]

On 3/3/2023 at 12:46 AM, Knarley-Bob said:

I thought I had it linked to the throttle but that isn't right.. Should it show on the info on the right side of the screen it's increasing?

I thought that increasing the throttle increased RPMs. I think we are going to learn something here.?

Simplest way to think about it; Prop rpm control is like the transmission in your car. Throttle lever is like the throttle pedal in your car. You set the RPM required for the regime you will be flying in, then control the manifold pressure (power of the engine) with the throttle. In your car, your select the gear that's appropriate (pulling away, climbing a hill, cruising, etc) and apply power to be transmitted to the wheels with the throttle pedal.

[R33GZ]

1 hour ago, [SABRE]umkhunto said:

Simplest way to think about it; Prop rpm control is like the transmission in your car. Throttle lever is like the throttle pedal in your car. You set the RPM required for the regime you will be flying in, then control the manifold pressure (power of the engine) with the throttle. In your car, your select the gear that's appropriate (pulling away, climbing a hill, cruising, etc) and apply power to be transmitted to the wheels with the throttle pedal.

Interesting way of looking at it.... if you want to see what is happening in real time with regards to prop pitch, watch the pitch clock (I don't know what the German name for it is) in the 109. As you increase/decrease throttle and/or altitude you will see the clock hands moving. They represent the angle of attack of the propeller blades, or as we know it, the pitch of the blades.

 

The early aircraft in CLoD model this quite well. You need to be making constant pitch adjustments to keep maximum thrust in combat.

 

You definitely would not want the throttle and pitch linked, you would almost never be getting maximum thrust out of your engine

[ZachariasX]

On 4/18/2023 at 4:15 AM, R33GZ said:

You definitely would not want the throttle and pitch linked, you would almost never be getting maximum thrust out of your engine

You never link power and pitch, you link power and rpm. Pitch is then always „as required“.

[RossMarBow]

On 4/21/2023 at 8:05 AM, ZachariasX said:

You never link power and pitch, you link power and rpm. Pitch is then always „as required“.

You might want to reread what you entered 

[ZachariasX]

2 hours ago, RossMarBow said:

You might want to reread what you entered 

And?

[R33GZ]

8 hours ago, ZachariasX said:

And?

Well... since you asked... you generally wouldn't want to 'link' RPM and throttle. As explained above, this would almost never give you maximum performance. Not to mention, that most aircraft with manual engine controls in this game have an RPM control with a governor that is constantly changing the pitch ie. Angle of attack of the propeller blades, to keep the RPM set by the pilot

[ZachariasX]

4 hours ago, R33GZ said:

Well... since you asked... you generally wouldn't want to 'link' RPM and throttle. As explained above, this would almost never give you maximum performance. Not to mention, that most aircraft with manual engine controls in this game have an RPM control with a governor that is constantly changing the pitch ie. Angle of attack of the propeller blades, to keep the RPM set by the pilot

Rpm and throttle require certain combinations for the engine to work most efficient (and most importantly: not to blow up on you). The aircraft manual states these combinations for the specific ratings. You use these ratings when flying the aircraft. Not doing so will make the aircraft not perform as best and as efficient as it can.

 

You are (in Spits, from Mk.II on and in the Mustang, etc.) technically free to set the rpm. But you set them to get specified MAP/rpm combinations. You are not wiggling the throttle in these aircraft like you do the gas pedal in your car. You set the rating and then fly in accordance. The throttle quadrant is also buillt such that you can move throttle and rpm with one hand synchronous and as long as the smaller rpm lever is next to the throttle lever, it will result in a suitable MAP/rpm combination. It is an assist for real creature comfort. Isn‘t it nice when people who design english cockpits finally give a thought about the pilot? The game actually moves both levers synchronous as one single throttle lever if engine assists are set on.

 

There are of course moments where you don‘t want the levers next to each other, like before taking off, landing etc. In the game, you also dont have them as the manual tells you to for purposes of gaming the game. This includes reducing rpm at full power in the Yak for better top speed or gaming the engine timers, then also not using full rpm for max. MAP. Excessive mean effective pressure is (sadly) not part of the engine logic, hence what would kill the engine much faster than running the engine at max. rated power actually doesn‘t kill the engine at all and can be used to prolong a very punitive timer setting for full power.

 

Prop pitch as such (in constant speed props) is always dependent on airspeed/shaft power/rpm and rarely of interest to the pilot.

[R33GZ]

Dude, in all honesty, you are talking dribble. Sorry for being drawn in to this. I will leave you alone now ?

1 hour ago, ZachariasX said:

Rpm and throttle require certain combinations for the engine to work most efficient (and most importantly: not to blow up on you). The aircraft manual states these combinations for the specific ratings. You use these ratings when flying the aircraft. Not doing so will make the aircraft not perform as best and as efficient as it can.

 

You are (in Spits, from Mk.II on and in the Mustang, etc.) technically free to set the rpm. But you set them to get specified MAP/rpm combinations. You are not wiggling the throttle in these aircraft like you do the gas pedal in your car. You set the rating and then fly in accordance. The throttle quadrant is also buillt such that you can move throttle and rpm with one hand synchronous and as long as the smaller rpm lever is next to the throttle lever, it will result in a suitable MAP/rpm combination. It is an assist for real creature comfort. Isn‘t it nice when people who design english cockpits finally give a thought about the pilot? The game actually moves both levers synchronous as one single throttle lever if engine assists are set on.

 

There are of course moments where you don‘t want the levers next to each other, like before taking off, landing etc. In the game, you also dont have them as the manual tells you to for purposes of gaming the game. This includes reducing rpm at full power in the Yak for better top speed or gaming the engine timers, then also not using full rpm for max. MAP. Excessive mean effective pressure is (sadly) not part of the engine logic, hence what would kill the engine much faster than running the engine at max. rated power actually doesn‘t kill the engine at all and can be used to prolong a very punitive timer setting for full power.

 

Prop pitch as such (in constant speed props) is always dependent on airspeed/shaft power/rpm and rarely of interest to the pilot.

 

[BlitzPig_EL]

Actually he is talking like a real pilot, because he is.  If the real aircraft were operated like they are by most people in the sim they would be blowing up engines so regularly that even the gigantic US wartime production facilities could not keep up with demand for replacement engines.

 

Do you even know what BMEP is?

 

I think not.

[CountZero]

11 minutes ago, BlitzPig_EL said:

Actually he is talking like a real pilot, because he is.  If the real aircraft were operated like they are by most people in the sim they would be blowing up engines so regularly that even the gigantic US wartime production facilities could not keep up with demand for replacement engines.

 

Do you even know what BMEP is?

 

I think not.

and thats why when you wont max performance of airplanes in game you dont fly them like real pilots would, you fly them how game wonts you to fly them...

[Charon]

20 hours ago, ZachariasX said:

In the game, you also dont have them as the manual tells you to for purposes of gaming the game. This includes reducing rpm at full power in the Yak for better top speed [...]

 

Oddly, I believe this is real and not a gamism. @the_emperor has posted the relevant bit from the manual before:

 

 

So the Yak (1?) is, according to the manual, actually slightly faster at 2550rpm than at 2700rpm at altitudes below about 1900m.

 

Why? I don't honestly know, and I'd love a convincing explanation.

[ZachariasX]

1 hour ago, I./JG3_Charon said:

Why? I don't honestly know, and I'd love a convincing explanation.

There are exceptions to everything and in this case, I think it is related to prop efficiency. There are probably other plans that can exhibit this more subtle effect.

 

But my main point was that the aircraft manual (or engine manufacturer) tells you what settings you should use for any specific ratings and if you want effeiciency and best engine life, you follow these instructions.

 

The game however does actually not punish internal engine load, but just nominal boost and rpm numbers, hence you can be creative to game the game and indeed don‘t fly as you would in a real aircraft if you fly competitively. The count has a point here. So you either give advice to operate an engine or you give advice to game the game. Like in Grand Tourismo 5 (yes that was a while ago) you could make fastest laps by circling the finish line posts. Knowing that doesn‘t help your driving, but it was all you needed to know to win.

[the_emperor]

7 hours ago, I./JG3_Charon said:

Why? I don't honestly know, and I'd love a convincing explanation.

 

my russian is quite bad, but it according to the Yak-manual it related to airscrew efficiency/drag, but you trade that for a lower FTH and climb rate (~1min to 5000m).

the low MAP of Klimov engine (~41inches) probably allows such things.

As opposed to US/Brit engines with MAPs >60inches which is only allowed at max rpm to prevent damage.

But as it was pointed out, there is no real engine simulation in this game just the timer mechanic, so we all have 

5 hours ago, ZachariasX said:

to game the game

 

 

On 4/26/2023 at 8:21 AM, ZachariasX said:

You are (in Spits, from Mk.II on and in the Mustang, etc.) technically free to set the rpm. But you set them to get specified MAP/rpm combinations. You are not wiggling the throttle in these aircraft like you do the gas pedal in your car. You set the rating and then fly in accordance. The throttle quadrant is also buillt such that you can move throttle and rpm with one hand synchronous and as long as the smaller rpm lever is next to the throttle lever, it will result in a suitable MAP/rpm combination. It is an assist for real creature comfort. Isn‘t it nice when people who design english cockpits finally give a thought about the pilot? The game actually moves both levers synchronous as one single throttle lever if engine assists are set on.

 

There are of course moments where you don‘t want the levers next to each other, like before taking off, landing etc. In the game, you also dont have them as the manual tells you to for purposes of gaming the game. This includes reducing rpm at full power in the Yak for better top speed or gaming the engine timers, then also not using full rpm for max. MAP. Excessive mean effective pressure is (sadly) not part of the engine logic, hence what would kill the engine much faster than running the engine at max. rated power actually doesn‘t kill the engine at all and can be used to prolong a very punitive timer setting for full power.

 

Hence why in later british and us planes interconnected throttles start to appear:

 

Spitfire Mk IX

Pilot Notes‘s for Spitfire IX, XI, XVI

Merlin Engine 61, 66, 70 or 266

Air Publication 1556j

3rd Edition September 1946

page 33

 

Spitfire Mk VIX

Pilot Note‘s for

Spitfire XIV & XIX

Griffon 65 or 66 engine

Air Publication 1565T 2nd Edition April 1946

page 39

 

 

 

 

Pilot flight instructions P-40N/Kittyhawk September 1944

 

 

 

 

Edited April 27, 2023 by the_emperor

[the_emperor]

On 4/26/2023 at 2:51 AM, R33GZ said:

Well... since you asked... you generally wouldn't want to 'link' RPM and throttle.

Quite the opposite. You really want that , and in best case the FW190 single lever control.

hence why in later stages allied airplanes interconnected throttles start to appear

unfortunately, the game is lacking in that regard