How to properly use prop pitch in IL-2 Cliffs of Dover

[Forcavitale]

Originally Posted by CaptainDoggles

There isn't one single ideal setting.

Forgive my bluntness but thinking of prop pitch in terms of % is looking at it the wrong way. Read below for explanation.

In the Bf 109E-3 for example, you have what's called a variable pitch propeller. That means you can adjust the blade angle, and the prop stays at that angle no matter what you do with the throttle. By comparison the Hurricane with the Rotol prop has a Constant Speed Propeller. What this means is that instead of selecting a particular blade angle, you're selecting an engine RPM that you want. Then when you play with the throttle, the prop governor tries its best to maintain that engine RPM. That leads us into the best way to visualize prop pitch.

Yes, pitch is the angle at which the blades bite into the air. But this isn't a helpful way to think of it, and neither is the analogy to shifting gears in your car.

In my humble opinion, the best way to think of prop pitch is in terms of engine RPM. Forget the blade angle and forget the percentage. Every engine has a range of RPMs where it works best. For the 109 this is about 2200-2400 RPM. So what you should always be doing is keeping your engine RPM in that range, by fiddling with the prop pitch.

You'll notice as you climb, your RPMs will go down. Time to raise them by going to a finer pitch setting.

In a dive your RPMs will rise dramatically. Time to lower them by coarsening your pitch.

It does model this, but most aircraft functioned like CSPs, not VPPs.

So whats the ideal RPM for a Hurricane Rotol?

[CaptainDoggles]

Originally Posted by Forcavitale

So whats the ideal RPM for a Hurricane Rotol?

I have no idea; I don't fly RAF.

According to this thread at the SimHQ forums the ideal range appears to be between 2600 rpm and 3000 rpm.

[SIDWULF]

Well....thanks, I kind of understand now.

I guess im going to be setting the pitch to a trim wheel axis and just adjusting it all the time.

I fear having to adjust the damn thing in combat tho...what is the best idea when in combat? its easy to adjust for diving and climbing....but combat? how do i set my prop pitch effectively without getting distracted by it all the time.

[MadBlaster]

Originally Posted by SIDWULF

Well....thanks, I kind of understand now.

I guess im going to be setting the pitch to a trim wheel axis and just adjusting it all the time.

I fear having to adjust the damn thing in combat tho...what is the best idea when in combat? its easy to adjust for diving and climbing....but combat? how do i set my prop pitch effectively without getting distracted by it all the time.

yes. it all boils down to what your using for controls. so put prop pitch and throttle on the "important" list. I'm not sure if any clod planes have auto prop pitch toggle on/off. If they do...I would want to be able to switch that on and off easily too.

It just takes some practice and little planning. You might want to consider building custom profiles for your controls for each plane you fly. this is the route I went with 46.

[CaptainDoggles]

Originally Posted by SIDWULF

Well....thanks, I kind of understand now.

I guess im going to be setting the pitch to a trim wheel axis and just adjusting it all the time.

I fear having to adjust the damn thing in combat tho...what is the best idea when in combat? its easy to adjust for diving and climbing....but combat? how do i set my prop pitch effectively without getting distracted by it all the time.

Fly the E4 or the Spit 1a. Otherwise you just have to learn. It's not as hard as you might think, but it does require some extra attention. One of the reasons constant-speed units were invented.

[SEE]

Originally Posted by Forcavitale

So whats the ideal RPM for a Hurricane Rotol?

Not sure if this applies to the Hurri but from the Spit Pilot accounts I have read they only mention PP settings for combat RPM. Geoffry Wellum states a specific figure of 2650 RPM once he was at altitude. This figure was confirmed by Group Captain Peter Gilpin when I asked him about prop pitch settings when flying his Spit during the BoB. The only additional comments he made were that the Spit performed better at this RPM but he did adjust the RPM to around 2800 when using boost (in his MkV).

In MP I know a lot of players who change the PP during combat but I tend to set it for 2700RPM and leave it at that. The important thing is not to cook the Merlin by over revving it and the rated max is 3000 RPM for a brief period of time but it soon gets to critical temp.

[Robo.]

Originally Posted by SEE

Not sure if this applies to the Hurri but from the Spit Pilot accounts I have read they only mention PP settings for combat RPM. Geoffry Wellum states a specific figure of 2650 RPM once he was at altitude. This figure was confirmed by Group Captain Peter Gilpin when I asked him about prop pitch settings when flying his Spit during the BoB. The only additional comments he made were that the Spit performed better at this RPM but he did adjust the RPM to around 2800 when using boost (in his MkV).

In MP I know a lot of players who change the PP during combat but I tend to set it for 2700RPM and leave it at that. The important thing is not to cook the Merlin by over revving it and the rated max is 3000 RPM for a brief period of time but it soon gets to critical temp.

Spit Mk.I and Hurri Mk.I have got exactly the same limits and RPM settings. Rather than pilot accounts I would suggest official Pilot's notes as they specify recommended MFP + RPM for each phase of the flight.

As for the game, this is ever so slightly off as the sim (as for now 1.05) is lacking correct modelling of overheating at alt, radiator drag etc. Merlin III was easy to cook, but the 'radiator rupture' message is quite unrealistic as there was a simple pressure valve releasing excessive pressure (steam) should your water temp become critical (easily done in RL). Also various settings are not too far off but as Osprey already stated, they would lead to overheating situations even at big alt (outside atm. pressure, but temperature and TAS)

Therefore, following info is regarding the Rotol Hurricane in the sim (1.05), not in the so called RL :

- it occurs that Mk.I Hurricane is the only plane modelling unique characteristics of every single plane leaving the factory. Especially regarding the water temp - you have to take off and see how hot she runs. Every plane is different. I haven't seen that being the case on a Spit or on a 109. This has never been confirmed by the devs, but it is quite obvious when you spend more time in a Hurricane as I happen to. It's my opinion based on experience, your results may wary.

- Take off fully warmed up at full boost (no BCC-O) and 3000RPM, then ease up to 2850 to power climb - rad fully open. At this stage, watch your water temp and you can see how she runs. If you're lucky you might get her running at higher RPM without overheating, even 2950 and temp stays around 105C. Sometimes though, you'll be struggling to get her above 2750-2800, because the temp is too high and it won't drop. Fair enough.

- Rad management - the point is high RPM = high temp = rad open = drag = your speed drops. In RL, you want to fly fast enough and high enough to keep your Merlin III cool. Extra power comes for the price of extra heat. If you have to fly with your rad fully open, it's not worth it as the extra speed you might squeez out of her at higher RPM is cancelled by the draggy radiator. You are running her hotter for no speed gain. Good compromise is setting your rad to 'normal flight' (50 percent or right in the middle) to reduce the drag and then run your RPM as high as the water temp allows you in combat. (this is more the case when chasing a 109 rather than turnfight at lower speeds). This can be anything between 2750-2850RPM depending on the machine. Careful at alt, see later.

- keep her cool while cruising, save full power for a combat situation. Then depends if you need to be fast (chasing a runner) or if you're engaged in a slower dogfight. If the fight gets vertical, I don't care about drag all that much and rad fully open and 3000RPM in a climb, full boost of course + BCC-O. Boost, RPM and water temp are the 3 gauges to be watched all the time, simple as that. When temp goes too high, open rad and take it easy with RPM.

- at alt of say 17-20k it's very difficult (quite the opposite from the reality) to keep her cool and you find it much easier to overheat. It is nearly impossible to fly at full power for longer periods of time up there. (this goes for any a/c in the sim) This I consider to be a bug and I am sure it will be fine-tuned in future patches. I try to fly her as per manual, whenever possible, but in a game (or is it a sim, I don't know ), I push it a bit furhter to get max performance as I don't need to worry about engine wear and tear.

[TomcatViP]

Originally Posted by Robo.

Spit Mk.I and Hurri Mk.I have got exactly the same limits and RPM settings. Rather than pilot accounts I would suggest official Pilot's notes as they specify recommended MFP + RPM for each phase of the flight.

As for the game, this is ever so slightly off as the sim (as for now 1.05) is lacking correct modelling of overheating at alt, radiator drag etc. Merlin III was easy to cook, but the 'radiator rupture' message is quite unrealistic as there was a simple pressure valve releasing excessive pressure (steam) should your water temp become critical (easily done in RL). Also various settings are not too far off but as Osprey already stated, they would lead to overheating situations even at big alt (outside atm. pressure, but temperature and TAS)

Therefore, following info is regarding the Rotol Hurricane in the sim (1.05), not in the so called RL :

- it occurs that Mk.I Hurricane is the only plane modelling unique characteristics of every single plane leaving the factory. Especially regarding the water temp - you have to take off and see how hot she runs. Every plane is different. I haven't seen that being the case on a Spit or on a 109. This has never been confirmed by the devs, but it is quite obvious when you spend more time in a Hurricane as I happen to. It's my opinion based on experience, your results may wary.

- Take off fully warmed up at full boost (no BCC-O) and 3000RPM, then ease up to 2850 to power climb - rad fully open. At this stage, watch your water temp and you can see how she runs. If you're lucky you might get her running at higher RPM without overheating, even 2950 and temp stays around 105C. Sometimes though, you'll be struggling to get her above 2750-2800, because the temp is too high and it won't drop. Fair enough.

- Rad management - the point is high RPM = high temp = rad open = drag = your speed drops. In RL, you want to fly fast enough and high enough to keep your Merlin III cool. Extra power comes for the price of extra heat. If you have to fly with your rad fully open, it's not worth it as the extra speed you might squeez out of her at higher RPM is cancelled by the draggy radiator. You are running her hotter for no speed gain. Good compromise is setting your rad to 'normal flight' (50 percent or right in the middle) to reduce the drag and then run your RPM as high as the water temp allows you in combat. (this is more the case when chasing a 109 rather than turnfight at lower speeds). This can be anything between 2750-2850RPM depending on the machine. Careful at alt, see later.

- keep her cool while cruising, save full power for a combat situation. Then depends if you need to be fast (chasing a runner) or if you're engaged in a slower dogfight. If the fight gets vertical, I don't care about drag all that much and rad fully open and 3000RPM in a climb, full boost of course + BCC-O. Boost, RPM and water temp are the 3 gauges to be watched all the time, simple as that. When temp goes too high, open rad and take it easy with RPM.

- at alt of say 17-20k it's very difficult (quite the opposite from the reality) to keep her cool and you find it much easier to overheat. It is nearly impossible to fly at full power for longer periods of time up there. (this goes for any a/c in the sim) This I consider to be a bug and I am sure it will be fine-tuned in future patches. I try to fly her as per manual, whenever possible, but in a game (or is it a sim, I don't know ), I push it a bit furhter to get max performance as I don't need to worry about engine wear and tear.

Excellent post Rob especially regarding the Hurri. I am so glad to read it written by someone else.

Regarding the Hurri range of quality it's 1 every two plane tht are performing good for me. The perfs decrease is abt 80%/90% with the needle of the oil gauge flirting with the max value each time you power up more than a min. Only Hurri seems to hve this feature. And I even wonder if it's not specific to the Rottol. I would be glad to see this feature in all plane modeled.

Concerning high alt temp raise, it's plain simple for me : you are running too rich. You can cruise at 17 to 20kft at 50% mixt at ard 180/200mph. Then increase the mixt to nearly full rich (something like full rich minus an inch every 1000ft above 14kft) entering a fight.

[Robo.]

Originally Posted by TomcatViP

Regarding the Hurri range of quality it's 1 every two plane tht are performing good for me. The perfs decrease is abt 80%/90% with the needle of the watter gauge flirting with the max value each time you power up more than a min. Only Hurri seems to hve this feature. And i wonder if it's not specific to the Rottol. I would be glad to see this feature in all plane modeled.

Exactly!

Originally Posted by TomcatViP

Concerning high alt temp raise, it's plain simple for me : you are running too rich. You can cruise at 17 to 20kft at 50% mixt at ard 180/200mph. Then increase the mixt to nearly full rich (something like full rich minus an inch every 1000ft above 14kft) entering a fight.

Oh yeah, I have no problem to run her as high as 24.000 ft, but I'd like to fly up high at full power, not at auto lean. I know you refer to the situation as it is ingame and that's very helpful and adds to the CEM of the RAF fighters very nicely, cheers for that!

As I see it though, the mixture should have no effect whatsoever at say 50% as there was only two positions - one being AUTO RICH (towards the pilot) the other AUTO LEAN, transition being instant not smooth although you can obviously move the Mixture lever all the way. It was recommended in Pilot's notes to move the lever to it's extreme position. Running the engine on low Boost and Auto lean was not physically possible. Also, mixture might have effect on the performance at altitude, but you can't run 'too rich' as the carb is automatic with two presets. Richer mixture also helps cooling the engine, not quite like in game where you have to throttle way back at alt in order to get some power without overcooking. This is all RL stuff and nothing to disagree with what you have said regarding the sim at 1.05 version!

On the other hand, Rotol Hurricane is the only RAF figher that has got the mixture lever correct, Spitfires and dH Hurricane are animated other way round and mixture as such is modelled wrong (effects on performance, temperature, fuel consumtion etc)

[Osprey]

Originally Posted by SEE

Geoffry Wellum states a specific figure of 2650 RPM once he was at altitude. This figure was confirmed by Group Captain Peter Gilpin when I asked him about prop pitch settings when flying his Spit during the BoB.

In combat? I'm pretty sure Wellum stated 1950 rpm to cruise, certainly on Operation Pedestal.