4.11 and Engine Overheat

[-)-MAILMAN-]

Originally Posted by Robo
"I just did a quick test in WIP 4.11.1 and you definitely will be able to fly her by the book now - cold start, taking off at full power (99p no ADI), maintaining climb power of ''44 @ 2550RPM to 5000ft."




5000 feet is still too low to be shifting from supercharger 1 (neutral blower) to supercharger 2 (low blower) in the F4U-1 Corsairs. The Real Life Corsairs (F4U-1/-1A/1C/1D) used the R-2800-8 and -8w engines and maintained 44" MAP up to 8000 feet before shifting from neutral blower to low blower then maintaining 48" MAP. This matches exactly the USN Pilot training film for the Corsairs and until v4.11 the game matched this.

Hellcats used the R-2800-10 and -10W engines and had a different carburetor than those used in the Corsairs. Once source has the Hellcat shifting from neutral blower to low blower at 5500 ft (USN training film uses this altitude) and another source has it at 7000 feet. The Hellcats in versions previous to v4.11 shifted at 5500 feet. Shifting the supercharger at 5000 feet in this version is also too low for the Hellcats.

[Whacker]

Originally Posted by -)-MAILMAN-

Originally Posted by Robo
"I just did a quick test in WIP 4.11.1 and you definitely will be able to fly her by the book now - cold start, taking off at full power (99p no ADI), maintaining climb power of ''44 @ 2550RPM to 5000ft."




5000 feet is still too low to be shifting from supercharger 1 (neutral blower) to supercharger 2 (low blower) in the F4U-1 Corsairs. The Real Life Corsairs (F4U-1/-1A/1C/1D) used the R-2800-8 and -8w engines and maintained 44" MAP up to 8000 feet before shifting from neutral blower to low blower then maintaining 48" MAP. This matches exactly the USN Pilot training film for the Corsairs and until v4.11 the game matched this.

Hellcats used the R-2800-10 and -10W engines and had a different carburetor than those used in the Corsairs. Once source has the Hellcat shifting from neutral blower to low blower at 5500 ft (USN training film uses this altitude) and another source has it at 7000 feet. The Hellcats in versions previous to v4.11 shifted at 5500 feet. Shifting the supercharger at 5000 feet in this version is also too low for the Hellcats.

I have the actual pilot manual for the F4U-1 series open right now, revision 1944.

The climb section calls for the following:

Max continuous normal rated power calls for 44" MAP at 2550 RPM, with the blower shift from neutral to low when MAP drops to 41.5" between 5500 and 7000 ft. above MSL.

Military power climb calls for 2700 RPM at 52.5" MAP, shifting to low blower when MAP drops to 45" between 1700 and 5500 ft. above MSL.

Edit - I posted this for discussion sake, not to indicate that anyone is wrong or right.

[Pips]

Originally Posted by Whacker

I have the actual pilot manual for the F4U-1 series open right now, revision 1944.

The climb section calls for the following:

Max continuous normal rated power calls for 44" MAP at 2550 RPM, with the blower shift from neutral to low when MAP drops to 41.5" between 5500 and 7000 ft. above MSL.

Military power climb calls for 2700 RPM at 52.5" MAP, shifting to low blower when MAP drops to 45" between 1700 and 5500 ft. above MSL.

Whacker, does the manual make any mention of radiator settings for the above? Does it also cover temps and times at certain RPM before overheating sets in? Cheers.

[Whacker]

Originally Posted by Pips

Whacker, does the manual make any mention of radiator settings for the above? Does it also cover temps and times at certain RPM before overheating sets in? Cheers.

No specific radiator settings are mentioned for those two profiles. Also no clear answer to your second question. Here's some data that seems to be relevant.

- There's no air speed restriction regarding any of the cooling flaps (cowl, intercooler, oil cooler) and apparently they can be open at any speed up to Vne, and are covered by some kind of "relief system".

- Max open cowl flaps can lead to some buffeting at the tail, so it's recommended they only be full open on the ground. Take off and climb are recommended at 2/3 open, and high speed or cruising are recommended full closed.

- Max cyl head temp *period* seems to be 260 degrees C (500 F), and the manual says at several places *never* to exceed that under any circumstances.

- Max rated continuous power cyl head temp is stated to be 232 degrees C, with the provision that 260 never be exceed as per previous bullet point.

- Take off and Emergency War Power engine profiles are to be used for no more than 5 minutes.

- Re: Emergency War Power, it doesn't say whether this is 5 minutes max per flight (and between ground servicing) or if it can be used multiple times. I imagine the Wasp radial ground service manual would be the authority for this. It's also clearly limited by the amount of water in the water tanks, but I can't determine if the total water capacity would be used up during that 5 minutes or not.

- Military Power is to be utilized for no more than 30 minutes. Again it doesn't say if this is the total per flight or if it can be used, let to cool down, then used again.

- If I had to make a semi-educated guess given what I know about radials, the 5 min/30 min limits for those power profiles is per flight, with some ground maintenance and checks that need to occur before the engine can be used again. Radials had rather low mean time between overhauls, and higher power settings and temperatures are going to cause rapidly increased wear and tear the worse it gets.

[Robo.]

Originally Posted by -)-MAILMAN-

5000 feet is still too low to be shifting from supercharger 1 (neutral blower) to supercharger 2 (low blower) in the F4U-1 Corsairs. The Real Life Corsairs (F4U-1/-1A/1C/1D) used the R-2800-8 and -8w engines and maintained 44" MAP up to 8000 feet before shifting from neutral blower to low blower then maintaining 48" MAP. This matches exactly the USN Pilot training film for the Corsairs and until v4.11 the game matched this.

Hi Mailman, I said it was around 5000-5500ft at that particular map (Crimea). The MFP is obviously very much depending on the atmospheric pressure and this is actually modelled in Il-2, e.g. your results may vary on a different map.

44'' up to 8000ft.? Which source is stating this as the alt where pilots normally switched from neutral to low blower?

US manual section b ''Power plant'', page 6:

neutral - S.L - 5500ft
low - 16500ft
high - 22000ft

= exactly what 4.11 Il-2compare states and what is also replicable in game in my climb test including best climbing speed and limit temperatures.

With water injection used, neutral blower only up to 2000ft, low from 2000 up to 15000ft. (e.g. page 24 of the British AP2351A manual)

It seems to me that the blower altitudes in 4.11 are pretty much spot on for Corsairs. Coud you please post some sources (preferably links) stating otherwise?

Originally Posted by -)-MAILMAN-

Hellcats used the R-2800-10 and -10W engines and had a different carburetor than those used in the Corsairs. Once source has the Hellcat shifting from neutral blower to low blower at 5500 ft (USN training film uses this altitude) and another source has it at 7000 feet. The Hellcats in versions previous to v4.11 shifted at 5500 feet. Shifting the supercharger at 5000 feet in this version is also too low for the Hellcats.

I have not tested the F6Fs yet. Again, shifting of blowers was fairly complicated, there were certain restrictions in throttle movement in Low and High blower position especially. Also, pilot had to reduce MFP and desirably RPM when switching, actual reaction time varied from plane to plane, and from the atmospheric conditions, that in the first place. Altitudes at normal rated powers should be as follows:

neutral 2550rpm, 44'' - SL - 7000ft
low 2550rpm, 49.5'' - 7000-22000ft
high 2550rpm, 49.5'' 22000ft up

From what I know from the Hellcat FM development, the 1st blower was impossible to set correctly withinh how the game works (I know nothing about that, sorry), and DT simply focused on getting the actual performance and speeds right at any altitude. The blower alt seems to be about 600m too low which is not a biggie considering you have got correct performance now. Hope that helped.

[-)-MAILMAN-]

Here is a link to the film used for pilot training for flying the F4U-1 Corsair from wing fold, start up, takeoff, climb, and landing. the narrator gives the Manifold Air Pressure, Propeller RPM, Radiator settings and altitudes that the supercharger shifts. At the normal rated power climb neutral blower is used, 43.5" MAP at 2550 RPM and shifts from neutral blower to low blower at "approximately" 8,000 feet. Viewing the film is free. In the past you had to use Real Player to view the film, but there are now new choices, I used WMP. Over the last few years I have watched the Hellcat, Thunderbolt, P-40, P-39 and P-38. This was the first reference I had seen to 44" (43.5" to be exact) up to 8,000 feet.

The film is using the F4U-1 with the framed canopy at a time frame when the six position national insignia was being used.

http://www.zenoswarbirdvideos.com/F4U.html

[Robo.]

Originally Posted by -)-MAILMAN-

43.5" MAP at 2550 RPM and shifts from neutral blower to low blower at "approximately" 8,000 feet. (...) This was the first reference I had seen to 44" (43.5" to be exact) up to 8,000 feet.
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Very interesting movie, thanks for that. As it seems, the devs seemed to stick to the actual manual which states 5500ft. It is not unusual to see different sources stating different values, it is hard to make a decision then. In this case, the movie happens to be the only source refering to 8000ft. Both US and British manuals state 5500ft.

As long as you can fly the a/c as per book (and you certainly can as I described above), I don't see any problem.

[Bolelas]

Not a question about the game itself, but as real life aircraft behaved: In a dive, in a over-rev situation (lets say i cut throttle but forgot to pitch back), does the plane heat the same way as if i was adding more fuel? (with less pitch). I know compressed air heats, plus there is fuel going in (the idle fuel), and also friction, but should it overheat slowly?
Hope you people can understand question, because it is a little confusing.
I have not much knowledge about engine, just what i read in foruns, books etc. Also in the spitfire manual it says that in a dive they could do a little over-rev, but had to add at least one third of throttle : Was this to lubbricate pistons?

[Whacker]

Originally Posted by Bolelas

Not a question about the game itself, but as real life aircraft behaved: In a dive, in a over-rev situation (lets say i cut throttle but forgot to pitch back), does the plane heat the same way as if i was adding more fuel? (with less pitch). I know compressed air heats, plus there is fuel going in (the idle fuel), and also friction, but should it overheat slowly?
Hope you people can understand question, because it is a little confusing.
I have not much knowledge about engine, just what i read in foruns, books etc. Also in the spitfire manual it says that in a dive they could do a little over-rev, but had to add at least one third of throttle : Was this to lubbricate pistons?

Over-revving any engine is very, very bad for it. It creates a lot of heat very rapidly (mostly from friction, not combustion), and it pushes parts of the engine far beyond what they were designed to work at.

Some common failures include piston rods breaking ("throwing a rod"), cam and crankshaft bearings rapidly being burnt out and seizing up, valve heads colliding with pistons, etc. Even if everything manages to hold together, it can also cause critical "soft" components like gaskets to fail, which may not cause an immediate seize-up but could cause other things to fail in a chain reaction.

It's very complicated and I don't pretend to understand the actual ways and means of doing it, but calculating a particular engine's red-line rev rating is done based on it's design. Beyond that red-line the probability of partial or total failure rapidly goes up to where it's essentially guaranteed.

Lastly, keep in mind this was almost 80 years ago. Aeronautics was a very young field and technology was pushing boundaries once held to be insurmountable. Warbird engines were pushed to their absolute limits and designed to run at just below those with minimal safety cushions. Overspeeding your prop and motor will invariably give you those really bad results, and the game seems to do a great job of simulating that as best as it can.

Hope that helps.

[K_Freddie]

So what were saying here is... a slower revving engine is a lot cooler, whether it be driven by wind or combustion.

Common sense says that combustion would be hotter