P-40 Engine Settings as I found them (a bit weird)

[Venturi]

I like all the above.

[CSW_Hot_Dog]

Does also anybody else noticed, that something has been changed recently with motor endurance? A month ago, it can been fly safely on full RPM and full throttle untill EMERGENCY POWER TIME EXCEEDED message appered and sometimes a little bit further (if engine was damaged, you were still able to return to the base most of the time on continuous setting), but now, every try to push RPM and throttle control full forward during combat leads to engine damage in few seconds (lets say 10 - 30 sec) without the message and even, if you immediately return engine to continuous mode, it will completely stop after minute or so... That is new behavior and not been so in the past. I dont know what im doing wrong, but now, i cant fly this bird in combat, but i was surely be able before:-(

Edited July 12, 2016 by Hot_Dog

[6./ZG26_Klaus_Mann]

Does also anybody else noticed, that something has been changed recently with motor endurance? A month ago, it can been fly safely on full RPM and full throttle untill EMERGENCY POWER TIME EXCEEDED message appered and sometimes a little bit further (if engine was damaged, you were still able to return to the base most of the time on continuous setting), but now, every try to push RPM and throttle control full forward during combat leads to engine damage in few seconds (lets say 10 - 30 sec) without the message and even, if you immediately return engine to continuous mode, it will completely stop after minute or so... That is new behavior and not been so in the past. I dont know what im doing wrong, but now, i cant fly this bird in combat, but i was surely be able before:-(

You are Over-Revving most likely. 

[Venturi]

Note on Dec 42 data sheet,

 

http://forum.il2sturmovik.com/topic/21234-p-40-engine-settings-i-found-them-bit-weird/?p=369889

 

max RPM allowable is 3120

 

fast changes in throttle or full throttle in dives will increase engine RPM faster than the ability of the governor to change propeller pitch to reduce engine rpm

 

additionally, in the real aircraft, engine RPM could be set greater than 3000 manually

Edited July 13, 2016 by Venturi

[Farky]

Haven't read whole thread, but is there any reason we don't have the bottom chart in game?

 

Yes, pretty good one - this specific chart was issued in 1944. Not in December 1942, that is date when Spec. AN-H-8 was issued. In other words, P-40E wasn't cleared for War Emergency Rating in December 1942.

[Crump]

Yes, pretty good one - this specific chart was issued in 1944. Not in December 1942, that is date when Spec. AN-H-8 was issued. In other words, P-40E wasn't cleared for War Emergency Rating in December 1942.

 

The particular version of AN-H-8 you are looking might be issued in December of 1944.  However, AN-H-8 as of November 1942 clearly sets the limits for the V-1717-39 engine IAW with specification sheet posted.  In December of 1942, P-40E's were flying under that specification after complying with any technical/maintenance instructions published by Allison.

 

Those V-1710-39 equipped with "Streamline Manifolds".  That means a MAP regulator is required to use 56"Hg for WEP.  Those without the MAP were not allowed to use a War Emergency Power rating.  Without the MAP, the engines were restricted to Military Power only.

Edited July 22, 2016 by Crump

[Crump]

The lack of a MAP regulator is a huge pain in the backside IMO...constant babysitting of the throttle lever in diving/climbing combat to keep the MAP at the right level for power but not destruction of the engine. Is there some good reason to not use one or did Curtiss/Allison just drop the ball?

 

 

I can't think of a single good reason not to use one.  The regulator was standard on all P-40 models after the P-40E and one subsequent V-1710 supercharged engines.  The manual says some V-1710-F3R engines were service or depot maintenance level retrofitted.  Most likely they were upgraded in the standard inspection cycle.  In other words, they did not haul aircraft out of an operational squadron to upgrade it.  They simply upgraded it when service and depot level inspection cycles were due.

 

That is typical.

[Farky]

 

The particular version of AN-H-8 you are looking might be issued in December of 1944.  However, AN-H-8 as of November 1942 clearly sets the limits for the V-1717-39 engine IAW with specification sheet posted.  In December of 1942, P-40E's were flying under that specification after complying with any technical/maintenance instructions published by Allison.

 

AN-H-8 (issued Dec.18,1942) was just general specification about charts, how to use them etc. So, AN-H-8 do not clear V-1710-39 in P-40E for War Emergency Rating. Same AN-H-8 was used for lot of other airplanes and for lot of other engines. For example P-51D, this aircraft do not even exist in 1942 -

 

 

Flight manual for P-40E ( Technical Order No. 01-25CF-1) issued February 25, 1943 and revised 4-10-43 do not mention WER at all and specifically states - 44.6 in Hg / 3000 rpm for 5 minutes only as Military Power.

 

 

Those V-1710-39 equipped with "Streamline Manifolds".  That means a MAP regulator is required to use 56"Hg for WEP. ...

 

There is no direct connection between "Streamline Manifolds" and manifold pressure regulators. By June 1942 Allison had developed the new Streamlined gas pipe and tee that allowed removing the tee backfire screens and soon begun produce engines with these manifolds. At that time, production of V-1710-39 was over. Some of  V-1710-39 were later retrofitted with Streamline Manifolds. It means what it says - "when you use V-1710-39 with Streamline Manifolds, use this chart." - nothing less, nothing more.

 

-------------

 

Anyway, allowed or not, pilots used very high Manifold Pressure (50 in Hg and higher, much higher) in combat on P-40Es. In emergency, it was more "panic button" then anything else, but they used this "button". Limits of V-1710-39 in game are basically right.

[Crump]

 

 

There is no direct connection between "Streamline Manifolds" and manifold pressure regulators

 

I understand what you mean and you are correct.  At first I thought you were claiming the V-1710F3R could not use 56"Hg until 1944.  That would be wrong!

 

Certainly there is a connection to the Streamlined manifolds in that you cannot use WEP on an V-1710F3R (-39) engine UNLESS you have the MAP equipped manifold.  When they retrofitted the screens....they installed the MAP as well as part of Service or Depot Level Inspection cycles.

 

 

 

 

 

AN-H-8 (issued Dec.18,1942) was just general specification about charts,

 

Yes.

 

 

 

Flight manual for P-40E ( Technical Order No. 01-25CF-1) issued February 25, 1943 and revised 4-10-43 do not mention WER at all and specifically states - 44.6 in Hg / 3000 rpm for 5 minutes only as Military Power.

 

 

That is because the 52"Hg is not Military Power...it is Standard Emergency Power.  In a V-1710F3R using Standard Emergency power, the Military Power rating was lowered from 44.6 in Hg to 42in Hg.

 

 In April of 1943, both the MAP equipped War Emergency Power of 56"Hg and the higher 52"Hg for Standard Emergency Power were approved and in use in P-40E's.

 

 

 

Now that is the Third Edition.  The Second Edition to the Operation and Overhaul Instructions was published in July of 1942.  The Technical Order that allowed the V-1710F3R was then published sometime between July 9, 1942 and April 1, 1943.

 

Somewhere in that time frame, V-1710F3R's were approved for War Emergency Power when equipped with a MAP at 56"Hg@3000rpm or Standard Emergency Power at 52"Hg@3000rpm.

 

Without the MAP, the manifold is a closed system.  Changes in airload on the propeller and ram pressure rise in the intake will cause the manifold pressure to change as well as the rpm.  If the engine could run safely at 56" with the MAP, the Standard Emergency Power of 52"Hg was limited by 4"Hg as a maneuvering buffer.

[Crump]

So the statement they were restricted to Military Power Only would be wrong after April 1 1943 or the date the Technical Order was published allowing the use of "Standard Emergency Rating".   

[Crump]

 

 

Flight manual for P-40E ( Technical Order No. 01-25CF-1) issued February 25, 1943 and revised 4-10-43 do not mention WER at all and specifically states - 44.6 in Hg / 3000 rpm for 5 minutes only as Military Power.

 

 

Even that was an increase because as late as September 1942, the engine was limited to 43.6 in HG for the 5 minute Military Power rating.

 

 

[Farky]

 

Certainly there is a connection to the Streamlined manifolds in that you cannot use WEP on an V-1710F3R (-39) engine UNLESS you have the MAP equipped manifold.  When they retrofitted the screens....they installed the MAP as well as part of Service or Depot Level Inspection cycles.

 

Where exactly in the document (ALD-3F2) is " you can not use War Emergency Rating (WER) unless you have Streamlined manifolds"? Nowhere. Why? Because instalation of new Streamlined manifolds was not requirement for use of WER ( for instalation of automatic manifold pressure regulator), Mustangs with V-1710-39 did use WER with old type of manifolds. No direct connection between new manifolds and WER.

 

 

 

That is because the 52"Hg is not Military Power...it is Standard Emergency Power.  In a V-1710F3R using Standard Emergency power, the Military Power rating was lowered from 44.6 in Hg to 42in Hg.

 

USAAF terminology do not knew term "Standard Emergency Rating", the same applies for other users of P-40Es (RAF, RAAF, SAAF, VVS-RKKA ...). Users never allowed 52 in Hg, only 56 in Hg.

 

Allison company use this term ("Standard Emergency Rating") and limit this to 52 in Hg, correct. But here is a catch ( or two) -

 - Standard Emergency Rating - what does it mean anyway? Because i don't know, Allison handbook do not explain that. Is it something for training units? Is it limit when i use 91 octane fuel? Can i use it without automatic regulator? I don't know. I can have a theory, even good theory, but true is i just don't know.

 - that Allison handbook (ALD-3F2) is not official document, it clearly states "For information only". So, it cannot approve a thing. It is more of a recomendations, not order. This is not official user document and users allow limits for engines. In cooperation with factory, of course, but users have last word on limits.

 

 

 In April of 1943, both the MAP equipped War Emergency Power of 56"Hg and the higher 52"Hg for Standard Emergency Power were approved and in use in P-40E's.

 

April 1943 is wrong. Let me explain why -

Automatic pressure regulator were not installed into P-40Es until the autumn of 1943, when T.O. No. 1-25C-112 ( Instalation of Automatic pressure regulator) was issued. So, War Emergeny Rating ( 56 in Hg) was approved for P-40E in autumn 1943, Standard Emergency Power - see above.

 

Very important is the fact, that P-40Es at that time were already withdrawn from combat units, maybe with some only minor exceptions.

 

 

 

Now that is the Third Edition.  The Second Edition to the Operation and Overhaul Instructions was published in July of 1942.  The Technical Order that allowed the V-1710F3R was then published sometime between July 9, 1942 and April 1, 1943.

 

Somewhere in that time frame, V-1710F3R's were approved for War Emergency Power when equipped with a MAP at 56"Hg@3000rpm or Standard Emergency Power at 52"Hg@3000rpm.

 

V-1710-39 (-F3R) was approved by USAAF for War Emergency Rating (56"Hg@3000rpm) in December 1942, Standard Emergency Rating - never approved.

 

 

Without the MAP, the manifold is a closed system.  Changes in airload on the propeller and ram pressure rise in the intake will cause the manifold pressure to change as well as the rpm.

 

Right, I absolutely agree.

 

As far as i knew, every report (official or not) about use of very high Manifold Pressure on V-1710-39 without automatic regulator goes like this - " I was in danger ( outgunned, outnumbered ...), so I use "overboost" to run away". In every case that I know it was fast straight flight, never dogfight or some kind of maneuvering.

 

 

 If the engine could run safely at 56" with the MAP, the Standard Emergency Power of 52"Hg was limited by 4"Hg as a maneuvering buffer.

 

Any official confirmation for this? You think or you knew?

 

 

Even that was an increase because as late as September 1942, the engine was limited to 43.6 in HG for the 5 minute Military Power rating.

 

Yes, it was an increase, actually for second time. At first, Military Rating was limited to 42 in Hg. Btw, this limit was in use by RAF and VVS-RKKA even during 1942.

Later limit increase to 43.9 in Hg and in July 1942 limit changes to 44.6 in Hg (for USAAF and RAAF P-40Es at least). July 1942, not September. For some reason, RAAF test issued in September 1942 was on old ratings. Here is RAAF Power table for V-1710-39 (-F3R) issued 3rd July 1942 -

 

 

 

[Venturi]

Battle of Moscow, Oct 1941 - Jan 1942........ F3R (-39) "official limit" = 42" MAP/3000rpm

 

Battle of Stalingrad, July 1942 - Feb 1943......... F3R (-39) "official limit" = 56" MAP/3000rpm

 

 

Same engines, same planes. Just an evolving realization that the engine should be rated higher by Allison/USAAF/RAF as the front line reports trickled in...

Edited July 29, 2016 by Venturi

[Crump]

 

 

Where exactly in the document (ALD-3F2) is " you can not use War Emergency Rating (WER) unless you have Streamlined manifolds"? Nowhere. Why? Because instalation of new Streamlined manifolds was not requirement for use of WER ( for instalation of automatic manifold pressure regulator), Mustangs with V-1710-39 did use WER with old type of manifolds. No direct connection between new manifolds and WER.  

 

Nobody EVER said it was....

 

The use of 56"Hg as War Emergency Power does REQUIRE the MAP regulator and therefore the specifications with "streamlined manifolds" MUST have a MAP.  End of Story.

 

That is what I said and have tried to tell you but you seem stuck to trying to disprove a claim I did not make.

 

 

 

V-1710-39 (-F3R) was approved by USAAF for War Emergency Rating (56"Hg@3000rpm) in December 1942, Standard Emergency Rating - never approved.

 

 

Not without a MAP....

 

End of Story.

 

 

 

that Allison handbook (ALD-3F2) is not official document, it clearly states "For information only". So, it cannot approve a thing. It is more of a recomendations, not order. This is not official user document and users allow limits for engines. In cooperation with factory, of course, but users have last word on limits.

 

No, It is the the official document on how the USAAF operated their Allison engines.  

 

You will not find a USAAF P-40E V-1710F3R engine using 56"Hg WEP unless it is equipped with a MAP to regulate the pressure in the Manifold.

[Crump]

 

 

Just an evolving realization that the engine should be rated higher by Allison/USAAF/RAF as the front line reports trickled in...

 

If we ignore the design changes required to raise the detonation limits and wish to believe the motor was magically morphed into being able to achieve more power than the engineers designed it for and assume they were just incompetent in the first place being completely unable to determine the structural strength and detonation limits of their own engine.

[Crump]

 

 

No direct connection between new manifolds and WER.

 

Read once again....

 

 

[Venturi]

If we ignore the design changes required to raise the detonation limits

 

And which changes were those? Simple answer, now.

 

The rating increase to 56" was in Dec 1942.

Edited July 30, 2016 by Venturi

[Crump]

 

 

And which changes were those? Simple answer, now.

 

Here discusses a few of the design changes.  In fact, it says the V-1710F series was a complete redesign of the engine over the V-1710 C series found in earlier P-40 models.

 

 

 

 

Ergo, the increased power rating was available before the mandate to use the pressure regulator.

 

And this is simply not true.  The stops limited the engine to 44.6"Hg or 52"Hg based on specific model engine installed.  

 

 

Only by increasing the propeller load thru maneuvering will the manifold pressure rise above 52"Hg or 44.6"Hg or whatever that particular engine is limited by in the Operating Instructions.

[Venturi]

MAP regulators not fitted.

 

56" approved Dec 1942.

 

Backfire screens had nothing to do with WOT.

 

Next.

[Crump]

 

 

MAP regulators not fitted.

 

 

[Crump]

I do not understand why the MAP is such a big deal to you Venturi.  The overhaul manual states that the MAP will be fitted to all V-1710F3R engines during their service and depot level inspections.  I am sure it only took a few months to outfit every P-40E in the inventory with them.  

[Venturi]

Because the MAP limiter completely changes the way the engine and aircraft are managed.

 

It is ahistorical to include a MAP limiter on Russian flown P40E1s in 1941/42 or even later, when it is based on a retrospective technical order originating on the other side of the globe in 1943.

 

 

Edited July 31, 2016 by Venturi

[Venturi]

Based on a 1943 technical order and April 1 1943 operating manual. For a retrospective refit of existing planes "when service overhaul is needed".

 

What about that Dec 1942 spec sheet approving 56"?

 

http://forum.il2stur...weird/?p=369889

 

 

Edited July 31, 2016 by Venturi

[Crump]

 

 

What about that Dec 1942 spec sheet approving 56"?

 

 

That AN-8 sheet is correct in that P-40E's were approved to use 56"Hg.  They just had to mount a MAP regulator to do it.

 

 

 

Based on a 1943 technical order and April 1 1943 operating manual. For a retrospective refit of existing planes "when service overhaul is needed".

 

Overhauls are not done at the Service level.  Overhauls are Depot level maintenance.  All service level maintenance is clearly defined in the manual.  Anything found on the periodic inspections that is covered by service level maintenance means the aircraft goes to service level maintenance.  

 

The instructions are very clear to me and follow normal aviation convention.  When the aircraft comes to service level maintenance OR Depot Level Overhaul, the MAP will be installed.  It is like a typical Mandatory Service Bulletin.  You do not have to ground an aircraft on the field because they are not change to the type certificate or an Airworthiness Directive.  Instead, the next time the aircraft comes in for maintenance, the bulletin gets complied with...

 

It probably did not take more than 6 months for every P-40E to be equipped with a MAP, Venturi.  Simple things like cigarette rolls on the ignition leads, exhaust gaskets, intake gaskets, everything covered in Section VIII of the manual is Service level maintenance.

I imagine by December 1942, it would be rare to encounter a P-40E on the frontline without a MAP.

[Venturi]

In the timeframe we are talking about, BOM 1941 and BOS 1942, there were no MAP regulators on Russian P40s.

 

You will not find a USAAF P-40E V-1710F3R engine using 56"Hg WEP unless it is equipped with a MAP to regulate the pressure in the Manifold.

 

Wrong, wrong wrong. Manifold period accounts by pilots and others say otherwise.

The engine could produce far in excess of 56" manifold pressure at low altitudes and pilots did indeed use this in combat, as the letter from Hazen, Allison's chief engineer alludes to. Among many other sources cited earlier in this thread.

[Crump]

 

 

In the timeframe we are talking about, BOM 1941 and BOS 1942, there were no MAP regulators on Russian P40s.

 

Correct.

 

 

 

Wrong, wrong wrong. Manifold period accounts by pilots and others say otherwise. The engine could produce far in excess of 56" manifold pressure at low altitudes and pilots did indeed use this in combat, as the letter from Hazen, Allison's chief engineer alludes to. Among many other sources cited earlier in this thread.

 

 

 

All engines can produce more manifold pressure than they are allowed.  They just tend to break just like the Allison!!

 

I just do not agree with you.  More likely, you are just seeing what you wish to see.  

 

Allison's instructions are clear on the matter IMHO.

[Venturi]

No one is arguing that they don't break more quickly. Remember that test I mentioned the USAAC ran with the less durable, earlier "long nose" Allison, the V-1710-33? 80min at 56" with only crankweb cracks, no outright failure. That would be unacceptable in a real squadron, where the next pilot may have failure on run-up.

 

However in the setting of the simulation, where every time someone takes off that bird is considered "new, fresh from factory", then the engines should be able to perform at least 56" for 5 minutes. I would argue they should be able to perform higher pressures, for longer periods.

 

Currently, they completely freeze at about 1.5-2 minutes in the simulation.

Edited July 31, 2016 by Venturi

[Crump]

 

 

Currently, they completely freeze at about 1.5-2 minutes in the simulation.

 

Yes, they should be able to run at their rated Manifold Pressures for their rated time period plus a little extra.  

 

Once that 5 minute warning (which I think is good....you are simulating a trained pilot and NOT actually a trained pilot) you should have to pull the engine back to avoid damage.

 

If you are not getting the full time the engine was rated for then something is wrong.

The 5 minute rating is 42"Hg in your game as per the VVS P-40's.  

 

Venturi, are you sure you are not using 45.5"Hg and experiencing engine failure after a few minutes?

 

45.5"Hg is a Take Off rating.....NOT Military Power (5 minute limit).

[Dakpilot]

How would one maintain a 'safe' 56" for 5 mins in P-40 when the gauge does not go above 50" 

 

surely it would be easy in some situations to easily go above 56"

 

The 75" MP gauge common to later P-40;s is not fitted in the lend lease BoS P-40E

 

it seems unlikely that a setting would be allowable from a spec sheet when that setting cannot be set or visually monitored?

 

Cheers Dakpilot

[Venturi]

Why don't you get the sim and find out for yourself, Crump? I'm sure you'll have all sorts of useful feedback based on your expertise with hi displacement piston engines, altitude or not altitude rated superchargers, and WWII aviation in general. 

How would one maintain a 'safe' 56" for 5 mins in P-40 when the gauge does not go above 50" 

 

surely it would be easy in some situations to easily go above 56"

 

The 75" MP gauge common to later P-40;s is not fitted in the lend lease BoS P-40E

 

it seems unlikely that a setting would be allowable from a spec sheet when that setting cannot be set or visually monitored?

 

Cheers Dakpilot

 

The pilot could choose to peg the needle at will. It was "verboten" but not mechanically "unallowable". You are right that with the earlier gauges, the pilot would have no way of knowing exactly how much manifold pressure the engine was producing, over 50".

[Crump]

How would one maintain a 'safe' 56" for 5 mins in P-40 when the gauge does not go above 50" 

 

surely it would be easy in some situations to easily go above 56"

 

The 75" MP gauge common to later P-40;s is not fitted in the lend lease BoS P-40E

 

it seems unlikely that a setting would be allowable from a spec sheet when that setting cannot be set or visually monitored?

 

Cheers Dakpilot

 

The stops achieve the preset manifold pressure of 52"Hg if the engine does not have a MAP in the V-1710F3R series.  You simply cannot select more than what the engine is set too.

 

Later P-40's had a different engine than the P-40E series and all were equipped with a MAP as standard equipment.

[Venturi]

This again?

 

It just shows you don't know what you are talking about.

 

Achieve 52" at what altitude, Crump? Are you saying the USAAF actually purposefully reduced the critical height the plane was able to operate at by limiting maximum butterfly movement on the carburetor?

 

I think not.

[Dakpilot]

Why don't you get the sim and find out for yourself, Crump? I'm sure you'll have all sorts of useful feedback based on your expertise with hi displacement piston engines, altitude or not altitude rated superchargers, and WWII aviation in general. 

 

The pilot could choose to peg the needle at will. It was "verboten" but not mechanically "unallowable". You are right that with the earlier gauges, the pilot would have no way of knowing exactly how much manifold pressure the engine was producing, over 50".

 

I thought Mr Crump already owned BoS.

 

So 56" is not 'approved' officially in BoS P-40, the Dec 1942 Doc is not really relevant to the VVS lend lease version, fitted with early  50" MP gauge, so if the pilot 'firewalled'/overboosted it is possible to go over 56" and not know it

 

Cheers Dakpilot

[Crump]

 

 

so if the pilot 'firewalled'/overboosted it is possible to go over 56" and not know it

 

Without the MAP...YES.  The manifold is a closed system.  On a cold day (low density altitude) and at high speed...it is very possible.  That is why the V-1710F3R manual and P-40 operating instructions have such detailed sections on recognizing detonation.

Engine not equipped with a MAP were limited to 52"Hg for the 5 minute emergency power.  This gives them a 4"Hg buffer to prevent overboosting.

[Venturi]

No one really knows what the gauges were on the Russian P40s unless you can find a period picture of one. We can only guess based on crashed planes in North Africa that the RAF and USAAF were using. And some of those seem to have had later gauges.

 

But let's say you're right and its the 50" gauge only. That doesn't mean the plane could not have used the Dec 1942 specification of 56" safely.

 

The Russian engines were the same, and so were the planes. The Dec 1942 uprating by Allison was for all 1710-39 / F3R engines. Mechanically they were the same engines originally rated at 44" before the sequential upratings by Allison (also with no changes to the actual engine).

 

Of course, even back in the days of the 42-44" max ratings, the engines were mechanically able to use higher MAPs and the frontline pilots had been doing so anyways, for sometime....

Edited July 31, 2016 by Venturi

[Crump]

Han already posted the VVS data for the time period of BoM.  It is on the first page.

[Venturi]

Yes, and that's what gets us the 1.5min engine explosion at 56"/3000rpm.

Edited August 1, 2016 by Venturi

[Crump]

http://forum.il2sturmovik.com/topic/21234-p-40-engine-settings-i-found-them-bit-weird/?p=340319

[LukeFF]

No one really knows what the gauges were on the Russian P40s unless you can find a period picture of one. We can only guess based on crashed planes in North Africa that the RAF and USAAF were using. And some of those seem to have had later gauges.

 

Granted, it's not an E model but rather an M, captured by Finland: 

 

[Willy__]

 

 

Granted, it's not an E model but rather an M, captured by Finland: 

 

Interesting that they removed the american gunsight and installed a russian one.