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

[Dave]

 

 

Time does weird things in combat.  Most combats lasted less than 5 minutes so "As long as necessary" does not seem unusual at all and certainly is not proof limitations were violated and appeals to the combat fairey normal. 

 

 

This doesn't tally at all with my research of the desert campaign. Typical combats there lasted between 30 minutes and an hour.

For example I just opened a book I have, "A history of the Mediterranean Air War 1940-1945" by Christopher Shores, randomly at page 327. Over the next 3 pages 2 combats on one day in 1942 are described - the first lasting 40 minutes, the second 65 minutes until the sun had set and the Tomahawks were able to escape. 

Fantastic 2 volume set by the way, packed with pilot accounts of combat, escape and evasion.

[Venturi]

Read the following very knowledgable post on this exact topic.

 

https://ww2aircraft.net/forum/threads/what-was-the-problem-with-the-allison-engine.29243/page-17#post-1261854

[=J13=xarann]

I have a simpe question.

There are any photos of P-40E cockpit with the maximum scale value of manifold pressure above 50'' ?

[=362nd_FS=RoflSeal]

I have a simpe question.

There are any photos of P-40E cockpit with the maximum scale value of manifold pressure above 50'' ?

National Museum of the United States Airforce's P-40E MP guage goes to 75"

 

 

Also in this video has MP guage go to 75", but obviously you can also see the cockpit instrument panel has been changed from the original

 

@ 3:45

 

I also wonder if its correct that the MP needle stops at 50".

My experience with analog guages is that unless there is a stop, they will keep circling as the value increase (best example is over revving your car )

Edited April 22, 2016 by RoflSeal

[Dakpilot]

The National museum P-40 also has a joystick with a hat switch, that looks like it's from an F-16 or suchlike

 

Cheers Dakpilot

[=J13=xarann]

1)National Museum of the United States Airforce's P-40E MP guage goes to 75" Also in this video has MP guage go to 75", but obviously you can also see the cockpit instrument panel has been changed from the original

 

2)I also wonder if its correct that the MP needle stops at 50".My experience with analog guages is that unless there is a stop, they will keep circling as the value increase (best example is over revving your car )

1) Sorry, I was speaking about historical materials. Present time ones are very doubtful

2) But in case with manometer if needle goes too far, the instrument will be broken(because of mechanical deformation of parts inside).

And one more thing: how pilot can set a manifold pressure 52'' or 56'' if gauge ends with 45'' or 50''? I wonder how people here arguing with each other about overbust, but no one asks about gauge diapason.

[MiloMorai]

Inside that boost gauge.

 

[Dave]

I have a simpe question.

There are any photos of P-40E cockpit with the maximum scale value of manifold pressure above 50'' ?

Plenty. They read to 75".

[=J13=xarann]

Plenty. They read to 75".

maybe link helps?

[MiloMorai]

US Type D-10

[=J13=xarann]

good picture of some manometer.

but where is the photo that connects it with P-40E exactly?

[Dakpilot]

 Untouched 1942 P-40E

 

 

Later P-40's, N model for example, most manufactured type had the 75" gauge

 

Cheers Dakpilot

Edited April 22, 2016 by Dakpilot

[=362nd_FS=RoflSeal]

Manifold pressure gages 10-50" and 10-75" are interchangeable

 

http://www.enginehistory.org/Accessories/TO00-25-29.pdf

 

Check Page 62-63

Edited April 22, 2016 by RoflSeal

[=J13=xarann]

Manifold pressure gages 10-50" and 10-75" are interchangeable

 

http://www.enginehistory.org/Accessories/TO00-25-29.pdf

 

Check Page 62-63

I believe there are interchangeability between 10..50'' and 10..100'' and so what? This fact tells nothing about P-40E and overbust.

[=362nd_FS=RoflSeal]

I believe there are interchangeability between 10..50'' and 10..100'' and so what? This fact tells nothing about P-40E and overbust.

Stop changing the goalposts.

 Your original question

 

 

I have a simpe question.

There are any photos of P-40E cockpit with the maximum scale value of manifold pressure above 50'' ?

 

 

About overboost in P-40E, read the rest of the thread. 

Edited April 22, 2016 by RoflSeal

[=J13=xarann]

Stop changing the goalposts.

 Your original question:There are any photos of P-40E cockpit with the maximum scale value of manifold pressure above 50'' ?

Ok. Back to my question. Historical photos of p-40e cockpit with 50+'' manifold gauge. I still do not see any. 

 

And about overbust: how did they do measurements if manometers maximum was only 50? I am talkin now only about P-40E, not about later models. 

Edited April 22, 2016 by =J13=xarann

[=362nd_FS=RoflSeal]

Ok. Back to my question. Historical photos of p-40e cockpit with 50+'' manifold gauge. I still do not see any. 

 

And about overbust: how did they do measurements if manometers maximum was only 50? I am talkin now only about P-40E, not about later models. 

Engage your brain...

 

There are pilot accounts of going over 50 inches, along with Allison documents talking of a WEP setting of 56"

 

There is a TO that says the 10-50" and 10-75" MP gage are interchangeable

 

1+1=?

[=J13=xarann]

Engage your brain...

 

There are pilot accounts of going over 50 inches, along with Allison documents talking of a WEP setting of 56"

 

There is a TO that says the 10-50" and 10-75" MP gage are interchangeable

 

1+1=?

Its just your imagination/guesswork. Where are the proofs? Maybe photo or video materials instead of reasoning? Maybe P-40E has manometer with maximum over 50''? If so, I would like to see some photos.

For now I have seen 75'' max only for P-40 of  later models, but not for P-40E.

Dakpilot share with us a beautiful photo. Any suggestion from you how pilot can set throttle for example on 52''? I just want to say that you can set 56'' only if you have an visual control over that pressure.

[Dave]

OK. Walk to the top of a building. Stand on the edge of the roof. Now close your eyes. And .... jump. Did that hurt? Are you sure? I mean ... you couldn't see the ground coming up at you.

[=362nd_FS=RoflSeal]

Its just your imagination/guesswork. Where are the proofs? Maybe photo or video materials instead of reasoning? Maybe P-40E has manometer with maximum over 50''? If so, I would like to see some photos.

For now I have seen 75'' max only for P-40 of  later models, but not for P-40E.

Dakpilot share with us a beautiful photo. Any suggestion from you how pilot can set throttle for example on 52''? I just want to say that you can set 56'' only if you have an visual control over that pressure.

Ask yourself this. How many clear cockpit pictures of aircraft deployed in the front lines are there from the 1940s? Answer is near to none. Nearly all cockpit pictures of aircraft during the 1940s are from manuals, not from the front line, and as such, things like pictures, may become out of date.

 

Anyway, back onto this gauge.

That P-40 is reported to have crashed 28th June 1942

 

Here is a chronology of relevant documents

 

First T.O. I can find mentioning 10-75"Hg gauge D-10 and AN 5770-1 are dated 20th July 1942 as  05-70C-1. Almost one month after.

 

Pilot's notes for the Mustang I (same engine) mentions a WEP of 56", dated August 1942.

 

T.O. 03-10HA-5 is released on Nov 30 1942. This details installing regulators and adjusting WEP settings of various Allison engines including ours (F3R in this case are to have regulators installed and to be set to WEP of 56")

 

On December 12th 1942 a cable is sent to Allison HQ regarding use of high boost values on Allison F3R and F4R engines, with manifold pressures of at least 66" being reported "Some pilots admit operating for prolonged periods at around 70"Hg". In other words the pilots know what MP they are at.

 

and again with "they are resetting boost controls to 66"

 

Of particular note I have just noticed is the first sentence "In the past week we have received reports...". Remember 2 weeks ago T.O. 03-10HA-5 was released

 

Then afterwards April 1943 is the Allison F series handbook, again detailing 56" of MP at WEP.

Edited April 22, 2016 by RoflSeal

[Venturi]

Fair enough, looks like it would simply stop at the end of the gearing

 

Inside that boost gauge.

 

[Venturi]

Basically, I read it like this:

 

V-1710-39 in P-40E1 was not initially rated for >46" MAP, (nor was the -33 engine) but was used above this regardless. However the early gauges only read to 50". Later the official rating went up to 52". Nothing changed on the engine, it was always able to produce more than 50" at lower altitudes, and I'm sure nothing really changed in how pilots used the engine when in combat. I suspect that the early type 50" gauges were swapped to 75" gauges retroactively when the rating went up. Again the rating change was an arbitrary increase in the official limits, the engines were identical, and I hardly imagine such a rating increase changed what the pilots were doing.

 

HOWEVER, such an official order would have dictated that the gauges be changed so as to be able to read them. 

[=J13=xarann]

Here is a chronology of relevant documents

 

First T.O. I can find mentioning 10-75"Hg gauge D-10 and AN 5770-1 are dated 20th July 1942 as  05-70C-1. Almost one month after.

 

Pilot's notes for the Mustang I (same engine) mentions a WEP of 56", dated August 1942.

 

T.O. 03-10HA-5 is released on Nov 30 1942. This details installing regulators and adjusting WEP settings of various Allison engines including ours (F3R in this case are to have regulators installed and to be set to WEP of 56")

 

On December 12th 1942 a cable is sent to Allison HQ regarding use of high boost values on Allison F3R and F4R engines, with manifold pressures of at least 66" being reported "Some pilots admit operating for prolonged periods at around 70"Hg". In other words the pilots know what MP they are at.

 

and again with "they are resetting boost controls to 66"

 

Of particular note I have just noticed is the first sentence "In the past week we have received reports...". Remember 2 weeks ago T.O. 03-10HA-5 was released

 

Then afterwards April 1943 is the Allison F series handbook, again detailing 56" of MP at WEP.

Do you want some chronology?

Time BoM is autumn-winter of 1941. And do you really believe that USSR get all shiny P-40's( in ''just from factory'' state) by lendlease program? If I remember corretly, it was early planes(tomahawks).

For consideration: first appearanсe of p-40E in USSR is spring 1942 but production of E model begins in early of 1941!

Time BoS  is end of summer 1942 -winter of 1943. P-40 was used by 126th IAP (was in battle from 20 august - mid of september 1942)and 731th IAP(end of august 1942 - 20+ september 1942) And again, do you really believe that p-40's were new (with production date at least spring of 1942)?

Bad developers, they dont give us a 5 min 70" overbust?

I think they were very generous to our P-40(of course I mean only lendlease P-40 of the given time period that presnted in BoM and BoS)

Edited April 23, 2016 by =J13=xarann

[JtD]

They sure gave us 70" of overbust, but we're looking at how feasible 70" overboost would be.

 

More to the question - instruments are generally fitted so that they can display the range given in the handbooks. The main point of the topic however is, that pilot exceeded handbook figures in frontline service if the situation became bad enough. And the engine did not immediately break down. The manifold pressure gauge broke, is what one pilot tells us.

The instrument would be interesting to see, but it is no indication or proof either way. Just because the speedometer in my car goes to 200km/h, it doesn't mean my car will go 200. It might go slower by factory default (probably will), or it might go faster if I do a little programming work on the turbo.

[=362nd_FS=RoflSeal]

Do you want some chronology?

Time BoM is autumn-winter of 1941. And do you really believe that USSR get all shiny P-40's( in ''just from factory'' state) by lendlease program? If I remember corretly, it was early planes(tomahawks).

For consideration: first appearanсe of p-40E in USSR is spring 1942 but production of E model begins in early of 1941!

Time BoS  is end of summer 1942 -winter of 1943. P-40 was used by 126th IAP (was in battle from 20 august - mid of september 1942)and 731th IAP(end of august 1942 - 20+ september 1942) And again, do you really believe that p-40's were new (with production date at least spring of 1942)?

Bad developers, they dont give us a 5 min 70" overbust?

I think they were very generous to our P-40(of course I mean only lendlease P-40 of the given time period that presnted in BoM and BoS)

AFAIK P-40E-1 production was from December 1941 to May 1942.

 

And anyway, I don't know what age has to do with anything, devs have said they were modelling aircraft as if they were factory fresh.

Edited April 23, 2016 by RoflSeal

[Dave]

Do you want some chronology?

Time BoM is autumn-winter of 1941. And do you really believe that USSR get all shiny P-40's( in ''just from factory'' state) by lendlease program? If I remember corretly, it was early planes(tomahawks).

For consideration: first appearanсe of p-40E in USSR is spring 1942 but production of E model begins in early of 1941!

Time BoS  is end of summer 1942 -winter of 1943. P-40 was used by 126th IAP (was in battle from 20 august - mid of september 1942)and 731th IAP(end of august 1942 - 20+ september 1942) And again, do you really believe that p-40's were new (with production date at least spring of 1942)?

Bad developers, they dont give us a 5 min 70" overbust?

I think they were very generous to our P-40(of course I mean only lendlease P-40 of the given time period that presnted in BoM and BoS)

The VVS P40s were initially a combination of donated RAF Tomahawks (they were brand new and diverted from RAF delivery to Russia instead because the RAF were taking delivery of Kitthawks) and new P40Es from USAMEF stock (the USAMEF were upgrading directly to P40Fs). None of them were hand-me-downs.

I don't recall wanting 70" of boost. Pretty sure we said 20 minutes at 60" being representative of reality. The mention of 70" is just an indication of the engine's documented ability to go well beyond the 60" it was officially cleared for by Allison.

RAF/RAAF units within the WDAF were setting their WEP limits to 66" in November 1942 - on P40Es they had received almost a year earlier.

[Dakpilot]

 

RAF/RAAF units within the WDAF were setting their WEP limits to 66" in November 1942 - on P40Es they had received almost a year earlier.

 

Some documentation/source on  that would be very helpful

 

Cheers Dakpilot

[216th_Lucas_From_Hell]

Not boost-related, but an anecdote from 129 GIAP P-39s in 1943.

 

There were combat losses and some planes had been falling out of action due to engine failures. The Allison engines installed on the Airacobras had been designed to fly from permanent aerodromes with concrete surfaces. We flew from a field aerodrome. Dirt and dust would get into the carburetor intakes, and along with air, into the cylinders and oil systems of engines. Sand had been destroying crankshaft bearings, evidenced by shavings in oil filters. The engines had been failing.

Edited April 24, 2016 by 55IAP_Lucas_From_Hell

[JtD]

Which was an advantage of the Allison powered P-40's, the engine air intake was placed on top of the nose. Dust and dirt did not cause the troubles it caused on aircraft with an intake below the nose, like Merlin powered P-40's, Spitfires or Hurricanes. On the P-39, the problem would rather be the far aft air intake, where it would be more exposed to dust created by the prop or even the front wheel.

[Crump]

Ask yourself this. How many clear cockpit pictures of aircraft deployed in the front lines are there from the 1940s? Answer is near to none. Nearly all cockpit pictures of aircraft during the 1940s are from manuals, not from the front line, and as such, things like pictures, may become out of date.

 

Anyway, back onto this gauge.

That P-40 is reported to have crashed 28th June 1942

 

Here is a chronology of relevant documents

 

First T.O. I can find mentioning 10-75"Hg gauge D-10 and AN 5770-1 are dated 20th July 1942 as  05-70C-1. Almost one month after.

 

Pilot's notes for the Mustang I (same engine) mentions a WEP of 56", dated August 1942.

 

T.O. 03-10HA-5 is released on Nov 30 1942. This details installing regulators and adjusting WEP settings of various Allison engines including ours (F3R in this case are to have regulators installed and to be set to WEP of 56")

 

On December 12th 1942 a cable is sent to Allison HQ regarding use of high boost values on Allison F3R and F4R engines, with manifold pressures of at least 66" being reported "Some pilots admit operating for prolonged periods at around 70"Hg". In other words the pilots know what MP they are at.

 

and again with "they are resetting boost controls to 66"

 

Of particular note I have just noticed is the first sentence "In the past week we have received reports...". Remember 2 weeks ago T.O. 03-10HA-5 was released

 

Then afterwards April 1943 is the Allison F series handbook, again detailing 56" of MP at WEP.

 

 

The manifold pressure on a closed system will change with atmospheric conditions and propeller load....

[=J13=xarann]

 Just because the speedometer in my car goes to 200km/h, it doesn't mean my car will go 200. It might go slower by factory default (probably will), or it might go faster if I do a little programming work on the turbo.

Yeah, yeah. But how you determine any certain speed over 200km\h of your car if your speedometer goes only to 200? Can you say for example that speed of your car was 240km\h? Maybe 260 or 220? Who knows?

[Dave]

Some documentation/source on  that would be very helpful

 

Cheers Dakpilot

I've already posted it and I'm growing tired of repeating myself.

[Dave]

Not boost-related, but an anecdote from 129 GIAP P-39s in 1943.

Not boost-related, but an anecdote from 3 SQN RAAF P40Es in 1942.

Q: Just one we'll just put in for the record. How did the Merlin compare with the Daimler-Benz engine?

 

A: I think .... One thing I've discovered since the war - I'm now 'buddy-buddies' with some of these German pilots that I was fighting against - the Merlin engine .... Well, I wasn't flying Merlins over there but I was flying behind the Allison and we were having great trouble with sand and dust because there's no greater thing that will damage an engine more than an oil and sand combination. We were getting twenty to twenty-five hours out of our Allisons. We had an Engineer Officer called Buck Abicair who invented an air filter. I carried out the flying for him while we tested the air filter and it was hugely successful. Allison adopted it in the subsequent models with some modifications of course and our engine hours went up to over 100 before they were due for complete engine overhaul. I was talking to one of these Germans who was in command of JG27 in the desert, flying Messerschmitts, and he told me that they were getting eighteen to twenty hours between overhaul, so they were really up against it.

[ACG_KaiLae]

P-40E's Allison engine is borked and is more fragile then a chandelier when it was completely the opposite in real life

 

Nov 1941 engine datasheet limits

 

 

 

 

 

Dec 1942 datasheet engine limits

 

 

 

 

 

Note extension of military power to 15 minutes and addition of WEP at 56".

 

 

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

[Venturi]

Because of the timing, according to some people. That's a Dec 1942 sheet and the 1941 sheet is what is in game right now as Stalingrad was Aug 42 - Feb 43 and most P40s took part in the early battle. In actuality, the Allison engines in the P-40E1 which received the factory Dec 42 "uprating" were identical to the ones already in existing planes.

 

Also, unlike other period fighters, there was no limiter on the manifold pressure installed on the P-40E1 which would have kept pilots from pushing up the boost on their own. In reality the engines were pushed much harder than the spec sheet gives by pretty much everyone who flew the P40E... Allison themselves acknowledged that the engines were being pushed much harder than their rated levels in a period memo from their chief engineer (listed early in this thread). In that memo Allison further also acknowledged that rated power and power duration were set at an arbitrary level determined by them to be safe, and that this was an choice based on their idea of a balance between performance and engine longevity. In fact, to determine the limits of these engines, the factory tested them at very high power levels and for very long times to determine failure points. In one test of an earlier Allison -33 series "long nose" engine (less durable than the "short nose" -39 in the P40E1), the engine went 80min at 56" MAP when it was rated for only 44" WER. That is 75min more than the -39 was later rated for at 56". It did however develop cracks in the crankcase webbing. Just goes to show how much safety margin was built in here.

 

The bottom line is that Allison's limits were there to prevent the engines from failing not on the first mission, nor on the second, or even the fifth. But rather, to keep them from failing before the scheduled overhaul of the engine (which I believe was much longer than the interval of the Db60x series).

 

P40 pilots needed the performance help which that extra power gave them against the 109F, and "pushed the limits" because it was safe to do so in the short term, and because their fear of being shot down due to being in an underperforming plane in a dogfight far outweighed their fear of engine failure.

 

Even so it did not help them against the 109F too much, the P40's climb rate being what it was.

Edited July 11, 2016 by Venturi

[6./ZG26_Klaus_Mann]

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

The lower Chart is for models with Manifold Pressure Regulator. Ours has direct Throttle and different ratings. 

PDF Pages 32 and 40 (34 and 26 of the Document) https://docs.google.com/file/d/0Bw4FNWq6qRgqclU4MzhqbFl4WEk/edit

 

Our engine is the F3R and rated for Standard Emergency. On page 26 it quite clearly states that War Emergency power is prohibited for use with the engines without Regulator, so a Standard Emergency Rating is given that is somewhat lower. 

With Regulator you get War Emergency of 56"

Without it 52" are permissible as per Manual (Since Manifold Pressure changes while manouvering it may safely achieve 56", the 4" difference is basically a buffer to prevent it from exceeding 56")

[Venturi]

The F3R is the same engine as the V-1710-39, which is plainly listed at the top of the Dec 42 chart. That manual is from April 1, 1943. The pressure regulator was not installed from the factory on V-1710-39s. Ergo, the increased power rating was available before the mandate to use the pressure regulator.

[6./ZG26_Klaus_Mann]

The F3R is the same engine as the V-1710-39, which is plainly listed at the top of the Dec 42 chart. That manual is from April 1, 1943. The pressure regulator was not installed from the factory on V-1710-39s. Ergo, the increased power rating was available before the mandate to use the pressure regulator.

One doesn't really contradict the other. 56" I think were always seen as the maximum Pilots should use for that engine, not to be exceeded. 52" were most likely just a safety measure. 

 

Since the entire engine documentation is a confusing Clusterf*** I'll take the official Allison Document as my most trusted Source. 

Edited July 10, 2016 by 6./ZG26_Klaus_Mann

[Venturi]

Great, then let's use the Dec 42 chart.

[6./ZG26_Klaus_Mann]

Great, then let's use the Dec 42 chart.

Well, I think we should keep the 52" as a recommended Value and put the 56" in brackets as a "do not exceed".

Our Current Map gauge doesn't read more than 50", so it's already quite impossible to correctly read any kind of Emergency Power. 

 

Of course you would always be able to achieve 70+" if you choose and given the correct circumstances, but you shouldn't, and I'm looking forward to realistic Detonation and Knocking Simulation. 

 

Edit: Should we get a better MAP Gauge I think we would just put the Red Line at 52", since this is the most plausible Solution. 56" should however be the Simulated Limit. 

Edited July 11, 2016 by 6./ZG26_Klaus_Mann