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6./ZG26_Klaus_Mann

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

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BTW, Allison could have blamed the "Allison Time bomb" on US serviceman not following the Limitations.  I think that contribute to the engine's reputation.  The Government would have had a very hard time proving it did not contribute.

 

While the US Government cannot be sued, it is not that hard to get tons of money out of them if you have a case.  Allison had a clear cut case to get out of their contract because the US Government was in violation the moment this overboosting came to light.

 

They could have entered a lawsuit against the US Government, it would have been immediately dismissed as you cannot sue the US Government.  The process then sends the case to an arbitration panel and the law is very clear.  Allison was wronged by the US Government.  Therefore the panel would have had no choice but to pay the amount or very close too the amount of damages Allison sought in their lawsuit.

 

It generally takes a lot less time to get your money when you "sue" the US Government.  Most civil suits result in quicker awards but good luck collecting the money, it almost never happens.

 

So Allison gave up a lot businesswise in writing that memo and standing by our serviceman.

 

I admire and respect Allison as a company for that character.  If you look at the history of aviation, it is rife with the US Government and its contractors suing each other back and forth.

Edited by Crump

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Welcome, guys! I'm from Russia. I do not know english, so I write through a translator. Excuse me.

 

Welcome to the English forums!!

 

I speak Russian, German, and Spanish so I understand the difficulty of translating from one.

 

For example, there was a V 1710 F series that was approved for 60"Hg at the time.

 

350ny8j.jpg

 

It just wasn't F series engine found in the P-40E.   You have to wonder if all this 60"Hg just wasn't a maintenance error in ordering the wrong carburetor linkage rods.  The rods would fit on F series engine are a preset length.  

 

Happens all the time.  Many aircraft engines, especially solid lifters, use preset push rod lengths to adjust the valve clearance.   I have seen several instances of the wrong size push rod being installed.  Usually it gets caught when you check the valve clearance.  Not always though and there a few instances were the error was not caught until after several hours of flight and the operator complaining the engine was not acting quite right!!

 

It happens....aviation is run by humans!

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And what do you /or players from Russia think about Fw 190? In this game is unrealistic... Fw 190 A3 was better then Spit Vb but not here..

 

The topic here is about the P-40, not the 190 or the Spitfire or any other plane, so show some courtesy to others by not dragging your complaints in here about other planes. 

Edited by LukeFF

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The topic here is about the P-40, not the 190 or the Spitfire or any other plane, so show some courtesy to others by not dragging your complaints in here about other planes. 

 

 

It is legitimate question to ask from someone from the Russian forums.   Frankly I would be glad to see more interaction and encourage it instead of trying to squash it....just saying.  Glad you edit'd your post too.

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In this discussion I stand with Crump since he is the only one who has consistenly provided Evidence for his points.

Like the point where he claims the P-40E's got a manifold pressure regulator and shows a document that states P-40N will get a single lever control? You're easily impressed.

 

Personally, I still trust the Allison chief engineer more than Crump.

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Personally, I still trust the Allison chief engineer .....

 

Excellent.  Should be nothing else to say on the subject.

 

 2e0mdfn.jpg

 

ei4mk8.jpg

 

Then we can listen to the Allison engineers and care not what Crumpp says....

 

And drop all this silliness trying to convince everyone 60" and 70"Hg was the norm......

The highest the P-40E was ever cleared for was 56"Hg and only if the engine mounted a MAP regulator.  That is what the Allsion engineers say....

 

mra9oo.jpg

 

anmucx.jpg

 

I have to laugh and totally agree that you should use exactly what the Allison engineers say....they hold the Type Certificate!!   :rolleyes:

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And drop all this silliness trying to convince everyone 60" and 70"Hg was the norm......

That silliness is all yours, considering that no-one has made that claim. As per usual, you invent your straw men and argue them. That's why I recommend you to argue with a mirror.
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That silliness is all yours, considering that no-one has made that claim. As per usual, you invent your straw men and argue them. That's why I recommend you to argue with a mirror.

 

It is black and white in print by the Allison engineers....

 

Explain how that is a strawman, LMAO!!??!!

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Oh boy, reading comprehension of a 6 year old.

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Oh boy, reading comprehension of a 6 year old.

 

 

Insults without facts, tell me about that strawman....

 

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OK. I've read every single post in this topic. And I still don't know - is our P40 performing as it should? ;)

 

Cloyd

Edited by Cloyd

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OK. I've read every single post in this topic. And I still don't know - is our P40 performing as it should? ;)

 

Cloyd

Yes. It should be better, but what is presented is mostly correct for what it is. 

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Yes. It should be better, but what is presented is mostly correct for what it is. 

Thanks Klaus-Mann for the synopsis - should be better, but mostly correct.

 

Cloyd

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OK. I've read every single post in this topic. And I still don't know - is our P40 performing as it should?

 

 

Klauss answered it.

 

Han posted these documents right at the beginning of this thread.

 

The 1942 VVS Manual which is what the game should be going by as it recreates the Eastern Front, shows 42"Hg as the 5 minute Military Power Limit.  That agrees with the Allison data from 01 April 1943.  However, it is slightly less than the 5 minute allowance from December 1941.

 

141qn90.jpg

 

This whole thing with the P-40 caught my attention when complaints of not being able to outrun a Bf-110 at low altitude.   

 

That is just not the case.  A P-40E is faster than a Bf-110 even with the P-40 using maximum continuous power.

 

nfmsf9.jpg

 

bebhg8.jpg

 

Nailing down the power production we should be seeing is the first step in determining any issue with aircraft performance.

Edited by Crump

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Isn't that Venturi's new nick? 

 

Nope. :cool:

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OK. I've read every single post in this topic. And I still don't know - is our P40 performing as it should? ;)

 

Cloyd

Better to see once than hear a hundred times. (Russian proverb).))

The atmosphere is standard.

At the top of the timer. On the right message about exceeding the time limit.

 

3000х45" Mode. Safe mode for the engine for 15 minutes. It is proved by documents.

post-2090-0-90083000-1470730991_thumb.jpg

 

3000х50" mode. Safe Mode for 5 minutes. It is proved by documents.

post-2090-0-48110600-1470731171_thumb.jpg

 

3000хFT (65"-66"). Which mode pilots used in combat if necessary. After 10-20 seconds. no one filed. It is proved by documents.

post-2090-0-98641100-1470731396_thumb.jpg

 

In Game:
1. Wrong.
2. Wrong.
3. Wrong.
On such a plane can not fly. None of the game or in life. It is death. Fifteen thousand kamikazes (as produced aircraft), is not it too much? We are against an infinite WER. It is not right. In the game take off=new plane. We have a reasonable compromise. Option proposed by the Venturi good.
 
I write as simple as possible. Translator distorts phrase. I continue later.
 
 

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Han led soveskoe guide rewritten from the US for students. It is ridiculous to fight for the leadership of the students.))

But Han read selectively. On the next page:

post-2090-0-72040300-1470735122_thumb.jpg

I translate. The manual says that F-40E carries a turn with a roll to 70 degrees. Lead time on the specified time 19-20 sec. The game is 32 seconds. Maximum roll 58 degrees. The game has a bug.

 

Glazing.

Here is a glass of the P-40:

post-2090-0-41819000-1470735469_thumb.jpg

 

Here's how to game:

post-2090-0-87538400-1470735594_thumb.jpg

Worse than the Soviet aircraft. It is not right. American Glass was the best in the world. In the Soviet Union there was an order to take the quality of the glass on the P-39 and P-40 for a sample. The game has a bad sample.))

 

The game lantern P-40 wedges on speed. As even earlier Soviet planes. There are documents confirming this? Or just for the company? The plane is fighting for the Soviets.))

 

Airplane P-40 has to do and do.

So I think. So I think of my friends.

 

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Better to see once than hear a hundred times. (Russian proverb).))

The atmosphere is standard.

At the top of the timer. On the right message about exceeding the time limit.

 

3000х45" Mode. Safe mode for the engine for 15 minutes. It is proved by documents.

Nope, for the F3R it's 5 Minutes + 5 Minute Emergency. Officially it's 5 Minutes

attachicon.gifil-2 2016-06-29 11-37-03.jpg

 

Actually it's up to 56", with 52" being the official number for our Aircraft.

3000х50" mode. Safe Mode for 5 minutes. It is proved by documents.

attachicon.gifil-2 2016-06-29 11-41-16.jpg

 

What you will achieve with FT varies, mostly will be much lower, around 60" when engine is set up correctly. 

3000хFT (65"-66"). Which mode pilots used in combat if necessary. After 10-20 seconds. no one filed. It is proved by documents.

attachicon.gifil-2 2016-06-29 11-43-35.jpg

 

In Game:
1. Wrong.
2. Wrong.
3. Wrong.
On such a plane can not fly. None of the game or in life. It is death. Fifteen thousand kamikazes (as produced aircraft), is not it too much? We are against an infinite WER. It is not right. In the game take off=new plane. We have a reasonable compromise. Option proposed by the Venturi good.
 
I write as simple as possible. Translator distorts phrase. I continue later.
 
Agreed, the Aircraft isn't really practical at all right now. 

 

Edited by 6./ZG26_Klaus-Mann

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Actually it's up to 56", with 52" being the official number for our Aircraft.

 

I agree with you and that is what the Type Certificate limits say.

 

Farky's point seem to be that this rating never existed in any P-40E in service and I think he proved that point as I have never seen any documentation from any P-40E user that shows 52"Hg in actual use outside of Allison's published limits.  Most Air Forces seem to have chosen a slightly lower 5 minute limit if the engine was not equipped with a MAP.  If equipped with a MAP, the 5 minute limit becomes the full 56"Hg.

 

It is small point in light of a closed manifold system but one that is worth digging into for more information.

 

It also does not change the fact that in a closed manifold system, pressure will change with air load.  The lower 5 minute limit used in service simply means more of a buffer to reach the ultimate limit of 56"Hg.

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Reference Handbook: Aircraft Engines. NKAP. USSR. 1943. (construction-operation & repair)

 

 

 

post-11474-0-31949000-1470755958_thumb.jpg

post-11474-0-56259000-1470755993_thumb.jpg

post-11474-0-16206800-1470756007_thumb.jpg

post-11474-0-94678700-1470756032_thumb.jpg

post-11474-0-69165700-1470756048_thumb.jpg

post-11474-0-15114400-1470756065_thumb.jpg

post-11474-0-44751100-1470756116_thumb.jpg

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Reference Handbook: Aircraft Engines. NKAP. USSR. 1943. (construction-operation & repair)  

 

Thanks for posting and very interesting!

 

That list's the 45.5"Hg for 5 minutes, does not violate the Type Certificate, and agrees with Farky's assessment that the 52"Hg was never used.   That is still an increase from the 42"Hg in 1942.

 

Next question is will they or can they model the closed manifold system and allow an ultimate manifold pressure of 56"Hg under an appropriate airload?  The 56"Hg is what the Type Certificate says the engine is approved as the ultimate manifold pressure.

 

It should not be an extra WEP but allow the P-40 pilots to somewhat "set it and forget it" at 45.5"Hg for most of the envelope in a high speed dogfight without having to unrealistically give constant attention to their Manifold pressure. 

Edited by Crump

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))

Documents Documents discord.)) And here is the engine that in 1941, that in 1943, that in 1945 the same. 

TO on Allison engines of 1945 for P-39 aircraft.

post-2090-0-68628700-1470818803_thumb.jpg

Motor -35 (E4) = motor -39 (F3R). 

1550 hp = 3000х60".))

 

There is no point in denying the obvious. Even if the obvious was recorded later. From the letter characteristics do not change.

 

 

 

 

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Stalling angle.

In the game P-40 it is 14 degrees. According to our calculations and in accordance with the wind tunnel should be 16.8 degrees. Therefore, the aircraft in the game has a bad turn and low resistance to stall.

16.8-14 more than 16.75-15.5. The pilots of P-40 pilots cry more than Fw-190.))

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))

Documents Documents discord.)) And here is the engine that in 1941, that in 1943, that in 1945 the same. 

TO on Allison engines of 1945 for P-39 aircraft.

attachicon.gifДвигатели Р-39.jpg

Motor -35 (E4) = motor -39 (F3R). 

1550 hp = 3000х60".))

 

There is no point in denying the obvious. Even if the obvious was recorded later. From the letter characteristics do not change.

 

There is not a single P-40 on there nor is there a single V 1710-39.  These are not engines installed on a P-40 so I am in trouble for denying the obvious!?!

 

:biggrin:

 

edit'd to add smile

Stalling angle.

In the game P-40 it is 14 degrees. According to our calculations and in accordance with the wind tunnel should be 16.8 degrees. Therefore, the aircraft in the game has a bad turn and low resistance to stall.

16.8-14 more than 16.75-15.5. The pilots of P-40 pilots cry more than Fw-190.))

 

If you need any data PM me.

 

The P-40 used the NACA 2215 / NACA 2209 airfoil combination.

Edited by Crump

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The "E" series and "F" series engines were very similar, the primary difference being the front crankcase cover, which was interchangeable between the two series engines.

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The "E" series and "F" series engines were very similar, the primary difference being the front crankcase cover, which was interchangeable between the two series engines.

 

It is not the F series and the reason why Allison separated them in the manuals is because they are different engines, Milo. 

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Series motors E and F are different from each other gearboxes screw.

Series E - gear unit in a separate housing.

Serie F - reducer directly on the engine block.

35 = 39, 63 = 73, and so on.

Otherwise differences in the package.))

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I'm curious - how do you guys measure the stalling angle or any of this other data in the sim?

1. 1. From the description of the airplane from the Han.

2. We put the plane in avtogorizont. Reduce the speed. We fix the position when the bot stops to keep the aircraft. We measure the angle. The accuracy is not perfect, but for a rough estimate of the working method.

 

Р-40.

Clear wing:

post-2090-0-84064000-1470908054_thumb.jpg

Mechanization, the landing gear:

post-2090-0-74018900-1470908071_thumb.jpg

 

Poor everywhere. But especially in the landing configuration. The aircraft landing on three points can not be right.

 

PS. Do not forget about the installation angle of the wing.

Edited by Vachik
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Hey look at that 3d model... I guess you overlaid actual dimensions?  ;)

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Mmm, unfortunately not quite understand.))

Side view of the drawing taken from it:

post-2090-0-26330700-1470994210_thumb.jpg

It imposes on the screenshot to find the right construction line. Then it's simple. The installation angle of the wing is known. Bot ceases to hold the plane for up to 1-2 degrees of failure. Calculate: 10 + 1 + 2 = 13 Close to said game. But far from the estimated 16.8.

The landing configuration is even worse. 2 + 1 + 2 = 5. The parking angle of 13 degrees. Very far. Landing on the three points is not possible.

Edited by Vachik
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Series motors E and F are different from each other gearboxes screw.

Series E - gear unit in a separate housing.

Serie F - reducer directly on the engine block.

35 = 39, 63 = 73, and so on.

Otherwise differences in the package.))

While that might seem to pass the common sense and be the easy thing to do...it is not how aviation works, LOL.

 

Instructions for E motor only apply to an E motor and vice versa.  No matter how similar the engines might have been, they were different enough to warrant a completely new designation and their own set of instructions.

 

Details are important and instructions are specific in aviation.

 

For example the F4R engined could use 60"Hg. The F3R engines in the P-40E could only use 56"Hg with a MAP. They could not use 60"Hg like the F4R.

 

Edit'd - time was short and my fingers fat when working on a smartphone keyboard!

Edited by Crump

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Normal Rated Power (Max. Level/Climbing Continuous in UK) : ALD-3F2 - 37.2 in Hg/ 2600 rpm ( no time limit ) vs RAF manual - 38.5 in Hg/ 2600 rpm ( no time limit ) - RAF limit HIGHER.

 

This is kind of mystery but the difference is negligible.  You are talking 1.3"Hg.  That is well within the normal adjustment tolerances of the set screws!!!  

 

I tend to think it has do with the gauge error on the manifold pressure gauges used by the RAF.   This may have something to do with units of measure.  There was not a world standard for an inch until long after World War II despite several attempts to make one.

 

Even more telling is the fact that the power produced at those settings agrees with Allison's limitations.  Both list 1000hp as the Maximum continuous setting.  It would be an aviation first and complete outlier for the RAF to violate convention on such a large scale contract.

 

Manifold pressure gauges in RAF Mustangs were made in USA, they didn't change them for RAF gauges. RAF manifold pressure gauges were using lb/sq.in. (pound-force per square inch), not inches of mercury.

 

As to "both list 1000hp as the Maximum continuous setting" - yes, on some power charts is 38.5 in Hg/ 2600 rpm rated 1000 hp. On some other power charts, 37.2 in Hg/ 2600 rpm is also rated 1000 hp. Power charts were revised from time to time, just like the limits of engine. But if you use only one power chart and check power rating of 38.5 in Hg/ 2600 rpm and 37.2 in Hg/ 2600 rpm, the results can not be the same.

 

Here is Power Control Chart from RAF Mustang manual -

 

post-13312-0-42323400-1471165811_thumb.jpg

 

 

 

 

Maximum Cruising/Auto Lean  (Max. Weak Continuous in UK) : ALD-3F2 - 28.2 in Hg/ 2280 rpm ( no time limit ) vs RAF manual - 30.5 in Hg/ 2300 rpm ( no time limit ) - RAF limit HIGHER.

 

Who cares?

 

This is not part of the Type Certificate that is mandatory.

...

Walk into any airport pilot lounge and ask about best cruise practices and you will start a discussion.  Even in aircraft as highly regulated as the Airlines, there are many techniques for best cruise practices.

 

I think you missed very important point - this is maximum limit for engine running with Auto Lean mixture. There are many techniques for best cruise practices, but you can't do what you want. If you go over manifold pressure limit for lean mixture, you can hurt engine very quickly - since engine will run on too lean mixture, detonations appear.

 

 

 

Of course they had to warn against use of such high Manifold pressure, it is pretty dangerous thing to do. As far as I'm concerned, it is like playing "Russian roulette". I am talking about 60 in Hg or more with V-1710-39 (- F3R).

 

 

Exactly.  You do understand that you cannot sit a sea level and get 60"Hg or more out of an Allison V 1710F3R engine?  You can only get that under certain atmospheric conditions of rammed flight with a load on the propeller.

 

Critical altitude for 60 inHg/3000 rpm without ram for all V-1710s with 9-1/2 inches impeler and 8.80:1 Supercharger gear ratio is 2500 ft . So you CAN sit at sea level and get 60"Hg or more out of an Allison V-1710-F3R engine. Well, theoretically - sitting on ground will not provide sufficient cooling at this MAP. That's why i don't get your point, why would anyone want to just sit on the ground and use 60 inHg or more? It makes no sense.

 

 

 

This picture is stupid, sorry. "Allison Time Bomb" is nickname from Lightning pilots flying in European Theater of Operations, nobody else used this nickname. Why is P-40 on this picture is a mystery to me, Allison engines in P-40s (well, at least from P-40D) were pretty reliable.

 

Certainly they were reliable when operated within their limitations.   The Allison was a good engine and many aviators in World War II owe their life to it.

 

I tend to think the reputation developed in part due to such practices as overboosting the engine when atmospheric and flight conditions permitted.

...

BTW, Allison could have blamed the "Allison Time bomb" on US serviceman not following the Limitations.  I think that contribute to the engine's reputation.  The Government would have had a very hard time proving it did not contribute.

...

So Allison gave up a lot businesswise in writing that memo and standing by our serviceman.

 

There was only one major crisis with Allisons during WWII, (in)famous "Allison Time bomb" crisis. What happened ?

 

P-38 in Europe at the end of November 1943 changed tactics and began to fly escorts at high altitude (typically 30 000ft). Immediately problems with the engines appeared. Lockheed and Allison investigate the matter and discovered that the engines in these altitudes are not working well.

 

The failures generally occurred during the high power runs and involved some form of piston failure, sometimes followed by thrown rods. They determined that the failures were due to extended low power cruise at low temperatures, which allowed the engines to get very cold. This caused difficulty with vaporization of the fuel, and resulted in poor fuel distribution and fouledspark plugs. The sudden increase to high power would initiate detonation and lead to failures.

 

Allison and Lockheed engineers resolved these problems with interim improvements in the F17R/L. Allison responded with two design changes, the first was to fit the “Madam Queen” air intake pipe, which incorporated a “boost venturi” to revaporize any condensed fuel. This feature was eventually retrofit onto most V-1710s around the world during the war. The second was the “Keystone” piston compression ring.

 

To be fair, this wasn't the only reason for the crisis -

 

The crisis in confidence that developed in England resulted in Lockheed Engineering Test Pilot Tony Le Vier making a visit to England (January-May 1944) for testing and demonstrating some of the new improvements in the P-38J aircraft. Immediately upon arrival he found a pretty grim situation in some operating units; they had new P-38Js, but they had no training or operational information on the airplane and its engines. In particular, he noted a lack of information concerning correct power combinations that was appalling.

 

“For combat missions some fellows were using anywhere from 2000 to 3000 rpm with whatever manifold pressure that would give them their desired air speed. Some were blowing up their engines with high manifold pressure and critically low rpm, while others were running out of gas and failing to complete missions because of such power combinations for continual cruise as 2800 rpm with 24”Hg. Many returned with hardly more than a cupful of gas remaining in their tanks, while others wereforced to bail out over enemy territory.”

“The reason they were cruising at 2600, 2800, and even 3000 rpm was that somewhere along the line they had been taught to use high rpm and low manifold pressure. They were under the impression that should they be jumped by a Jerry they could get their power faster if they already had it at high rpm.”

“The fact is you can get your power quicker if you have a low rpm and a high boost which gives you a higher turbo speed. With the turbo already putting out you have only to increase your (engine) rpm to get your desired power.”

 

Tony gave them a new rule of thumb appropriate to cruising on a lean mixture, increasing their range considerably. Many pilots were soon returning from missions with as much as 150 to 200 gallons of fuel remaining. A benefit of the new strategy was that by keeping boost high the air temperature entering the carburetor was also higher, which improved mixture distribution and smoothed engine operation.

 

So yes, USAAF pilots played a role in the crisis as well.

 

There were also other factors, for full "Allison Time Bomb" story see article "The Allison Time Bomb By Daniel D. Whitney" in "Torque Meter" Volume 1, Number 2 (Journal of the Aircraft Engine Historical Society). Parts of this post in italics are directly from this article. Here is link for those interested, It costs $8.00 - http://www.enginehistory.org/sales.shtml

 

My point? "Allison Time Bomb" crisis was not caused by overboosting. And since this crisis happened in winter 1943-44, Allison memo dated December 1942 has obviously nothing to do with "Allison Time Bomb".

 

 

 

For example, there was a V 1710 F series that was approved for 60"Hg at the time.

 

350ny8j.jpg

 

It just wasn't F series engine found in the P-40E.   You have to wonder if all this 60"Hg just wasn't a maintenance error in ordering the wrong carburetor linkage rods.  The rods would fit on F series engine are a preset length.

 

It's simple - V-1710-F4R (-73) was physically stronger than -F3R (-39) engine, which is the only reason for higher MAP limit for -F4R.

 

 

 

Documents Documents discord.)) And here is the engine that in 1941, that in 1943, that in 1945 the same. 

TO on Allison engines of 1945 for P-39 aircraft.

post-2090-0-68628700-1470818803_thumb.jp

Motor -35 (E4) = motor -39 (F3R). 

1550 hp = 3000х60".))

 

There is no point in denying the obvious. Even if the obvious was recorded later. From the letter characteristics do not change.

 

This is very interesting, I have never seen such limit for V-1710-35 (-E4). It is indeed 60 inHg/3000 rpm, which wasn't authorized for this engine in USAAF use. So, here is my question - can this limit be confirmed from second source? It can be error, typo.

 

 

Next question is will they or can they model the closed manifold system and allow an ultimate manifold pressure of 56"Hg under an appropriate airload?  The 56"Hg is what the Type Certificate says the engine is approved as the ultimate manifold pressure.

 

Developer already did this, at least find out what are the limits in the game and how the engine works there.

 

Limits directly from the game, P-40E specifications -

 

Nominal (unlimited time) - 2600 rpm, 37.2 inHg

Combat power (up to 5 minutes) - 3000 rpm, 42 inHg

Take-off power (up to 2 minutes) - 3000 rpm, 45.5 inHg

Maximum possible power (prohibited by flight manual) - 3000 rpm, 56 inHg

 

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

 

Later, i will post my point of view on engine in game, I've had enough of writing for now.

 

Edit: 9-1/5 inches impeler to 9-1/2 inches impeler.

Edited by Farky
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There were also other factors, for full "Allison Time Bomb" story see article "The Allison Time Bomb By Daniel D. Whitney" in "Torque Meter" Volume 1, Number 2 (Journal of the Aircraft Engine Historical Society). Parts of this post in italics are directly from this article. Here is link for those interested, It costs $8.00 - http://www.enginehistory.org/sales.shtml

 

 

Excellent post and for interested parties who have not read my previous posts, let me reiterate that Mr. Whitney is a world authority on the subject of Allison engines.

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Here is my opinion on Allison V-1710-39 in game ...

 

Oil pressure.

It's constantly out off the limits, which annoys me. It has no real function, it's just there. Fix should be quick and easy.

 

Temperatures of oil an coolant.

Temperatures are way too low. For example according to the RAF test date for Temperate Summer Conditions , in climb on 145 mph IAS with radiator full open temperature of oil should be at 20 000 ft around 85°C, coolant temperature at least 100°C. In BOM on Stalingrad Summer map, you overcool engine before you reach 20 000 ft (coolant temperature ...I don't know ... 0°C, oil barely 30°C). You need fully closed radiator (or almost closed) to maintain temperatures in "green". For 99% of time in game, you can set radiator on Neutral and you'll be fine.

 

Time limits.

The problem is that the time limits in the manuals are often understood incorrectly. 5 minutes limit doesn't mean that after this time you're starting to overload the engine and you will soon destroy it. What USAF manuals say about the time limits -

 

"A time limit as given in Section III ( = power tables and power charts - Farky) is necessary for operation at any power above normal rated power to keep the coolant and oil temperatures within operating limit and prevent failure of the engine".

 

I don't like hard coded time limits (at all), but I think they can work pretty well. However, they must by connected with temperature limits. In other words, exceeding  of time limit should be accompanied by exceeding  of temperature limit(s). This leads us to the next point ...

 

Warnings.

The engine should warn the pilot that he harms him. In real world, when something is wrong, it will usually appear on instruments. Pilots using engine modes with time limits were monitoring temperatures and pressures on instruments, not stopwatches like we do. Engine failures are happening without warning and this is not correct.

 

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Engine modes ( specifications from game).

 

Nominal ( unlimited time): 2600 rpm, 37.2"Hg ( 1000hp/10 800ft ).

Actual MAP limit is 39.5"Hg, 40"Hg triggers Combat power mode. No problem.

 

Combat power ( up to 5 minutes) :  3000 rpm, 42"Hg (1150hp/12 000ft ).

Actual MAP limit is 43.5"Hg, 44"Hg triggers Emergency power mode. I know that V-1710-39 was cleared for 15 minutes at 44.2"Hg/3000 rpm, but it didn't happened until late 1943 or even 1944. I don't know why, so I will be conservative here. 42"Hg can be used much longer than 5 minutes, so this mode work for me just fine.

 

Take off power ( up to 2 minutes) : 3000 rpm, 45.5"Hg (1150hp/S.L.).

Time limit is actually 3 minutes +, not 2 minutes. I will rather have 46.2"Hg/2800rpm (5 minutes), but this is ok.

 

Maximum possible power ( prohibited by flight manual ) : 3000 rpm, 56.0"Hg (1470hp/S.L.).

V-1710-39 was at the end of 1942 approved for 56"Hg/3000 rpm (5 minutes limit), we all know that. This was permitted only if automatic MAP regulator was installed, we know that too. From technical perspective, automatic MAP regulator doesn't matter, as long as you don't exceed the limit. It really doesn't matter who moves the throttle, automatic device is just more precise and definitely safer.

 

56"Hg MAP was overload for engine and for cooling system. Temperatures should be IMHO very high, close to maximum limits even in fast level flight in standard atmosphere with radiator almost fully opened. It should be possible use 56"Hg/3000 rpm for at least 5 minutes in this situation, but every maneuver should decrease time (increase the temperatures ), a lot.

 

Term " Maximum possible power" frightens me. I hope this doesn't mean that 56"Hg/3000 rpm at sea level is really maximum possible power in game, I really hope. I cannot check this, since we have MAP gauges limited to 50"Hg. Real maximum possible power of V-1710-39 at sea level and 3000 rpm on full throttle was approximately 1750 hp, 66"Hg. Without ram. I know what Allison memo dated December 1942 says -

 

"... on the average engine 66" boost is approximately 1745 B.H.P. at sea level or 1770 H.P. at 2000 feet and can only by obtained either under ramming flight conditions at 3000 R.P.M. or by overreving the engine it can be obtained to considerably higher altitudes."

 

I am sure, that "can only by obtained either under ramming flight conditions at 3000 R.P.M." applies only to 2000 ft altitude, not on sea level. 66"Hg/3000rpm/S.L was absolute performance limit of V-1710-39, that's what I'm saying.

 

Unfortunately I do not have convenient power chart  for V-1710-39, but it does not matter, I can show this on power charts for V-1710-35 (-E4) and V-1710-63 (-E6).

Before anyone starts writing "you cannot use power chart of different engine for -39" - please, do some research first, they were exactly the same in terms of performance.

 

post-13312-0-34622100-1471443435_thumb.jpg

 

post-13312-0-85831100-1471443444_thumb.jpg

 

Critical altitude ( Full Throttle Height) for 56"Hg/3000 rpm without ram was 4300 ft (Whitney's "Vee's for victory", page 162). Let's add some 2200 ft for ramming flight conditions. So, our safe (within maximum MAP limit) altitude for full throttle at 3000 rpm should by 6500 ft and higher. This is important, because our MAP gage ends at 50"Hg (historically correct IMHO).

 

56"Hg/3000 rpm was ultimate safe limit for V-1710-39 and there wasn't margin of safety. There are two major factors for engine limits. First is "knock rating" of the fuel or detonation characteristics of engine. We know (from Allison memo), that even more than 60"Hg was ok with regard to detonation point. It doesn't mean that P-40E pilots never run into detonations, it depends on many inputs. However, this wasn't limiting factor for this engine. Second limiting factor is strenght of the engine structure or mechanical limitations. In case of V-1710-39 was limiting factor structural strenght. Everything over this limit (56"Hg/3000 rpm) was very dangerous and it was pure gamble.

 

We know from various sources about pilots using 60" or even 70"Hg and survived to tell the tale. However, this reports are very rare and they  usually lacking some important informations. We usually don't know if they were running with overheated engine (probably yes). We don't know how frequent it was and how many pilots ruin their engines when they try this. We usually don't for how long they use this brutal overboost. And unfortunately, we will never know. It's gray zone and we should be very careful with this.

 

Should it be possible in the game? I'm a little bit split here. From a technical point of view - it was technically possible, so answer is yes. But it must be tremendous risk and uncertainty. I think some kind of a "dice roll" can do the job. Big question here are coolant and oil temperatures. From a historical perspective - no. Why not? Because players will immediately take advantage of it and honestly, I think that 56"Hg is already on the edge of historical accuracy. And as I see it, it would not be fair to other airplanes. But I don't know, I am really split here.

 

I would like to see more sophisticated simulation of engines with limits based on temperatures and other factors (for example backfires), but I understand that resources available to developers are limited.

 

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Thanks again for a well written and informative post.

 

WRT mechanical stresses, I'd like to add two things.

First, overloads in engines of WW2 weren't generally limited to static problems. This means that not only did the pure load generated by the torque matter (boost related), but also harmonic frequencies (rpm related) of the components. Some rpm settings would therefore be much more critical than others, and would lead to engine damage at lower boosts that others.

Second, one of the limiting components of the Allison were the propeller reduction gears. In particular early versions were structurally weak and proved to be a source of trouble. Normally, by the nature of gear teeth contact, only extreme overloads will lead to instant damage (ripping teeth off), but even moderate overloads will lead to short time damage (insufficient lubrication, contact fatigue, excessive wear, metal chips).

Edited by JtD

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It's simple - V-1710-F4R (-73) was physically stronger than -F3R (-39) engine, which is the only reason for higher MAP limit for -F4R.

 

To clarify, I wasn't talking about the V-1710F4R but referring to the V-1710F3R.

 

 

 

You have to wonder if all this 60"Hg just wasn't a maintenance error in ordering the wrong carburetor linkage rods.  The rods would fit on F series engine are a preset length.  
 

 

Refers to the anecdotal evidence presented here.  60"Hg was never approved by anyone for the V-1710F3R engine.  

 

 

 

Combat report of Sgt. Butler (75. sqn. RAAF), 25th April 1942, Kittyhawk A29-48 ( ex-USAAF P-40E 41-5535) -
 

 

If you understand the details of adjusting the manifold pressure, it would be very easy to install the wrong preset length rods.   Would not be the first time the wrong part has been installed in aviation or the wrong instructions followed.

 

 

 

Critical altitude for 60 inHg/3000 rpm without ram for all V-1710s with 9-1/5 inches impeler and 8.80:1 Supercharger gear ratio is 2500 ft . So you CAN sit at sea level and get 60"Hg or more out of an Allison V-1710-F3R engine. Well, theoretically - sitting on ground will not provide sufficient cooling at this MAP. That's why i don't get your point, why would anyone want to just sit on the ground and use 60 inHg or more? It makes no sense.

 

You are talking about the V1710F4R which WAS approved for 60"Hg and I am talking about the V-1710F3R engine which was never approved for 60"Hg.

 

In a V-1710F3R engine adjusted for 56"Hg, you cannot get 60"Hg manifold pressure out of it under static conditions on a standard day.  You could run it all day long and it will not get 60"Hg...end of story.  

 

If it was adjust for the 52"Hg without a MAP, then you will only get 52"Hg static conditions on a standard day.  There must be an airload on the propeller, rammed air, or al lower density altitude.  Something must change the relationship in the real gas laws in order to see that manifold pressure change under static conditions.

 

That is the nature of a closed manifold pressure system and the point I made to you.

 

 

 

I don't like hard coded time limits (at all), but I think they can work pretty well. However, they must by connected with temperature limits. In other words, exceeding  of time limit should be accompanied by exceeding  of temperature limit(s).

 

Really, these are not connected in this game?  How do you manage the engine?

 

LOL, it is like the time I played CloD.  Asked a guy on Teamspeak what's the best climb setting on the Spitfire MkIa and he gave me some meaningless percentage instead of RPM, Manifold Pressure, and airspeed to hold. 

 

 

 

 

Unfortunately I do not have convenient power chart  for V-1710-39, but it does not matter, I can show this on power charts for V-1710-35 (-E4) and V-1710-63 (-E6).

 

It most certainly absolutely does matter and is not applicable to a V-1710F3R installed on the P-40E. 

 

 

 

 Real maximum possible power of V-1710-39 at sea level and 3000 rpm on full throttle was approximately 1750 hp, 66"Hg. Without ram. I know what Allison memo dated December 1942 says -

 

"... on the average engine 66" boost is approximately 1745 B.H.P. at sea level or 1770 H.P. at 2000 feet and can only by obtained either under ramming flight conditions at 3000 R.P.M. or by overreving the engine it can be obtained to considerably higher altitudes."

 

I am sure, that "can only by obtained either under ramming flight conditions at 3000 R.P.M." applies only to 2000 ft altitude, not on sea level. 66"Hg/3000rpm/S.L was absolute performance limit of V-1710-39, that's what I'm saying. what I'm saying.

 

 

66"Hg is overboosting the engine because pilots were not pulling the manifold pressure back on a closed manifold system and Allison wrote the memo to tell those who did it to stop it.  It cannot be achieve under static conditions by any V-1710F3R engine.

 

The memo puts the power production in terms the mechanics and pilots can understand by converting it to equivalent power at sea level to illustrate the degree of overboosting to emphasize the stress being placed on the engine.

 

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What components of the engine were changed to allow for the increase in manifold pressure?

 

A control rod movement of 2" will be still 2" whether the rod is 7" or 8" long unless something else has been changed.

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