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

[Crump]

But airplanes do not work nor are they flown like that Venturi.  

 

Even If you shove the throttle forward, it only goes to the stops.  Those are set IAW the Operating Limitations.   Unless those stops are physically moved it is not going to give you anything more.....

 

The limits of the P-40E's Allison V-1710-39(F3R) are clear in April 1943 at 56"Hg.  The V-1710-F4R which is a different engine was cleared to 60" at that time but not the engine found in the P-40E.

 

Unlike the rare extraordinary tales...the reality is most combatants who rely upon the combat fairey die as a result.  It is just not reality, experience, or engineering physics to think otherwise.

 

Look at from the perspective of all those who died as a result of the Allison time bomb and why did it get that name??

[Dakpilot]

How do we know what boost we get in game? at about 82% throttle you have exceeded the  aircraft MP gauges range at 50"hg maximum and can achieve a handy nearly 450kmh at 300m, this from level flight cruise, before warning of emergency power time exceeded

 

Cheers Dakpilot

[Venturi]

Again, Crump, I beg to disagree. It is interesting to note your statement also contradicts the letter shown earlier.

 

Your comments make it very plain you have little to no experience with boosted a/c engines nor their components.

 

Are you telling me that the same throttle setting for max boost at sea level gives the same max boost at crit alt?

 

Think about your answer carefully.

 

But airplanes do not work nor are they flown like that Venturi.

 

Even If you shove the throttle forward, it only goes to the stops. Those are set IAW the Operating Limitations. Unless those stops are physically moved it is not going to give you anything more.....

 

The limits of the P-40E's Allison V-1710-39(F3R) are clear in April 1943 at 56"Hg. The V-1710-F4R which is a different engine was cleared to 60" at that time but not the engine found in the P-40E.

 

Unlike the rare extraordinary tales...the reality is most combatants who rely upon the combat fairey die as a result. It is just not reality, experience, or engineering physics to think otherwise.

 

Look at from the perspective of all those who died as a result of the Allison time bomb and why did it get that name??

Edited March 23, 2016 by Venturi

[Venturi]

In reality the needle should be able to move past the 50" mark.

 

 

How do we know what boost we get in game? at about 82% throttle you have exceeded the aircraft MP gauges range at 50"hg maximum and can achieve a handy nearly 450kmh at 300m, this from level flight cruise, before warning of emergency power time exceeded

 

Cheers Dakpilot

[=362nd_FS=RoflSeal]

P-40E hasn't got throttle stops since it has no automatic boost control fitted as standard.

 

If throttle doesn't change, boost changes with altitude and speed.

[Venturi]

Bingo

 

P-40E hasn't got throttle stops since it has no automatic boost control fitted as standard.

 

If throttle doesn't change, boost changes with altitude and speed.

[=362nd_FS=RoflSeal]

Bingo

 

Yeah its not like the P-51D/Spitfire IX where you can put the throttle up to the wire and the mechanical systems will keep engine boost to 61" whether you are at 140mph, 400mph,15,000ft or 500ft. (there are limits obviously)

 

Or ingame comparison: every other fighter.

 

Dive in the P-40E without the throttle pulled back and you increase MP so much engine will detonate.

Edited March 23, 2016 by RoflSeal

[Venturi]

And this is why the letter mentions differing environmental and "ramming" effects that were utilized to achieve certain levels of boost. Because in reality the only limits on boost from the supercharger in the Allison/P40e were from the limits of mechanical boosting ability (again crit altitude is 15k ft, 4,4km) and from the environmental factors such as temp, alt, airspeed (ram effect).

 

At sea level full throttle would have produced a vet high boost level. Which if one was unaware of, could kaboom the engine. Obviously it was discovered incidentally that Allison was over conservative (again, the chief engineer more or less admits this in his letter) and smart pilots used the higher performance. Given the Soviet usage of a/c in general, which was to wring every last bit of performance from them, I have NO DOUBT that they also used them in this way. More germanely, the P40 was ALWAYS, AT ALL TIMES capable of over posting by nature of its design.

 

To arbitrarily limit the engine to some conservative MP value specified by the manufacturer (who, again, STATES they are being conservative) is simply being penny wise and pound foolish.

[6./ZG26_Klaus_Mann]

How do we know what boost we get in game? at about 82% throttle you have exceeded the  aircraft MP gauges range at 50"hg maximum and can achieve a handy nearly 450kmh at 300m, this from level flight cruise, before warning of emergency power time exceeded

 

Cheers Dakpilot

This would indicate 70".

 

Anyways, completely different but related question. 

From the Wiki for the F-series. 

"Supercharger gear ratios were: 6.44:1, 7.48:1, 8.10:1, 8.80:1 and 9.60:1"

Were these freely interchangeable between engines of the 39 series, or do the different series indicate these Superchargers?

If the later was the case, what'S the gearing for the -39?

If they were freely interchangeable, the higher gears would be quite destructive when running 70" at Sea Level. I would hazard a guess at all due to preignition. 

[=362nd_FS=RoflSeal]

Not interchangeable. F3R (used on P-40E, P-51), F4R (P-40K/P-51A) used 8.8, F20R used 9.6 (P-40M/N, P-51A), F21R was 7.48 (A-36 Apache) off the top of my head

[Venturi]

Not interchangeable. F3R (used on P-40E, P-51), F4R (P-40K/P-51A) used 8.8, F20R used 9.6 (P-40M/N, P-51A), F21R was 7.48 (A-36 Apache) off the top of my head

The gearing is directly proportional to the level of boost generated at any given altitude.

 

There is a design decision made on this based on the desired critical altitude of the supercharger. A higher gearing will produce a higher crit altitude but at a cost of more parasitic drag and power loss at lower altitudes where it is producing excess manifold pressure. Obviously if one did not have a blow off valve or no limiter for the excess pressure, as in the case for the P40e, then a higher supercharger gearing combined with lower altitude could produce a very high manifold pressure.

 

In this case it would be incumbent on the pilots to determine what throttle setting and manifold pressure was needed because the PILOT is the MP limiter, so to speak. If, as in the case of the P40e, there was discovered that a certain amount of the excess pressure was safe, then it could be easily utilized for more power.

 

Obviously with a two-stage supercharger (later Merlins, BMW801, etc) or variable gearing (db601/605) you get two or more gearing choices, so can fine tune the crit alt and trade offs for each gearing.

Edited March 23, 2016 by Venturi

[Dakpilot]

Why do you keep saying that the P-40 is restricted to "about'' 50"hg's ? not talking about time limits here

 

The fact that we are arbitrarily limited to "WEP" settings of 50 something just shows that the modeling of the single stage supercharger is quite off. 

 

 

When you push past the 50"hg at SL and use the extra 15%+ of throttle available there is a significant performance increase, certainly seems more than you are saying. The MP gauge may not show it because it cannot read past 50, but you can certainly feel it and note a large speed increase

 

 

Cheers Dakpilot

[Venturi]

That 15% of throttle may be 56", or less, or more. It certainly doesn't seem like an extra 300-400hp.

 

Why do you keep saying that the P-40 is restricted to "about'' 50"hg's ? not talking about time limits here

 

 

 

When you push past the 50"hg at SL and use the extra 15%+ of throttle available there is a significant performance increase, certainly seems more than you are saying. The MP gauge may not show it because it cannot read past 50, but you can certainly feel it and note a large speed increase

 

 

Cheers Dakpilot

[Venturi]

The reality is that the cause and effect you have posted is backwards, here. The mp level is based primarily FROM the supercharger gearing and the altitude.

 

Preignition is a problem, this is the cause of destruction of these engines at high boost levels. Correct octane fuel can eliminate pre ignition/detonation in part or totally depending on boost level, ambient temp, engine temp, engine specific compression ratio, etc.

 

This is the mechanism by which MW50 operated to allow more boost (effectively an octane-booster).

 

Obviously the Allisons were capable of higher MPs than nominal but not indefinitely and not without limits. Obviously there was an element of "Allison time bomb" here. My opinion, it is due to the fact that the PILOT was the MP regulator. Just from what you can see in this thread (and from what I have observed from other, REAL pilots attitude towards engines), it should become obvious that the concept is not simple to grasp for everyone. It seems to follow that pilots who were trained in other a/c may have simply pushed the throttle full forward thinking this was nominal, when in reality they needed to adjust throttle position based on MP. Everything is fine for a time, then "boom". Obviously it was THE ENGINES FAULT, right?

 

This would indicate 70".

 

Anyways, completely different but related question.

From the Wiki for the F-series.

"Supercharger gear ratios were: 6.44:1, 7.48:1, 8.10:1, 8.80:1 and 9.60:1"

Were these freely interchangeable between engines of the 39 series, or do the different series indicate these Superchargers?

If the later was the case, what'S the gearing for the -39?

If they were freely interchangeable, the higher gears would be quite destructive when running 70" at Sea Level. I would hazard a guess at all due to preignition.

 

Edited March 23, 2016 by Venturi

[6./ZG26_Klaus_Mann]

The reality is that the cause and effect you have posted is backwards, here. The mp level is based primarily FROM the supercharger gearing and the altitude.

 

Preignition is a problem, this is the cause of destruction of these engines at high boost levels. Correct octane fuel can eliminate pre ignition/detonation in part or totally depending on boost level, ambient temp, engine temp, engine specific compression ratio, etc.

 

This is the mechanism by which MW50 operated to allow more boost (effectively an octane-booster).

 

Obviously the Allisons were capable of higher MPs than nominal but not indefinitely and not without limits.

 

An early G-2 with 1.42 ata could best case achieve about 560 with 1475PS. 

The P-40 has roughly  at 56" has roughly 1450hp, more drag and weight but ingame has no trouble breaking 580kph. 

It is therefore quite reasonable to assume 70+"

[Venturi]

Really, it's faster than a G2? Not my observation. In any case should be ok for higher time at power.

 

An early G-2 with 1.42 ata could best case achieve about 560 with 1475PS.

The P-40 has roughly at 56" has roughly 1450hp, more drag and weight but ingame has no trouble breaking 580kph.

It is therefore quite reasonable to assume 70+"

Edited March 23, 2016 by Venturi

[Matt]

 

 

That 15% of throttle may be 56", or less, or more. It certainly doesn't seem like an extra 300-400hp.

 

Those 15% throttle give a speed increase of around 60 km/h.

[Venturi]

How long before kaboom?

 

Those 15% throttle give a speed increase of around 60 km/h.

[Dakpilot]

That 15% of throttle may be 56", or less, or more. It certainly doesn't seem like an extra 300-400hp.

 

 

Surely it cannot be that hard to find what speeds Western P-40's were getting at certain MP levels?

 

See, now you are being more reasonable, going from " The fact that we are arbitrarily limited to "WEP" settings of 50 something"  to "It certainly doesn't seem like" is a far better argueing point 

 

Cheers Dakpilot

[Venturi]

I respond well to reasonable people.

 

Surely it cannot be that hard to find what speeds Western P-40's were getting at certain MP levels?

 

See, now you are being more reasonable, going from " The fact that we are arbitrarily limited to "WEP" settings of 50 something"  to "It certainly doesn't seem like" is a far better argueing point 

 

Cheers Dakpilot

[Matt]

How long before kaboom?

Around 60-90 seconds before engine damage, probably another minute before the engine stops running completely.

 

In any case, for that time, it's faster than anything else in BoS/BoM, so yes, i would assume 100% throttle means about 70" at low altitude.

[Venturi]

Alright, so 1 minute doesn't seem like enough time given the multiple accounts here. Although certainly the engines couldn't run indefinitely a more appropriate time would be 5min + a variable factor, say 5 + 1-10 min. In fact this variable factor added to a "constant" time limit would be beneficial to all engine modeling in game

 

Around 60-90 seconds before engine damage, probably another minute before the engine stops running completely.

 

In any case, for that time, it's faster than anything else in BoS/BoM, so yes, i would assume 100% throttle means about 70" at low altitude.

Edited March 23, 2016 by Venturi

[=362nd_FS=RoflSeal]

Surely it cannot be that hard to find what speeds Western P-40's were getting at certain MP levels?

 

See, now you are being more reasonable, going from " The fact that we are arbitrarily limited to "WEP" settings of 50 something"  to "It certainly doesn't seem like" is a far better argueing point 

 

Cheers Dakpilot

Only up to 44" you see tests being done on P-40E, though on Mustang Mk I they do speed tests at 56" with the F3R

[Matt]

Alright, so 1 minute doesn't seem like enough time given the multiple accounts here. Although certainly the engines couldn't run indefinitely a more appropriate time would be 5min + a variable factor

Sure, but the devs decided to stick to time limits based in pilot instructions of that period, so unless someone can find a x amount of time for 70 "hg in a pilot handbook or the devs change their opinion about this, i don't see this changing.

[6./ZG26_Klaus_Mann]

I get 150 Seconds of Full Throttle easily and 585 kph at Sea Level. SO it's defintely around 70"

I think keeping that at 2 Minutes is definetly reasonable as long as we at some point get 56 for 5 Minutes and 45" for 15 Minutes. 

Edited March 23, 2016 by 6./ZG26_Klaus_Mann

[Venturi]

I get 150 Seconds of Full Throttle easily and 585 kph at Sea Level. SO it's defintely around 70"

I think keeping that at 2 Minutes is definetly reasonable as long as we at some point get 56 for 5 Minutes and 45" for 15 Minutes.

 

Still think that longer but variable periods of time are the ticket. No one says "time at power is 5 mins, and then kaboom". What they say is "SAFE time at power is 5mins, then it's danger". In Allisons case they were very conservative and the letter clearly states 60" WEP. How long is WEP cleared for in the manual? 5min, right?

[6./ZG26_Klaus_Mann]

Still think that longer but variable periods of time are the ticket. No one says "time at power is 5 mins, and then kaboom". What they say is "SAFE time at power is 5mins, then it's danger". In Allisons case they were very conservative and the letter clearly states 60" WEP. How long is WEP cleared for in the manual? 5min, right?

In the Context of the game I'm ok with 56" for 5 and 2 Minutes above that. 

I'm mainly interested in increasing time limits for the take-off/climb/mlitary power rating of 44-45"@3000rpm to 15+5 Minutes. 

[Venturi]

What are the current time limits at each setting?

 

In the Context of the game I'm ok with 56" for 5 and 2 Minutes above that.

I'm mainly interested in increasing time limits for the take-off/climb/mlitary power rating of 44-45"@3000rpm to 15+5 Minutes.

 

Edited March 23, 2016 by Venturi

[6./ZG26_Klaus_Mann]

What are the current time limits at each setting?

 

Look in the OP. 

[Venturi]

So just to recap for the audience

 

Right now:

Full WEP (assuming 70") is 2-3min

45" is 3-4min

----

Seems to me based on evidence all around,

full WEP should be 5min

45" should be 15min

 

Those values seem conservative and they line up with the documented sources

 

 

 

Look in the OP.

 

Edited March 23, 2016 by Venturi

[6./ZG26_Klaus_Mann]

So just to recap for the audience

 

Right now:

Full WEP (assuming 70") is 2-3min

45" is 3-4min

----

Seems to me based on evidence all around,

full WEP should be 5min

45" should be 15min

 

Those values seem conservative and they line up with the documented sources

 

 

 

As a compromise for the BoM I would like the 70" to remain at 2 Minutes, but introduce 56" as  the 5 Minute Emergency Mode, similar to the 109s which normally have a 1 Minute and a 5 Minute Emergency (1.42 and 1.3 for the E-7 for example) and a 45"@3000 5+15 Minutes semi recoverable setting as Military+Take-Off Setting in which you can ever so often recover the 15 Minutes, maybe after 30 Minutes at Continuous or so.

Edited March 23, 2016 by 6./ZG26_Klaus_Mann

[Crump]

P-40E hasn't got throttle stops since it has no automatic boost control fitted as standard.

 

If throttle doesn't change, boost changes with altitude and speed.

 

 

It does have throttle stops.....all engines that are not FADEC designs have them.   In the USAAF Squadron discussed in the Allison memo the mechanics had adjusted the cable and moved the stop locations to achieve 70"Hg. 

[LukeFF]

 

 

The V-1710-F4R which is a different engine was cleared to 60" at that time but not the engine found in the P-40E.

 

Please re-read that letter from Allison. 

[Crump]

 

 

Please re-read that letter from Allison. 

 

I have readi it several times and have a copy of my own.  It is a letter and not a Technical Order or Operating Instructions.

 

 

In other words it is not a legal instrument that either a pilot or a mechanic use to determine their authorized operating limitations.  It is also dated December 1942.

 

The April 1943 Allison Engine operating instruction supercede anything before that date and are clear in the fact the V-1710-39 (F3R) engine as found in the P-40E was only authorized 56"Hg manifold pressure at it highest limit.

[Venturi]

LOL, you're really something. In the real world people do things that aren't found in SOP. Sometimes they even work.

 

I have readi it several times and have a copy of my own.  It is a letter and not a Technical Order or Operating Instructions.

 

 

In other words it is not a legal instrument that either a pilot or a mechanic use to determine their authorized operating limitations.  It is also dated December 1942.

 

The April 1943 Allison Engine operating instruction supercede anything before that date and are clear in the fact the V-1710-39 (F3R) engine as found in the P-40E was only authorized 56"Hg manifold pressure at it highest limit.

[=362nd_FS=RoflSeal]

Oh they can definitely put a throttle stop, but since there is no regulator that throttle setting will only hit 56" at a certain speed and certain altitude band. Above that speed and below that altitude it will exceed it, below that speed and above that altitude it will be below it, not exactly ideal if you still have throttle left to increase, but it is blocked.

Edited March 24, 2016 by RoflSeal

[Venturi]

Lol, what does "full authority digital engine controls" have to do with WWII aircraft?

 

TROLL alert

 

 

It does have throttle stops.....all engines that are not FADEC designs have them.   In the USAAF Squadron discussed in the Allison memo the mechanics had adjusted the cable and moved the stop locations to achieve 70"Hg.

 

[=362nd_FS=RoflSeal]

Lol, what does "full authority digital engine controls" have to do with WWII aircraft?

 

TROLL alert

 

 

Ayyyyyyyyyyyy lmao just noticed that.

 

P-40E throttle doesn't even have a mechanical regulator nevermind a digital control.

Edited March 24, 2016 by RoflSeal

[Venturi]

No throttle stop in the case in the P40 Allison, or for that matter the bf109e-3, etc etc etc. Blow off was by limiting boost manifold side, not throttle input, in any a/c. "Breaking the wire" refers to increasing throttle/MP set point to WEP in a/c with boost limiters, and not applicable here, not even in same category.

 

Don't let him derail this thread. Everyone knows what's up.

 

Oh they can definitely put a throttle stop, but since there is no regulator that throttle setting will only hit 56" at a certain speed and certain altitude band. Above that speed and below that altitude it will exceed it, below that speed and above that altitude it will be below it, not exactly ideal if you still have throttle left to increase, but it is blocked.

Edited March 24, 2016 by Venturi

[Crump]

 

 

Blow off was by limiting boost manifold side, not throttle input, in any a/c.

 

Crazy how you need both air and fuel to increase power....

 

 

Don't let him derail this thread. Everyone knows what's up

 

I hope they do......