Another 10000 P-36/40 aircraft?

Schweik said:

Allison improved the heat treatment by work-hardening (peening) and tempering the (steel) crank case and crank shaft, and then they coated the bearings with a metal called indium.

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Crankcase was aluminium.

P-39 Expert said:

Wasn't there also an improvement in fuel that allowed the increase from 1150hp to 1325hp?

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Short answer.

The improved fuel allowed the engine to make 1325hp (and a higher WEP) for short periods of time (seconds or a few minutes).
It was the improved materials and heat treatment/processes that allowed the engine to make the higher powers on a more regular basis for longer periods of time without breaking.

ThomasP said:

Hey Schweik,

Thanks for the info - on both metallurgical subjects.

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You are welcome, I thought some folks might find it interesting to see some of the deep roots of this technology, especially in Central Europe.

Sorry for the derail.

Shortround6 said:

Short answer.

The improved fuel allowed the engine to make 1325hp (and a higher WEP) for short periods of time (seconds or a few minutes).
It was the improved materials and heat treatment/processes that allowed the engine to make the higher powers on a more regular basis for longer periods of time without breaking.

Click to expand...

P-40K was rated at 1550 hp and 60" Hg for 5 minutes at sea level for WEP, and
1325 hp and 51" Hg at sea level for takeoff, also for 5 minutes.

That is with a V-1710-73 or an overhauled V-1710-39

My source for that is Shamburger, Page & Christy, Joe. "The Curtiss Hawks". Wolverine Press, 1972. Library of Congress No. 79-173429

wuzak said:

Crankcase was aluminium.

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My bad, corrected.

Shortround6 said:

Short answer.

The improved fuel allowed the engine to make 1325hp (and a higher WEP) for short periods of time (seconds or a few minutes).
It was the improved materials and heat treatment/processes that allowed the engine to make the higher powers on a more regular basis for longer periods of time without breaking.

Click to expand...

As I understand it, the fuel allowed the engine to develop 1325HP at takeoff for 5 minutes without detonation. The strengthening (improved materials and heat treating) were needed for the engine to handle that extra power. Maybe we are saying the same thing.

Schweik said:

P-40K was rated at 1550 hp and 60" Hg for 5 minutes at sea level for WEP, and
1325 hp and 51" Hg at sea level for takeoff, also for 5 minutes.

That is with a V-1710-73 or an overhauled V-1710-39

My source for that is Shamburger, Page & Christy, Joe. "The Curtiss Hawks". Wolverine Press, 1972. Library of Congress No. 79-173429

Click to expand...

You may very well be right on the overhaul. I highlighted the "overhauled" part as the newer crankshafts would drop into the older crankcases,

The fuel may allow the engine to run at those manifold pressures and power levels without detonation.
However the Engines had to pass a type test, which for American engines was at least 150 hours total running time.
10 hours (which could be broken into 120 5 minute segments) at take-off or military power, and 40 hours at "Normal" (Max continuous) or 91% of take-off power, which ever was greater ( they may be some discrepancy here) The engine also had to run at 10 hours in an over speed condition but not making full power, this part of the test could also be run in 120 30-60 second segments.
When WEP ratings showed up the test included 7 1/2 hours at the WEP rating either continuously or in the 5 minute segments.

Sometimes engines were put into production before they past a type test, or sometimes if there was little difference the type test was waived (change of type of magneto?)

What pilots/mechanics did in the field was one thing but the the guys in the supply chain didn't want engines wearing out/breaking before they were supposed to. It turned out that even 20% spare engines was nowhere near enough at times and pushing engines for extra performance meant shorter times between overhauls even if the engine/s didn't fail in flight.

Just like with hot rods and modified motorcycles making more power is seldom a big problem, getting the engine to survive the extra power is where the trouble is.

Yes I don't disagree with you on that. Having read now thousands of pages of pilot interviews and squadron records and memoirs and so on, I get the impression that running any military aircraft engine in WW2, especially in the kind of field conditions you might find in say the Aleutians, or Guadalcanal, or Rangoon, or Darwin, or Tunisia... was an extremely dicey proposition. Even flying from nice grassy fields in England it wasn't unusual for a dozen planes to take off and 3 of them to have to turn around with engine trouble before they even reached a target, let alone pushing into overboosting or wild high G maneuvers. And this included for the so-called 'reliable' planes like P-40s and Wildcats and Hurricanes etc.

And yet we do know they did push the limits, because their life depended on it. Eventually they did it so much that some of the 'field mods' became standardized. It's clear in the early days with the Hurricane and the P-40 the Soviets were burning out engines in a matter of just a few hours of flight time (probably didn't help that many of their aircraft were already clapped out from time in the Middle East or wherever). I think that also happened a lot in Java and the Philippines etc. It wasn't just the pilots who had a steep learning curve, the armorers and mechanics and everyone dealing with maintenance and logistics had incredible challenges to overcome.

Some folks posting here have offered fascinating insights into modern maintenance and performance of Warbird engines for air shows and air-races have seen and themselves participated in producing incredible results. But I don't think every unit was able to get that kind of performance in New Guinea or Egypt, at least not right away. Gradually best practices and tricks and work-arounds were figured out. But it took time.

Clearly some units had some friggin ACE mechanics. Reading through the 79th FG histories, it's incredible the number of captured German and Italian aircraft they were able to get into flying order, and they were not the only ones - RAF 112 and RAAF 3 for example had a bunch of 'pet' enemy aircraft. This implies not only mechanical skill which rivaled what was available back in the home country (some of these captured aircraft were not deemed flyable by the USAAF brass) but also an amazing knack for logistical creativity, no doubt some of it dipping into the black market, to get all the necessary parts and consumables aside from just the fuel.

I suspect the units which were pushing the performance so hard, at least the first ones to do so, were also the ones with the truly gifted mechanics and creative people in the ground crews who figured out how to get the most out of these flying race cars and make them give their pilots that extra performance edge they o badly needed to surive, and to overcome the enemy. I think also that this process was considerably more chaotic, though eventually by and large successful, among the Anglo-American troops (especially US and Australian) than it was with the Germans. I suspect from reading about the Russians that they too had enormous variability in maintenance and production standards, particularly up to say 1943. Those units where you had multiple aces flying LaGG-3, no doubt they got a good batch of planes from the right factory and then also got lucky with their mechanics. The Japanese seemed to struggle to just keep some of their more exotic birds flying but certainly they too worked wonders with the Ki-43s and the A6Ms.

In other words, I think there is a hell of a story to tell, and one we (or at least I) really haven't heard yet, about the field mechanics in the front line units, as well as the ones in the depots further behind the lines, and the (somewhat better known) saga of the engineers and designers and planners back in the home country, about how they pushed these somewhat iffy, twitchy new colts and made them into strong, reliable championship winning race horses.

Shortround6 said:

You may very well be right on the overhaul. I highlighted the "overhauled" part as the newer crankshafts would drop into the older crankcases,

The fuel may allow the engine to run at those manifold pressures and power levels without detonation.
However the Engines had to pass a type test, which for American engines was at least 150 hours total running time.
10 hours (which could be broken into 120 5 minute segments) at take-off or military power, and 40 hours at "Normal" (Max continuous) or 91% of take-off power, which ever was greater ( they may be some discrepancy here) The engine also had to run at 10 hours in an over speed condition but not making full power, this part of the test could also be run in 120 30-60 second segments.
When WEP ratings showed up the test included 7 1/2 hours at the WEP rating either continuously or in the 5 minute segments.

Sometimes engines were put into production before they past a type test, or sometimes if there was little difference the type test was waived (change of type of magneto?)

What pilots/mechanics did in the field was one thing but the the guys in the supply chain didn't want engines wearing out/breaking before they were supposed to. It turned out that even 20% spare engines was nowhere near enough at times and pushing engines for extra performance meant shorter times between overhauls even if the engine/s didn't fail in flight.

Just like with hot rods and modified motorcycles making more power is seldom a big problem, getting the engine to survive the extra power is where the trouble is.

Click to expand...

Just to clarify, the 150 hour test was continuous, right? The segments were just throttle/rpm/mixture changes while the engine was continuously running.

P-39 Expert said:

Just to clarify, the 150 hour test was continuous, right? The segments were just throttle/rpm/mixture changes while the engine was continuously running.

Click to expand...

The test was supposed to be continuous. However a few breaks were often allowed for "minor" repairs or servicing, like changing spark plugs or perhaps a broken valve or valve spring.
Some engines "passed" even though on tear down and inspection small cracks were found in crankcases or cylinder blocks.
Some of this may have depended on how desperate things were at the time. The First Packard Merlin to go through the test needed several repairs to make the 150 hours although it did make 100 hours without too much trouble.

One book I read in my teen years (1950s) told of the many parts the mechanics in the PTO could make from a US copper penny.

special ed said:

One book I read in my teen years (1950s) told of the many parts the mechanics in the PTO could make from a US copper penny.

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Expand please.

Of course, I can no longer remember which book. Due to lack of funds, I was restricted to the school library and then the public library. As well as my foggy memory remembers, It was probably the P.I. or early in Australia. Maybe Guadalcanal, but the details of lack of small parts being made by mechanics from various other salvaged parts, pocket change, etc was impressive to a 15 year old.

Due to the need for copper they started making pennies out of steel during WW2 at some point

Only the 1943 pennies were zinc plated steel.

Don't forget the "war-nicks". The "nickels" were made out of steel. For those elsewhere, a five cent piece is called a nickel in the U.S.

I'll have to look that up because I think it was not steel but only an alloy change. Back in a few.

Here's the straight skinny. The wartime U.S. five cent piece (the nickel) went from 75% copper, 25% nickel to 56% copper, 35% silver, 9% manganese for 1942 through 1945.

Right, silver, not steel. And I thought I would be enjoying senility more.