P-40 what-if

[Clay_Allison]

36L was medium/small displacement for a better part of ww2 - only when compared with Merlin's 27L it looks huge. Griffon was to late for US planes, since R-2800 Merlin already filled the needs perfectly.

For a V-12 it's huge. Merlin: 27L; Allison: 28L; Hispano 36L; Klimov 35L; DB601 34L.

 

[Markus]

Pay? Owe. Big difference. Take it out of the lend lease they still haven't paid off. (They haven't screwed us out of it, they make payments very slowly because our rate of inflation is higher than the interest)

I´m afraid pay it will be. LL wasn´t "on" before 1941. You wanted to kill the V-1710 before the war. That means the US manufacturer has to pay RR royalties and since we talk about a contract between two private companies the UK´s LL debt does not even come into play.

 

[Clay_Allison]

I´m afraid pay it will be. LL wasn´t "on" before 1941. You wanted to kill the V-1710 before the war. That means the US manufacturer has to pay RR royalties and since we talk about a contract between two private companies the UK´s LL debt does not even come into play.

Well, if the US govt' wanted Merlins or Griffons, Allison or whomever would have to make Merlins or Griffons. If a slightly higher unit cost were to come from royalties, they can make it up by not having so many planes shot down in North Africa.

 

[Markus]

One last note - In some earlier discussion, it seemed some here were trying to "re-design" the P-40 into, essentialy, a "P-51 type" aircraft.
Why?
If you want the performance factors of a P-51, get a P-51!


Elvis

True but the Mustang I entered production in mid-41, the Brits got the idea of putting a Merlin into it a year later and the "result" did not see combat before the end of 1943. IMO a good reason to continue to improve the P-40. Another is that we have the benefit of hindsight, contemporary decision makes could not have been sure about the huge success of the P-51B.

 

[Markus]

Well, if the US govt' wanted Merlins or Griffons, Allison or whomever would have to make Merlins or Griffons. If a slightly higher unit cost were to come from royalties, they can make it up by not having so many planes shot down in North Africa.

P-40F did quite well in NA as a whole. Very well below 20,000ft, not so well above but for that task enough Spits were around. And regarding the cost, the cheapest sollution is still an earlier effort to make aux-stage SC for the Allison. Something Allison considered necessary as early as 1938.

 

[Clay_Allison]

P-40F did quite well in NA as a whole. Very well below 20,000ft, not so well above but for that task enough Spits were around. And regarding the cost, the cheapest sollution is still an earlier effort to make aux-stage SC for the Allison. Something Allison considered necessary as early as 1938.

If that were possible, yes. Shortround seems to consider that task 150% IMPOSSIBLE.

 

[Markus]

If that were possible, yes. Shortround seems to consider that task 150% IMPOSSIBLE.

The first Allison with an aux-stage SC actually existed and worked in mid-42. Ok,the critical altitude was not just as good as the Merlin´s but that was fixed with the next version.

 

[Shortround6]

The first Allison with an aux-stage SC actually existed and worked in mid-42. Ok,the critical altitude was not just as good as the Merlin´s but that was fixed with the next version.

having one engine in flight test (or even 6 engines in flight test) is not the same as as rolling them out door a dozen a day.

Allison had a few advantages and a number of disadvantages during this period. Back in the late 20s and early 30s they had subcontracted supercharger production for GE, that is they fabricated superchargers to GE designs for deliver to other engine manufacturers. Advantage in manufacturing knowledge but not in design knowledge. GE supercharges weren't particularly good. A number (Both?) of other engine makers abandoned the GE designs and started designing their own as did Allison. Allison was a small company under going enormous expansion in 1939 as were the other major engine makers.

P&W quadrupled their floor space in under two years. Allison built an entire new plant for production and that one only sufficed for war production because so much of the Allison engine was contracted out to other GM divisions. Many of these plants did not have enough engineers to start with and with such rapid expansion getting enough new ones was a problem.

Allison got caught in several production problems. in Early 1939 the actual number of engines either delivered or on order was very small. Of these engines there were 5 or 6 different models, so in an attempt to squeeze some profit out of what they were making Allison had taken the approach of building a central power section and then adding accessories (gear drives, extension shafts and the like ) to this central, standard section. For people who say this was short sighted it is good to remember that R&D contracts are not like today. Back then the Army only paid for the successful completion of a test, if then. If a test engine blew up on the test stand the company had to supply a replacement at it's own expense. in the spring of 1939 (months after Allison had decided a 2 stage supercharger might be needed) the Army was over 900,000 dollars in arrears to Allison and weaseled out of paying this by getting Allison to forgive the debt in return for allowing Allison to export the V-1710 to France and England.

Allison started by trying to use the same size impeller in the aux stage as on the engine (sharing of parts to save costs?) but had to change to a larger diameter impeller. They also changed the drive system. They went from a single speed drive for the auxiliary stage to a hydraulic variable speed (much like the DB supercharger drive). there were many other changes along the way. the -47 model went through engineering changes A through G. The final supercharger system may have been better than the R-R system in terms of power used at lower altitudes and less power fluctuation with altitude ( smooth curve vrs a saw tooth profile) but didn't force a change in the central power section (engine block) but was not as economical in space/volume and did not incorporate an inter-cooler, not for lack of trying. The subcontractor/s failed to deliver a workable unit in spite of months of time spent.

As far as just throwing more money, some things just weren't available. At one point Allison had orders from the Government and overseas for several thousand engines and enjoyed an "A1A" priority rating rating and yet was still short around 800 machine tools to fill existing factory space.

 

[Clay_Allison]

As far as just throwing more money, some things just weren't available. At one point Allison had orders from the Government and overseas for several thousand engines and enjoyed an "A1A" priority rating rating and yet was still short around 800 machine tools to fill existing factory space.

What is unknowable is if throwing more money AND TIME at the problem might have been enough. Make AUX supercharging a priority in 1938 and you may have it by Jan 1942.

 

[Cromwell]

Thank you for the suggestion.

Some other engines went through a similar increase.

The Water/ Methanol method was used by a number of American planes and offered some real improvement when combined with an inter-cooler. Inter-coolers also allowed for some high speed-high altitude cruise settings without worry over exhausting supply.

For high altitude work the N2O does show a good increase but unless the boost needed is of short duration the installation may compete with turbos and inter-coolers for weight. The longer the endurance needed the better the turbo/intercooler set-up looks.

I am not sure how much of a secret N2O still is given the amount of use it gets in street performance cars.

I wondered about that

- But apparently to this day no-one has quite figured out how DB could get so much power out of their engines with such rough aviation fuel made from coal mostly.

You can read it all in the article I referred to above in Aeroplane.

 

[Cromwell]

I wondered about that

- But apparently to this day no-one has quite figured out how DB could get so much power out of their engines with such rough aviation fuel made from coal mostly.

You can read it all in the article I referred to above in Aeroplane *.

* Footnote: I refer to that magazine as a reference source not to promote sales in a commercial context.

 

[Cromwell]

I was thinking about the P-40 and the reasons it wa considered a stopgap at best. What if, though, the P-40 had been reengined, not with the Merlin (as in the P-40F) but with the RR Griffon (if it had been turned over to an American comany for development when it was de-prioritized). Would that have worked?

It is true that engines can make all the difference, even the Bloomin awful 'Beef-alo' responded to the Wright 1820

See the following from Military History Encyclopedia on the Web

"F2A-2

This was by far the best version of the Buffalo. It had a more powerful Wright R-1820-40 engine, producing 1,200 hp. This increased its top speed to 344 mph at 16,500 feet, making it quicker than the F4F Wildcat."

This is as fast or possibly faster than the Hurricane, which was Merlin powered as you know.

 

[Clay_Allison]

It's funny but I've come full circle back to the conclusion that a Griffon powered P-40 would have provided the power and altitude performance to make it competitive and keep it competitive as the power plant produced more and more horsepower.

 

[Cromwell]

It's funny but I've come full circle back to the conclusion that a Griffon powered P-40 would have provided the power and altitude performance to make it competitive and keep it competitive as the power plant produced more and more horsepower.

Personally I am amazed at the complexities (of WW2 engines) that these forums constantly throw up.

There are some highly knowledgable people on here, and the arguments and counter-arguments rage on for weeks sometimes.

For example, I never realised how much Allison struggled to keep up with the game. Really it was a bit of a mess.

But then - It makes you wonder how Packard managed to get their act together so relatively quickly ?

 

[Colin1]

It's funny but I've come full circle back to the conclusion that a Griffon powered P-40 would have provided the power and altitude performance to make it competitive and keep it competitive as the powerplant produced more and more horsepower.

An expensive waste of powerplants
the Griffon would be getting the best out of the airframe, the airframe would not be getting the best out of the Griffon. Airframe refinement easily kept pace with powerplant development, allowing the match-up to get the best out of each other; just dropping a cutting-edge powerplant into a mid-30s airframe would put you at a disadvantage to your enemies who've considered the aerodynamic aspects.

The Mustang I with the V-1710-39 was around 30mph faster than the P-40E with the same powerplant.

 

[Cromwell]

An expensive waste of powerplants
the Griffon would be getting the best out of the airframe, the airframe would not be getting the best out of the Griffon. Airframe refinement easily kept pace with powerplant development, allowing the match-up to get the best out of each other; just dropping a cutting-edge powerplant into a mid-30s airframe would put you at a disadvantage to your enemies who've considered the aerodynamic aspects.

The Mustang I with the V-1710-39 was around 30mph faster than the P-40E with the same powerplant.

For some reason, some airframes just 'max out' and you just have to go an light your fire somewhere else

I think the P40 was as good or as flawed as the Hurricane - best kept for ground attack beyond a certain point as the designs were not going to get much better or give you much more either.

Then run for home and pray you don't get bounced

 

[Markus]

having one engine in flight test (or even 6 engines in flight test) is not the same as as rolling them out door a dozen a day.

Sure, but "Vees for Victory" says 2,000 V-1710-47 were actually ordered in April 1942. That strongly indicates the engine was ready. Even if it was 100% ready, neither was the P-51B. Her production did not begin until a full year later. Plenty of time for Curtiss-Wright to improve the P-40 more than in OTL.

@Cromwell:

I disagree, the XP-40Q made 422mph at 20,000ft, not 25,000ft thus I´m convinced the Warhawk had a lot of unused potential.

 

[Colin1]

the XP-40Q made 422mph at 20,000ft... ...the Warhawk had a lot of unused potential

Which would remain unused
the P-51D was available by 1944 and it was flying faster, higher and further. The XP-40Q was pushed as far as it could be pushed by a small team of dedicated Curtiss engineers and USAAF test pilots; Curtiss themselves weren't interested by this stage.

 

[Markus]

Which would remain unused
the P-51D was available by 1944 and it was flying faster, higher and further. The XP-40Q was pushed as far as it could be pushed by a small team of dedicated Curtiss engineers and USAAF test pilots; Curtiss themselves weren't interested by this stage.

First, this is a "what if", so we assume C-W was interested. Second, if the plane can make 422mph@20ft it will be faster at a higher altitude iif the engine is rated for a higher altitude. Some Allisons were some were not as the customers prefered max. performace at 20,000ft. Third, IIRC the P-51B was not that available at first. All went to the UK for some time, resulting in complaints from the Med for example.

 

[Colin1]

First, this is a "what if", so we assume C-W was interested. Second, if the plane can make 422mph@20ft it will be faster at a higher altitude if the engine is rated for a higher altitude

Thank you
if Curtiss hadn't realised by 1944 that the war in the ETO was raging 5,000ft higher than your XP-40Q was capable of flying at then Curtiss's interest is a what-if too far