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US V-12's


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#1 Armand

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Posted 15 March 2017 - 12:02 AM

As Jeff another place compared the early P-40 as a realistic contender to Spitfire 1, it strikes Me how much Spitfire developed in just 5-8 years wich mostly lies in the development of the Merlin engine (merging to Griffon) meanwhile the American V-12 aircraft engine became almost untouched in the same period.
The P-40 is generally quite denounced due to it's lack of power, but with the same willingness to develop the engine as the Brits, could the P-40 have been a totally other aircraft!
BTW: Wonder how the heritage of the P-51 would have been in comparison to the P-40 without the Packhard built Merlins :-/

#2 GregP

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Posted 15 March 2017 - 07:40 AM

Well, the P-40 designer, Don Berlin, resigned from Curtiss when he was not allowed to develop the P-40. That says something to me.

 

The P-51 would still have beena  good aircraft, but the turbo Allison would not quite match the wartime Merlins of the same year. They lagged a bit, due to lack of interest by the U.S. government, who would have had to FUND development.

 

Allison asked about developing superchargers on several occasions and was told to concentrate on the S/C-T/C end of it. They did. They were NEVER asked to deliver a new engne with 2,000+ HP, though.

 

When I look at the Allison specs. they are "stuck" at 1,100 - 1,400 hp for the war. Where is the 1,800Hp Allison V-12? Nobody ever asked for it. Much of teh Allison's gain between dash numbers was in altitude ratings. They went from a sea level rated engine to one that would made 1,300+ hp, but did so at 25,000 feet. That natrually meant more power avilable when lower, but noit quite Merlin power, most of the time.

 

But it would definitely run and keep a tune longer than any Merlin and still does today.

 

If I had ONE warbird, it would have a Merlin if I could find a good one or two. If not, an Allison would be great since I'd want to stay VFR and play with fighter maneuvers, not fly straight and level in IFR serenity. The U.S. FAA has completely forgotten that we used to fly VFR combat missions at 35,000 feet in WWII with hundreds of planes. They think you'll get lost of you don't have instruments at an arbitrary low-level.

 

They'd die of shame if they ever read WWII aviation history books!



#3 flying kiwi

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Posted 15 March 2017 - 11:29 AM

I suspect we saw 1930s Merlin type technology in British bikes of the 60s and 70s. They also needed a lot of care.


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#4 CORSNING

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Posted 15 March 2017 - 01:41 PM

     When it comes to engines, Greg has a lot more knowledge than I.

But lets not forget about the overboosting 66, 70 and even 72"Hg

that was going on in the very early Allison. Those babies could take

a beating and push out 1,745 - 1,780 hp. + from sea level to around 2,000 ft.

At the end of 1942 Allison (General motors) sanctioned the use of 60"Hg

(1,570 hp.) for the early 8.8:1 blower ratio engines. The later Allison

with its 9.6:1 supercharger blower gears were limited to 57"Hg for

engine detonation reasons. 1,480 hp. from ground to a much higher

level than the 8.8:1 engines.

     Even with all this there was the turbo-supercharged engine of the

P-38L (1,600-1,720 hp.) :)

 

I'm done that's about the limit of my engine knowledge.

 

PS: Armand has sparked another long time interest of mine.

 

BTW: Wonder how the heritage of the P-51 would have been in comparison to the P-40 without the Packhard built Merlins :-/

In 1942-1943 the production of the Allison V-1710-81, -83 & -85 found its way into the

P-51, P-40 and P-39. It has always been interesting to me the fact that these birds

could hold their own with the best of the enemy at low / medium altitudes their part

has been played down and over shadowed by the newer aircraft arriving on the sceen

at the same time, P-51 merlin, P-38, P-47 and Hellcat. By the way, except for the

fact that they were not flown off of flight decks, these later Allison powered P-39s and

P-51s had performances at low / medium altitudes superior to the Hellcat of the time

period. The P-40N-1's performance was in the same ball park. B)


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#5 Rick65

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Posted 16 March 2017 - 12:56 AM

The Triumph Speed Twin was developed in 1937 as an air cooled 500cc motor. No OHC, two valves per cylinder so lower tech than the liquid cooled, supercharged OHC , four valve per cylinder Merlin.

By the time they finished producing the Triumph in the 1980s it was a 750cc. The equivalent Norton finished at something like 828cc so the basic designs was stretched  and stretched and stretched rather than being replaced. Add intrinsic vibration and sometime poor build quality to this and you had a motorcycle that needed care and understanding. The arrival of the smooth, tough, reliable SOHC Honda 4 was a revelation especially if you did as my brother did and put it in something like a Rickman frame so that it was lighter and would go around corners and stop better.

The Merlin remained at design capacity of 1650 cu inch, smaller than most of it's contemporaries. Even the Griffon was only 2240 cu inches.

If the Merlin capacity had been increased  by the same amount as the Triumph motors its capacity would have been 2475 cu inch!

Instead the power of the Merlin was increased with design refinement, better fuel and most notably by increased and improved supercharging.

The Allison largely missed the supercharging changes and improvments.


Edited by Rick65, 16 March 2017 - 06:54 AM.


#6 Rick65

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Posted 16 March 2017 - 03:30 AM

Since we are digressing, The success of the Hellcat was a result of a combination of attributes that suited the opposition it was facing.

Saying the Allison engined planes had the same low/mid level performance as the carrier capable Hellcat is not huge praise unless they also offered some of the other advantages of the Hellcat.

The Hellcat was never fast but critically it was faster than a Zero, was tough, had good handling and firepower and reasonable range.

That it was good enough for the task at hand was shown by the minimal changes made throughout the life of the model.

Against the late war Japanese plane designs it's speed was marginal but the skilled opposition by then were too few and the Japanese planes often couldn't achieve their best performance.

 



#7 GregP

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Posted 16 March 2017 - 08:28 AM

Hi Jeff,

 

I was not going to even mention Allison overboosting, but they DID it when it was needed, VERY successfully. I have seen one run at 95" Hg! Probably 2,900 HP to the prop. But ... nobody wants to race one at Reno because nobody ever tried with any knowledge of the Allison engine coupled with a well-engineered prop.

 

That's OK. We KNOW what it will do. Too bad nobody wants to actually DO it, but ... that's life.

 

It'll be OK. They still make beer and we can still build Allisons to spec because, unlike the Merlin community, we still have good parts available.

 

Cheers. I'd still run a Merlin anytime. Great engine, and always HAS been. Arguably superior in wartime to the Allison, to boot.

 

Actually, I like the Allied and Axis V-12s and the allied radials. I might like the German radials, too, but have never even heard one run. I DID hear the Jumo 213 in the former Doug Champlin Fw 190D run once, at idle. Sounded pretty good. It could start (maybe once out of twice), but the high-speed jets were missing, so you could NOT accelerate it much beyond 1,200 rpm high-idle. That plane is in Seattle now, with the FHC. I don't know if they start it ... but it CAN or, at least, COULD at one time, when Doug owned it.



#8 CORSNING

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Posted 16 March 2017 - 08:43 PM

Saying the Allison engined planes had the same low/mid level performance as the carrier capable Hellcat is not huge praise unless they also offered some of the other advantages of the Hellcat.

The P-51A (September 1943):

     OK....then how about this (just for starters because I have very limited time tonight):

The P-51A, while introduced in the PTO was faster than any first line fighter in European

skies up to 10,000 ft. in 1943. Only the P-51B-1 introduced 1 December 1943 was faster

and that started just under 15,000 ft. At 407 mph./10,000 ft. the P-51B-1 was the fastest

piston engine aircraft in the European skies. The P-51A could make 413 mph./10,000 ft.

In September 1943 when the P-51A became operational its internal fuel range was 1,000

mls./232 mph./10,000 ft. and 2,350 mls./228 mph. with external drop tanks. The P-51B-1

was the undisputed king in that area in Europe in 1943. Its internal range was 810 mls.

and its absolute maximum with external tanks was 2,200 mls.

 

There, that's a fairly good start driving my point home. Hmmm...lets see now..... <_<

 

P-40N-1 (March 1943):

      Lets see, what first line fighter in European skies at that time could turn inside it below

15,000 ft.? Careful, this with the exception of the very first light weight Tomahawks was the

tightest turning of the breed. Maybe the Spitfire V/IX but at this time I have no proof either

way. (Now compare that to everything else). :) Then we will start talking range and

ruggedness. :)  ;)

 

Let see..oh yea...

P-39N (November 1942):

     This little jewel could out climb any first line Bf.109G up to 15,000 ft. for almost a year

when the Bf.109G-10 was introduced in September 1943. ;) It could turn inside them all

also.

 

OK then, just how are these little buggers considered second rate under 15,000 ft. when

they were introduced? :huh:

 

     Actually, I am serious. I did an extensive study back in 2012. It dealt with the best first

line fighters operational during 1943. The above statements are based on that study. B)


Edited by CORSNING, 16 March 2017 - 09:22 PM.


#9 Rick65

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Posted 16 March 2017 - 11:21 PM

My comment was not to denigrate the Allison planes at mid to low level but to question the comparison with the Hellcat which was a great all rounder but not a standout in performance terms, hence the preference for the Corsair in post war.

Your post indicates that some of the Allison engined planes offered better low/mid level performance than the Hellcat in some aspects which is the point I was trying to make.

One of the reasons the P-51 was fitted with the two stage Merlin was it's outstanding performance at low level with the Allison.



#10 Kutscha

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Posted 17 March 2017 - 12:50 AM

P-39N (November 1942):

     This little jewel could out climb any first line Bf.109G up to 15,000 ft. for almost a year

when the Bf.109G-10 was introduced in September 1943.

 

The G-10 came a few weeks after the K-4 and that was in Oct 1944.






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