Liberty L-12 vs Allison V-1710

Discussion in 'Engines' started by gjs238, Jan 28, 2010.

  1. gjs238

    gjs238 Well-Known Member

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    I'm wondering if the design, development production of "America's WWII Inline Aircraft Engine" should have been handled like the Liberty Engine of WWI was, i.e., a collaborative effort amongst major designers manufacturers instead of leaving it to what was essentially a speciality racing shop outfit like Allison. Liberty L-12 - Wikipedia, the free encyclopedia
     
  2. Colin1

    Colin1 Active Member

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    What was military contract tendering like back in WWI US?

    I'm asking because I've got no idea but with Wright, Pratt Witney and Curtiss enjoying the film star treatment from the USAAC, I can't see them being too willing (or bothered) to share the good times with an up and coming small outfit like Allison.

    They weren't going to share the good times with each other either, not a chance. Alot of Wright engineers defected to Pratt Witney, who thereupon prospered considerably; the rivalry was bitter, make no mistake.

    No, I don't see a 'Liberty engine' for WWII materialising, both Pratt Witney and Wright were going to win their own contracts despite each other and they certainly weren't going to pave the way for a new entrant to prosper in their market sector.
     
  3. davebender

    davebender Well-Known Member

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    I thought Allison was a division of General Motors. A giant in the automotive world.
     
  4. Shortround6

    Shortround6 Well-Known Member

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    Engines had gotten a lot more complicated since WW I. The Liberty came about because, in spite of the large US manufacturing base in auto engines we had no high powered aircraft engine. The Liberty was also an example of how things could go wrong.

    The Liberty was about the size of a Merlin and yet was good for 400hp. it was much lighter and turned much slower which held stresses down. there was no supercharger AT ALL. Quality control was all over the map. Some Liberties from certain makers were very good engines, engines from other makers probably should have been broken down for scrap upon delivery.

    Some airframes stood up to the Liberty fairly well and others were practically dismantled by the vibration. 6 and 8 cylinder versions were planned and few built. These vibrated much worse than the 12 and were basically useless.

    In some ways the Liberty was a triumph and in other ways it showed (as did the license built Hispano fiasco)that not just any car engine builder can build aircraft engines.

    Considering that the only people with experience in aircraft V-12 engines in the US were Curtiss-Wright and they had stopped development around 1930 or so, with production toddling along for another few years and Packard who while continuing development at a very low level were basically trying to update a mid 20s design (it was massed produced in WW II to power PT boats) I am not sure how a collaboration between these two is going to net anything better than what Allison was doing. The Army sure wasn't buying anymore of what they were selling individually.

    P&W and Wright both had lots of experience with air-cooled engines but while Pratt at least had a few liquid cooled engines in development they dropped them all to concentrate on what they knew, air cooled radials.

    By WW II new engines were sometimes run for thousands of hours before one was put in a test mule aircraft with a live pilot. The days of roughing out a design in a few days in hotel room were long gone.
     
  5. Shortround6

    Shortround6 Well-Known Member

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    It was, but I haven't got the book in front of me at the moment to check when GM bought Allison. General Motors provided tremendous support to Allison right before and all during the war. Allison also made hard shell bearings, contracted with GE for the supply of superchargers to GE designs and provided the reduction gears for Packard aircraft engines of the 1920s amongst other projects.
    However IF Allison hadn't gotten the orders in the spring of 1939 that it got GM was ready to pull the plug on the aircraft engine project. With over a 1/2 million dollars of GM money keeping Allison afloat and the Army $900,000 in arrears on contract payments GM was running out of patience.
     
  6. Colin1

    Colin1 Active Member

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    #6 Colin1, Jan 28, 2010
    Last edited: Jan 28, 2010
    The fortunes of your giant at the beginning of the 30s

    US Navy contract for 1 x liquid-cooled powerplant in 1931
    US Navy contract for 3 x liquid-cooled powerplants in 1933


    Compare and contrast with

    Pratt Witney R-1830 air-cooled powerplant in production by 1932
    Wright Cyclone R-1820 air-cooled powerplant in production by 1931


    and ten years later the V-1710 still isn't running right. The fortunes of automotive success didn't always translate into aviation success; Packard managed it, others didn't.
     
  7. davebender

    davebender Well-Known Member

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    Someone in the U.S. Army Air Corps must have really like Allison. As soon as examples of the DB601 and RR Merlin were available for comparison I would have cancelled the Allison contract.
     
  8. Shortround6

    Shortround6 Well-Known Member

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    Why?

    Very early Merlins (MK I) or the ramp head models had to be redone. The mid 30s DB 600 didn't set the world on fire and had a number of teething problems. In addition to it being carburetored and having a single speed (non-variable) supercharger drive.

    The US had no other V-12 on offer at anywhere near the state of development. Both the Continental and the Lycoming 12s were far,far from production and the Packard was out of date.

    By the time the Merlin MK III is available for testing or a DB 601 as installed in a 109E commitments had already been made.

    There are also fundamental differences between some Allison models. A lot of major changes from the C series engines and the E and F series engines.
     
  9. Clay_Allison

    Clay_Allison Active Member

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    A shame that Packard didn't develop their own, higher displacement engine to compete with the V-1710. Not an update of the old V-2500, but a brand new V-2000 with all modern features.
     
  10. Colin1

    Colin1 Active Member

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    They certainly had the know-how
    Their own proprietary powerplant, the 1A-2775, was developing 1,300hp and that was in 1929.

    Things seemed to go downhill for US liquid-cooled development around the mid-20s. The Schneider Trophy was won in 1925 by a US liquid-cooled unit, the Curtiss V-1400 - the most advanced powerplant in the world at the time. The Atlantic was then crossed in 1927 by a radial in the form of the Wright J5 Whirlwind. A year later, the Pratt Witney Wasp joined the party.

    The pace of the inline was lost behind the durability of the radial and fortunes slid further with the US Navy Bureau of Aeronautics endorsing the use of the radial in all future aircraft programs. That's where the contracts were and that's where the three main US powerplant manufacturers, Curtiss, Pratt Witney and Wright, concentrated their efforts.

    Curious, at the end of the 20s, the principal powerplant considered for aeronautical programs was the Pratt Witney Hornet B at 575hp; curious because there were around a dozen liquid-cooled powerplants available that offered more than 575hp, including the afore-mentioned 1A-2775.
     
  11. Shortround6

    Shortround6 Well-Known Member

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    The Packard 1A-2775 was an X-24 engine. See:

    http://www.enginehistory.org/Packard/jpgs/1A-2775 direct drive.jpg

    While it may have used a common cylinder head it continued to use separate cylinders.

    See also the supercharged version:

    http://www.enginehistory.org/Packard/jpgs/1A-2775 supercharged.jpg

    Perhaps not the engine of choice for a Spitfire/109 competitor, although it might have been the basis for for an early American Typhoon:)

    In the late 30s it may have offered 3 times the power but it also came at the cost of around 3 times the weight.
     
  12. Colin1

    Colin1 Active Member

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    Not bad considering it wasn't even the the 30s yet
    though I've a feeling you missed my point; US liquid-cooled powerplant development was out there and it's interesting to speculate where it would have been at the time the PV-12/Daimler-Benz were coming into production - 10 years is a long time in engineering with the right finance
     
  13. Jabberwocky

    Jabberwocky Active Member

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    #13 Jabberwocky, Jan 31, 2010
    Last edited: Jan 31, 2010
    There was nothing fundamentally wrong with the V-1710.

    The V-1710 actually compares quite favourably with the Merlin in some areas, such as weight (fractionally), reliability, cost of construction and time between overhauls and ease of maintenance.

    Where it loses out is frontal area (slightly), power at altitude (due to poorer supercharger design), specific fuel consumption per hp and ultimate hp development (mostly because Rolls-Royce poured more effort into developing the Merlin than Allison did for the V-1710).
     
  14. Shortround6

    Shortround6 Well-Known Member

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    Actually the Allison may have had a better "specific fuel consumption per hp" due to it's higher compression. At least at cruising speeds. This also limited it's peak HP for any given fuel?point in time, because the higher compression limited the ultimate level of boost.
     
  15. gjs238

    gjs238 Well-Known Member

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    Yet in 1931 the Navy purchased the first V-1710 B models and installed them on the airships Akron and Macon. Wonder why they didn't use radials?
     
  16. davebender

    davebender Well-Known Member

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    I agree.

    The problem is the U.S. Army Air Corps was willing to settle for a sub standard (compared to Britain and Germany) supercharger installation. If the U.S. Army Air Corps had insisted on a better supercharger "or else we will purchase RR Merlins from Britain" then it would have happened.
     
  17. Clay_Allison

    Clay_Allison Active Member

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    If what Shortround says is true, they needed to start saying it pretty early (1938 at the latest) to get it done by Jan 1942.
     
  18. Colin1

    Colin1 Active Member

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    I agree

    or rather, the government poured more effort into the Merlin than the Allison Division of GM did ie government funded over company funded. This was reflected in the development lead times of 4 years for the Merlin vs around 10 years for a V-1710 that was still having problems.
     
  19. Colin1

    Colin1 Active Member

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    #19 Colin1, Feb 1, 2010
    Last edited: Feb 1, 2010
    That was the pivotal year
    by 1938 turbocharging still wasn't delivering. The USAAC clearly realised that they needed something and both Allison and Curtiss-Wright convinced them that the V-1710 with the inherent limitations of the power section would service USAAC requirements; at the time, they weren't actually wrong. Promises of power section development never materialised.

    I don't know why Allison settled on a standardised power section, apart from the fact that it would service all marks of the powerplant with a single production line. This made good business sense in one respect but had the unfortunate effect of hamstringing the V-1710 (and by extension, the P-40) in future development; technology and events rapidly overtook both.
     
  20. Shortround6

    Shortround6 Well-Known Member

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    as has been pointed out, WHEN is this determination to be made?

    What year?

    In 1938 the Merlin, while a production engine, offered no real advantage over the Allison at the time. In fact the Merlin III was rated below the Allison for take off power even at 9lbs of boost which needed some sort of fuel over 87 octane.

    Just when did the Germans show up with their better supercharger installation?

    There was darn little extra capacity in England to supply engines to the United States, British were building shadow factories as fast as they could in England. It took Packard about a year to roll the first ceremonial engine out the door once the contracts had been signed and several month more ( up to 6?) to actually get production moving in numbers, And this was after the US aero engine industry had spent from 1938 to late 1940/early 1941 gearing up. The companies that supply the carburetors and the magnetos, pumps, valves, bearings even aircraft grade nuts and bolts, all under subcontract.

    Please note that Allison started work on a two stage supercharger at the end of 1938 with their own money.

    SO JUST WHEN DO YOU THREATEN THEM?

    Considering that in the Spring of 1939 the Army owed Allison over 900,000 dollars for already successfully completed contracts GM might have just told the ARMY "Go ahead, we aren't doing any more work or delivering any more engines for free."
     
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