USN adopts V-12 engines: pros cons?

Discussion in 'Aviation' started by tomo pauk, Oct 14, 2012.

  1. tomo pauk

    tomo pauk Creator of Interesting Threads

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    As widely known, USN fighters (and others) were powered by radial engines. So, is there any proponent here that could make a strong case for the USN adopting the V-12 engines for it's fighters (not only those?), from 1940 until the end of the war? The engines that can take part here are the V-1710s and V-1650s, maybe even the V-3420s, all while respecting the time line of engines production in the USA.
     
  2. ShVAK

    ShVAK Member

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    #2 ShVAK, Oct 14, 2012
    Last edited: Oct 14, 2012
    What kind of fighter are you proposing instead of the F2A and F4F? A P-40B/C/E with folding wings? I would think it'd roughly be in the same tier as most variants of the Sea Hurricane, a little better than the Wildcat performance wise but the narrow landing gear would make it a bear on carrier landings. It would also have lesser ceiling and range (P-40E was 650 miles w/ 29K ceiling, F4F-4 830 miles w/ 34K ceiling) along with a more vulnerable liquid cooled engine. Not sure if better performance is worth the trade for higher losses due to those factors. Certainly if boom and zoom worked for the AVG it should work for the USN, along with the Thatch Weave, so I don't expect that the type would be Zero bait by any means.

    More Allisons for the USN also means less for P-38's, P-40's etc. in the USAAC at least initially. Maybe that can be worked around but I don't know how many factories were focused on cranking out V-12's in '41 and '42. Considering how far behind we were at the start of the war, production volume is critical.
     
  3. tomo pauk

    tomo pauk Creator of Interesting Threads

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    I'm not proposing an outright navalisation of the USAAF planes (though there are some interesting candidates).
     
  4. ShVAK

    ShVAK Member

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    #4 ShVAK, Oct 14, 2012
    Last edited: Oct 14, 2012
    Were there any USN prototypes that even used the Allison? Far as I can tell they were strictly interested in radials. An F4F with a skinny nose and radiator would look really weird. :p

    A navalised P-38 would be pretty interesting, and would certainly rack up kills against the Zero while providing greater safety than a single-engined type. That tricycle gear would have to be heavily beefed up though. It would also take up a LOT of room even with folding wings. Maybe as a land-based fighter for the USMC?
     
  5. davebender

    davebender Well-Known Member

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    Only if the people managing U.S. aircraft engine production do a poor job. Otherwise Allison engine production capacity would be increased to match demand.
     
  6. rinkol

    rinkol Member

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    #6 rinkol, Oct 14, 2012
    Last edited: Oct 14, 2012
    There was an unsuccessful development of the P-39 intended for naval use.

    From the naval perspective, the air cooled engines had significant pluses:

    - potential for higher climb rate resulting from (typically) lower installed weight for a given power output
    - reduced vulnerability to combat damage resulting from a more compact engine layout and the absence of the radiator and associatd plumbing
    - reduced maintainance and fewer spares (a big issue on an aircraft carrier)

    The first of these was of particular relevance from the viewpoint of responding to airborne attacks on naval forces.

    Note that the last reason was also important in commercial aviation - by the early 1930's, there were hardly any transport aircraft being built with liquid cooled engines.
     
  7. tomo pauk

    tomo pauk Creator of Interesting Threads

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    There is no doubt that USN had the well grounded reasons not to adopt the liquid cooled engines. However, I'd like to hear more from the liquid cooled engines' proponents :)
     
  8. norab

    norab Well-Known Member

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    The primary reason I've always heard cited for the USN preference for radials was quicker power recovery in the event of a wave off. The v blocks couldn't regain power quick enough in those circumstances and would have a higher crash rate.
     
  9. Balljoint

    Balljoint Member

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    One advantage of naval use of the V-1710 –though not to the navy- would perhaps be a steepening of the learning curve in engine development. The Allison was rounding into a pretty good engine towards war’s end. The lack of commercial use and of course politics are suspects for this. Naval requirements for turbo/supercharging might have focused more effort on the needed development.
     
  10. Shortround6

    Shortround6 Well-Known Member

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    In 1940 you only have the V-1710 in actual production. The deal is signed for the V-1650 but by the time they will become available the TBF is already flying as is the Curtiss SB2C and neither V-12 is powerful enough to take over from the R-2600. Attack aircraft further out in timing need either the R-2800 or R-3350 and the V-3420 is really only a good substitute for the R-3350. This leaves the V-12s as suitable for a fighter only.

    Now can you design a fighter that meets the Navy's requirements for range (=lots of fuel), Short take-off and low landing speed ( = big wing) and fire power with lots of ammo ( 100rpg for six .50s is over 180lbs) with a 1300hp engine?
     
  11. tomo pauk

    tomo pauk Creator of Interesting Threads

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    Maybe a Spitfire-sized fighter is the answer - USN's Seafire in general shape? Anyway, a wing area of 250 sq ft (but not as tick a wing like F4F had), 4 HMGs with decent ammo capacity (350-400 rds), inward retracting U/C, 150 US gals. An early war machine.
     
  12. wuzak

    wuzak Well-Known Member

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    Turbos were an army thing, so I guess what you are trying to say is that navy use of the V-1710 would have accelerated the development of the 2 stage or 2 speed supercharger for the Allison.

    The Navy did sponsor a liquid cooled engine - the H-24 H-3130/3730.
     
  13. Shortround6

    Shortround6 Well-Known Member

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    #13 Shortround6, Oct 14, 2012
    Last edited: Oct 14, 2012
    The Navy didn't like the F4F because of a lack of fuel. Four .50s with 350rpg weigh just a touch more than the two 20mm and four .303s and ammo of a Spitfire. Edit> or about as much as twelve .303s with 350rpg. We have a lot debates about the F4F vs the Sea Hurricane. Granted you are claiming a thinner wing but then the Sea Hurricane didn't have a folding wing or as much fuel as an F4F.

    You could make it but is it really going to do much that the F4F won't? Unless you use the V-1650-1 the performance at altitude won't equal the F4F.
     
  14. VBF-13

    VBF-13 Well-Known Member

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    Here's an interesting link. This was provided by RCAFson in another thread. It's a December, 1942 USAAF Intelligence Summary rating some of these fighters against the Zero...

    http://www.wwiiaircraftperformance.org/japan/intelsum85-dec42.pdf
     
  15. tomo pauk

    tomo pauk Creator of Interesting Threads

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    With 150 gals. as proposed, the fual quantity equals the F4F and P-40, while offering 20 % more than Hurricane. Sleeker plane will do better mileage.

    The P-40E, not the very much liked variant, was faster than any F4F from deck up to 18000 ft, planes being of equal speed above that (topping 320 mph at 20000 ft), on military power*. We all know that Mustang I was faster than P-40E by some 50 mph, on same engine, at military rating. The plane that can perform somewhere in-between the two (eg. ~370 mph at 15000 ft) is not something the US designers cannot achieve, a year before Mustang I is in service.

    * WER being a bonus for the V-1710, ~1500 HP at 4500 ft (no ram); grey zone being the timing of the WER (both authorized and unauthorized). Handy to use when pilot flying the CAP realized that his controller positioned him 3000 ft under the incoming strike package. Will check out that 'Allison abuse' document ASAP :)
     
  16. davebender

    davebender Well-Known Member

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    Why?

    WWII era CV based aircraft normally operate no higher then 15,000 feet. That should be the critical altitude for a naval V-1710 variant.
     
  17. wuzak

    wuzak Well-Known Member

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    F4F - 2 stage 2 speed engine
    F6F - 2 stage 2 speed engine
    F4U - 2 stage 2 speed engine

    I see a pattern!
     
  18. Shortround6

    Shortround6 Well-Known Member

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    For the US Navy to buy it it has to work off US Navy carriers. Both P-40s and Mustangs had longer take-off runs, higher take-off speeds and higher landing speeds than F4Fs. Later carriers had heavier decks and upgraded arresting gear to handle heavier aircraft. Increasing the landing speed by 10% increases the amount of energy the arresting system has to handle by 21%. A 14% increase in landing speed ( and that is percent not mph or KPH or knots) increases the energy by 96%. The P-40 and mustangs had take-off runs around 300 ft longer than an F4F in calm wind. A P-40E with drop tank needs over 600ft even with a 30kt head wind, making deck parks and flying off without catapult difficult and/or tedious. Using Catapults for large group launches slows down the take-off rate and means that the first planes launched have to stooge around for 15-20 minutes (or more) until the last planes launch. Another reason the Navy wanted more fuel and why operational ranges varied so much from "book" or "Yardstick" ranges. Same problem on the return. If 20-30 planes arrive as a group how long does it take to get them down? They do not turn of the runway and taxi to dispersal under their own power. Any accident even small, can block landings for precious minutes leading to ditching.

    Take off performance is more than just wing loading and power to weight ratio. The actual co-efficient of lift of the wing comes into play and that is part airfoil and other factors.
     
  19. Shortround6

    Shortround6 Well-Known Member

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    only if you want to get bounced with monotonous regularity by Zeros. The Sakae 21 engine offered 980hp at 19,685ft in high gear didn't it?
     
  20. RCAFson

    RCAFson Well-Known Member

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    The F2A and F4F-3A and F4F-4B used 1 stage, 2 speed blowers.
     
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