Pratt Whitney R-2000 Twin Wasp (upgrade for R-1830 powered planes?)

Discussion in 'Aviation' started by gjs238, May 16, 2014.

  1. gjs238

    gjs238 Well-Known Member

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    #1 gjs238, May 16, 2014
    Last edited: May 16, 2014
    An enlarged version of the R-1830

    Would a much earlier availability of this engine have been a feasible upgrade for R-1830 powered planes?
    I'm thinking that major modifications and production disruptions would not be necessary.

    How would R-1830 powered planes have performed with the R-2000?

    Pro: Perhaps planes such as the F4F could have seen worthwhile performance increases earlier than their replacements like the F6F were fielded.
    Pro: Perhaps planes such as the B-24, which served with R-1830's for the length of the war, could have seen worthwhile performance increases.
    Con: Perhaps expediting development of the R-2000 would have come at the expense of the R-2800 or R-4360.


    [table="width: 750"]
    [tr]
    [td]Secifications (R-2000-3)
    Data from*FAA Type Data Certificate (TCDS)[1]
    General characteristics
    • Type:*Twin-row radial engine, 14 cylinder
    • Bore:*5.75 in (146 mm)
    • Stroke:*5.5 in (139.7 mm)
    • Displacement:*2,004 cu in (32.8 L)
    • Length:*61.02 in (1550 mm)
    • Diameter:*49.49 in (1257 mm)
    • Dry weight:*1570 lb (714 kg)

    [/td]
    [td]Specifications (R-1830-S1C-G)
    Data from* Tsygulev (1939).[3]
    General characteristics
    • Type:*Twin-row radial engine, 14 cylinder
    • Bore:*5.5 in (139.7 mm)
    • Stroke:*5.5 in (139.7 mm)
    • Displacement:*1,829.4 inĀ³ (30 l)
    • Length:*59.06 in (1,500 mm)
    • Diameter:*48.03 in (1,220 mm)
    • Dry weight:*1,250 lb (567 kg)

    [/td]
    [/tr]
    [/table]
     
  2. oldcrowcv63

    oldcrowcv63 Well-Known Member

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    Weight increases by factor of 1.26, as does frontal area by factor of 1.06 whereas engine power to weight ratio drops from 0.96 hp/lb to 0.86 hp/lb. Seems like it might not provide much benefit for the effort. Dunno if there are other considerations.
     
  3. davebender

    davebender Well-Known Member

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    For another 500lbs you can have a 1,600hp R2600 engine. Which is probably why USN dive and torpedo bombers skipped over R2000 engine for the R2600 engine.
     
  4. tomo pauk

    tomo pauk Creator of Interesting Threads

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    The R-2000 was skipped because it was too late to matter - 1st run, going by Wikipedia (usual disclaimer applies) was in 1942.
     
  5. gjs238

    gjs238 Well-Known Member

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  6. gjs238

    gjs238 Well-Known Member

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    Yeah, I agree, but the R-2600 is a fatter engine.
    The R-2000 perhaps offers the promise of a slick upgrade.
     
  7. davebender

    davebender Well-Known Member

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    Fat R2600 engines work just fine in fat and rather slow dive and torpedo bombers.

    Fighter aircraft might have been a different matter. However USN opted for 2,000hp over weight and aerodynamic considerations when writing specifications for F6F and F4U.
     
  8. Shortround6

    Shortround6 Well-Known Member

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    I think we have been over this at least once :)

    R-2000 engine is much later in timing than the R-2800.

    They built 9 engines in 1941, 8 of them in December. While not a large production item in 1942 that could have been changed if needed. Problem is that the R-2000 didn't really offer much for combat planes in 1942 over the R-1830s.

    The early R-2000s were rated on 100 octane fuel (not 100/130) and were good for 1350hp for take-off, 1350hp military at 2000ft and 1100hp at 13,200ft in high gear. A R-1830 rated on 100 octane was good for 1200hp take-off, 1200hp at 4900ft and 1050hp at 13,100ft. Apparently they didn't change the supercharger much from the R-1830 to the R-2000. Unless the R-2000 powered plane stays really low it doesn't have much advantage over the R-1830 powered plane.
     
  9. Shortround6

    Shortround6 Well-Known Member

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    Timing.

    R-2600 was available over 2 years before the R-2000.

    They didn't skip over it. It didn't exist when design work was started on the USN dive and torpedo bombers.
     
  10. Shortround6

    Shortround6 Well-Known Member

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    Actually they considered the aerodynamics rather well.
    A R-1830 has about 12.6 sq ft of frontal area and 1200hp down low and 1000 hp (with a two stage supercharger) at 19,000ft. POWER per sq ft of frontal area is 95.24 down low and 79.37 at altitude.
    A R-2800 has about 14.8 sq ft of frontal area and 2000hp down low and 1650 hp (with a two stage supercharger) at 22,000ft. POWER per sq ft of frontal area is 135.14 down low and 111.49 at altitude.

    That one seems like a no brainer. Corsair's wing was only about 21% bigger than a Wildcats wing so the power per unit of skin friction seems pretty good.

    Throw in the fact that a 1200hp engine couldn't cope with load of guns and ammo the the Navy wanted and the choice doesn't need anymore explanation.
     
  11. davebender

    davebender Well-Known Member

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    Meanwhile typical V12 engines had frontal area of 6 to 7.5 sq feet and were plenty powerful enough for contemporary fighter aircraft such as Spitfire, Me-109 and Macchi C.205. USN could have specified Allison or Packard V12 for next generation fighter aircraft. Instead they opted for maximum engine power.
     
  12. Shortround6

    Shortround6 Well-Known Member

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    Switching the argument here?

    The F6F and F4U were Navy planes and weren't going use liquid cooled V-12s if there was another option.

    Now lets throw in the fact that the US Navy wanted more range/endurance than the Spitfire, Me-109 and Macchi C.205 could offer. A 1200-1300hp V-12 couldn't handle the required fuel load. Granted the R-2800 sucked up a fair amount of fuel but throttle back to slow cruising speeds and the Corsair was burning about 25% more fuel than a Spitfire or P-40. Considering that the fuselage tank held about twice as much fuel as a Spitfire or 109 this gives it a LOT more range /time to find the carrier when returning from a mission.
     
  13. Aozora

    Aozora Well-Known Member

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    Lets also throw in the fact that the R-2800 was highly reliable, and could cope with lots of battle damage that the average liquid-cooled engine couldn't; there were a lot of USN pilots who were very grateful for the choice made by the USN when facing a flight of (say) 250 miles across deep, empty oceanic waters.
     
  14. Shortround6

    Shortround6 Well-Known Member

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    The R-2800 hadn't shown shown it's resistance to battle damage at the time it was chosen (1939-41) but one less system to wrong (the liquid cooling system) was a consideration.
     
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