P-51 fuel consumption during dog fights?

Discussion in 'Classic Mustang Specific Tech' started by Jon350, Jan 14, 2004.

  1. Jon350

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    This is probably a really stupid question to the older readers here, but i was just thinking about the old p-51's. I know how much of a **** it can be if i take a corner hard enough in my fb and envoke fuel starvation. What on earth keeps the fuel consumption constant on a old fighter plane like that when the dog fighting begins?
     
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  2. Edbert

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    1st...cough....talk...cough :D
    2nd...
    The P51-B (and later) used the Merlin engine from Rolls Royce. The P51A came with an Allison motor and the performance was underwhelming. The merlin engine was originally in the Spitfire as far back as 1939, was also in the late model P40s, and during the war it also changed drastically in performance. The P51B came with a 1,550HP version but by the end of the war they were nearly 1,800 and in Korea (the H version) they were even more.

    Basically it was an inverted, liquid cooled V-12 is all and the redline was a paltry 3,000RPM. Gererally pilots cruised at partial throttle and only used full during a dogfight and for takeoff. Once things got hairy though the pilot could use WEP (War Emergency Power). WEP varied greatly among the different motors, sometimes it was simply water injection, some aircraft used nitrous, some a water-methanol mixture, and others could overdrive the superchargers. Altitude also had a big effect on fuel consumption due to the density of the mixture. In fact a pilot had to manually adjust the mixture settings to compensate for this.

    Ummm...what was the question again? Oh yeah...during a dogfight the engine was at or near 3,000 RPM and despite IAS/TAS there was not a big difference in the load experienced by the propellor (only atmospheric pressure changed that) so the "MPG" would be roughly the same as long as WEP was not used.
     
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  3. Jon350

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    lol.....wow, that was like listening to the history channel....i take it your a WWII buff. That was really informative Edbert, but you kinda missed the point of my question. Lets try this again shall we?.....I meant what keeps the fuel constantly going to the motor when the fuel is swooshing around during hard manuvers? is there a special compression or suction mechanism that that stays in contact with the gas to prevent air from entering the fuel lines instead of fuel?
     
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  4. slapper

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    The fuel tanks have inverted check ball floats in the vents to prevent fuel spillage due to gravity, and there is a stand pipe in the tank with a check ball to prevent the pump from drawing in air and cavitating.
    Some applications have a boost pump to keep a constant head pressure on the engine driven pump.No,...the aircraft cannot sustain indefinate inverted flight.
    The carburetor in usually a Marvel Shribler pressure carb designed for such applications.
    Your's truely,....an aircraft mechanic of 23 years.
     
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  5. gp001

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    Hey! You stole my line! :D
     
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  6. SuperDave

    SuperDave Early-Model Mentor
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    I'll fly a couple of combat missions on my Microsoft Flight Simulator (European theater) and let you know. I can fly the P-51H against Messerschmits, Folke-Wulffes or and number of "Kraut" aircraft.
     
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  7. Edbert

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    Or Discovery Wings :D
    See my Avatar?
    Indeed I did, I got hung up on the "consumption" bit I guess. Basically they used pressurized (and self sealing) fuel cells along with mechanical injection. Indeed early WWII aricraft suffered from carbuerated engines and would sputter and stop in a negative-G maneuver. Of course in a combat situation pulling a negative-G maneuver was a defensive (and desparate) thing to do. Even today with afterburners almost all combat maneuvers (ACM/BFM) are of the positive-G variety. The ability of the motor to keep running during sustained positive-G moves is far greater than the ability of the pilot to do the same without losing consiosness. That was true in WWII and is even more so today.

    MS Combat Flight Sim 1 (European theater) is pretty dated there SD. MSCFS2 was better (set in the pacific) and MSCFS3 is the best yet (back to Europe). The best one hands down right now though is IL2-Sturmovik. I own almost 20 WWII flight simulators :D For a real challenge to your fighter pilot skills though you need to try it online versus human competitors. I strongly recommend "Aces High" http://www.flyaceshigh.com, I spend a few hours per week in the virtual skies (sad as that may be).
     
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