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Thread: P-51 Radiator = Thrust | Forums

  1. #1
    Hi folks,
    I assume I lot of you know about the P-51s radiator actually creating a jet thrust effect,
    known as the "Meredith Effect".

    In game, it seems everyone recommends closing the radiator for top speed.

    So am I right in thinking the P-51s radiator thrust is not modelled?


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  2. #2
    Hi folks,
    I assume I lot of you know about the P-51s radiator actually creating a jet thrust effect,
    known as the "Meredith Effect".

    In game, it seems everyone recommends closing the radiator for top speed.

    So am I right in thinking the P-51s radiator thrust is not modelled?


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  3. #3
    Senior Member VW-IceFire's Avatar
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    Oi...this one could get long. We had multipage arguments about this a few years back. Until it finally got worked out.

    Long story short...the Meredith Effect decreases the drag of the radiator but it does not cancel it out. Its still a cleaner airframe with the radiator port closed just like any other airplane. Its just that when open the drag is slightly less because of forward thinking design. There's a reason that North American managed to get Spitfire XIV levels of top speed and overall performance without the added 500 horsepower.

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  4. #4
    However the top speed decreases as much for the p51 as for any other plane in game when the radiator is open! A loss of ca 25km/h
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  5. #5
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    That radiator gave some thrust but less than the drag. The outgoing air did push, so 'thrust'.
    But it was only effective so much at high speeds and automatic operation. The rear gate did
    constrict the flow to make it work, at least from what the more technical descriptions said.

    drag - thrust = less net drag than otherwise.
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  6. #6
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    There was a lengthy article in Flight Journal [IIRC] on the influence of the Meredith Effect radiator upon the Mustang's performance. It was pretty dramatic compared to conventional radiator design. Whereas a conventional radiator might produce a net 400 lbs of drag, the drag cost of the Meredith design was something like 100 lbs.

    I'm guessing that was one of the important factors in the Mustang's very high cruising speed.
    BLUTARSKI

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  7. #7
    the difference between expected(calculated)drag and effective drag means thrust. The exhausting warm air fro mthe coller is slower than a/c acuatlly flies, so to speak of thrust is a bit questionable.
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  8. #8
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    The ultimate thrust from the P-51 was a P-51A the RAE modified by putting a series of small ramjet tubes in the rear of the radiator enclosure. Such a system was originally suggested as a ventral pack for the Spitfire I to boost the speed in 1940, but development time meant that it was not possible in that timeframe.
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  9. #9
    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blutarski2004:
    There was a lengthy article in Flight Journal [IIRC] on the influence of the Meredith Effect radiator upon the Mustang's performance. It was pretty dramatic compared to conventional radiator design. Whereas a conventional radiator might produce a net 400 lbs of drag, the drag cost of the Meredith design was something like 100 lbs.

    I'm guessing that was one of the important factors in the Mustang's very high cruising speed. </div></BLOCKQUOTE>

    What constitutes is a 'conventional radiator design'...? WW1 radiators or?

    I do not think there was anything particularly unique in the Mustang radiator internal layout compared to other mainstay fighters of the era. They all generate a certain amount of thrust.

    Meredith Effect Radiator sounds like to me as Elliptical Planform Wing. Or Hamilton Standard Propeller. Or Supercharged Engine. All with capitals suggesting that it something special about it, unique only to this and that aircraft, a sort of built-in-magic-wamd when this was not the case. The same technologies were used with varying degree of success/expertise.

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  10. #10
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    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by KIMURA:
    the difference between expected(calculated)drag and effective drag means thrust. The exhausting warm air fro mthe coller is slower than a/c acuatlly flies, so to speak of thrust is a bit questionable. </div></BLOCKQUOTE>


    ..... True in conventional radiator design, but the Flight Journal article insists that effective thrust WAS produced - not enough to cancel radiator drag altogether, but sufficient to substantially reduce its net effect.
    BLUTARSKI

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