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Thread: Sport Class speed potential

  1. #21
    Join Date
    Sep 2007
    San Diego

    Default Re: Sport Class speed potential

    Turbo props would provide all the entertainment of the jet class. ZZZzzzzzzzz
    What do you find entertaining about air racing Race 5?

    Is air racing “boring” to a deaf person?

    I thought this was all about speed. Not necessarily "entertainment”.

    Speed in its purest form.

    To me, air racing has been a threefold effort for speed, airframe, pilot skill and powerplant.
    Why limit ourselves to “how much horsepower can we squeeze out of a 1000cc or 200cc or whatever class size recip. engine before it blows”, in the powerplant category?

    The potential is there to have the sport class evolve into a Super Sport class with turboprops.

    And what about the inevitable electric class? Is it doomed to fail because all you will hear is prop noise?

    What will air racing be like in 50 years? You and I will be dead and gone, but I know we both want there to be air races in the year 2070.

    I would bet WWII era aircraft won’t be racing in 2070. Perhaps Race 5 might even be powered by a small turboprop unit that your granddaughter 3D printed in her bedroom.

    Last edited by planecrazy2; 11-20-2019 at 07:43 AM.
    '71 S.D.1000, '85-'91,'95,'97-'99,'02,'04,'06,'08,'10,'13,'14 NCAR.

  2. #22
    Join Date
    Aug 2004

    Default Re: Sport Class speed potential

    Its like they never thought they could break the speed of sound or go to outer space. Kelly Johnson(Lockheed) & Von Braun had the foresight to advance aviation & space travel to prove the short sighted wrong. All of you involved with advancing air racing should continue to do so. By the year 2070 they will probably have Outer Space Races.
    Lockheed Bob

  3. #23
    Join Date
    Jul 2003
    Maui, Hawaii

    Default Re: Sport Class speed potential

    Who says I won't be at the races in 2070?????????? I think 112 is doable.

  4. #24

    Default Re: Sport Class speed potential

    Sport Class speed potential is a balancing act between thrust, drag, lift and weight (gravity). To maximize thrust you have to increase the torque output of the engine and utilize a propeller that can efficiently transform the torque into thrust. Increasing the torque output of the engine invariably requires additional heat rejection, wether the engine is air cooled or water cooled. This addition cooling requirement will come at the expense of increased drag. Air cooled race engines rely on a sufficient supply of slip stream air forced into the cowling as well as the latent heat of vaporization of a cooling liquid sprayed on the cylinders and into the induction system. The weight of the liquid coolant is countered by increasing the lift of the wing which increases induced drag. Liquid cooled Race engines rely on air/liquid heat exchanger exposed to the slip stream as well as spaying an additional liquid over the cooling tubes to increase the efficiency of the exchanger.
    These cooling requirements all increase the total drag on the airframe. Air cooled engines have an advantage in that their cooling capacity relys more on spraying a liquid than forcing air over the cylinders. Liquid cooled engines must have a heat exchanger exposed to the slip stream and suffer the result of the increased drag. However, the liquid cooled engines are all “geared” engines, that is they use a propeller speed reduction gearbox to reduce the propeller speed in relation to engine speed. Consequently, a 540 cubic inch V type liquid cooled engine with a 2:1 prop speed reduction effectively has twice the cylinder swept volume of a 540 cubic inch Lycoming with a direct drive propeller. The liquid cooled engine will be heavier and more complicated that the Lycoming, but it’s torque potential will be much greater. Here is where the balancing act comes in. The speeds at which the top tier Sport Class racers are flying, drag reduction is tremendously important. To increase the aircraft’s speed, you have to widen the imbalance of thrust versus drag by maximizing thrust and minimizing drag increases. At what point will a heavier, increased drag, liquid cooled engine racer producing substantially more torque, be faster than a lighter, slicker, air cooled racer? Don’t know myself, but I would love to see a 1200 HP forced induction Thunder Mustang try.

  5. #25
    Join Date
    Jul 2013

    Default Re: Sport Class speed potential

    I wonder how long it will be until someone runs an engine that is closer to the 1000 cubic inch limit? Seems like the IO-720 isn’t the ticket, so it would probably have to be developed from something else

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