1. #1
    A question for you avionics wiz kids

    I know keeping your radiator open will lower your planes max speed.

    I also know that taking 100% fuel vs 25% does not effect max speed very much if at all, but it does hurt acceleration and climb (as confirmed by Oleg).

    How does the drag added by an open radiator effect acceleration? Obviously it won't help acceleration but how much does it hurt acceleration? How significant is it? Has anyone quantified it in FB?

    Thanks!

    :FI:Snoop Baron
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  2. #2
    A question for you avionics wiz kids

    I know keeping your radiator open will lower your planes max speed.

    I also know that taking 100% fuel vs 25% does not effect max speed very much if at all, but it does hurt acceleration and climb (as confirmed by Oleg).

    How does the drag added by an open radiator effect acceleration? Obviously it won't help acceleration but how much does it hurt acceleration? How significant is it? Has anyone quantified it in FB?

    Thanks!

    :FI:Snoop Baron
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  3. #3
    Since the total drag force increases with speed, I imagine it hurts acceleration more at high speeds than at low.

    Like 200-300km/h, drag is minimal, and the force would be negligable. But from 500km/h+, the total drag force is higher, and it would resist acceleration more.
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  4. #4
    It would have to reduce acceleration. The more drag, the more power must be used to overcome that drag to mainain speed. The more power used maintaining a given speed, the less power there is availible to accelerate the aircraft.


    Now I have a question of my own regarding "radiator" drag. On liquid cooled engines, we all seem to have a pretty good understanding of how drag is affected by opening and closing the air tracts. But on an air-cooled radial, the cowl flaps open to exhuast air from the engine cowling. The airflow isn't stopped from the front, so wouldn't opening the cowl flaps allow air to flow through the engine with less deacceleration and less restriction? I suppose opening the cowl flaps would disrupt the airflow external to the cowling, but then it is a question of which has the greater effect. Can anyone help me out here?
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  5. #5
    Franzen's Avatar Senior Member
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    Jun 2002
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    I found that sticking my hand out the window as I drive along the freeway dramatically reduces my speed. I think it's cause I have big hands,......or was it the toll booth?
    lol!
    Sorry guyz, just really bored.

    Fritz
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