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7 Answers

To maximize the time in the air with engine out, would a flaps or no flaps configuration be optimal?

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Aerodynamics

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7 Answers



  1. Brian on Feb 22, 2014

    Clean configuration is best. No flaps.

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  2. Wes Beard on Feb 22, 2014

    Whatever the POH states for the glide speed. Most will state to keep flaps and gear up and feather the propeller if you are able to.

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  3. Mark Kolber on Feb 22, 2014

    Wes, Notice the question was time in the air (best sink) not distance (best glide).

    Best sink is usually not in the POH.

    I think the answer is like the one for max performance takeoff. It will depend on whether a flap setting produces more net lift than it does drag. But I’d guess Brian is right that at last got most of the fleet clean will be best.

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  4. Brian on Feb 22, 2014

    “It will depend on whether a flap setting produces more net lift than it does drag.”

    I’m unaware of a flap setting on any aircraft that will accomplish this. This question differs from the takeoff/best climb angle question in that it does not include thrust in the equation. Flaps increase drag. Period. Since minimum drag is the goal for maximum time in the air (min sink), anything that increases drag will be inauspicious.

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  5. Mark Kolber on Feb 23, 2014

    But Iā€™d guess Brian is right

    Were you disagreeing? šŸ˜‰

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  6. Wes Beard on Feb 23, 2014

    Mark , you’re right!

    Not all flap settings create more drag than the increase in lift. As we all know there are four basic flap designs for small aircraft: plain, slotted, split and fowler.

    If the airplane has fowler flaps, an increase in flap setting will increase the surface area of the wing (up to a point) and provide very little drag in the process. The end result is greater lift with very little added drag. I would say on these types of airplanes having up to 10Ā° flaps would be beneficial.

    On the other end, split flaps will only provide drag with no extra lift. In the middle are the plain and slotted flaps with slotted flaps providing less drag than the plain flaps.

    One of the reasons why we should all strive to know what equipment our airplanes has on it..

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  7. John D Collins on Feb 25, 2014

    So far, I haven’t come across an airplane with fowler flaps that reduces sink rate. The Bonanza I fly uses fowler flaps and I would not use them to extend the time in the air. The best glide speed for my bird is 105 Kts at MGW and a minimum sink is close to 80 Kts.

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