Can the STOL modifications made to an airplane's wings, vortex generators, etc, be made to a helicopter's rotor blades, and if not why?


While in the military someone explained a helicopter's rotors are basically like wings, ie same aerodynamic principles. If possible, integrating STOL modifications would increase the efficiency of the blade.

3 Answers

  • John R
    Lv 7
    4 years ago
    Favorite Answer

    There would be no point in this, and they would actually detract from performance.

    STOL modifications do not increase total lift, they simply allow the wing to generate lift at a lower speed, often by allowing it to operate at higher angles of attack without stalling.

    But there is no such thing as a free lunch in aerodynamics - while a higher AOA allow you to create the needed lift at a lower speed, a higher AOA also means greater induced drag, wasting the power you would use to climb.

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    • Richard4 years agoReport

      I thought I read the noise came from the blades spinning through the air. The faster they spun the louder they were. I thought if you could increase the amount of lift, but decrease the number of times the blades spun this would make it quieter. Thanks for clearing this up.

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  • 4 years ago

    No, you can't. Rotor blades are made with symmetrical airfoils to prevent the center of pressure from moving with changes in angle of attack. Since helicopters can already hover... and since a certain blade RPM is required to maintain rigidity of the rotor... ...and since a lower blade RPM would mean a lower airspeed for retreating blade stall... there is no advantage of making a rotor 'STOL'.

    Some of the rotors for the human powered helicopters have STOL characteristics like very high camber... but these are very lightly loaded (so VGs wouldn't be of any use) and are quite impractical for any meaningful directional flight.

    • Richard4 years agoReport

      I thought the STOL type improvements would mean the blades could move at a lower RPM, but still generate the same lift.

      Thanks for telling me about the human powered helicopters. It kind of supports what I was saying and shows me this wasn't a completely stupid question. Have a great week.

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  • 4 years ago

    a helicopter can VTOL so STOL modifications are a moot point.

    Improvements to helicopter rotors have included paddle tips or swept tips, the blades themselves are probably too narrow for modifications like vg's to have any meaningful effect.

    People have investigated blowing from helicopter blade leading edges as a means of improving performance, eg link.

    • Richard4 years agoReport

      I've also thought it could be too narrow. I've seen those modifications. That's partly why I ask. I believe they're are made to STOL aircraft wings. I've also wondered if the issue is the whole blade changes pitch rather than just flaps. Blowing from the leading edge may produce supercavitation.

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