Some aircraft with an angle of incidence or cambered airfoils are capable of climb without any angle of attack, Is there a V speed for the speed at which an aircraft starts a positive climb?

  • $\begingroup$ I'd like to point out that aircraft with an angle of incidence does not equate to zero angle of attack. It means that the wing will have a positive angle of attack when the fuselage is aligned with the relative wind. Regarding your question: I will let the engineers answer, but yes, if a wing is capable of producing lift at zero angle of attack it will obviously start climbing once it attains a certain speed... Are you asking how to calculate this? $\endgroup$ – Michael Hall Oct 22 '19 at 16:03

No, there is no V-Speed associated with zero angle of attack, nor is climb associated with angle of attack. Since zero angle of attack does not directly translate to minimum drag for a production aircraft in operation, it is not a meaningful performance gate, which is what V-Speeds are designed to represent.

However, this is not to say that having a zero flow incidence against the fuselage is not desirable:

  1. If the body-axis is aligned with the fuselage longitudinal axis, it would be desirable from a passenger comfort standpoint to fly at zero AOA during level cruise. We don't want to have an inclined martini glass for the whole duration of the flight.
  2. Non-zero flow incidence against the fuselage does create drag. It would be desirable from a performance perspective to decrease any form of drag during cruise or climb.

This is achieved during aircraft design. The wing setting angle against the fuselage is tuned such that the average operational flow incidence angle against the fuselage is minimized.

  • $\begingroup$ My apologies, I'm confused, My question was for if there was a V-Speed Indicating the aircraft speed at where the lift force would be equal to weight at a zero angle of attack, such as a "Level flight" speed. (Of course, very dependent on the current weight of the aircraft such as fuel level and passengers aboard) $\endgroup$ – James Davis Oct 23 '19 at 20:14
  • $\begingroup$ "Vtos" Is the minimum speed for climb with one engine operative, But what about in normal function? I was thinking vlof, but that does depend on angle of attack due to rotation on takeoff. $\endgroup$ – James Davis Oct 23 '19 at 20:15
  • $\begingroup$ @James The question is, why do you want to lift off at zero AOA? What's special about zero AOA? If you have a tricycle, being able to rotate allows you to decrease the drag during ground roll, which increases field performance. $\endgroup$ – JZYL Oct 24 '19 at 2:13
  • $\begingroup$ general aviation question for me honestly, What about a cruise/level flight where you want to be as level as possible without a change in pitch? ( I understand on my airplanes this requires a 1-2 degree nose up attitude ) $\endgroup$ – James Davis Oct 24 '19 at 3:15

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