Does the induced drag increase with speed?

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Discussion Overview

The discussion centers on the relationship between induced drag and airspeed at a fixed angle of attack (AOA), particularly during the ground roll phase of takeoff. Participants explore how induced drag behaves under these conditions and its implications for different types of aircraft.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions whether induced drag increases with speed for a fixed AOA during ground roll, noting that most graphs allow AOA to vary.
  • Another participant asserts that for a fixed AOA, induced drag will increase with speed, along with lift, and explains that AOA is typically reduced to maintain constant lift at higher speeds.
  • A different participant suggests that during ground roll, induced drag is less significant compared to when the aircraft takes off and AOA increases.
  • One participant proposes that induced drag is approximately proportional to the square of the velocity (V²).

Areas of Agreement / Disagreement

Participants express differing views on the behavior of induced drag at fixed AOA and during ground roll, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants do not clarify the specific conditions under which induced drag is measured, nor do they resolve the implications of varying AOA on induced drag during different phases of flight.

MaxKang
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Does the induced drag increase with an increasing air speed for a given angle of attack?

Most graphs I found online seem to suggest that the amount of induced drag increases as the speed increases but they actually allow the AOA to vary so I was wondering for a case of fixed AOA(ground roll for take off), how the amount of induced drag will vary.

Also for low speed RC airplanes, what is the biggest type of drag on ground roll before taking off? I think I read somewhere on the Boeing website saying that for bigger aircraft, up to 70% is the induced drag for take off but I am not sure if this was related to the ground roll phase or immediately after the plane has taken off.

Thanks!
 
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For a fixed AOA, the induced drag will increase more. Also the lift will increase. The reason that they reduce the AOA is to keep lift constant for the increasing speed. They are interested in level flight with increasing speed.

During the ground roll, the induced drag would not be nearly as great as when the pilot pulls back on the stick for a take off. Pulling back on the stick pulls the nose up, increases AOA, increases lift, and causes a corresponding increase in induced drag.
 
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As a first approximation, the induced drag will be proportional to V2.
 
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Thank you so much!
 

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