Wing flaps: Increase/decrease flow separation at low speeds?

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    Flow Separation
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Discussion Overview

The discussion centers around the effects of airplane wing flaps and slats on flow separation at low speeds, particularly in the context of their role in increasing lift and drag during landing. Participants explore whether flaps help avoid flow separation or contribute to it, and the implications of using these devices at different speeds.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions whether flaps reduce flow separation at lower speeds, comparing a wing with flaps to one without.
  • Another participant suggests that if flaps cause separation, it indicates they are being used incorrectly at excessive speeds.
  • A different participant notes that both flaps and slats can reduce stall speed, implying a relationship between these devices and flow behavior.
  • One participant confirms that flaps increase lift and drag, emphasizing their importance for safe landings, while cautioning against inducing stall conditions.
  • It is mentioned that leading edge slats are a newer development that help maintain stable airflow at lower speeds.

Areas of Agreement / Disagreement

The discussion contains multiple competing views regarding the effects of flaps and slats on flow separation and stall speed, with no consensus reached on whether flaps definitively reduce or increase flow separation at low speeds.

Contextual Notes

Participants express varying assumptions about the conditions under which flaps and slats operate, including speed and angle of attack, which may influence their effectiveness in managing flow separation.

koolraj09
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Hi all,
I was just reading about airplane flaps. From I what I understood, they increase lift and drag (at lower speeds) to help land the aircraft.
Do flaps also reduce the tendency of flow separation at lower speeds?
Let's say we have an airplane wing with no flaps (Case I) and airplane wing with flaps (Case II)? At lower aircraft speed does the case II help in avoiding flow separation or it will increase flow separation?

What about slats? Do they reduce the flow separation at lower speeds?

Thanks
 
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If they cause separation, they are being used wrong at too high a speed.
 
Yes they increase lift and drag. which is exactly what you want for the safest landing.
Not to the point where the flow over the wing becomes unstable though, that's a stall.
Lift gone, but still much drag.

Flaps do most of the work; the leading edge slats are a more recent development which help keep the airflow stable at lower speeds.
 
Last edited:

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