What effect does lowering flaps for takeoff have?
- Reduces takeoff speeds only.
- Reduces the landing speed only.
- Reduces both takeoff and landing speeds.
Explanation
Selecting flap for take-off raises the maximum lift coefficient, so the wing reaches the required lift at a lower speed, shortening the take-off run. The question concerns the take-off case, so the reduction applies to take-off speed; landing speed is a separate selection not in scope of this take-off scenario.
thatoneonly asking:
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Community Comments (2)
3
3g_nitro Posts: 3 06.10.2016 / 18:09
Flaps increases the mean camber line hence more lift is produced. Therefore, less speed is required during the take off roll to generate the same amount of lift if the flaps were up.
The answer is "reduces takeoff speeds only" because for take off the flaps are deployed slightly (e.g 15 degrees) as opposed to during landing where you will need full flaps down (e/g_ 45 degrees). This is due to the drag and other factors.
The answer is "reduces takeoff speeds only" because for take off the flaps are deployed slightly (e.g 15 degrees) as opposed to during landing where you will need full flaps down (e/g_ 45 degrees). This is due to the drag and other factors.
J
JD2016 Posts: 54 12.12.2016 / 00:47
This is another dodgy question.
Flaps reduce both takeoff and landing speeds. But if the questioner only wants to know about takeoff, then I suppose reduces take off speed is correct. If so, the object of this question is not to test your knowledge of flaps, take off and landing performance etc but to see if you can read the question precisely!
You don't need flaps to land at all. You can carry out a flap-less landing. World War 1 biplanes didn't have flaps at all. However flaps allow a lower approach and touch-down speed and a lower nose attitude, giving a better view of the runway.
For takeoff, use of say 10 degrees flap results in an earlier lift-off because the flaps give a higher CL (Lift coefficient) in the formula L = 1/2 x rho x V squared x CL x Area, than a clean wing. That means better obstacle clearance for a short field take off. The climbout profile will be flatter/less steep with flap.
Flaps reduce both takeoff and landing speeds. But if the questioner only wants to know about takeoff, then I suppose reduces take off speed is correct. If so, the object of this question is not to test your knowledge of flaps, take off and landing performance etc but to see if you can read the question precisely!
You don't need flaps to land at all. You can carry out a flap-less landing. World War 1 biplanes didn't have flaps at all. However flaps allow a lower approach and touch-down speed and a lower nose attitude, giving a better view of the runway.
For takeoff, use of say 10 degrees flap results in an earlier lift-off because the flaps give a higher CL (Lift coefficient) in the formula L = 1/2 x rho x V squared x CL x Area, than a clean wing. That means better obstacle clearance for a short field take off. The climbout profile will be flatter/less steep with flap.
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