• Flaps on short and soft field takeoffs?

    I'm sure this has been discussed, but I can't find it. I have two CFIs for partners in the Sundowner and they have different opinions on using flaps for short and soft field takeoffs. You CFIs out there, do you teach using flaps for short and soft field takeoffs? If so, how much flap? Do you dump flaps on a short field landing or use flap drag to slow down?

    For the rest of us, do you use flaps for short or soft field takeoffs? How about the Mousevator?
    Comments 6 Comments
    1. Unclerap's Avatar
      Unclerap -
      Not a CFI, but according to the POH the lowest stall speed is with full flaps, that means full flaps creates the greatest lift. So if soft field length is not the issue, and if the field is really soft (mud?), then I'd use full flaps for takeoff and landing. Soft and short, match the flap to the aileron and go.

      Rap
    1. AtlantaSundowner's Avatar
      AtlantaSundowner -
      I respectfully disagree about taking off with full flaps. The first notch of flaps at 15 degrees will create more lift than drag. 25 and 35 degrees of flaps will create more drag than lift, although they do also create more lift. With full flaps you are going to increase your ground roll, since the engine is pulling an airframe with more drag.
    1. Unclerap's Avatar
      Unclerap -
      You actually agree with me, full flaps create more lift. The drag thing will create the need for a longer runway, hence my "if soft field lenght is not an issue."
    1. rkittine's Avatar
      rkittine -
      Yes, more flaps will create more lift but at a certain point the drag created is more than the lift, hence why you take off flaps (from full) in a go-around, stall recovery etc. As pointed out 15% of flaps in these airplanes is about the where there is more lift created than drag, hence it can be approach flaps or take off flaps. When I do transition training in the Sierra, part of the early air work is to let the student do a drag vs. lift / sink, demonstration so they can see what each flap setting does as well as what happens gear up or down and prop high pitch or low. I teach all my instrument students to use Approach Flaps (level of flaps that they have been able to demonstrate that has more lift than drag, from the procedure turn inbound. Also all I use for soft or short field takeoffs, though rotation, flying in ground effect all are different for the different requirements.

      Bob
    1. Pat Long's Avatar
      Pat Long -
      Here’s my two cents. I am a CFI and I teach what the aircraft manufacturer recommends. For the Sundowner, it recommends no flaps for soft or short field take off. Although I did try it a couple of times. Did a soft field take off with partial flaps deployment, I can’t remember if I used 15 or 20 degrees. The result was, I was airborne earlier but the airplane was a lot sloppier while I accelerate it in ground effect. I found no benefit to trying something that is not recommended by the manufacturer. No it’s not prohibited, but in my opinion, not worth the effort. Pat
    1. maxmason's Avatar
      maxmason -
      Quote Originally Posted by Unclerap View Post
      You actually agree with me, full flaps create more lift. The drag thing will create the need for a longer runway, hence my "if soft field lenght is not an issue."
      Full flaps on the mice have no benefit whatsoever during your take off run. It is the equivalent to 40% throttle. Yup you will get airborne eventually.

      PS.. I sure would not want to be sitting in it, with the stall horn blowing none stop and the sluggishness of a beached whale.
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