Hi

I was presented with the following problem a few days ago: how to precisely land on a forest clearing or a small field.  A conventional landing wouldn't work because the fields are  surrounded by tall trees and the ground is not flat and probably full of small trees and bushes. The size of the clearings is unknown.

I have considered the following methods for precise and short landing:

Spoilers - increase drag and reduce lift.

  • Pros: steepen the glide slope
  • Cons: increase stall speed

Flaps - increase lift and drag.

  • Pros: reduce stall speed
  • Cons:

Deep Stall Landing - the airplane "falls" to the ground in a stable stall.

Example --> http://youtu.be/dRr4AVZgr0Q?t=1m23s

  • Pros: low horizontal speed (short landing distance)
  • Cons: high vertical speed ( about 5 m/s or more), might damage the payload

Parachute - the parachute can be attached either to the entire plane or the payload alone. In the after-mentioned case the payload would be dropped by parachute and the plane could be landed normally on a short field because it has become very light.

  • Pros: precise landing
  • Cons: complex deployment system, has to be correctly packed, extra weight on the plane, might get stuck on a tree

Hover landing - the plane pitches up, achieves a stable hover and hovers vertically to the ground.

I have not seen this method being used. I've only seen aerobatic planes and foamies hover like this.

  • Pros: low vertical speed, precise landing
  • Cons: no idea whether it works, requires a big motor

Net landing - the plane lands in a net of some sort. The plane dives into the net.

  • Pros: precise landing
  • Cons: the net would be a hassle to set up

I do not have any experience with any of the mentioned landing methods. I would like to keep things very simple and not use a parachute or a net for landing.

I am not sure whether flaps/spoilers are enough to steepen the glide slope enough to make a very short landing.

I really like the deep stall method, because of its simplicity, but am afraid that the vertical speed is too high for a safe landing.

I also like the hover landing, but I don't even know if the idea is reasonable or not.

What are your thoughts on this subject? What method would you suggest?

Do you know any other methods for making short landings?

Regards

Martin

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Replies

  • Developer

    Take a look at the landing here with 90 degree flaps on a funcub. (near beginning of video).Throw in an auto-pilot that can slide-slip and you would be able to come in even steeper !. Add in Sonar landings, to detect the ground for the flare.

  • I have a similar problem with some of the stuff I do. I have a quadshot that I will be testing soon.

     http://thequadshot.com/

  • A spiral or corkscrew pattern like used by the military for Baghdad International should work. Helicopter pilots in Vietnam  used the spiral technique for taking off when overweight and needing to build up forward airspeed while in ground effect.

     

    Regards,

    Mike

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