Wheel Landings

[Bob Kuczewski]

There's no doubt that wheels on a hang glider contribute to increased overall safety. But just as with seat belts and air bags, there are times when they don't work as planned and can even make matters worse. I'm posting this video not to discourage pilots from using wheels, but to make pilots aware of their limitations.

This video clip was taken recently at Dockweiler of a pilot making an intentional wheel landing. The wheels used in this case were very broad and intended for landing on sand. But even in this case, the wheels happened to hit the sand in a manner that severely limited their effectiveness. Here's a frame by frame clip played at 1 second per frame:

This clip contains about 50 frames. It may take a little while to load, but once loaded it should play at 1 frame per second.

F_2420_to_2471.gif (2.41 MiB) Viewed 5972 times

Conclusion: Wheels are great, but beware of their limitations!!!

[SamKellner]

Hi Bob,

The frame by frame gives one perspective of what went on, the continuous video might be helpful too.

From what I see, the wheels, rolling or not, had little to do with the glider nosing over.

It's difficult to tell.

[Frank Colver]

Yes, it looked to me as though he didn't attempt to flare, so the glider nosed over. It might have even done this on a hard surface as well, if there was not enough angle of attack to support the front of the wing.

fcolver

[Bob Kuczewski]

I posted the frame by frame version because the full-speed version goes by very quickly. I had a lot of trouble uploading it, and some of the early versions (up to a few minutes ago) didn't show all the frames. So you might want to watch it again now that it's all there.

I'm somewhat convinced that the wheels stuck in the sand because of the way the pilot's body swung forward into an almost upright position just after touch down. There was little or no flare because the pilot was doing an intentional wheel landing - intending to roll the glider onto the ground. As an airplane pilot, I was trained to flare slowly holding the landing gear off the ground as long as possible until there just wasn't enough lift to keep the gear from touching. Of course that means that the wheels must be just inches (or less) from the runway or you'll get a bit of a bounce when it stalls and drops. We called that "greasing it in", and it was very smooth when done properly. In a hang glider, that can be a challenging task ... especially for someone relatively early in their training.

My post here was mostly to point out that a wheel landing can sometimes be much more challenging than a "stand up flare" or a "run it out" landing. Human legs are much more nimble and adaptable than wheels, and they have a lot more "give" when needed (up to a point of course). I don't believe in "one size fits all" approaches, and each technique has its advantages and limitations. It's good to know when each technique will work and when it might not.

[Frank Colver]

I always used wheels on all of my hang gliders but mostly for those "oops" landings to protect the down tubes and me from the sudden stop. However, another big reason was for ground handling. Moving the glider to launch and then moving out of the LZ without having to carry the glider. I don't recall ever landing on the wheels on purpose.

FC

[JoeF]

tag: safe splat safe-splat
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? Limit line
? Sand ski
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Pilot may not have understood a need to push out at the effective moment to get inertia of mass pushing the wheels approximately parallel with sand deck. Limit line on pilot body to keel or basebar would have saved some lives and some broken necks in the past.
It would be interesting to know how high incident pilot was in chest clearance at prone hang check.

[Bob Kuczewski]

Pilot may not have understood a need to push out at the effective moment to get inertia of mass pushing the wheels approximately parallel with sand deck.

... he/she should have pushed out as far as possible just before the wheels touched down. Dragging feet would help slow the glider and lift the nose also as the wheels hit the sand.

I think you're both right.