A Windy Flight


The winds were calm on Saturday evening May 10 so I decided I would try for a Sunday morning "dawn patrol". The plan was to fly the 14 miles from the airport back to my farm and then make the official first landing on the new 20 acre field (purchased this winter) which will become my new runway. The runway will actually be a mowed level portion of the new horse pasture. We just got it harrowed and seeded and the little grasses are already up. I made a couple flybys last Fall but had never actually touched down.

I walked the field Saturday evening picking up rocks where I intended to land, some the size of softballs. I thought at the time how nice it would be to have some headwind for my landing the next morning as the field was still rough. The forecast was for south winds at 10MPH (perfect) and a night time low of only 43 degrees. A might chilly. Later winds were to increase to 20MPH with a chance of rain about noon.

Driving to the airport before dawn I almost ran off the road to avoid hitting a Great Blue Heron which flew in front of my truck. By 6:15AM I was nearly ready for takeoff and the wind was south 10-12. The takeoff was normal until I reached about 400 ft AGL when I noticed the ground sliding sideways quite a bit. Apparently the winds aloft were stronger and more from the southeast.

I made excellent time flying back home with a quartering tailwind but by the time I got there I was flying a ridiculous crab angle. The plane pointed south as I flew due east looking over my left shoulder to see where I was going. There was also a fair amount of turbulence near the ground downwind from any trees or buildings. My new runway is parallel to a woods and the turbulence there will no doubt be considerable.

I decide to keep my flyby simple probably without a full landing. I can see my wife watching below and she has never seen me fly in this much wind before. It's obvious I'm being tossed around. She said later it reminded her of a Monarch Butterfly on a breezy day. I made two passes each time a little lower and could have actually landed but decided not to risk it. On the 3rd pass I stayed high but slowed up as much as I could and headed straight into the wind. Nose high, hanging on the prop, I actually did park it up there and actually lost ground for a bit. It was really windy.

Time to head back, so I climbed up to 800 AGL where it was smooth and warmer and pointed her toward the airport. Nothing happened. I added throttle and waited some more but saw little ground movement. I could see it would take much too long to get back this way. The wind up here was really cooking.

My choice was to drop back down to 150-200 feet where the ride was much bumpier due to ground turbulence but where I would make decent progress. If I saw a 2-3 mile stretch of land with very few trees or buildings I would drop down even more. Gone were those dreams of a quiet dawn flight skimming low and pleasantly along the bare planted fields. This was real rodeo air. From my flight times I estimate the wind at 25-30 with gusts, though the official surface wind was 15MPH. Landing back at the airport was very short and I found it was too windy to taxi. I had to get out and push it by hand. It was windy!

Most of the time during the flight I felt reasonable safe. Ultralights can fly in considerable wind if you avoid exceeding your maneuver or structural cruising speeds so the gusts loads don't break the wing. I did have unplanned excursions of the bank angle of up to 30 degrees but seldom more than that. Landing in such conditions is the problem. Regardless of the power of your ailerons or engine, a really good gust or downdraft at 10-20 feet AGL will probably bend something.

I noticed something unusual during the return flight with it's strong direct crosswind. The Sky Pup ultralight kept trying to turn downwind. PLEASE, before you jump up to remind me that a plane can't tell which way the wind blows, I know, I know. But I discovered it CAN tell from which direction the gusts are blowing. A traditional ultralight with dihedral (6 degrees) such as my Sky Pup or a quicksilver will respond to a side gust by raising that wing and beginning a turn. It always tries to coordinate itself.

After a 30 minute cross country flight with a strong crosswind, my left foot was tired from kicking rudder countering the gusts trying to raise the upwind wing. I suppose a flat winged ultralight with little or no dihedral might respond differently. Mine kept trying to turn downwind. I assume that positive wind gusts must outnumber negative gusts (or lulls) or something else must be going on. It's not the mythical downwind demon, it's wind gusts. Earlier in this flight, I made easy smooth turns in the upper layer of even faster warm air which had no turbulence.


I am reminded that sometimes they shut off the ultralight flying at Oshkosh due to wind. Even though the planes and pilots can manage, the windy conditions are too much for the spectators. It's not a pretty sight, watching ultralights bouncing around the pattern like little rowboats on the ocean. It scares the visitors and guests.

Daniel Grunloh (grunloh@uiuc.edu)
University of Illinois at Urbana-Champaign

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