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.
P.S
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.
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Daniel Grunloh (grunloh@uiuc.edu)
University of Illinois at Urbana-Champaign
http://www.staff.uiuc.edu/~grunloh
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