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Old 10-05-2003 | 02:25 PM
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majortom-RCU
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From: Merrimack, NH
Default RE: Scale factor and wind velocity

I cannot resist stepping up to this business about stable flight in steady wind. Where is this steady wind about which I have read so much? Does it ever occur in RC model airspace?

Yesterday, against my better judgment, I finally put on a flying demonstration for my niece & nephew and a couple other family members who have been asking for a couple years when were they going to see me fly. It was a windy day. Trees were bouncing all over the place. But having driven a few hours to visit them, I said we'd go to the field and decide then whether it was too windy. Got to the field, checked the windsock, about 12' up from ground level, it was streaming about 45 degrees out, didn't look all that bad, and of course it was straight across the runway.

So I took off my pretty little Venus. As soon as I reached about 20' altitude, it was like flying inside a washing machine. Hairiest flight I've ever made or seen. I really thought somebody must have de-trimmed everything on my plane. Half the time I had zero recognition of change in flight corresponding to change in controls. The only stable attitude seemed to be knife-edge, blowing away from me (far away, fast!), just like a boat overpowered by strong wind and heavy seas.

I was really proud of myself for saving a low-level inverted nosedive that came out of somewhere upwind. The peanut gallery was cheering me on, thinking all this was part of my demonstration. Three times I brought it around and tried to crash it not too hard. The third time I got it a few feet off the ground, upright, headed down the cross-wind runway, and somehow put it on the ground in one piece. I looked the plane over carefully, expecting to see all the surfaces out of trim. But they were all nice and neutral.

The only stable parts of this flight were within a few feet of the ground. Above let's say ten feet there was no stability whatever. I like to fly with soft and smooth inputs. Practically every move I made on this flight was full stick one way or full the other, and even then it wouldn't move the way I wanted, or if it did it would snap over and go the wrong way in the other direction.

When I came back to the fence, I got raving compliments about the great show, but how come the flight didn't last longer? In the outward calmness of my desperate concentration on flying, as far as they could see or imagine, I was in total control.

I suppose there is a valid theoretical notion about steady wind of any velocity supporting stable flight in any attitude. But the practical value of this concept for flying real models in real wind, in my experience, is close to zilch. If you want to land safely, I will say less than zilch. I hope the theoreticians will pardon my getting this off my chest.