Sunday, March 30, 2008

A little local dolphin flying

Saturday's weather was better than I expected, with nice scattered CU's from about noon until about 2:30, though not high enough to go very far from the airport. I took fellow pilot N for a ride in the Grob 103 - I did all the flying, he helped with lookout and strategy. As it turned out, I should have listened to him more.

We let off at 4200' MSL (2700' AGL) in lift under a cloud. The clouds were fairly constant to the north, and we were able to "dolphin fly" a few miles. That means that there's enough lift, and the sources of lift (generally marked by clouds) are close enough that you can fly straight and stay in lift, without stopping to circle. When you're in lift, you slow down to minimum sink speed in order to stay in it as long as possible - ride it as high as you can. Then when you get out of it, into neutral or sinking air, speed up to get to the next lift as soon as you can. So you end up going up and down like a dolphin. (Not at all the same thing as "porpoising," which is an uncontrolled up-and-down pitching - also known as a pitch PIO. Go figure.)

To stay clear of the clouds, the highest we could go was 4600'. When we reached the north end of this little cloud street, we headed southeast across the Hemet valley, moving between more scattered little clouds. We found that the lift was weaker, more narrow, and ragged. No more straight flying, we had to work the thermals, and could not get up to cloudbase as well. N kept telling me it was probably better to the west (over the hills). After getting back near the airport, we headed southwest to try to work some more lift, and didn't find anything useful. Soon we were back down to pattern altitude and had to come back in for a 36-minute total flight. Disappointing, since things were working, and others had longer flights.

The lesson sfrom this flight (seems like there's always a lesson) are:
  • The clouds over the valley were obviously more ragged, less well-defined, than the ones over the hills, but I failed to pick up on that fact. For some reason I thought that a cloud was a cloud, or that they were forming there. The valley clouds had no lift under them. They probably formed over the hills, broke off and drifted downwind over the valley, and then decayed there. Should have listened to N - should have bailed out of the valley back to the hills earlier.
  • When I was under the clouds over the hills, all I could see was the bottoms - they were so close together I could not see the tops of the ones futher ahead. The tops probably had the well-defined outlines that indicate growing CU, but I couldn't see them from below.
After we landed, a student pilot and I considered going up for another flight, but by then the cloud cover was getting much more prevalent. With the sunlight to the ground greatly reduced, we figured the lift would not be working too well, and it was starting to get windy.

On the ground, some of the new student pilots are approaching me with questions on weather and various other topics, which is great since I'm working toward becoming an instructor.

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