Sunday, April 06, 2008

First solo spins

Today the general weather forecast was not so great, so I guess that's why no other pilots were at the field. But the thermal forecast was actually not that bad, and a "marine layer with reverse clearing" meant that there was a lot of moisture to form clouds. There was quite a bit of CU over the hills, and it was working well, if not very high. Cloudbase was about 5200' MSL, so I got up to about 4700' most of the time. It started getting murky rather than being a very defined cloudbase. One time I got a thermal off to the side of a cloud and got to 5200'. One time I got down to about 1800' AGL and thought I might drop out, but I found more lift and was soon up to cloudbase again.

Other than a couple of commercial glider flights and a hang glider, there was NO ONE else up in the air. I ended up with a flight of an hour and 20 minutes, and I could have stayed up longer. (This was in the PW5.)

Since I had a consistent source of lift for a change, and enough altitude to be well above the 1500' AGL aerobatic floor, I took the opportunity to do my first solo spins. I've done them with two different instructors in Blaniks (a long time ago and recently) and as a passenger in a biplane, and I've studied several resources such as the pilot's manuals for all of our gliders. I've also studied some online articles to firm up my "book" knowledge of how spins really work. Some time ago I did spins (not always intentionally) in the SOTS flight simulator. I figure if I'm going to become an instructor, and I'll have to teach spins eventually, I might as well start getting more comfortable with them.

I started off with some stalls, and hardly noticed the wing-drop tendency I had seen in the PW5 some weeks ago. It took me a while to get my courage up to actually enter a spin... but I was as prepared as I was ever going to get.

The first time I tried, it did not spin, just kind of dropped off to one side and self-recovered. The next time I kicked the rudder fully left, and down we went. I came out of it after only a half turn... but it was fully spinning, with quite a nose-down attitude. Boy was my heart pumping!

Later in the flight, after nearly getting down to pattern altitude and then working back up to cloudbase again, I did one more spin. This time I came out after 3/4 of a turn. It seems to take forever to go around! Just before or as I was coming out, it seemed like I was pulling quite a bit of G force. I didn't get dizzy or anything, but did get a bit of a head rush. When I had completely pulled out I was doing about 70 knots. When I upload my flight trace, it'll be interesting to see what speed was recorded during the spin and recovery.

I've decided that the hardest thing I've done so far in the air was to NOT apply opposite rudder right away! All my training and instincts make me want to stay straight and level, to avoid spinning out of a turn. To do it intentionally, to watch the ground spin up at me, and to know there was no instructor along, and to STAY in the spin, was scary. I'm sure it will get easier the more I do it.


Update: I analyzed my flight trace, and found that my peak speed (as estimated by GPS) was 82 knots at the end of the spin; I had estimated it at 70. What I didn't write yesterday was that I was not sure whether that was faster than normal. I know that spins should have a stable speed, and spiral dives can increase in speed, so I wanted to be sure I was spinning and not spiraling, since that speed struck me as rather fast. But I went back to the PW5 manual, and it says spin recovery is at 81 knots. And it says the load factor is 4 Gs, so the head rush was not all in my head. So these spins were perfectly normal.

The GPS doesn't record anything that would indicate the glider position (and therefore turns) during the spin. The flight trace, recorded at 4 second intervals, just points straight down. But my ground track before and after the spins confirm about 1/2 turn and 3/4 turn, which I had visually estimated based on ground features.