Friday, November 24, 2006

Passenger flight

Friends were in town for Thanksgiving, and one wanted to go for a flight. So we headed out today. Since it was a Friday, there were very few people at the gliderport... just one other from my club. We took off in a Blanik L13 at 10:40. We intentionally went early to have smooth air, since this was Mark's first time in any small aircraft. I've learned from taking other passengers that it's best to take it really easy - no thermaling, 'cuz the circling can make people airsick if they're not used to it. And it certainly was smooth. Not even a hint of lift until we were back down to about 1200' AGL, and then it wasn't even zero sink, not enough to sustain us.

Mark had a great time, looking around at the mountains and lakes and taking pictures. We took a 4000' tow since we knew there would be no lift. It was pretty hazy at ground level, but clear above about 2500' AGL. No other gliders aloft, no birds... a couple of power planes well below us. Mark was fine with the flying and turning, so I circled once or twice just as we were at the Initial Point, no more than about 35 degrees of bank. Later he said that was his favorite part! So he probably would have been fine with thermaling, but you never know.

I flew from the rear seat, which I have not done for quite a while. In the Blanik, it's really quite easy to fly from there - the visibility is great. And this particular ship flies really nice. It just came out of annual, and it's really smooth. (I noticed I was a little high on early tow, fighting to keep down with the towplane. Trimming farther forward took care of that problem.) Later, I flew hands-off for a while, and it stayed perfectly on pitch and stayed wings-level for probably 15-20 seconds. We ended up with a 24-minute flight, a little less than I expected. I focused on my landing, since I've had a few rough ones lately. I spotted my aiming point better, kept my speed up through the flare, and had a very smooth two-point touchdown and short rollout. Very nice!

Tuesday, November 21, 2006


Saturday, November 18, 2006

Although the ground temperature got pretty warm today, high 90's, the temperature aloft was too warm to to allow thermals to develop. It was just plain stable all day. None of the club private pilots flew at all. Only the students took flights... and none of them found any lift.

There's this one guy with a private ship... not part of a club. P7 takes off early and stays away all day, when no one else can do anything. I don't know how he does it.

On the plus side, I spent some time working with the club's Volkslogger in the PW-5 and was finally able to get it to send live data to SeeYou Mobile on my IPAQ. (I got an email from the Volkslogger tech support group with the connection info. The VL uses a different baud rate for upload/download mode than it does for flight mode - I never would have figured that out.) I'm anxious to see how flights logged that way differ from flights recorded with my Transplant GPS unit. Based on some ground testing, I suspect my traces so far are off by a couple hundred feet, consistently to one side. I don't know if it's the Transplant or the SeeYou... the test with the VL feed will tell me.

Saturday, November 04, 2006

Staying high

One of our club members recently accomplished a 300 kilometer flight in our PW5. Today we were talking about it, and he related something that I too have felt after my best flights. The feeling of elation and accomplishment stays with you for up to a couple of weeks. After my first solo, my first 10,000' flight, my practical test, and my first cross-country flight, I just did not come down for many days. I kept reliving the flight and felt very excited every time I thought about it. I don't think non-pilots quite understand how thrilling and satisfying it is to accomplish a new flying milestone. But I know my wife has noticed it on a couple of occasions 'cuz she's mentioned it to others.

I think that's partly why I started this blog. I just felt that I needed to write about soaring and share it with whoever would listen... and family and friends can only listen so much. ;-)

Comments welcome! I get very few comments on my blog entries these days... maybe no one's reading. But I'll keep writing.

Thermal forecast spreadsheet

A few months ago I created an Excel spreadsheet to produce the standard thermal forecast chart. In training you learn how to take the forecast high temperature on the ground and the standard lapse rate, compare it to the forecast "soundings" at 3,000' intervals, and calculate a probable maximum thermal height and thermal index. This gets tedious, and would take a lot of time in the morning when preparing for a day of soaring. There are various resources on the web that present this information in one way or another, but not in an easy-to-take-along format.

So, being a computer programmer, I naturally thought of automating it. And since I thought others might want to use it, I wanted a platform that could be easily shared. I decided that Microsoft Excel would be suitable - especially since it has graphing capabilities. It took me a couple of days to work it out, and a couple of versions to get the bugs out. I offered it to people on my club's mailing list and a few took me up on it.

The NWS does not prepare a sounding forecast for Hemet. The closest ones available are for Miramar NAS near San Diego and for Ontario. They're about equidistant from Hemet, and I think the Miramar forecast would have too much ocean influence, so I built my program to use both and calculate an average. It seems to work pretty well. I still use it, every soaring day.

One thing I learned is that just a few degrees of difference at the ground level can cause a huge difference in thermal height. There's a "trigger temperature" at which thermal production should start. Often the forecast maximum ground level temperature is close to the trigger temp, which would mean little or no lift. Just a few more degrees means that the thermals can go thousands of feet higher. Playing with the spreadsheet really shows this. I've always looked at a lot of weather info on each soaring day, and one thing I've noticed is that the forecast temps for Hemet are almost always lower than the maximum we see at the airport. I look at the newspaper (I don't know their source), and Weather Underground, and the NWS. They're all low a lot of the time. Today the forecast was 76F to 78F, and the actual high on our thermometer (4 ft from ground level, in the shade, out of the wind) was 87F.

So I've learned to be a little more optimistic than my thermal forecast indicates.

I don't think there's any way to upload files to this blog site. If anyone wants a copy of my graphing thermal forecast spreadsheet, please reply to this post with your email address, and I'll send it to you. It is not totally generic, it's specific for our field's 1500' MSL altitude. If you want to work with a different field elevation, you'd have to study and adjust some formulas.

A short flight

The weather was sunny and warm with a few high cirrus. The forecast high for Hemet was 76F, and because the forecast soundings were pretty warm that would have meant poor or no lift. Fortunately it was much warmer, about 87F by about 1:30. There were enough thermals for a few folks to get 1 to 1.5 hour flights. I got 39 minutes. Although I found a couple of thermals, they only averaged about 1.5 kt and I could not get above 3500' AGL.

I shared a thermal with one of the commercial Schweitzer 2-33's. Neither of us went up very much. They ended up returning right at the same time I did - I adjusted my pattern a bit to avoid them. Wouldn't you know, I found weak lift on downwind. They were way low and I was way high!

I'm still having an issue with landings. I think I've figured out part of it. I think I'm coming down a little too steeply and rounding out too early, which puts me too far from the landing area. Then I end up closing spoilers a bit - I know not to stretch the glide with elevator! But I do end up slow at just about 1 foot off the ground, and setting down hard as it stalls out. I think I need to pull my base leg closer to the runway so I can keep the spoilers and glide slope about the same, and round out later.