Thermal flight - shoulda, coulda, woulda

Labor Day weekend had great weather for thermal soaring at Crystal. It got up to about 97F.The forecast was for thermals to 15K-18K, and there was a little moisture in the air which meant there was a possibility of cumulus clouds at about 14K. After dealing with some maintenance issues, I took off in the PW5 about 1:30. We really climbed fast on tow, and by the time we got to the First Ridge we were already at 2500 AGL and flying through thermals. I thought I'd be smart, save a little on the tow, and let off in a good thermal instead of towing up into the mountains. I let off with the vario nearly pegged, but when I tried to get into it I could find no lift. No sink, but no lift either. I worked little bits of lift near the golf course and the wash (not known to be great sources) and could not seem to climb, and could not get away from the airport. At one point I got down to about 1500 AGL and was thinking about landing to take another, higher tow, but I stuck it out and finally found a decent thermal. There was a significant wind from the west, and I had to hunt upwind to stay in it. Finally it really started to cook, and I got up to about 9,000 MSL (5,600 AGL). That enabled me to head into the mountains and work the Second Ridge.

In the mountains I found thermal lift and some lift that seemed to be ridge. At least one glider was visible thousands of feet above me, working up near the base of one of the few CU's within striking distance. Eventually I got up to about 11,000 MSL and headed deeper into the mountains. I've had a goal of reaching the top of Mt. Baldy, which several of our club pilots have already done (and some did that day). But I had wasted a *lot* of time scratching in that first thermal, and I knew that G was waiting for his turn in the glider after me. So I had to turn back a few miles short of Baldy. As I headed back west I continued to go up, and reached 12,000 MSL quite easily. I could have gone up to probably 14K if I had had more time, but I stopped at 12K and headed back.


Since I was now over the desert at over 11,000 feet, I headed northeast and overflew a private airport known as Gray Butte, and still got back to Crystal with thousands of feet to lose. After pulling spoilers to lose altitude more quickly, I landed after a total of an hour and 24 minutes. My altitude gain was 6,100 feet. I recorded the flight on my GPS/PDA but have not had time this week to upload and analyze it.

I shoulda held on to the tow instead of letting off early and wasting at least a half hour hunting the first good thermal. Then I woulda had more time at high altitude and coulda reached Mt. Baldy. So that goal is still in the future...

Nice Thermal Passenger Flight at Crystal

Some months ago I met a colleague M at work who is an instrument-rated power pilot but had never been in a glider. We finally got our schedules in sync and went out to Crystalaire this Sunday. We talked about flying there from Fullerton airport in his club's Cessna to maybe save some time. (Conversely, I've never been in a Cessna.) But there was a good possibility of morning overcast in the LA basin, so we decided to drive up instead. The forecast high was about 95-99F with only 5 knots of wind from the southwest, so it looked like a good day for thermals. I printed out both the thermal forecast and the wave forecast so I could go over them with him on the drive.

We talked about the contrast between M's flying experience and mine:
- He typically flies in congested airspace, and usually files IFR even in VFR conditions.
- I typically fly in uncontrolled airspace, and have only talked to ATC during a couple of flights.

One of his main concerns is staying clear of other traffic. Usually all we see are other gliders and the towplanes. Occasionally a military transport or helicopter passes through the Crystal area, but they're pretty rare. When we do see other gliders in the air, we often circle with them in a thermal in very close proximity, so this was going to be a quite different experience for him.

After prepping the glider and having some lunch, we had quite a delay waiting for a tow. Seems the second tow pilot scheduled for the day was sick, so things were taking a while with just one. It was plenty hot on the ground, probably about 99 or 100F; the OAT gauge in the Grob 103 read quite a bit higher and I didn't believe it. We took off about 1:30, took a 3500' tow (up to 6900' MSL) and let off in strong lift. Other pilots had reported "zero sink everywhere, and narrow thermals". That's what I found over the Second Ridge - bits of lift that would take us up 100' or so at a time, but nothing great. And it was not acting like the wave lift from my last flight. (The wind was not strong at all, and no rotor turbulence.)

I tried all the way down the slope of the Second Ridge and found little, so we headed back over the desert. I always hate to give up on the mountains, because although there's often good lift over the flatlands, it's never been tall enough to let me get back up on the hills. On the way back I let M take the stick and rudder for a few minutes to get a feel for these long wings.

Not far from the airport, we found one of the "house thermals" and climbed quite well. It took some work to stay in it, but we quickly gained over a thousand feet. After tanking up a bit, we flew around looking at the area, tried a couple of stalls, and worked some other minor thermals.

We went back and found that house thermal again. It got stronger and easier to exploit the higher we went. M spotted another glider off in the distance, and it soon came over to join us, at least a thousand feet below. It was a high-performance DG-1000, and soon outclimbed us: better ship, better pilot. Once M saw how this whole "gaggling" process worked, he was fascinated and really enjoyed the experience. Although the other ship was just a few hundred feet away from us at times, his climb was slow relative to our position. We kept our positions pretty well on opposite sides of the circle, so we really never approached each other. It's really quite fun to thermal together - a slow dance in the sky - as long as there are not too many ships to keep an eye on. M had a great time. A third glider (a lower-performance trainer) came in below us, at least a thousand feet down, and never got up near our altitude.

We got up close to 8,000 MSL, and the DG headed for the hills, so we did too. I found a little bit of lift over the lower part of the hills, and we flew for a while about a thousand feet higher than we had released in that same area. So that marks the first time I have been able to get back from the desert to the mountains. I did not find anything to take us higher than 8,000', but I think the DG pilot did.

After about an hour and a half of flight, we decided to head back. M was nearly out of water, and that's a long time to sit in a glider the first time. We came back in for a total flight time of 1:40. M was amazed at the distance the glider floated in ground effect after flaring - another difference due to those long wings.

All in all, a fun day introducing another pilot to soaring.

Mountain wave passenger flight

My friend Jim has been wanting to go for a glider flight for a long time, and we finally decided the only way we'd work it into our schedules was to take a day off work and just go. He'd been in a small power plane before, so we figured he'd do fine in a glider. Today the forecast for Crystalaire was for 99F, good thermal lift, winds out of the west-southwest at 10 to 15 knots.

We took off about 1:00 in light south-southwest winds and let off in good lift over the Second Ridge. We very easily gained 2,000 feet, and then another 1,000. Couldn't quite break the 10,000' mark, but it was working well. I kept the banking to about 35 degrees, and Jim handled it just fine. I looked around for more lift, and all I found was light sink and some turbulence upwind of the ridge. It was a little puzzling, because the south side of the ridge wasn't working like ridge lift based on where I thought the wind was coming from. Not finding a second thermal, we dropped off the hills and out to the desert... and found no lift there either. We landed after 38 minutes. I knew the lift must be better than that, because other gliders had been up for an hour or more. Jim was game, so we decided to give it another try.

We let off again in good lift, a little higher this time. I heard two other gliders on the radio trying to make visual contact, and one said he was at "13,400 in wave over the Punchbowl". Hmm... I'm over the Punchbowl too, but about 4 to 5 thousand feet lower. Huh? Wave? Duh! Of course! Wave! That wasn't thermal lift last time, and it wasn't random turbulence south of the ridge, it was rotor! The wind was blowing over the tops of the mountains, bouncing off the floor of the valley south of Second Ridge, and going up. So... I flew parallel to the ridge and immediately contacted smooth wave lift at about 5 knots. Then 6 knots. Occasionally 8 knots. Eventually 10 knots! In no time we were over 11,000 feet. I found where the rotor started south of the wave, and found the apparent east and west limits of the lift. We got as high as 12,200 feet, though much of the time we were down around 10,500. This is more like it!

This was really only my second time flying in serious wave lift, so I spent some time exploring the limits of it and just enjoying the view and giving my friend a nice smooth scenic ride - that wave lift is amazingly smooth! After about an hour and a half we decided to head back out over the desert and shoot for a two-hour total total time. I knew that losing 6,000 feet would take a while. Heading north, I found sequential patches of moderate turbulence and smooth lift. So I think I traversed secondary and tertiary waves. As we were wrapping up our flight, I heard one of those two other gliders going in for a landing, but the other checked in at 16,000'. We ended up just two minutes short of two hours on that second flight.

So my lesson for today: a south or southwest wind across the San Gabriel mountains can set up wave where I have been looking for thermal and ridge lift. What's surprising to me is how short the wavelength is. From the top of the ridge where I think the wind is getting deflected upward, to the upward flow of the primary wave seemed to be about just 3.5 miles. All the soaring educational materials I've seen about wave talk about the wind bouncing off a stable air layer down low, not off the ground, so I have not been thinking about the wave setting up right in the mountains, but that's what it seems to be doing. And the wind was not all that strong: 10 knots on the ground, not sure how strong at altitude. So I need to think about wave forming in a wider variety of conditions than the books talk about.

A great day!

Thermal and ridge lift today at Crystalaire

Our club planned an outing for the long weekend, but it did not go as planned due to the weather. The NWS issued wind warnings for the Antelope Valley, and many of our club members decided not to go. I've seen that sometimes the Crystalaire area is not as windy as the surrounding area, and we already had reservations at a place nearby, and we had nothing else planned for the weekend, so my wife and I went anyway. Well, I should have listened to the NWS this time! Saturday started out not too bad, just light winds at ground level, but upstairs it was a different story. Some very experienced glider pilots and tow pilots came back saying it was the worst turbulence they'd ever seen, and by about noon everyone was calling it a day. Sunday was forecast to be cool, cloudy, and windy, so we packed up and went home. These things happen sometimes with weather-related sports.

Monday was looking much better, so I headed back out. It was warm, clear, light wind forecast. The morning inversion was forecast to dissipate, with thermals possible up to 8500' or so. (I use NOAA's soundings web site at http://www-frd.fsl.noaa.gov/mab/soundings. Check it out! If a formal sounding is not available for your favorite soaring site, it will interpolate one from the closest available ones.) Forecast high was for 76F, but NWS often underestimates desert high temps, and I know it got up to about 81F in the afternoon.

Some other folks wanted to do dual flights in the Grob, so I flew the PW5, taking off a little before 2:00. I let off in lift at 7700' MSL, and found a weak thermal right away, but it only took me to 8200. Eventually I found some that got me up to 9200, and I went farther east than I have before, just a couple of miles. I'm still kind of conservative at this site - I like to stay fairly close to home until I get comfortable with how much altitude I need to get back from various locations. (I did not take my flight computer today.) I could see other gliders at least a couple thousand feet higher, but I could not seem to beat 9200'.

One problem is that the variometer on this glider is intermittently unreliable. That may sound redundant, but it's true. Some days it works fine, other days it's all over the place. Last time I flew, it was fine, and we concluded that maybe there was water or debris in the static lines that had resolved itself. Well, the gremlins were back today! I intentionally took along my clip-on electronic vario, but there are two problems with it: 1) it's not very loud, and 2) it only tells me about lift, not sink. Flying in the mountains, I'd like to keep an eye on the sink as well. So... although it may sound like an excuse (especially to the seat-of-the-pants gurus), partial vario info makes me not want to go very far into the mountains. I think we need to tear the whole static system apart and clean it out.

Some of the lift was too widespread to be thermal, so I began to think it was ridge lift. There was a bit of a northwest wind - I could tell from my drift. I did not think it was strong enough to really generate much ridge lift, but apparently it was. I need to rethink my image of ridge lift: instead of a classic ridge perpendicular to the wind, this terrain was a bunch of short ridges, some of which were oriented against the wind. So each little spur was generating its own lift in a small area. Something to remember and try to exploit in the future.

I developed a bit of a headache after an hour or so. I turned on the oxygen for a while although I was only at about 8500', thinking it might help... it didn't. So I didn't push it, I came back to some of the closer ridges and worked some well-known thermal generators such as the Chimney. I was able to work a thermal up to 9700'. After about an hour and a half I decided to go out over the desert and try a few things.

I realized some time ago that my flying style is pretty "tame": wings-level most of the time, fairly gentle turns, never getting much above best L/D speed except to get out of sink. I've wanted to loosen up and have a little more fun in the air, but often I do not have enough excess altitude to experiment very much. Today I did, so I played around with some dives and climbs and steep climbing turns. Not quite what you would call wingovers, but definitely more extreme than I usually do. (Yes, instructors, I did clearing turns first.)

I found a few thermals over the desert, and could have stayed up longer, but I came in at just under two hours.

The lift was definitely working today - other club members went to the top of Mt. Baldy - I just didn't quite connect with the best stuff. That's on my to-do list for a day when the instruments are working better, and after I've studied the charts a bit more so I know the distances and escape routes.

RSS Feed

I've set up my blog with an RSS feed. You may now see an RSS logo in your browser which you can just click to add Roger's Soaring Blog to your RSS reader. If the icon doesn't appear or doesn't work, you can use the following URL:

feed://rogersoaring.blogspot.com/feeds/posts/default?alt=rss