Sunday, April 29, 2007

There's more than one way to climb a mountain

Yesterday turned out to be a booming lift day and I had a great flight. It almost didn't happen... I had stuff to do in the morning, I am trying to get over a cold, and I was just planning to do a checkride with an instructor in the Grob 103. But when I checked the thermal forcast, it was for over 10kt lift to 14,000', and I knew we had some assembling to do, so I headed out to Hemet. As it turned out, we didn't have an instructor, the PW5 had been reassembled (thanks, guys... I owe you one), and no one was planning to fly it. So after taping the wings, doing a thorough post-assembly inspection, problems hooking up my PDA, and resting a bit to make sure my cold was OK, it was nearly 3:00 before I took off.

It was 103 F! I had not done my usual detailed weather study, so I didn't know the forecast temperature profile, but as I was driving in I could see that the few clouds were only over the high peaks and the bases looked to be about 14,000', so wow - looked like great conditions. Some of the experts on the radio were reporting in anywhere from 12 to 15,000' MSL.

I released at 4500' MSL and hooked a nice thermal right away up to 7500'. Then it was off to the "S" ridge. I found some moderate thermal lift on the low ridge and worked my way up the side of Mt. San Jacinto. I had been here one time before, in the Grob 103 last July. Last time was pure thermal lift, strong and topped by lots of cumulus clouds at about 10,500'. The clouds were the reason I did not get to the top that time.

As they say, though, every flight is different. This time the lift was not so strong, and not so clearly thermal. I found some anabatic lift coming off the ridges, and rode that up a ways. That is really weird stuff. When it's working, you fly toward the ridge of the mountain and the lift pushes you up, keeping you a fairly constant distance above the "spine" of the ridge. I remember thinking it was like magic - but I don't quite trust it, and San Jac's ridges are steeper than where I learned it in the Tehachapis. I don't have a huge amount of experience in the mountains, so I made sure I stayed some distance off the ridge, and turned away when I seemed to be getting too close. I got as high as about 9,100' MSL.

I also knew that there was about a 10kt wind from the west-southwest, and since I was working the side of the mountain that was roughly perpendicular to the wind, there should be orographic ("ridge") lift. But this isn't a classic "ridge", there are lots of canyons to break it up, so I wondered how strong it might be. I have never had any dual instruction in classic ridge lift, so I was really careful. I went back and forth along a fairly steep, rocky cliff and found sustaining lift, but not enough to take me any higher.

By that time I had been up about an hour and a half, and didn't feel like trying something else to get to the top, so I headed back. There was some lift all the way across the valley, so even though I had a 10kt headwind, I got back to the airport at about 5000' AGL. I floated around for a while trying to lose altitude, and I just couldn't. I think the shear line had moved in, because everywhere I went I found sustaining lift. I wanted to stretch it out to a 2-hour flight, which turned out to be easy!

So... that sustaining lift came back to haunt me during my pattern and landing. I hardly lost any altitude on the downwind leg. I extended my downwind leg so I would have some more room to lose height, and even used airbrakes on downwind, which I almost never do. I planned to try for a more precise landing by adjusting my "aiming point" closer to the field, because I've been landing just a bit short lately. Although my airspeed was a bit high on base leg, it was fine on final. I rounded out, and floated... and floated... and floated... Now, a bit of float is expected because of ground effect, but this was ridiculous. I didn't want to pull airbrakes too hard, 'ciz that sometimes causes hard landings. But I was near the end of the landing zone and still in the air. There's a taxiway that crosses west of the landing zone, and it's rough to roll over. At that low altitude and with decaying airspeed, it's not safe to "zoom" over it. So eventually I closed airbrakes and "hopped" over it, then pulled them out and landed on the other side. It's an approved landing area, but usually for downwind rope-break practice... unusual to land there upwind. I've done it before, with an instructor on board. It all worked out OK... it was the right decision for a safe landing. Pilots on the ground agreed. But it was weird. I played back the flight on my IPAQ, and I think my speed was right where it should have been. So... maybe there was lift in the landing zone, if the shear line was active all the way down to ground level? Maybe the wind died, or even reversed? Not sure why it happened, but I was glad to know I handled it correctly.

Sunday, April 01, 2007

Some work and some fun

Saturday we did some more maintenance work on the Grob 103. We took out the seats and some of the interior coverings so we could clean and lubricate all of the accessible linkages. One of our club members has over the last couple of weeks installed several replacement instruments and repaired the landing gear doors. (He's qualified as an aircraft mechanic - it's great to have him as a member!) That's one of the nice things about being in the club: I get to learn to do minor work on the gliders, and there's always someone who has done it before. All that needs to be done now is to get the weight and balance recalculated. That was supposed to happen yesterday, too, but the inspector had a foul-up with his equipment, so it'll have to wait until next weekend. We're all eager to get the big ship flying again, for several reasons:
  • It's a more attractive ship in which to take someone for a ride.
  • It's more comfortable than a Blanik L-13 for some larger club members
  • It soars beautifully. I think I can feel the lift much better in the Grob than in the others.

The afternoon shaped up into a really nice soaring day. Lift was plentiful and relatively strong. The ground temperature heated up to 86F, about 6 degrees higher than forecast and 10 degrees higher than my calculated thermal trigger temp. My thermal tops forecast was 5200' MSL and the NWS's was 6685.

I took off about 2:00, and had a weird tow. The tow started off fast, about 70 kt instead of the usual 60. I kept getting strong lift on tow, got out of position on the high side and got *lots* of slack. I never lost sight of the towplane but did have a big loop of rope under me. I was able to get it out but it was the worst I've ever seen - I usually have very little slack line. The next time the vario showed a really high rate of climb, maxing out at 10kt, I released, at 2600' AGL = 4100' MSL. I got into the lift right away and took it up to a bit over 5000' pretty easily and went in search of more lift. In three or four decent thermals I worked it up to 6000' MSL and that's where it seemed to top out. I cruised over to the Ramona Bowl and back... not very far, but in a different direction than I usually fly.

When my hour was nearly up, I tried some stalls, but the PW-5 doesn't really stall very much for me. It just kind of mushes down. I then tried pulling up more steeply, and it stalled but it pretty much recovered itself.

After I landed, with a 0:56 flight, the next fellow took off at 3:36 and got a 2.5 hour flight nearly to Elsinore, returing on strong shear line lift. I heard some folks got to 7 and maybe 8,000 feet.