This weekend I was the commercial pilot on duty and shared a thermal with our club's Duo Discus on a couple of occasions. The first time, he started lower than I did and passed me up in the thermal. Now, granted, the pilot was one of our guys who does a lot of racing so his skill level is higher than mine and he has more stick time than I do for sure so maybe it's not a fair comparison.
And, I was with a passenger. Having cleaned up vomit in the cockpit before, let's just say I'm careful about circling with passengers! But this passenger didn't mind and I kept checking to make sure he was okay. So maybe it doesn't count so much.
I guess what bothered me most was that I had hold of the thermal and was on about the third circle without successfully centering it all the way around. The Duo joined us, circled a couple of times, then seemed to move about 1/4 of a mile away and started a similar circle where the lift was stronger. I sighed and moved over there. Sure enough, the lift was better over there.
How did he know? Luck? I doubt it.
The second time the Duo appeared about 200 feet below me in a thermal and quickly made it up to my altitude but then was unable to outclimb me. We circled and rose at approximately the same rate. I suppose the lift could have been stronger below me and weaker where I was. Or, I just got more competitive and attuned as the Duo got closer.
Or, I just adopted the Duo's circling pattern and managed to match his rate of climb.
I also made a discovery as we were circling at the same altitude. It may APPEAR that the guy on the other side of the circle is climbing but what may be happening is that you are flattening out or descending. I realized this as I exited what I thought was the weaker side of the thermal and watched the Duo enter the same air. He appeared to catch an updraft and moved from even with the horizon to slightly above it.
How could that be?! I had JUST BEEN THERE and there and the lift was weak over there. How could he be climbing? After a moment, I entered the same spot he was in, expecting to get lift the same as he did but didn't really get much. I glanced over to the Duo and realized we were even in altitude again. Since I didn't climb, he must have descended.
Eventually, he exited the thermal at my altitude after another minute or two. The contest was a draw, except that I started higher then he did and he ended up at my altitude but couldn't climb above me.
Maybe I shouldn't let it bother me and perhaps it is just a part of my learning process. I'm an okay pilot, I can certainly stay in the air and don't come down any more frequently than anyone else, but I want to be better than that. I understand the process of finding the lift and centering it. I've concentrated on trying to center it quickly, within 1-2 turns. I can usually do that and when I've had trouble, other pilots tell me that they've had similar trouble, so I know I'm at least average at thermal hunting and centering.
What I'm lacking, perhaps, is the search element of thermaling. I try to lock on to the best lift in a thermal. I'm not afraid to move my circle around to try to find it. I vary my bank angle to find the best lift. All good, but I would NOT have decided to move my circle a full quarter mile away to see if there was stronger lift over there. I would think that would be a waste of time. The conditions were blue and there was nothing to indicate even the size of the lift area, like the size of the cloud above. Still, he moved over there and that was better.
Did he observe in other thermals that the lift was better northeast of the main thermal? Was it simply luck? It's hard to say and that makes it harder to learn.
Perhaps a ride with a cross country instructor would help. Or maybe just some more practice.
3 comments:
Hey! I have heard from the Ohlmann Courses that they activly fly into sink areas to confirm that it is there, just to establish the mental model of the air currents flowing about.
The competition pilots often have exepectations to a thermal. If it's not as strong as it "should" be they fly on and look for it.
The often proposed mental image of a round uniform thermal is actually wrong.
Thermals often are coming from several sources and the laminar flow of one thermal often draws another thermal into its path.
We should imagine thermals more like fluids, or air bubbles in water in slow motion.
So in short: if the thermal isn't fitting into the normal "average" but the overall picture should yield a stronger climb, so its very likley that there is a stronger one around.
This is what I gather so far. Its my theory and it may be wrong entierly.
"air bubbles in water in slow motion" is absolutely right. I tell my students to spend time observing big pots of boiling water. Note how the the bubbles:
- Often start at stationary positions at the bottom of the pot
- Change course, split up, merge with others on their way to the surface.
- Note how some grow, some diminish and simply disappear
- Observe how bubbles interact with each other, e.g. move around when a faster one ascends nearby.
Now imagine this in a grand scale, super slowmotion.That will give you at least some idea of the chaotic environment we fly in.
Just reviewing comments in the blog - thanks for your inputs. I've gotten better at thermaling on average but sometimes find myself in a situation where I have good lift on one side, sink on the other. Moving the circle towards the strong lift doesn't help. Tightening the bank to more than 45 degrees has helped on those occasions when the core was obviously small.
There are still those elusive ones where I just never seem to connect. Fortunately, there are fewer of those than when I first wrote my post. I know it's a lifelong learning process, which is what makes it very interesting!
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