Saturday, November 08, 2008


One of the requirements for the Commercial practical test is landings twice as precise as for the Private certificate. The Practical Test Standard says "stopping short of and within 100 feet of a designated point". I'm told that at our field, that translates to touching down and stopping within the first of our two landing boxes, which I think is about 500 feet long. I've had some issues with touching down too soon, i.e. short of the box, and I've been planning to work on this for some time. But the weather conditions have been pretty good lately, so I've tended to go soaring rather than spend time (and money) on landing practice.

I really need to practice this in a Blanik, since that's what I'll take the test in, but one was busy with students all day and the other had its control surfaces removed for replacement of the fabric, so I decided to practice in the PW5. It's different from the Blanik: lighter, doesn't have flaps, and is different in many ways, but my problem hasn't been with those aspects. My problem has simply been the glidepath to the aiming point. For some reason I tend to pick an aiming point too far downwind from the box border, making it so I have to float too far. In other words, I have tended to come down too steeply during the base and final legs.

Flight #1: I let off at the Initial Point at 1000' AGL. In lift! By the time I got to the point of turning base, I was STILL at nearly 1000'! I extended my downwind leg much further than usual. Full spoilers and forward slip and turning slip brought me down steeply, but again my roundout point was too far downwind. The standard advice is to not adjust spoilers after rounding out, but sometimes I do close them slightly to slow the sink rate. At least with the PW5, that's hard to get right, and it's easy to balloon up a bit. I touched down about 15' short of the line. Braking on the ground was very good (there was about a 6-knot headwind component), and stopping smoothly within the first box was easy. (Speed control is crucial to touching down with little energy, making for a short rollout. This I seem to have no problem with.)

Flight #2: This time I didn't have a bunch of lift on downwind, and had a more normal pattern and approach. Speed was right on, didn't have to mess with spoilers, just kept easing the stick back and floating... floating... floating... touched down about 1-2 feet short of the line. Good rollout again.

Flight #3: I decided to do a normal tow and do some soaring. Gotta have some fun, right? Uneventful flight: let off in lift, went up to about 5800' MSL, didn't find any other major lift. Nice clear day! A bit of lift on downwind, but not nearly as much as the first flight. Speed was a little high but I fixed it. Touchdown was... hmm... I don't really remember, I think still about a foot short of the line. Rollout again was nice and short. The wind was just right to "ground fly" balanced on the wheels for about 30 seconds or so.

On all three flights, I think I only used about 2/3 of the first box - the PW5 really stops short and smooth. So... I should definitely move my aiming point even more upwind on the field, to float further into the box, at least when there's a light headwind. I think that's part of the problem: trying to estimate how much the wind will help kill the float - maybe I'm underestimating that aspect. And flying all three different aircraft doesn't help. They're all different weights and different glide ratios, so adjusting for multiple variables is tricky. When I can nail landings in the first box in both Blanik and PW5, in varying wind conditions, then I'll know I'm ready for the practical. (Not a chance in the Grob - it's way too heavy and its wheel brake is weak. I was lucky to stop it in about 1200' a few weeks ago.)

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