Exercise 10: slow flight

My last lesson was supposed to be about slow flight, but I learned a bigger lesson. You know those "A-ha!" moments, where you abruptly understand something? Satori, the Japanese call it. Sometimes the change in understanding is so big you even find it hard to understand how you didn't understand it before. Learning to fly seems to be a succession of such moments.
The weather was quite gusty, but the wind was straight down the runway, so we didn't have a problem taxying and taking off. As has now become usual, I took the rudder control during the take-off run, and nearly managed to keep it straight down the runway. I took full control in the climb-out, and flew us to the local training area.
On the way, we revised the climbing and descending turns. As I've always been, I was very methodical about each attitude change. To enter a climb, I gradually increased the throttle to full, watching the RPM gauge, added left rudder while keeping an eye on the side-slip indicator, gently pulled the nose up as the airspeed increased, noted it was in the right position above the horizon, checked we were at the 65 mph climb speed, felt for the out-of-trim condition (back pressure on the stick), adjusted the trimmer a little, felt the stick again, adjusted the trimmer again. We were nearly 400 feet above our original altitude by the time I had the aircraft balanced and trimmed for the climb. The story was similar when entering a glide to descend.
After a few rounds of this, the instructor got a little exasperated. "Give me control, and I'll show you what I want." From level flight, I handed over control. He pulled the throttle back smoothly but quickly, keeping the aircraft perfectly balanced, and as soon as the airspeed reached 65 mph he put the nose exactly to the right position. In all, it only took a couple of seconds before we were balanced and trimmed in the glide. He levelled off, and demonstrated entering the climb the same way.
This was a big eye-opener. I'd been treating these changes of attitude as a methodical problem of following the list, like pre-flight checks, but they should be flown as a single, natural movement. With experience, I should be able to tell in advance what the correct attitude, rudder pressure, and trim will be like, and go straight to that position instead of feeling my way there every time.

The other novelty was the experience of flying in wind. It was gusty, and the bright sun brought with it some strong thermals, so keeping a natural movement was quite hard. Just as I'd get everything stable and trimmed, a gust would roll us to one side, or we'd cross a thermal and gain 50 feet before I could recover. Remember that sickly "rollercoaster" feeling I got when I first started, when the instructor was controlling the aircraft? It was like that again, but this time when the stick was in my hands. Although I was flying the airplane, the air currents were sometimes flying it more than I was. Usually, once I get into the right attitude, in balance and trim, there's a chance to shift focus: look at my surroundings more, notice the landmarks, and generally enjoy the flight. But today, I had to concentrate all the time, continually reacting to changes.

The slow flight itself wasn't a big challenge. My flying book warned me that I'd have to adjust the throttle a lot. Below the optimum speed, you need more power the slower you fly, so if your attitude is slightly off and you lose speed, you have to increase the throttle even to maintain that slower speed. Small adjustments grow into big adjustments quickly. I'd psyched myself up for doing that, but it turned out not to be like that. Because of the uncertain weather, we set a stately target speed of 65 mph, which is the speed of the Tiger Moth's best lift/drag ratio. (That's why you climb and descend at that speed: the best lift/drag also gives you the best rate of climb.) At that speed, there was still enough power to recover from small changes in speed, so it wasn't quite the challenge I'd been primed to expect. We didn't even get as much slow flight as expected: on the way back to the airport, the wind was behind us, so our speed over ground was more like 75 mph, and we were back before we knew it.

All in all, I got a lot of experience this lesson, but maybe not the experience I was supposed to get. But as the PPL has a required minimum number of hours at slow flight, I'm sure better opportunities will come along.

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