Effects of Controls

In which I discover that my Instructor is a lefty, learn about a random assortment of concepts and attempt to taxi without crashing into anything.

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Today I was back to Lilydale for my first official lesson – but really, I suppose, my second lesson. After spending the week counting down to the lesson, I can safely say that I made the right choice in choosing to continue learning to fly – it appears to be addictive.

We started with a briefing again, again using a cute model plane although this time we had to use our imaginations somewhat, as the only model around had two wing engines rather than the single nose engine. J quizzed me on what I remembered from last time about the primary/secondary effects of the different controls. I remembered nearly all of them, except for a (soon corrected) slip about the secondary effect of the Rudder – I said it was airspeed instead of roll.

We then went over what we were going to work on today. Luckily, before we started J warned me that most of the stuff we did today really wouldn’t make much sense at the moment. Since I’m pretty vague on it all already, I’m pretty glad he said that! Today we looked at the effects of airspeed on the controls, slipstream, use of flaps, trim and something else that J wrote on the board (he’s a lefty!) that I’ve completely forgotten atm.

Now, let’s see what I can remember. Slipstream is the flow of air down the fuselage of the plane caused by the propellor.

The slipstream flow of air has the effect of pushing on the left side of the Rudder/vertical fin which pushes the nose of the plane slightly to the left. Slipstream also has the effect of making the rear controls, the Rudder and Elevator, more responsive.

Airspeed also has an effect on the controls. Slower airspeeds, such as when climbing, mean that the Ailerons are less responsive as there is less air passing over them. The Rudder and Elevators are still responsive (or more responsive) because more air is passing over them because of the slipstream.

When lowered, the flaps cause the back of the wing to bend downwards, which means the air flows over the back of the wing is a more downward direction. Wow this sounds confused. Basically, they increase lift by increasing the strength of the upward force under the wing and increase drag which slows the plane.

This picture is a Cessna, but the basic idea of flaps is the same (the dark bits are the flaps if you haven’t guessed already)

When lowered in flight, the flaps cause the pitch of the nose to raise and lower as the plane tries to find it’s new cruising pitch, and the nose ends up slightly lower than it was before.

Finally, I was told that trim would be best explained while in flight. So, we headed off to the plane.

Here, I was given a new challenge – to taxi to the runway. ‘Oh shit’ I thought. J got us trundling, then I took over. Taxiing is controlled by the Rudder and the throttle. The Ailerons don’t have any effect on the ground, and the Elevator is fairly pointless when taxiing. So, I had to control this plane, on bumpy grassy ground, using nothing but pedals and the throttle. We started heading off, and I managed to vaguely correct our course using the Rudder. Steering with my feet felt completely insane. Taxiing is meant to be done at a slow walking speed, which reminds me of music lessons and trying to work out what speed to play when told to play Andante (at a walking pace). I hate things described as ‘a walking pace’ because people all walk differently! J’s walking pace (since he’s about a foot taller than me) would be a hell of a lot quicker than mine I bet. It’s like the ‘reasonable person’ in law, it’s all vague guesswork in the end! Anyway, J told me to slow down a little and I looked at the throttle in dismay. The throttle is a knob that you pull out/push in to change the speed. Me, being observant, hadn’t been watching J do it so I had no idea which way was which. So, I figured I’d find out through experimentation. I pushed in it a little. Bad choice. ‘Oh shit’ says I as we shoot forward, luckily not into anything. I also found out where the brake is and that if you use it while going too fast, you drive the Prop into the ground, which is a bad idea (oddly enough).
After a bit, I managed to get us to the end of the runway in one piece and J did the takeoff.

In the air, we went through what we’d discussed during the briefing. First the effect of slipstream where he put the plane into the climb and I got to experience just how much more responsive the rear controls are at slow airspeed. However, apparantly in the Jabiru, the controls are responsive anyway but there’d be more of a difference in something like a Cessna. Cool, I think I get it.

Then we did effects of airspeed on the controls. I would describe how it felt, but to be honest I totally can’t remember.

Then, we looked at the effect of the flaps. He demonstrated how to lower the flaps (a switch you push down on the instrument panel) and showed me the guage which indicates how much the flaps are lowered. The guarge is located on the left side (my side) on the edge of the windscreen and has a little ball thing inside which goes up/down the tube as the flaps are moved. There is a line in the middle to indicate when the flaps are half lowered. It was interesting, the pitch of the nose moved quite a lot after the flaps were moved as the plane found it’s new cruising altitude and the nose ended up noticably lower.

Finally, we worked on trim. There is a knob (in the Jabiru, a wheel in other planes such as a Cessna) which controls the trim. Basically, by adjusting the trim, it is possible to fly the plane without holding onto the stick. That doesn’t sound quite right. Ok, in normal flight (when untrimmed) the pilot will need to push/pull the control column slightly to keep the nose at the correct attitude. By trimming the plane, it corrects this so the plane with fly at the correct attitude without needing to hold the stick. I think of it as being like a wheel alignment in a car – when the wheels are aligned, you can take your hands off the wheel and still drive in a straight line.

After all that, it was time to head back to the airport. I was allowed to head us back towards the airport, and to lower the flaps on the way. One thing I’m going to have to get used to it using clock numbers as direction indicators – J said “head towards 10:00” and I seriously almost needed to look at my watch to work it out!

J did the landing – a crosswind landing, meaning that to head straight down onto the runway, he had to point the nose towards the right on the approach. It was quite odd to be honest.

I got to taxi us back. Once again, we went slightly too fast and I had to slow us down. Did I remember what I’d learnt earlier about the throttle? Apparantly not, because I pushed it in slightly again. Once again I went ‘oh shit’. Feeling frustrated I muttered ‘I can’t get that right, argh!’ which prompted a chuckle from J I think (hmpf :P). Anyway, I managed to get us back and use the brake which was good.

Next lesson I get to buy some theory books and a logbook. Logbook = proper student, yay! I’m actually excited about the theory books too, if for nothing more than I can revise all the stuff I’ve forgotten today!

Random things I learnt today:

  • Pushing the throttle in = FASTER
  • Smaller sunglasses make the headset a lot more comfortable
  • Without a cushion behind me I can reach the rudder pedals. However, as I discovered during the lesson, reaching the throttle, the brake and the flaps switch is not so easy. I think next lesson I’m going to have to look daggy and use a cushion and basically just accept the fact that I’m short (grrr).
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