2.2 (9) Aircraft Performance

At this time, I was a third of the way through TEST PREP. I had to repeatedly review what I learned before while learning new items because I was easy to forget. That was really a problem.

When I flipped through the pages of this chapter “Aircraft Performance,”

I had a bad feeling.

It's all math problems... and the long explanations are all in English.. That's right, everything you learn here is calculation (with some tables and graphs) because these are the Weight and Balance, Density Altitude, Takeoff Distance, Cruise Power Setting, Landing Distance, and Headwind and Crosswind Components that you will learn here.

But it went well as the instructor carefully taught me how to do the calculations, which were addition, subtraction, multiplication, and division, which even I could do. Moreover, I was able to calculate better if I tried them repeatedly while thinking about the meaning of the calculations. Only in terms of the written exam...

The “Weight and Balance" is, as the name suggests, a calculation of two items: weight and center of gravity (CG).

First, I learned about the Weight. The heavier the aircraft is, the higher the required takeoff speed is, resulting in a longer takeoff run. If you take off from the short runway, that would be a vital situation. The too heavy aircraft would cause reduced rate of climb as well as cruising range and speed reduced. Furthermore, the excessive loads would be imposed on the structure, especially the landing gear. Any of these is not good.

What impressed me the most was a video that my instructor showed me later in the ground school in the US. It was a video of a small plane overloading and crashing shortly after takeoff. This was a shocking video to me, and I knew I can never disrespect the weight calculation. My consideration was that there is already a default method of calculation, so it is enough to do it correctly, but the important thing is to calculate it with a strong sense of safety.

The same applies to the Center of Gravity (CG). It would also affect stability, which was referred to in my past article “2.2（2）Basic Aerodynamics” (2.2 (2) Basic Aerodynamics | 自家用操縦士訓練物語～超怖がりな私が空を飛んだ日（My PPL Training Days） (ameblo.jp) ) of the aircraft, which is one of the important safety issues. For the Cessna 152 that I flew in the training, it would be OK that we should mainly think about longitudinal stability (pitching) unless the both sides’ fuel consumption is unequal. Even this kind of thing was surprising to me.

In Chapter 10 of the PHAK, the center of gravity (CG) is defined as a point at which the aircraft would balance if it were suspended at that point.

From my PHAK Translation Notebook

If the CG is not within the range specified by the aircraft manufacturer for each aircraft (CG Range), it will adversely affect recovery from a stall, performance, and required control forces. The CG Range is published in the data contained commonly in a thick binder, called POH (Pilot Operating Handbook).

Since the CG varies depending on instruments and equipment installed, POH should be published by aircraft even if the type of aircraft is the same, which must be on board. Therefore, for everyday studying, we use a booklet called Information Manual which states common information only. This means that we must use the data stated in the POH of the aircraft to be flown for computing the weight and balance.

The Information Manual (or POH) contains not only the weight and balance data but also lots of important information such as aircraft data that we are to memorize at the oral exam, Emergency Procedures to be demonstrated at the checkride, routine Preflight Inspection, the aircraft’s Performance data, and so on. Above all, the most impressive to me was Airplane & Systems Descriptions full of small English letters on each page.

In my second flight school, suggested by an instructor because I was not good at the aircraft systems, I was taught about it more times than the other students. At the time, reading these pages alone was beyond my ability and aspirations and I had no drive. But fortunately, I read them with him, which made me get interested in aircraft systems that I had not been good at.

This chapter was useful for actual flights. For example, when I was learning about "New Engine Break-In and Operation," I never thought I would fly the plane with the engine newly installed. But later, in fact, I flew the airplane right after tits engine was replaced. I recall that the different type of oil should be used until a total of 50 hours has accumulated and that gentle control of power should be needed. When increasing power slowly, I was suggested by my instructor it was too slow... LOL

The items in TEST PREP include the takeoff distance, cruise power setting, landing distance, headwind and crosswind component, and maximum range performance.

To begin with, I had no idea what the aircraft performance means. As for air density, it took me a long time to understand that air density is determined by air pressure and temperature. It would be easier to understand if the air were color-coded according to the density varied.

Furthermore, the definite disadvantage was I cannot read a graph. I was probably the only one who asked the question, "What does this graph mean?" I was truly a bad student.

But once the flight started, performance computations were in fact important for various considerations, such as whether the distance required for takeoff was sufficient, whether the aircraft could land safely in these wind conditions, or whether the runway was sufficient to extend the touch down point to avoid wake turbulence due to the preceding aircraft that just took off from behind during landing. Under such circumstances, I found performance computation important and enjoyed thinking about it. Another important thing for flying was air temperature, which I recognized while solving the computation problems of TEST PREP.

Anyway, I tried to practice computations repeatedly to solve them exactly. To be honest, it was such a hassle.

At this time, despite my complaints, I was coming to the end of TEST PREP and had already learned a lot. It was around this time that I realized how much fun it is to be a pilot, thinking about how many different types of studies you really do. Little did I know that I would actually get scared and cry when actually flew (LOL).

Next, I will discuss the Enroute Flight. It is about computations using a flight plotter (something like the combined version of a ruler and a protractor) and flight computer as well as preliminary knowledge for navigation. (continued)