Page 513 - PPL-engelsk 2025
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Principles of flight
If the thrust is too high,
the aircraft will
accelerate until a
speed is reached
where thrust and drag
are equal.
When going from climb to horizontal straight flight:
- 50 feet before altitude, the aircraft’s nose is lowered
- a little before the desired speed, the PWR is reduced to cruise flight setting
- the aircraft then is trimmed
5.10.3.1 Force, effect, speed
Force is an influence on a body that causes it to accelerate.
When the plane is stationary with the engine at full speed, it pulls well and the
thrust force is high.
As the speed increases, the excess thrust force decreases (the blue line)
Power is performance per unit of time, e.g.
Hp. The power output increases the faster
the plane flies. The power of piston engines
decreases with altitude, unless there is a
turbo (the green line)
5.10.3.2 Best range and best endurance
When we are going to fly horizontally straight, the speed can, theoretically, vary
between being a low safe speed, where there is a good margin for stall speed,
and being a speed where we use the highest permitted continuous engine
power.
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 513
