Just to illustrate what I had in mind when I wrote about a phugoid in post #493.
The following graph shows the variation of speed and height that would result in the following conditions:
- the airplane is initially in level flight at a constant speed of 110 kts TAS
- at t=0 thrust is instantaneously increased to that required for stabilized climb at a flight path angle of 8.5 degrees
- after t=0 thrust and drag are constant and both act in the direction of the flight path, i.e. no thrust component normal to the flight path
- angle of attack is constant, i.e. no damping
- the variation of air density is negligible
This is of course entirely theoretical, but it illustrates the effectivity of the artificial damping in OK465's simulator exercise, combined with the effect of increasing thrust in 2-3 seconds instead of instantaneously and of the thrust component normal to the flight path.
It also illustrates the fundamental difficulty of controlling the flight path with thrust alone, without the ability to control angle of attack.
P.S.
The graph illustrates the point I made in the discussion: the acceleration starts immediately, the flight path changes after some speed increase.
