Hi gums,
the magnitude of the phugoid oscillations is a function of the thrust change from that required for level flight. If thrust had been set for a gradient of 4 degrees the amplitude of the speed oscillation would have been halved and 100 ft achieved after 10 seconds.
A gradient of 8.5 degrees with landing flap and gear down near stall speed is quite healthy for a transport airplane.
Last edited by HazelNuts39; 21st Feb 2014 at 15:14.