D.P. Davies V AP 3456
Hi everyone,
I was wondering about a certain statemet made by the author of the famous book "Handling the Big Jets" and its validity weighed up to statemnts made in the famous RAF training manuals, specifically the flying one - AP 3456 Volume 1, Flying.
On page 149 of HTBJ, three statements are made as to why an aircraft pitches nose-down during the transonic flight regime. The author points out that, for one, the aircraft pitches nose-down because of the flow desturbance over the wing caused by formation of shockwaves on the upper surface of the wing, thereby causing the CoP to shift rearwards. Now, based on the explanations in the AP3456, this is not true. The rearward shift occurs because, eventually, the upper shockwave starts mowing rearward due to lack of resistance to the airflow at a high Mfs number, thereby restoring the lift coeffecient, because at this stage, BOTH shockwaves are at the rear, thus the whole wing is again producing lift.
The second "problem" I have is that, the author says the A/C becomes unstable during this nose-down pitching scenario, whereas in the AP3456, the exact opposite is stated i.e. the aircraft has increased longitudinal stability - I agree with the latter based on my understanding of stability in general.
Could those aerodynamic gurus please clarify the above (I hope I have typed it out rather clearly) since I value both sources, but in this case they are in conflict.
Thanks...