"match the rate of rotation is not a recognised or even slightly valid technique."
Originally Posted by
gulliBell
That's right.
souldn't mix recognised and valid here. maybe not recognised but
obviously valid.
if, by yaw, one keeps the horizontal component of thrust vector directed towards the center of a turn then the acceleration is towards the center of the turn.
no overall horizontal speed increase will occur. The bearing of the main rotor thrust needs to not be allowed to change (too much) with yaw if horizontal airspeed is desired, otherwise the new direction of mr thrust will negate some/most/all the speed increase.
seperately: the increased power consumption comes either from the engine (a move sometimes referred to as a 'sexy mushroom', if height is maintained) or in this case a higher rate of descent than would otherwise by the case. the measurement of speed in a steep nose down attitude is slightly confused by the rate of descent counting as speed wrt the longditudinal axis of the disc plane. that is why a flare is (effectively) possible at the bottom of a steep (funnel like) dive with very little horizontal speed.
i hope that answers the points about recognised methods, physics and flare from dive.
i am intruiged by
Scorpygixxer skadi and
Non-PC Plod posts, they do point to some other kind of confusion in this case. I suspect they are right.
Do we think this was a straight forward TR loss of thrust? Does seem strange as these 3 point out.
ShyTorque do you think this kind of helicopter has so little 'weather cocking' that it would go to 90 degrees from the cruise? Difficult to believe.
Hands off on autopilot i can see the pilots might get a bit behind events, especially if accustomed to YStab system dealing with normal yaw variations, but surely a pretty modest reduction in lever and a stick displaced to the right would preserve out of balance controlled flight.
Maybe they retarded the engines (classic mistake) as
Scorpygixxer implies? (I cant really make out the coning angle on my screen, anyone?)
Can't wait to see the report (bets on 2 years plus?), maybe they just did what their sim instructor showed them after he'd talked to a pilot that once did the same
mistake method?
["(Not Vyrnwy but LLyn Peris)" Not LLyn Peris either but Llyn Padarn according to the MOD report. Appendix A, Page 28, of this CAPAP2003_01.PDF is worth a read eg this: "- Shortly after the aircraft appeared to achieve stabilised flight, the nose began to rise and the aircraft decelerated. The aircraft was now close to its critical yaw angle, beyond which airflow separation over the rear fuselage/tail pylon occurs, thereby removing its yaw stabilising, ‘weather-cock’ effect. This angle appears to have been reached after 13 seconds of stable flight, when the yaw began to increase significantly.
" and "that there was a lack of adequate training for such an emergency" (in the RAF? surely not?)]