Originally Posted by
Mars
That timeline is interesting.
Those among you who flew the S61 on the North Sea (Penzance, and probably elsewhere) in the 70s will remember the 'oblique' take-off procedure - probably the first use of an approved quasi-vertical procedure. The language of the procedure was interesting: after rotating from the hover, wait for the ASI to flicker (a technical term), rotate and pull full power; for a failure at or before TDP (can't remember what it was) maintain the Nr (hope that the topping was set correctly) and maintain the burbles (another technical term), overpitch to land.
It was absolutely necessary at the specially built facility at Forus, Stavanger and Penzance (can't ever remember calculating the TODR).
I wonder if there were any other of those approved pioneering profiles for other types?
Bristow devised a profile for the B212 they named the 'Group A Overland' , that involved operating at RTOMs considerably higher than the RFM Group A Helipad profile. The technique was to climb vertically to 20 ft, checking both engines were matched and producing full power, then rotate 5 degrees down - effectively putting the nose on the horizon and then climbing on the 'edge of the burble' without actually passing through ETL. TDP was when the tips of the pitot tubes passed the boundary of the rejected take off area, or 180 ft, whichever came first. The rejected take off technique varied a bit with height, but immediately prior to TDP involved a large nose down pitch, with Nr recovery, and then a flare at the bottom assuming you had managed to build up some useful airspeed. As a TRE there was very little margin for error and intervention and, like many training exercises, there were more accidents practicing than from real engine failures - mostly just bent skids and dented egos! I had one candidate have a brain freeze when I rolled off the throttle and he pulled back on the cyclic - I can still recall the sensation of vertical speed in my stomach, as I grabbed the controls!