Originally Posted by
134brat
Wot no drag chute?
No allowance is made for the Brake Parachute in the Stop element of the takeoff calculation. The chute only figured in the brake energy calculation where you could find the Normal and Emergency Maximum Brake speeds (NMBS/EMBS) with and without the ‘chute. In any event, the brake parachute is more effective at high speed, When you realise you’re going to overrun it’s probably not going to make any difference.
It’s important to bear in mind that takeoff performance calculations only assume a failure of the most adverse power unit. No other failure is allowed for. This is why when carrying out a deliberate accelerate/stop manoeuvre you have plan it very carefully as there are additional factors in play. It pays to be very conservative in your approach and execution.
It is many years since I did any Vulcan takeoff performance planning.and IIRC the philosophy was a “high” V1, called Decision Speed in those days. Lower figures would be Vmcg limited. This of course would not apply in a pre-planned accelerate/stop where it might be prudent to restrict the speed below what would theoretically be possible.
It will be interesting to learn what actually occurred but I fear it might be a “Shoreham” moment for accelerate/stop demonstrations.
YS