The definitions of V1, V2, ASDR and TODR are all based on the failure of one engine being detected at V1.
But if any given aircraft type were to be able to continue the take-off with more than one engine inoperative, then the same physical principles would apply.
Acceleration rate is greatest with all engines operating. If any of the engines are inoperative, the acceleration rate will be less, so the distance required to complete the take-off will be increased.
If we carry out the entire take-off with all engines operating we will use a cert TODR to reach V2 at screen height.
If we carry out the entire take-off with one engine failed, the acceleration rate will be less, so the (TODR) distance required will greater.
Changing the value of V1 changes the fraction of the take-off that must be carried out in each of the two conditions. Reducing V1 increases the fraction of the take-off that must be carried out at the reduced acceleration rate. So the TODR required is increased. Increasing V1 increases the fraction of the take-off that is carried out at the higher acceleration rate. So the TODR required is reduced. So increasing V1 reduces TODR and decreasing V1 increases TODR.
Last edited by keith williams; 19th February 2014 at 11:40.