Originally Posted by
Roger Munyard
Firstly, thank you all for taking the time to reply. In answer to B2N2. I am looking at a situation where a BAe146 fire fighting aircraft is taking off heavily loaded with 3000 gallons of retardant on a runway where it would possibly be more prudent to get airborne following an engine failure than to try to stop. ITo enable this it would be nice to be able to reduce V1 to as close to vmcg whilst still having enough room to get airborne. It is possible there may be software that can give me the information and it would be nice to know if there is and the cost. For a small operator it may be better if there was a formula that could be used to work it out.
I'm just a pilot so FWIW.
When I flew light business jets, Our V1 was almost always Vr. But there were plenty of longer runways where I could have "aborted" from a 100' AGL with the gear up, and easily come to a stop on that same runway.
If you are talking about a balanced T/O V1, it is simply the speed where, given the weight&weather the aircraft can come to a stop before the end of the runway, and the aircraft can continue the T/O, with 1 engine not running, and cross the end of the runway at the appropriate height, and continue climbing afterwards....
Lowering the V1 without changing anything else will achieve your desire to be able to come to a stop on the runway, but it will make it impossible to achieve the required height crossing the DER. The only way to achieve a lower V1, and still get airborne after an engine failure is to reduce TOW.
If you just want a bigger margin on the runway, you could calculate the max TOW, reduce it by a margin for safety, and run the numbers for the lowest V1, or maybe just run numbers for a wet runway...
But there will always be a TOW penalty when you change the numbers from the the optimal balanced T/O performance V1.
(and as someone who has never flown the BAE146, from what I little I know about the performance, I still would be surprised if Vmcg was a big factor in V1)