> A train without breaks isn't really comparable because the planes can break using thrusters.
I'm pretty sure a plane at V1 can't break using thrusters.
I'm pretty sure a plane at V1 can't break using thrusters.
This could be true; it's also not particularly reassuring as a passenger :-)
(Not doubting you specifically, but it'd be nice to have one of the many pilots on HN opine here. My understanding as a passenger is that commercial airliners use breaks because the margins are very narrow, especially in the presence of a tailwind or busy runway designed with breaks in mind.)
Accelerate-stop is the distance needed to accelerate to V1, lose an engine instants before that, take the first action to abort at V1, and the resulting accelerate-stop is the distance between the start and end of roll. On an uncontaminated runway, this is computed without thrust reversers. On a contaminated runway, you can compute it with thrust reverser on the assumed non-failed engine(s).
Accelerate-go is the distance needed to accelerate all engines to just below V1, lose and recognize the loss, continue to Vr, rotate, climb, accelerate to V2, and reach 35 feet above the ground at V2.
When the accelerate-stop and accelerate-go are the same for the chosen V1, we call that the balanced field length.
Brakes are critically needed to achieve anything close to the book accelerate-stop distance.
Technically I think the takeoff speed is VRotate, where the plane is rotated and actually starts to leave the ground.