If on V-rotate or rotate - the point at which the aircraft begins to lift from the ground – something went afoul, could the nose be brought back down and the aircraft brought to a halt before the runway ran out?
This is in regards to jumbos and other heavy masses of flying tin.
I am pretty sure once the nose gear is off the ground it is past the point where the take off can be aborted but it would depend on the legth of the runway. For example, if the runway was 15 miles long then I am quite sure it would be ok.
Thank you sailor
A 15 (fifteen) mile long runway. Those must be big. Where are they? Do you have a cite?
I don’t know of any that are 15 miles long. IIRC, Edwards Lakebed is quite long though. A quick google search just came up with the 3 mile runway and the 9000ft over-run into the lakebed. IIRC, there is a seperate, massive lakebed runway though.
Going back to the OPs question, the pilots could cut the power and bring the nose down, there is physically nothing to stop them. However, the almost certain end result of running off the runway loaded with pax and fuel would likely be a catastrophe. So, if at rotate something drastic happened it is almost certainly safer to try to go get airborne and go around, which is why they would do that. Odds are far better to get airborne, dump fuel and land. They train for that scenario religiously.
Generally, not at Vr, the so-called “rotation speed.” Before Vr is V1, the “takeoff decision speed.” Even if a catastrophic failure occurs at or before V1, the decision to abort takeoff should be make because the aircraft cannot fly, not on whether it can stop. As bernse said, high-speed rejected takeoffs tend to be far riskier than simply circling to land again.
Didn’t Area 51 supposedly have a 10+ mile-long runway?
bernse and av8rmike
From what you both have siad, I will assume, that once a jumbo gets to takeoff velocity, the pilot is commited to flying the plane.
The pilot can not choose to abort the the takeoff, because there is not enough runway left. Am I understanding this correctly?
LL
Yes. You’ve pretty much got it.
IIRC, a 747 takes off at approximately 180mph (I don’t have the data in front of me). A typical (if there is such thing) runway is approximately 2 miles long-ish.
So, if the aircraft was going said 180mph and they needed to abort, they have to bleed all of that speed very quicky. Unless it is a very long runway, they’ll run out of asphalt well before they run out of forward velocity. That is not a good thing.
That is basically what happened with the AF Concorde a few years back. Concorde takes off at approx 230mph and they knew before they even got off the ground they had a problem. However, the Captain thought he’d have a better chance trying to make another airport than almost certainly becoming a 400,000LB bomb plowing into the turf at the end of the runway. End result was about the same though, unfortunately.
BTW, Lower Lip, I just found this page. It gives a nice breakdown of the various V[sub]speeds[/sub] and what they mean and how they are decided.
I was even pretty close with the figures I gave. Go me!
http://www.aerospaceweb.org/question/performance/q0088.shtml
Great replies bernse and everyone else.
As av8rmike pointed out, V1 (takeoff decision speed) occurs before Vr (rotation speed). This means that the decision to continue the takeoff or abort is made before rotation is initiated. In fact, it’s usually made before V1. V1 is an action speed, meaning that action to initiate the abort must be started at OR BELOW that speed in order to safely abort. Considering that the decision process takes at least a couple of seconds, most people will commit to the takeoff about 5 knots below V1.
If a 747 (or any large passenger jet) actually rotated and then tried to abort there’s a very good chance that it would end up going off the end of the runway - at what speed depends on how tight the V1/Vr split was.
As someone else pointed out, high-speed aborts are one of the most dangerous things you can do in an airplane. Even with an engine failure right at V1 its much safer to take it into the air and come back around for a landing than to try to stop after passing V1.
Sounds like it’d be time for a TOGA party?
(Take Off, Go Around) 
Yes, but you see, the TOGA party is always an unplanned but welcome party!
Always carry your sheet, because you never know when a TOGA party will materialize!!
Thaks pilot141 and Bernse for the web link and to av8rmike for your help.
LL
And a small clarification that ought to cause this thread to sink like a flamed-out F-104:
Vr, Vmc, and V2 are dependent on aircraft weight and configuration.
V1 is a combined consideration of aircraft performance and runway length. If you were ever to take off from Rogers Lake or Rosamond Lake up at Edwards my guess is you don’t bother calculating V1. Of course United doesn’t fly out of Edwards anymore.