December 14, 200520 yr Here's an interesting article I happened on:http://www.weathergraphics.com/tim/747sim/They do a simulated takeoff run and abort right at V1, but using only the brakes, they overshoot the runway. The moral of the story is, use thrust reversers.But wait! If you lose an engine, isn't reversing thrust on the other potentially dangerous?
December 14, 200520 yr Would it be cheaper to potentially roll the plane, or to take out a few hundred thousand dollars worth of approach lighting and localizer equipment? :-hah----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach John Morgan "There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach
December 15, 200520 yr >Would it be cheaper to potentially roll the plane, or to take>out a few hundred thousand dollars worth of approach lighting>and localizer equipment? :-hah>It's cheaper to take out the approach lighting. Right?You'll most-likely collapse the nose gear too - in an airplane full of fuel!I guess my question was, do they really set V1 so high that they can't stop without thrust reversers? I didn't know that. I always assumed V1 was a brakes-only stopping speed.
December 16, 200520 yr Obviously, the article was written by somebody who does not actually work for United. You are supposed to be able to stop without reverse, because one of the scenarios of a V1 cut is loss of powerplant or powerplants. In the article, he obviously was a little meek with the brakes at the beginning of the abort and wasted much valuable runway and time in applying sufficient deceleration.
December 16, 200520 yr Author The accelerate-stop distance does not include the use of reverse thrust. You should be able to stop the airplane on the runway (or runway plus stopway if there is a stopway) from V1 without using the thrust reversers.A few comments:1. V1 is the speed at which the brakes are applied. If you hear the V1 call, and you have not yet applied the brakes, you will not stop within the certified accelerate-stop distance.2. There is no mention of spoiler deployment. If the spoilers are not deployed, braking effectiveness is drastically reduced.3. The runway length should have been more than enough for a successful rejected takeoff at their takeoff weight.Don S.
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