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According to a poster, 60% and 15% would be added if no brakes or reverse thruster.
So if a 737 normally used 3000 feet landing at 125 mph, adding 75% is 5250 feet. That's about a mile for a 737 to roll to a stop?
That poster would be incorrect. I don't believe the poster is a pilot as there are no landing distances published for "no brakes". That poster is confusing braking distances derived from losses of system(s) with your question regarding coasting to a stop (zero brakes).
I'm type rated in numerous transport category jets and I can assure you there are no published stopping distances for a scenario involving no brakes. We have "non-normal landing configuration" charts involving loss of various hydraulic systems, anti-skid, partial flap, zero flap, assymetrical flaps, jammed flight controls, etc. but nothing regarding how far it takes to coast to a stop.
There is no "general rule" in regards to coasting to a stop.
A 737-700 at 130,000 pounds with no wind on a dry non-sloped runway has an unfactored landing distance (including 1000 feet of air distance) of about 3000' using flaps 40 and max manual braking. You've likely never experienced max manual braking on an airliner unless you were onboard during a high speed rejected takeoff. The brakes may start on fire. Tires may deflate or explode. It can be a big deal.
5750' is not going to happen unless the runway is uphill into the wind and made of sand. Forget the previous poster's "general rules".
Not 5750, but 8250. Also, the 3000 assumes spoilers and reverse thrust, correct?
The OP specifically mentioned "no brakes or reverse thrust". Since he mentioned "rolling to a stop", spoilers are immaterial to the discussion and landing distances are not predicated upon reverse thrust anyways. Do you know why spoilers deploy after landing?
OP,
There is no easy answer to your question. You would have to do some serious plugging and chugging on your Casio TI-34 to come up with any hypothetical numbers. Suffice to say, if the absolute theoretical best a a 737-700 (which is a small, slow landing variant of the 737 series much lighter than any 767) can do repeatedly is around 3000 feet under perfect conditions with max braking, it would be a fair distance more to stop by coasting.
High bypass jet engines have cascade thrust reversers which mostly dump forward thrust as opposed to the old clamshell buckets that generate true reverse thrust. You could actually power back from the gate in the old days. Not so with cascade style reversers.
Last edited by Campfires; 02-14-2017 at 08:58 PM..
With all of the research and studies of aircraft, it's surprising that a 'no brakes' experiment has never been done. [or we don't know about it]
I can assure you that flight tests include landing with no brakes. I frequently land with no brake application until about 25 knots, about the time I am turning off the runway. This is in A320 series aircraft with full reverse and adequate runway. Especially helpful on hot days with a quick turn and you don't want to heat up the brakes (no brake fans ).
Edit: by the way, I am not turning off at the end of the runway, but the last high speed.
With all of the research and studies of aircraft, it's surprising that a 'no brakes' experiment has never been done. [or we don't know about it]
Not really. It's nearly impossible to have no braking ability. Even with a loss of all hydraulic fluid, the accumulators still have fluid to apply pressure as long as you don't pump the brakes.
There are multiple redundancies for every system on commercial aircraft. Many airports now have EMAS in the overrun areas so even if your scanario played out, a pilot could likely pick a long runway and use aerodynamic braking until they ran off the prepared surface. That would significantly slow the aircraft in the high speed regime. I'm confident I could slow a 737 aerodynamically enough on most runways we fly into to roll off the end at a speed that would result in few if any serious injuries. With EMAS, I'd feel very confident.
The OP specifically mentioned "no brakes or reverse thrust". Since he mentioned "rolling to a stop", spoilers are immaterial to the discussion and landing distances are not predicated upon reverse thrust anyways. Do you know why spoilers deploy after landing?
OP,
There is no easy answer to your question. You would have to do some serious plugging and chugging on your Casio TI-34 to come up with any hypothetical numbers. Suffice to say, if the absolute theoretical best a a 737-700 (which is a small, slow landing variant of the 737 series much lighter than any 767) can do repeatedly is around 3000 feet under perfect conditions with max braking, it would be a fair distance more to stop by coasting.
High bypass jet engines have cascade thrust reversers which mostly dump forward thrust as opposed to the old clamshell buckets that generated true reverse thrust. You could actually lower back from the gate in the old days. Not so with cascade style reversers.
But spoilers and reverse thrust could be used on a landing without brakes. That's why I broke it down for each failure.
But spoilers and reverse thrust could be used on a landing without brakes. That's why I broke it down for each failure.
The OP clearly specified "no reverse". He appears to be looking for landing distance predicated on aerodynamic braking only.
Please show us the flight test data from Boeing and/or Airbus confirming your assertion that flight testing has been done with no brake application. It isn't in any of the non-normal landing distance charts at any of the 4 airlines (2 majors) that I've flown at.
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