General > General Technical Chat
With Travel Halted, What Happens To The Planes?
paulca:
--- Quote from: langwadt on August 12, 2020, 06:35:13 pm ---
--- Quote from: jogri on August 12, 2020, 04:45:10 pm ---
--- Quote from: langwadt on August 12, 2020, 08:43:56 am ---that's not a landing that is an aborted takeoff
--- End quote ---
Yeah, and a nominal V1 (maximum speed at which a start can be aborted) is around 160 knots while a landing with MTOW will get you in the same range (usual landing speeds are in the 130-150 knots range)... So the only main difference is that the tires never left the ground for the aborted takeoff, but other than that a fast landing produces a similar strain on the aircraft than an aborted takeoff.
--- End quote ---
at an aborted takeoff there probably much less runway left to stop on, braking is much much harder
afaik thrust reversers are not even on the minium equipment list
--- End quote ---
Original video looks like flight trials. The rejected takeoff test has to be V1, maximum takeoff weight, no thrust reversers, the plane must stop on the runway and be able to exit the runway. Meaning it must be able to put the brake fire out and taxi under it's own power off the runway. Often when a rejected takeoff happens the brakes can go on fire and lock up, closing the runway until engineers can unlock the wheels.
No thrust reverses is because rejected takeoffs very often happen when there is an engine failure and you can't really use thrust reverses without symetric thrust.
Thrust reversers are usually banned at airports for out of schedule movements... ie. out of hours, like at night when there are stricter noise abatement requirements.
On gliding an airliner (or anything for that matter) it's all about the number 1 gauge, speed. Fly the pitch/aoa to maintain the speed you need and take whatever descent rate you get. It's a recurring problem that airline pilots are so heavily trained in procedures, checklists and "flying the numbers" that they simply forget to "fly the damn plane".
langwadt:
--- Quote from: paulca on August 13, 2020, 10:37:16 am ---
--- Quote from: langwadt on August 12, 2020, 06:35:13 pm ---
--- Quote from: jogri on August 12, 2020, 04:45:10 pm ---
--- Quote from: langwadt on August 12, 2020, 08:43:56 am ---that's not a landing that is an aborted takeoff
--- End quote ---
Yeah, and a nominal V1 (maximum speed at which a start can be aborted) is around 160 knots while a landing with MTOW will get you in the same range (usual landing speeds are in the 130-150 knots range)... So the only main difference is that the tires never left the ground for the aborted takeoff, but other than that a fast landing produces a similar strain on the aircraft than an aborted takeoff.
--- End quote ---
at an aborted takeoff there probably much less runway left to stop on, braking is much much harder
afaik thrust reversers are not even on the minium equipment list
--- End quote ---
No thrust reverses is because rejected takeoffs very often happen when there is an engine failure and you can't really use thrust reverses without symetric thrust.
--- End quote ---
asymmetric thrust must not be a big issue since the MMEL for the A320 allows for one nonfunctional thrust reverser
paulca:
--- Quote from: langwadt on August 13, 2020, 11:26:43 am ---
--- Quote from: paulca on August 13, 2020, 10:37:16 am ---
--- Quote from: langwadt on August 12, 2020, 06:35:13 pm ---
--- Quote from: jogri on August 12, 2020, 04:45:10 pm ---
--- Quote from: langwadt on August 12, 2020, 08:43:56 am ---that's not a landing that is an aborted takeoff
--- End quote ---
Yeah, and a nominal V1 (maximum speed at which a start can be aborted) is around 160 knots while a landing with MTOW will get you in the same range (usual landing speeds are in the 130-150 knots range)... So the only main difference is that the tires never left the ground for the aborted takeoff, but other than that a fast landing produces a similar strain on the aircraft than an aborted takeoff.
--- End quote ---
at an aborted takeoff there probably much less runway left to stop on, braking is much much harder
afaik thrust reversers are not even on the minium equipment list
--- End quote ---
No thrust reverses is because rejected takeoffs very often happen when there is an engine failure and you can't really use thrust reverses without symetric thrust.
--- End quote ---
asymmetric thrust must not be a big issue since the MMEL for the A320 allows for one nonfunctional thrust reverser
--- End quote ---
That's odd. "non functional" thrust reverser could also mean the actual mechanism has failed. The throttles come up to 80% or something on reverse, if one of the engines has a broken reverser it will be producing 80% forward thrust.
I found this:
https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2007/SAFO07007.pdf
Which states:
--- Quote ---Subject: Thrust Lever Position during Landing with One Deactivated Thrust Reverser on
Airbus A318, A319, A320, A321 Series Airplanes.
Purpose: This SAFO emphasizes the operational procedure of selecting idle thrust on both
engines during a landing conducted with one deactivated thrust reverser
--- End quote ---
Which is line with my thoughts that if either engine or reverser is "out of operation" then thrust reversers (or at least thrust reverser beyond idle reverse) is not permitted.
EDIT: Although reading it more clearly the accidents were because the pilot left the non-operating reverser engine in "CLIMB" position, rather than IDLE. It then states as to whether the pilots should move the throttles to IDLE REVERSE or MAX REVERSE is up to the airlines. I would expect the plane itself determines in either/both/neither reverser should be activated when one is failed.
EDIT: Remember in a normal landing the braking is automatic. There is literally a "Auto brake selector" knob, usually, with positions "RTO, OFF, 1, 2, 3" or similar. It sets a constant retardation rate. 1 and 2 are common settings. The idea behind the the thrust reversers is not that the aircraft needs help to stop, but to reduce brake wear. The aircraft MUST be able to stop with 0 reverse in all conditions, including permitted snow/ice conditions for which the aircraft is rated.
langwadt:
--- Quote from: paulca on August 13, 2020, 12:02:49 pm ---
--- Quote from: langwadt on August 13, 2020, 11:26:43 am ---
--- Quote from: paulca on August 13, 2020, 10:37:16 am ---
--- Quote from: langwadt on August 12, 2020, 06:35:13 pm ---
--- Quote from: jogri on August 12, 2020, 04:45:10 pm ---
--- Quote from: langwadt on August 12, 2020, 08:43:56 am ---that's not a landing that is an aborted takeoff
--- End quote ---
Yeah, and a nominal V1 (maximum speed at which a start can be aborted) is around 160 knots while a landing with MTOW will get you in the same range (usual landing speeds are in the 130-150 knots range)... So the only main difference is that the tires never left the ground for the aborted takeoff, but other than that a fast landing produces a similar strain on the aircraft than an aborted takeoff.
--- End quote ---
at an aborted takeoff there probably much less runway left to stop on, braking is much much harder
afaik thrust reversers are not even on the minium equipment list
--- End quote ---
No thrust reverses is because rejected takeoffs very often happen when there is an engine failure and you can't really use thrust reverses without symetric thrust.
--- End quote ---
asymmetric thrust must not be a big issue since the MMEL for the A320 allows for one nonfunctional thrust reverser
--- End quote ---
That's odd. "non functional" thrust reverser could also mean the actual mechanism has failed. The throttles come up to 80% or something on reverse, if one of the engines has a broken reverser it will be producing 80% forward thrust.
I found this:
https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2007/SAFO07007.pdf
Which states:
--- Quote ---Subject: Thrust Lever Position during Landing with One Deactivated Thrust Reverser on
Airbus A318, A319, A320, A321 Series Airplanes.
Purpose: This SAFO emphasizes the operational procedure of selecting idle thrust on both
engines during a landing conducted with one deactivated thrust reverser
--- End quote ---
Which is line with my thoughts that if either engine or reverser is "out of operation" then thrust reversers (or at least thrust reverser beyond idle reverse) is not permitted.
EDIT: Remember in a normal landing the braking is automatic. There is literally a "Auto brake selector" knob, usually, with positions "RTO, OFF, 1, 2, 3" or similar. It sets a constant retardation rate. 1 and 2 are common settings. The idea behind the the thrust reversers is not that the aircraft needs help to stop, but to reduce brake wear. The aircraft MUST be able to stop with 0 reverse in all conditions, including permitted snow/ice conditions for which the aircraft is rated.
--- End quote ---
the way I read it the pilot should just make sure operate both throttles as normal and not only use the one with a functional reverser
NiHaoMike:
--- Quote from: cdev on August 12, 2020, 08:30:19 pm ---I suppose some could do what this man has done.. Live in one...
--- End quote ---
Looks like a great home for the technical hobbyist. Turn the cockpit into a flight simulator complete with authentic instruments and controls (easiest way probably would be to build a shed around the front part of the plane, then add projectors for video), turn the cargo bay into a RF shielded lab. The wings would make great places to mount solar panels. Perhaps the fuel tanks can be turned into thermal storage tanks by adding insulation on the outside?
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