JumboJim747 From Australia, joined Oct 2004, 2400 posts, RR: 53 Posted (7 years 1 month 4 days 9 hours ago) and read 4941 times:
Why do pilots use the reverse thrusters on long runways.
Im not talking about planes like the a320 where the reversers come in automatically but the 737 that can pull up without the need to apply reverse thrust.
Any help on this would be appreciated
Oly720man From United Kingdom, joined May 2004, 6081 posts, RR: 12 Reply 1, posted (7 years 1 month 4 days 9 hours ago) and read 4893 times:
Usually to clear the runway quickly for other landing/departing aircraft.
Saves the brakes.
It depends on the airport I expect as well and where the terminals are in relation to the runway and where the taxiways are to leave the runway. I expect that if there's no other traffic and it's more convenient a pilot may use the full length of the runway and just use the brakes, or a low level of reverse thrust.
Man City p3 w3 d0 l0 f4 a0 P9 - hey it may never happen again!
Philsquares From , joined Dec 1969, posts, RR: Reply 4, posted (7 years 1 month 4 days 8 hours ago) and read 4861 times:
1) The A-320 and all Airbus aircraft have the same reverse system logic the Boeings have. The pilot controls them.
2) Most airlines have policies where the reversers are deployed on all flights, then it's pilot's discretion as to how much reverse to use. If you're going all the way to the end, I agree, there is no need for anything other than minimum reverse and wheel brakes below 100 knots. But, that's technique, not procedure.
JumboJim747 From Australia, joined Oct 2004, 2400 posts, RR: 53 Reply 6, posted (7 years 1 month 4 days 8 hours ago) and read 4829 times:
Oly720man
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JetMechMD80
Philsquares
HAWK21M
I thank you for the answers to this question that has puzzled me for so long.
You guys are wonderful to have in the forums im learning so much thanks again.
CX flyboy From Hong Kong, joined Dec 1999, 6057 posts, RR: 57 Reply 7, posted (7 years 1 month 4 days 4 hours ago) and read 4784 times:
Just to throw a spanner in the works, we have a policy of using idle reverse only on normal landings. From the outside, it appears as though they might be using reverse thrust, but it is just reverse idle. Activating the reverser allows them to be 'at the ready' for in case we need them.
Many new airliners use carbon brakes, and these actually work better and last longer when more braking action is used. We normally land with an autobrake setting rather than manual brakes. This is the policy of most airlines. An autobrake setting will slow the aircraft down at a preset rate (X number of kts per second for example). If you use full reverse for example, the aircraft won't slow down any faster, but you will put less stress on the brakes. The same preset deceleration rate will still be maintained. By using this method on carbon brakes, it can be said that you are actually wearing them down faster.
Also, it costs a lot more to replace and service thrust reverser parts than it is to change a few brake discs on certain aircraft, so even within the same airline, there may be different policies on reverse thrust usage from fleet to fleet.
However, it is of course ultimately up to the crew whether they will use reverse or not as the company merely has guidelines for this sort of thing. There are times when you may prefer to use reverse and put less strain on the brakes. One situation is when you have a short turnaround time landing at a hot airport. If you overheat the brakes you can actually delay your departure, so it makes more sense to use full reverse thrust, even if the company guidelines are to save money by using idle reverse only.
JumboJim747 From Australia, joined Oct 2004, 2400 posts, RR: 53 Reply 8, posted (7 years 1 month 3 days 22 hours ago) and read 4661 times:
CX flyboy I also thank you for the input.
What are the servicable parts in the reverser other then the doors.
Sorry if i sound uncluey but im just curious now.
Thanks in advance and thanks for all future answers.
Skysurfer From United Kingdom, joined Sep 2004, 1112 posts, RR: 17 Reply 9, posted (7 years 1 month 3 days 17 hours ago) and read 4582 times:
I was lucky in that when i flew into FAR and then flew into ORD onboard a UAX CRJ the pilots used a hell of alot of reverse thrust to stop us.....i'm asuming it's due to the fact that when we landed, we'd already passed the terminal we were going to. I was quite impressed.
Cheers
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Ramper@IAH From United States of America, joined Dec 2001, 240 posts, RR: 1 Reply 10, posted (7 years 1 month 3 days 17 hours ago) and read 4574 times:
A lot of it has to do with habit. I sometimes catch myself using reverse thrust needlessly.
TWAMD-80 From United States of America, joined Oct 2001, 1006 posts, RR: 5 Reply 11, posted (7 years 1 month 3 days 11 hours ago) and read 4476 times:
Another serviceable part of the reversers other than the doors would be the door actuators (the things which deploy and retract the doors). I'm pretty sure that's the name of them. Hope this answers your question.
TW
Two A-4's, left ten o'clock level continue left turn!
TWAMD-80 From United States of America, joined Oct 2001, 1006 posts, RR: 5 Reply 14, posted (7 years 1 month 2 days 22 hours ago) and read 4316 times:
I am not quite sure what methods are used to get the doors to withstand the thrust, but I know that on the MD-80 specifically, with its JT8D's that there are thrust limits when the reverser buckets are deployed. I don't know of the figure but I believe that the pilots are limited to a given EPR when using reverse thrust.
TW
Two A-4's, left ten o'clock level continue left turn!
JumboJim747 From Australia, joined Oct 2004, 2400 posts, RR: 53 Reply 15, posted (7 years 1 month 2 days 21 hours ago) and read 4305 times:
A350
You are welcome
TWAMD-80
Im not sure of the limit but even in idle the thrust must be very high for those little doors to withstand .
Thank you for the input
Stirling From Italy, joined Jun 2004, 3943 posts, RR: 32 Reply 17, posted (7 years 1 month 2 days 1 hour ago) and read 4114 times:
Don't some airports have restrictions on when RT can be used?
I seem to remember SNA has such rules....Are they for noise abatement purposes? I can't think of any other reason why an airport would put restrictions on the use of Reverse-Thrust....?
And why is it RT is louder? (Sorry for such a silly question...)
Cloudy From , joined Dec 1969, posts, RR: Reply 18, posted (7 years 1 month 22 hours ago) and read 3988 times:
Seems like using reverse engine thrust is kind of like downshifting to slow down in a car, as a supplement to the brakes. If you are driving downhill on a steep mountain road, this is necessary to avoid burning out the breaks. But it can still save break wear and tear in ordinary situations, and it gives you another layer of safety as well
Kindjordan From United States of America, joined Nov 2004, 59 posts, RR: 0 Reply 19, posted (7 years 4 weeks 1 day 1 hour ago) and read 3801 times:
I was on Jetblue 189 to MSY....apon landing on rwy 1, we had a long rollout without using reverse thrust all the way to the very last turnoff. I beleive with the cost of fuel, this is becoming as common as 1 engine taxi's....MHO
CRJ900 From Norway, joined Jun 2004, 1922 posts, RR: 1 Reply 20, posted (7 years 4 weeks 1 day ago) and read 3778 times:
Stupid question, probably, but here goes:
When reversing thrust, does that include reversing the way the huge air inlet fan rotates as well? Like, does the fan go from spinning very fast clockwise to complete stop to spinning anti-clockwise in a matter of seconds, and then stop and back to clockwise spinning to bring the aircraft to the terminal gate?
If yes, doesn't that put a huge strain on the fan and its blades?
2H4 From United States of America, joined Oct 2004, 8897 posts, RR: 66 Reply 21, posted (7 years 4 weeks 1 day ago) and read 3773 times:
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Not a stupid question, CRJ900. When reversing thrust, the fan continues to rotate in the original direction. At no point does it reverse direction. Instead, the air being propelled through the engine is physically diverted sideways and forward by gates or "scoops".
Just search the database for "reversers", and you'll get all kinds of hits showing them in use.
Kindjordan From United States of America, joined Nov 2004, 59 posts, RR: 0 Reply 22, posted (7 years 4 weeks 1 day ago) and read 3769 times:
CRJ says:
When reversing thrust, does that include reversing the way the huge air inlet fan rotates as well? Like, does the fan go from spinning very fast clockwise to complete stop to spinning anti-clockwise in a matter of seconds, and then stop and back to clockwise spinning to bring the aircraft to the terminal gate?
No CRJ, the fan blades do not reverse direction......
(in most aircraft such as 737,747,319,320,330) when the reverse thrust is applied, a rear section of the engine cowling deflects backward effectively redirecting the thrust from the rear of the engine to the sides and front. The thrust doesn't necessarily shoot forward, but off to the sides all around the engine, thus slowing the aircraft down.
On such aircraft like the Md-80 and 737-200....buckets (as they are called) are deployed which also redirect the thrust from the rear thus slowing down the aircraft.....
N243NW From United States of America, joined Jul 2003, 1267 posts, RR: 29 Reply 24, posted (7 years 4 weeks 17 hours ago) and read 3685 times:
And why is it RT is louder? (Sorry for such a silly question...)
Not a silly question at all, Stirling. I would imagine that the noise originates from the extremely turbulent air in and around the engine as the reversers are deployed.
Not only does the air in essense "slam" into the metal blocker gates/cascades/buckets as it makes its way out of the engine, you have this air pushing against the plane's motion while the air rushing past the plane is still moving at over 100 knots. Imagine how much the air must "clash" with the atmosphere, hitting a mass of air moving at a very high speed in the opposite direction.
So, I would assume that the shock waves and pressure differences that result from these air masses meeting produces the noise we all love.
-N243NW
TCAS SYSTEM TEST OKAY.
25 Night_Flight: As most folks know, Denver has very long runways. Why are they so long, since the air is thinner, we need more runway to takeoff and land. Usually in
26 CX flyboy: On a fairly light 777-200, believe it or not, we can have a final approach speed of around 120-125kts! Thats very slow for such a huge airliner.
27 JumboJim747: On a fairly light 777-200, believe it or not, we can have a final approach speed of around 120-125kts! That's very slow for such a huge airliner. WoW
28 Jonty: CCA said in another forum that "buckets stop the entire flow while translating cowl reversers only stop the fan air, the core is still providing forwa
29 SlamClick: It is true that the core outflow, the actual exhaust of the engine is not reversed in the cascade type reverser, but since the fan air is providing th
30 Michi: Hi guys, there is a cool down period after usage of reverse thrust out of idle reverse. In case you expect a short taxi time after landing, you should
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