Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Advancement In Engine Thrust Reverser?  
User currently offlinecelestar From Singapore, joined Jul 2001, 415 posts, RR: 0
Posted (4 years 3 months 2 weeks 3 days 2 hours ago) and read 5522 times:

I wonder what kind of improvement engine maker has done to the commercial engine thrust reverser design. Recently, I flown on an old 737-300 and it brings back the old day memory of how loud the thrust reverser can be. That is also the case with current 747-400 My question is, are they some sort of advancement on new engine on B777 (RR or GE) or on A330 (RR or PW or GE) because the noise generated during thrust reverser application was significantly lower and sometime you could hardly feel or hear them. Very interested to know what had been done to the engine design?

10 replies: All unread, jump to last
 
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (4 years 3 months 2 weeks 2 days 19 hours ago) and read 5438 times:

Quoting celestar (Thread starter):
I wonder what kind of improvement engine maker has done to the commercial engine thrust reverser design.

For a while it was essentially nil, since the reverser companies were different than the engine companies. Some of the engine companies created or purchased reverser companies (GE & RR) but they operate as semi-independent divisions. But two of the biggest vendors today (Spirit Aerospace & Goodrich) aren't tied to any engine company.

Quoting celestar (Thread starter):
My question is, are they some sort of advancement on new engine on B777 (RR or GE) or on A330 (RR or PW or GE) because the noise generated during thrust reverser application was significantly lower and sometime you could hardly feel or hear them.

A lot of that is the use of idle reverse...the modern large twins can stop perfectly happily on most runways without using reversers at all, so they often deploy them but don't spin up the engines.

CFD has also considerably improved the design of the cascade vanes in sliding sleeve reversers (and I assume the petals in petal reversers) to improve reverse thrust efficiency, which gives you an automatic noise drop anyway.

Tom.


User currently offlineprebennorholm From Denmark, joined Mar 2000, 6542 posts, RR: 54
Reply 2, posted (4 years 3 months 2 weeks 2 days 12 hours ago) and read 5322 times:

Quoting celestar (Thread starter):
...the noise generated during thrust reverser application was significantly lower and sometime you could hardly feel or hear them.

At more and more airports - especially in Europe - the use of reversers is now forbidden due to noise regulations. Mostly it works the way that the reversers are engaged, and the engines are spun up slightly above idle. It doesn't provide any noticeable brake force, but it does provide a much faster spin up in case of accidental wheel brake failure.

Wheel brakes have become a lot better, so nowadays reversers are mostly treated as sort of backup for the wheel brakes. In older days reversers provided the cheap way to save wear on the wheel brakes.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineflyboy80 From United States of America, joined Jul 2001, 1880 posts, RR: 3
Reply 3, posted (4 years 3 months 2 weeks 2 days 9 hours ago) and read 5257 times:

I love the thrust reversers on the 737, 757, 767, and A320. Always seems when they are deployed, and the engines are spooled up, they "rattle" the flap assembly- sometimes very violently- during the breaking action. I've never noticed this on tail mounted engine types, and I would assume because there is no turbulent air being generated around the assembly itself because of engine placement. The Airbus seems to have a large gap between the spoilers and the flap and that must contribute to the shaking as well.

Has anyone witnessed thrust reverse on the Ejet aircraft? If so, does the flap assembly tend to shake like the 737s and airbus twins?


User currently offlinekimberlyrj From United Kingdom, joined Mar 2008, 385 posts, RR: 1
Reply 4, posted (4 years 3 months 2 weeks 1 day 17 hours ago) and read 5112 times:

Hey hey

I miss the noise of reverse thrust on all (okay, most/some ish) flights I crew... It was always nice to hear when landing at LHR or LGW it was a very nice welcome ‘home’  

These days in the UK reverse is not often used (well at the bigger airports) and when it is it's idle or maybe just above.

A lot of pilots seem to use idle reverse – I am sure this means that if reverse thrust is suddenly needed it would be quicker to arrive?

There are a few airports around the world our pilots seem to use plenty of reverse thrust (depending on the runway) no matter what the conditions, but the runways tend to be quite far away from any urban areas etc.

Last year I was quite amazed when I flew with Monarch Airlines on an Airbus A300-600R from LGW to KGS on a night flight. On landing (in heavy rain) the aircraft stopped amazing quickly without any use of reverse thrust (not even idle).

From what I understand the runway is 7,874ft long and we landed on runway 32 and took the first exit so we used around 4000ft (ish) amazing in heavy rain and no reverse thrust in fact we slowed down so quickly it was very uncomfortable (or maybe I am just so used to sitting facing backward – as I’m cabin crew).

After that landing the Airbus A300-600R gained a lot of my respect, well its brakes did!

An example that reverse thrust can’t make that much difference? Though I was surprised to pilots did not idle them just in case!

Question, do pilots from certain airlines or certain countries tend to use reverse thrust no matter what the airport recommends? Or local conditions?

Is there any airline policy on this matter? Or the use of idel?

Kimberly


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 5, posted (4 years 3 months 2 weeks 1 day 14 hours ago) and read 5051 times:

Quoting kimberlyrj (Reply 4):
A lot of pilots seem to use idle reverse – I am sure this means that if reverse thrust is suddenly needed it would be quicker to arrive?

Correct. It takes a few seconds for the reverser to deploy, and reverse idle is usually higher than ground idle, so you can get up to full reverse thrust much more quickly if you're already in idle reverse.

Tom.


User currently offlinepilotpip From United States of America, joined Sep 2003, 3152 posts, RR: 10
Reply 6, posted (4 years 3 months 1 week 5 days 9 hours ago) and read 4856 times:

Quoting kimberlyrj (Reply 4):
There are a few airports around the world our pilots seem to use plenty of reverse thrust (depending on the runway) no matter what the conditions, but the runways tend to be quite far away from any urban areas etc.

Last year I was quite amazed when I flew with Monarch Airlines on an Airbus A300-600R from LGW to KGS on a night flight. On landing (in heavy rain) the aircraft stopped amazing quickly without any use of reverse thrust (not even idle).

From what I understand the runway is 7,874ft long and we landed on runway 32 and took the first exit so we used around 4000ft (ish) amazing in heavy rain and no reverse thrust in fact we slowed down so quickly it was very uncomfortable (or maybe I am just so used to sitting facing backward – as I’m cabin crew).

After that landing the Airbus A300-600R gained a lot of my respect, well its brakes did!

An example that reverse thrust can’t make that much difference? Though I was surprised to pilots did not idle them just in case!

Question, do pilots from certain airlines or certain countries tend to use reverse thrust no matter what the airport recommends? Or local conditions?

Is there any airline policy on this matter? Or the use of idel?

Modern antiskid brakes are very efficient and actually do better as they heat up due to being carbon brakes versus metallic. Also, reversers are not taken into consideration in performance calculations and can be deferrered with no penalty. To be perfectly honest, 99% of passengers have no idea how strong airliner brakes really are. If I wanted to use max braking on the aircraft I fly (ERJ-170) you would likely end up with a bruise from the seatbelt. Our aircraft don't have autobrakes but even on short runways like MDW I don't have to give a full application.

It also heavily depends on the type of reverser employed. Cascade style reversers only change the direction of the bypass air. They redirect it sideways more than forward and they decrease effectiveness as you slow. They also increase risk of FOD ingestion as you slow. Clamshells have a much more pronounced aerodynamic effect as well as redirecting all air.

My airline requires use of full reverse on every landing. It's an operational requirement in our SOP. Not really a fan of it because there are plenty of times where you don't need it, like landing on 22R at ORD where they want you to turn off at the end, but I do it anyway. Usually in a case like that I just bark 'em, let them spool up to max and then return to idle reverse quickly.

As for airport requirements, there aren't any in the US that I can think of that have any sort of ban against them and you can bet if I were at an airport that did, and I needed them I would use them.

There are situations where they're particularly useful like wet or snow-covered runways because quite frankly, you want everything you have helping you stop in those situations and the anti-skid might be doing it's job keeping the wheels spinning versus skidding.



DMI
User currently offlinebond007 From United States of America, joined Mar 2005, 5454 posts, RR: 8
Reply 7, posted (4 years 3 months 1 week 5 days ago) and read 4792 times:

Quoting prebennorholm (Reply 2):
At more and more airports - especially in Europe - the use of reversers is now forbidden due to noise regulations.

I'm not sure 'forbidden' is correct, unless I'm mistaken. Many airports have regulations concerning the use of anything but idle reverse, but on contaminated runways or whenever there is a safety issue, there is no restriction on their use.

Quoting pilotpip (Reply 6):
Also, reversers are not taken into consideration in performance calculations and can be deferrered with no penalty.

Well, for accelerate-stop distances on contaminated runways they can, right?

Bond



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlinebonusonus From United States of America, joined Nov 2009, 403 posts, RR: 0
Reply 8, posted (4 years 3 months 1 week 3 days 21 hours ago) and read 4658 times:

Quoting kimberlyrj (Reply 4):
Question, do pilots from certain airlines or certain countries tend to use reverse thrust no matter what the airport recommends? Or local conditions?

I've noticed that many airliners use significant reverse thrust at smaller airports (and not just on short runways). It seems like the only reason is to slow down faster to be able to hit the earlier taxiway turnoffs. Can anyone confirm using them for this purpose?


User currently offlineaerotech777 From United States of America, joined Aug 2009, 69 posts, RR: 0
Reply 9, posted (4 years 3 months 1 week 1 day 16 hours ago) and read 4467 times:

Hi,

Wondering which thrust reverser (petals or cascades) provides more stopping distance?

During high speed RTO, if one engine fails or dispatched inoperative can the crew use the thrust reverser for the operating
engine(s)?

Feedback appreciated


User currently offlinebikerthai From United States of America, joined Apr 2010, 2197 posts, RR: 4
Reply 10, posted (4 years 3 months 1 week 1 day 16 hours ago) and read 4454 times:

Quoting aerotech777 (Reply 9):
ondering which thrust reverser (petals or cascades) provides more stopping distance?

As I recall, the cascades are more efficient in terms of airflow because the blocker doors covers more of the fan flow and the cascade vanes does a better job of re-directing the flow. You can only cover so much with the pedals. However, I think the petal design is simpler, less expensive, and might even be lighter. I'm familiar with the cascades but not the petals design

bikerthai



Intelligent seeks knowledge. Enlightened seeks wisdom.
Top Of Page
Forum Index

Reply To This Topic Advancement In Engine Thrust Reverser?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
757 Water Sound In Thrust Reverser? posted Mon Aug 6 2001 21:01:22 by FSPilot747
Spikes In Engine/Pack Noise During The Cruise? posted Thu Apr 1 2010 02:20:13 by faro
In-Flight Thrust Reverser Usage posted Sat Sep 26 2009 18:46:08 by C5LOAD
Engine Thrust Specs posted Mon Jun 29 2009 07:34:11 by SpeedBirdA380
Will 747-8I Have Four Thrust Reverser posted Thu Nov 13 2008 19:07:59 by 747400sp
Deciding Factors In Engine Choice+Overhaul Q'tion posted Sun Oct 26 2008 15:03:37 by SInGAPORE_AIR
Engine Wash Integrated In Engine? -Tank Stripping? posted Mon Sep 8 2008 23:59:14 by NicoEDDF
A340 Thrust Reverser Question posted Fri Apr 11 2008 14:27:58 by Viscount724
Thrust Reverser Problems With GE90's? posted Fri Nov 30 2007 13:41:56 by 747Dreamlifter
Little Stick (or Probe?) In Engine Intake? posted Thu Nov 29 2007 15:39:24 by Jawed
Spikes In Engine/Pack Noise During The Cruise? posted Thu Apr 1 2010 02:20:13 by faro
Engine Thrust Specs posted Mon Jun 29 2009 07:34:11 by SpeedBirdA380
Will 747-8I Have Four Thrust Reverser posted Thu Nov 13 2008 19:07:59 by 747400sp
Deciding Factors In Engine Choice+Overhaul Q'tion posted Sun Oct 26 2008 15:03:37 by SInGAPORE_AIR
Engine Wash Integrated In Engine? -Tank Stripping? posted Mon Sep 8 2008 23:59:14 by NicoEDDF
A340 Thrust Reverser Question posted Fri Apr 11 2008 14:27:58 by Viscount724

Sponsor Message:
Printer friendly format