PHX787
Topic Author
Posts: 7877
Joined: Thu Mar 15, 2012 7:46 pm

787 Thrust Reverser Question

Thu Jul 12, 2012 1:05 am

Hi all, ran a search, couldn't find much on it


View Large View Medium
Click here for bigger photo!

Photo © Charles Cunliffe - ReaperPhotography



How does that thrust reverser work? It looks almost seamless. Does the entire cowling move back when the thrust reverser is activated?


Thanks, Z
Follow me on twitter: www.twitter.com/phx787
 
User avatar
817Dreamliiner
Posts: 3209
Joined: Sun Jul 27, 2008 4:12 pm

RE: 787 Thrust Reverser Question

Thu Jul 12, 2012 1:30 am

Im not sure how much plane spotting youve done, but to answer your question, other aircraft have similar thrust reverse systems so its not really new:


View Large View Medium
Click here for bigger photo!

Photo © Gianni Deligny




It works by diverting the air being drawn in by the fan outside the core, out through that opening when the cowling slides back. Also yes the back part of the cowling slides back entirely.

This should help give a basic idea if you dont understand:

http://en.wikipedia.org/wiki/Thrust_reversal

[Edited 2012-07-11 18:33:20]
Please let me know... If you know this is the end of the world, Let me know... If you know the truth...
 
yeelep
Posts: 724
Joined: Mon Apr 04, 2011 7:53 pm

RE: 787 Thrust Reverser Question

Thu Jul 12, 2012 2:40 am

Its a translating sleeve/cascade type T/R, very common. When the sleeve translates aft there are blocker doors that move into the fan bypass airflow to redirect it through the cascades ( the black parts you can see in the OP pict.).
 
User avatar
jetmech
Posts: 2316
Joined: Wed Mar 29, 2006 2:14 am

RE: 787 Thrust Reverser Question

Thu Jul 12, 2012 3:19 am

Quoting PHX787 (Thread starter):
Quoting yeelep (Reply 2):

It works as illustrated in the following diagram.



This arrangement is very similar to that I've seen on many CF6's. Some of the earlier RB211's had a slightly different design where the blocker doors were actuated by pushrods instead.

http://www.youtube.com/watch?v=bvpj1BV-sCk
http://www.youtube.com/watch?v=dZ-wh8Kuh1M

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
PHX787
Topic Author
Posts: 7877
Joined: Thu Mar 15, 2012 7:46 pm

RE: 787 Thrust Reverser Question

Sat Jul 14, 2012 6:50 pm

Quoting 817Dreamliiner (Reply 1):
Im not sure how much plane spotting youve done,

Not much where I'm up and close to the planes

Quoting jetmech (Reply 3):

That's what I was looking for. Thanks!

I've seen thrust reversers operate on the A343 and the A320 for example which the cowling opens outward and that diverts the thrust but i wasn't sure how this one worked.
Follow me on twitter: www.twitter.com/phx787
 
User avatar
817Dreamliiner
Posts: 3209
Joined: Sun Jul 27, 2008 4:12 pm

RE: 787 Thrust Reverser Question

Sat Jul 14, 2012 10:36 pm

Quoting PHX787 (Reply 4):
That's what I was looking for. Thanks!

I've seen thrust reversers operate on the A343 and the A320 for example which the cowling opens outward and that diverts the thrust but i wasn't sure how this one worked.

Have you tried using the search function or even google? This answer would have been there.
Please let me know... If you know this is the end of the world, Let me know... If you know the truth...
 
AA737-823
Posts: 4888
Joined: Wed Mar 01, 2000 11:10 am

RE: 787 Thrust Reverser Question

Tue Jul 17, 2012 1:47 am

Quoting PHX787 (Reply 4):
I've seen thrust reversers operate on the A343 and the A320 for example which the cowling opens outward and that diverts the thrust but i wasn't sure how this one worked.

Those are called pivot-doors. They're lighter weight than the translating cowl, because there are far fewer parts, and also fewer actuators. A CFM-56 on a 737 has six actuators, three for each cowl half, while the CFM on an A320 has just four, one for each pivot door.

Quoting 817Dreamliiner (Reply 5):
Have you tried using the search function or even google? This answer would have been there.

You're quite the rude snob today, aren't you? If you don't have anything nice to say..... as the saying goes.

Quoting PHX787 (Thread starter):
How does that thrust reverser work? It looks almost seamless. Does the entire cowling move back when the thrust reverser is activated?

For reference, all in-production Boeing aircraft use this design. Many Airbus do as well, though the Rolls on the 333, and the CFM on the 320 use the pivot doors.
 
User avatar
817Dreamliiner
Posts: 3209
Joined: Sun Jul 27, 2008 4:12 pm

RE: 787 Thrust Reverser Question

Tue Jul 17, 2012 2:03 am

Quoting AA737-823 (Reply 6):
You're quite the rude snob today, aren't you? If you don't have anything nice to say..... as the saying goes.

I didnt say anything mean, I was only suggesting that he should have done a search before asking such a question. The forums here has a good amount of information regarding different aspects of aviation, in this case the tech/ops forum would have something related to thrust reversers that has been previously discussed. Even if he didnt find anything here, he could have used a search engine like google to find what he needed. If you didnt like how I answered then thats just your problem. Theres nothing wrong with telling someone to do a google search.
Please let me know... If you know this is the end of the world, Let me know... If you know the truth...
 
User avatar
Polot
Posts: 4606
Joined: Thu Jul 28, 2011 3:01 pm

RE: 787 Thrust Reverser Question

Tue Jul 17, 2012 3:02 am

Quoting AA737-823 (Reply 6):
Those are called pivot-doors. They're lighter weight than the translating cowl, because there are far fewer parts, and also fewer actuators. A CFM-56 on a 737 has six actuators, three for each cowl half, while the CFM on an A320 has just four, one for each pivot door.

What is the disadvantage with them then? If they are lighter and perform equally I would figure that all new designs would have this type of reverse thrust design. It can't be just a patent issue in Boeing's case, Airbus used the cowl type for the A380 on both engine types.
 
BoeEngr
Posts: 128
Joined: Thu Feb 11, 2010 3:31 am

RE: 787 Thrust Reverser Question

Tue Jul 17, 2012 3:07 am

If a Tech/Ops forum on an aviation site is not the place to ask technical questions about aviation, we're all in trouble...

 
 
User avatar
bikerthai
Posts: 2153
Joined: Wed Apr 28, 2010 1:45 pm

RE: 787 Thrust Reverser Question

Tue Jul 17, 2012 1:30 pm

Quoting 817Dreamliiner (Reply 7):
I was only suggesting that he should have done a search before asking such a question.

Often times, it is easier and faster to ask the guys who know then try to find it on the web.

Quoting poLOT (Reply 8):
What is the disadvantage with them then? If they are lighter and perform equally I would figure that all new designs would have this type of reverse thrust design.

The disadvantage is that the doors are not as efficient in diverting the flow. The cascades provide more control in where you want to direct the reversed flow.

The picture that jetmech showed did not show the different angles to which the cascade direct the flow. Along the circumference of the nacelles, the cascades direct the flow in different direction. In one or two area, the cascades are actually blocked off to prevent the flow from impinging on the aircraft (body or wheels) or blow air in front of the airplane where FOD may get ingested back into the engines.

Also, I am not sure if the pivoting doors close out as much fan air as the cascade type doors. If someone have an axial view of a pivoting door compared to translating cowl doors deployed, it may be useful.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 787 Thrust Reverser Question

Tue Jul 17, 2012 5:09 pm

Quoting poLOT (Reply 8):
What is the disadvantage with them then? If they are lighter and perform equally I would figure that all new designs would have this type of reverse thrust design.

Cascade reversers provide better reverse thrust performance and scale up better. If you use petal reversers (aka pivot reversers) and you want to go up to 777 size you're pretty much screwed. Using cascade reversers across the board means you're just working with one design (this may be a legacy from Boeing having a centralized nacelle design group for all models for a long time).

Tom.
 
PHX787
Topic Author
Posts: 7877
Joined: Thu Mar 15, 2012 7:46 pm

RE: 787 Thrust Reverser Question

Wed Jul 18, 2012 7:08 pm

Quoting 817Dreamliiner (Reply 7):

Montserrat? How is it?  
Quoting bikerthai (Reply 10):
The disadvantage is that the doors are not as efficient in diverting the flow. The cascades provide more control in where you want to direct the reversed flow.

That might explain why the AF343 that was landing at CVG used the entire runway, but the DL777 at CVG used about half of it, while landing (back when both of those planes operated at CVG) I get it. Thanks!
Follow me on twitter: www.twitter.com/phx787
 
User avatar
bikerthai
Posts: 2153
Joined: Wed Apr 28, 2010 1:45 pm

RE: 787 Thrust Reverser Question

Wed Jul 18, 2012 9:59 pm

Quoting PHX787 (Reply 12):
AF343 that was landing at CVG used the entire runway, but the DL777

There may be more issue involved with the example you gave (Landing weight of aircraft, 4 smaller engines vs 2 larger engines, how good were the brakes etc.) .

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
DocLightning
Posts: 19624
Joined: Wed Nov 16, 2005 8:51 am

RE: 787 Thrust Reverser Question

Wed Jul 18, 2012 11:48 pm

Quoting tdscanuck (Reply 11):
Cascade reversers provide better reverse thrust performance and scale up better. If you use petal reversers (aka pivot reversers) and you want to go up to 777 size you're pretty much screwed.

The A330 Trent 700s (which aren't *that* much smaller than on the 777) use them. I wonder why?
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
User avatar
Starlionblue
Posts: 17057
Joined: Fri Feb 27, 2004 9:54 pm

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 12:37 am

Quoting PHX787 (Reply 12):
That might explain why the AF343 that was landing at CVG used the entire runway, but the DL777 at CVG used about half of it, while landing (back when both of those planes operated at CVG) I get it. Thanks!

Probably not due to reversers. Brakes and landing weight have a far bigger effect.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 3:00 am

Quoting DocLightning (Reply 14):
The A330 Trent 700s (which aren't *that* much smaller than on the 777) use them. I wonder why?

RR has a long history of doing their own nacelles, unlike the other two engine makers. Did they do the A330 nacelle? That may be a contributor but I don't know why they would have chosen that trade.

Tom.
 
User avatar
DocLightning
Posts: 19624
Joined: Wed Nov 16, 2005 8:51 am

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 6:22 am

Quoting tdscanuck (Reply 16):
RR has a long history of doing their own nacelles, unlike the other two engine makers. Did they do the A330 nacelle? That may be a contributor but I don't know why they would have chosen that trade.

The Trent 700 nacelle is of a classic Trent design with the the bypass duct running the full length of the engine.


View Large View Medium
Click here for bigger photo!

Photo © Alexander K.



This shows the general arrangement with the clamshell doors clearly visible. I can't find one with them deployed.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
User avatar
bikerthai
Posts: 2153
Joined: Wed Apr 28, 2010 1:45 pm

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 1:53 pm

Quoting DocLightning (Reply 14):

The A330 Trent 700s (which aren't *that* much smaller than on the 777) use them. I wonder why?

Aren't some of the A380 T/R the doors type also? And they also only have two engines with reverser.

Quoting tdscanuck (Reply 16):
That may be a contributor but I don't know why they would have chosen that trade.


As we all know, the TR are not essential for certification of the aircraft.

So, basically you are trading the cost/efficiency of the doors vs the wear and tear on the brakes. Someone would have to dig up the brake replacement cycle of a door T/R aircraft vs a cascades TR aircraft and work out the various cost involved . . . along with the weight delta, fuel burn impact, maintenance etc . . .   

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
DocLightning
Posts: 19624
Joined: Wed Nov 16, 2005 8:51 am

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 3:26 pm

Quoting bikerthai (Reply 18):
Aren't some of the A380 T/R the doors type also? And they also only have two engines with reverser.

AFAIK, both RR and EA engines on the A380 are the petal-type.


View Large View Medium
Click here for bigger photo!

Photo © Mark McGrath
View Large View Medium
Click here for bigger photo!

Photo © Olmo Müller



RR on the left, EA on the right
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
User avatar
bikerthai
Posts: 2153
Joined: Wed Apr 28, 2010 1:45 pm

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 3:48 pm

Quoting DocLightning (Reply 19):

Hum, if you are right, then there may be something about the cascades type being more efficient if it was used exclusively on the A380 (because the outboard engines do not have T/R).

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
DocLightning
Posts: 19624
Joined: Wed Nov 16, 2005 8:51 am

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 4:01 pm

Quoting bikerthai (Reply 20):
Hum, if you are right, then there may be something about the cascades type being more efficient if it was used exclusively on the A380 (because the outboard engines do not have T/R).

Not sure that's the reason. I suspect ground clearance is a bigger issue.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
Gatorman96
Posts: 795
Joined: Wed Dec 07, 2005 2:22 am

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 4:40 pm

Quoting bikerthai (Reply 20):
Hum, if you are right, then there may be something about the cascades type being more efficient if it was used exclusively on the A380 (because the outboard engines do not have T/R).

bt

BT,

I believe the A380 doesn't have outboard T/R's because the engines hang over the width of the runway in many cases. If they did, they could kick up FOD into the inboard engines and wings.
Cha brro
 
User avatar
bikerthai
Posts: 2153
Joined: Wed Apr 28, 2010 1:45 pm

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 6:46 pm

Quoting Gatorman96 (Reply 22):
I believe the A380 doesn't have outboard T/R's because the engines hang over the width of the runway in many cases. If they did, they could kick up FOD into the inboard engines and wings.

Understood. My inference is because it doesn't have the outboard T/R, it then have to go to a more efficient design for the inboard T/R to make up some of the difference.

Quoting DocLightning (Reply 21):
Not sure that's the reason. I suspect ground clearance is a bigger issue.

Could be . . .

But from this angle on a different airplane, its seems that you can design a door that will open and not extend beyond the lower part of the nacelle.

http://en.wikipedia.org/wiki/File:Easyjet_thrust_reversers_arp.jpg

Then again, you lose efficiency.


This is a great shot of how a cascade type door, blocks the whole fan duct.

http://www.flickr.com/photos/wbaiv/2736667356/

I can't seem to find a comparable picture of one for the door type.


bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 787 Thrust Reverser Question

Thu Jul 19, 2012 9:03 pm

Quoting DocLightning (Reply 19):
AFAIK, both RR and EA engines on the A380 are the petal-type.

The pictures in your post clearly show cascade reversers, not petal reversers.

Tom.
 
User avatar
jetmech
Posts: 2316
Joined: Wed Mar 29, 2006 2:14 am

RE: 787 Thrust Reverser Question

Fri Jul 20, 2012 3:07 am

Quoting DocLightning (Reply 17):
I can't find one with them deployed.
Quoting bikerthai (Reply 23):
I can't seem to find a comparable picture of one for the door type.

There actually appears to be quite a few gaps with the deployed petal type TR.


View Large View Medium
Click here for bigger photo!

Photo © Brandon Archer



Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
User avatar
bikerthai
Posts: 2153
Joined: Wed Apr 28, 2010 1:45 pm

RE: 787 Thrust Reverser Question

Fri Jul 20, 2012 1:44 pm

Quoting jetmech (Reply 25):

There actually appears to be quite a few gaps with the deployed petal type TR.

Good picture.

That's what I'm thinking. Although they may be able to optimize the coverage by locating the gap at the struts support and cutting the internal blocking skin to fit.

Would like to see inside the duct itself to be sure.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
DocLightning
Posts: 19624
Joined: Wed Nov 16, 2005 8:51 am

RE: 787 Thrust Reverser Question

Fri Jul 20, 2012 8:06 pm

Quoting tdscanuck (Reply 24):
The pictures in your post clearly show cascade reversers, not petal reversers.

Sorry! I meant to say "cascade."
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan

Who is online

Users browsing this forum: Bing [Bot], Channex757 and 15 guests