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ZaphodHarkonnen
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A Future With No Thrust Reversers?

Thu Dec 03, 2015 8:49 pm

Should we be expecting a future where thrust reversers become optional equipment for airliners? Or maybe are dropped altogether?

I have seen across many threads on these forums I've seen repeated mentions that thrust reversers are lightly used and that modern carbon fibre brakes are rated to a number of applications so if you use them for a little you might as well use them for a lot.

I have also seen repeated mention that Airbus only put 2 reversers on the A380 because the FAA demanded it. That the USAF removed the reversers on the CF6s they equipped onto their KC-135Rs.

And in the end having reversers does mean more weight and stuff to maintain when airlines are looking for every kilo to shave off and dollar to save.

The search and some threads I looked at before starting this thread.

https://www.airliners.net/aviation-fo...type=all&starter=1&search_active=1
Jet-Liners Without Thrust Reversers
Do All Airlines Use Reverse Thrust Breaking?
 
ZaphodHarkonnen
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RE: A Future With No Thrust Reversers?

Thu Dec 03, 2015 10:02 pm

Because?

If they aren't really used the vast majority of the time and braking certification doesn't take them into account then why fit them? Just because something is nice to have doesn't mean it needs to or should be fitted.
 
kurtverbose
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RE: A Future With No Thrust Reversers?

Thu Dec 03, 2015 10:08 pm

RR are looking at a variable pitch fan that will do all the reversing.

Quote:
The carbon titanium fan system is further developed to allow the deletion of the thrust reverser, enabling a truly slim–line nacelle system.
 
thegman
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RE: A Future With No Thrust Reversers?

Thu Dec 03, 2015 10:11 pm

Quoting ZaphodHarkonnen (Reply 2):
If they aren't really used the vast majority of the time and braking certification doesn't take them into account then why fit them? Just because something is nice to have doesn't mean it needs to or should be fitted.

Yeah in the TOLD calculations the computer does in the C-17 the standard is 3 engines in idle reverse and 1 in forward reverse even though when we land we generally go to max reverse. It is possible to change it to make the box calculate differently.
 
BravoOne
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RE: A Future With No Thrust Reversers?

Thu Dec 03, 2015 10:37 pm

Quoting ZaphodHarkonnen (Reply 2):
Because?

If they aren't really used the vast majority of the time and braking certification doesn't take them into account then why fit them? Just because something is nice to have doesn't mean it needs to or should be fitted.

James,

It's not just nice to have. Probably not something you would appreciate or understand unless you have landed a large transport on a rain slicked runway...or worse. The fact that they are not factored into stopping distance has little if anything to do with their enhancement to assisting in getting the airplane stopped but rather the conservative nature of performance certification. Bean counters and computer geeks come up with this kind of logic all the time. Pilots on the other hand live and sometimes die with these foolish designs.

The C46 Tanker does not have R/T and it was a decision by one General who is the laughing stock of so many under his command.
 
ZBBYLW
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 12:39 am

Quoting ZaphodHarkonnen (Reply 2):
Because?

If they aren't really used the vast majority of the time and braking certification doesn't take them into account then why fit them? Just because something is nice to have doesn't mean it needs to or should be fitted.

Parachute Jumpers hardly ever use their reserve chute, but I think they would rather keep them installed.

We use reverse regularly when the situation demands it. I fly in and out of Canada. On a contaminated runway, sometimes the braking can be very poor and use of full reverse thrust can greatly help braking. Another good usage is when flying a heavier 321 at a hot airport with no wind (LAS, PHX come to mind) at potentially higher elevations. Using max rev thrust helps limit the required brake usage at higher speeds which help keep our brakes at a cooler temp. Landing well underweight, at a cool airport with a long runway we hardly ever need it. But when landing at an airport that has other challenges they can be a useful tool.
Keep the shinny side up!
 
flight152
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 1:59 am

Quoting ZaphodHarkonnen (Reply 2):

Stick to software development and not the finer points of aircraft design. I can't tell you how many times those "useless things" saved my ass on a slick runway.
 
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Moose135
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 2:09 am

Quoting BravoOne (Reply 5):
Probably not something you would appreciate or understand unless you have landed a large transport on a rain slicked runway...or worse.

I flew the KC-135A in all sorts of weather conditions without thrust reversers and somehow lived to tell about it...
KC-135 - Passing gas and taking names!
 
flyDTW1992
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 2:30 am

Quoting ZaphodHarkonnen (Reply 2):
If they aren't really used the vast majority of the time

What are you basing that on? I don't remember the last time I saw a transport-category aircraft land without using TR.
Now you're flying smart
 
hivue
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 2:37 am

Quoting moose135 (Reply 8):
I flew the KC-135A in all sorts of weather conditions without thrust reversers and somehow lived to tell about it...

What was the brake wear like?

Quoting flyDTW1992 (Reply 9):
I don't remember the last time I saw a transport-category aircraft land without using TR.

I don't remember ever being a passenger on one where TR wasn't used. My subjective impression is that it produces some serious stop.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
atct
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 4:08 am

It's an extra tool used to mitigate potentially hazardous situations. I only flew turboprops but I can't think of any landing except on a 12,000ft dry runway, where I parked at the end, where I didn't at least go into beta. I'd rather have them and not use them, then need them and not have them.
Trikes are for kids!
 
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Moose135
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 4:11 am

Quoting hivue (Reply 10):
What was the brake wear like?

That wasn't my department...  

But I was responding more to the idea that it's not safe to operate transport-category aircraft without TRs, not so much the difference in brake wear. But since I was flying with 1950s-designed brake systems using 1980s-era components, I suspect it was more than it would be on a modern system.
KC-135 - Passing gas and taking names!
 
CanadianNorth
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 12:31 pm

For what it's worth I've personally witnessed a jetliner with a decent load of passengers on board hydroplane during approximately the last 1/3 of the landing roll on a shortish runway and as a result came to a grinding hault with less than 50 feet of runway remaining. The captain had just stowed the reverse thrust and luckily was quick on the draw to realize what was happening and pulled the reversers back out and put some coals to it, despite the instruction book clearly stating reversers must be stowed by that speed. Later discussions revealed that although some damage was done to the engines by having the reversers out at that stage, there is zero doubt in my mind or either of the pilots' minds that if those reverse levers were not pulled when they were then there would have most definitely been a crash that day.
HS-748, like a 747 but better!
 
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747classic
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 2:13 pm

Quoting moose135 (Reply 8):
I flew the KC-135A in all sorts of weather conditions without thrust reversers and somehow lived to tell about it...




On 13 January 1969, USAF RC-135S, 59-1491, called "Rivet Ball", was returning from an operational reconnaissance mission, when it landed at Shemya Air Force Base, AK in a snowstorm. Runway conditions appeared to be within limits according to all reports. After a normal touchdown she struggled to brake on the runway slush and then began to hydroplane. She was unable to stop in time and hydroplaned off the end of the runway 28 into a 40' ravine. Later "Ball" aircraft were equipped with thrust-reversers on their TF-33 turbofan engines, but this aircraft had J-57 turbojet engines without reverse thrust capability. All eighteen crew members successfully evacuated the aircraft. The aircraft was written off as damaged beyond repair, but many unique components specific to the reconnaissance mission were salvaged ( in one of the most expensive operations during that time) for later use in other RC135 aircraft.


Shemya, RC-135S (#59-1491) , January 1969

http://www.rc135.com/0000/CRASH_2.JPG
Original uploaded by R.Hawes, see : http://www.rc135.com/0000/INDEX.HTM

[Edited 2015-12-04 06:14:19]
Operating a twin over the ocean, you're always one engine failure from a total emergency.
 
BravoOne
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 3:19 pm

Quoting moose135 (Reply 8):
lew the KC-135A in all sorts of weather conditions without thrust reversers and somehow lived to tell about it...

Landing a KC135 in all sorts of weather a several times a month does not make you a good example for airlines to follow. The last SAC base I recall seeing had 12,000+ of runway and in many cases, 300' wide runways. The stats are against your analogy at this point in time.
 
A320FlyGuy
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 3:21 pm

Don't forget - the A380 only has 2 thrust reversers due to the capacity and engineering of the aircrarft brake system. Also, the BAe-146 didn't have thrust reversers, so it's not like this is a revolutionary concept.

Just my $0.02
My other car is an A320-200
 
BravoOne
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 5:09 pm

Quoting A320FlyGuy (Reply 16):
Don't forget - the A380 only has 2 thrust reversers due to the capacity and engineering of the aircrarft brake system. Also, the BAe-146 didn't have thrust reversers, so it's not like this is a revolutionary concept.

Just my $0.02

Yes we get your point. Also the Folker 100 did not have TR's either as I recall. Just means it was an airplane built around compromise and not what worked best 

Some Lear Jets had reverse and some didn't just depended on what the customers operation profile looked like. Heck, some Lear Jets had drag chutes.
 
FlyHossD
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 5:28 pm

Quoting BravoOne (Reply 5):
The fact that they are not factored into stopping distance has little if anything to do with their enhancement to assisting in getting the airplane stopped but rather the conservative nature of performance certification. Bean counters and computer geeks come up with this kind of logic all the time. Pilots on the other hand live and sometimes die with these foolish designs.

FYI, as I recall, the 737NGs do use reverse thrust as part of the normal landing distance calculations.

[Edited 2015-12-04 09:29:12]
My statements do not represent my former employer or my current employer and are my opinions only.
 
BravoOne
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 8:44 pm

Quoting FlyHossD (Reply 18):
I, as I recall, the 737NGs do use reverse thrust as part of the normal landing distance calculations.

I think you are correct but not being that familiar with the NG I hesitated to comment. Seems like that was an issue in the MDW SWA 737 accident?

Some airports in Europe do not want to see reverse thrust used as a matter of noise abatement but good operating practice would dictate you crack them open, just in case
 
thegman
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 8:51 pm

Quoting hivue (Reply 10):
I don't remember ever being a passenger on one where TR wasn't used. My subjective impression is that it produces some serious stop.

Your subjective opinion also doesn't take into account that at the same time the TRs come out, the pilot is slamming on the brakes.
 
BravoOne
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RE: A Future With No Thrust Reversers?

Fri Dec 04, 2015 9:53 pm

Quoting thegman (Reply 20):
the TRs come out, the pilot is slamming on the brakes.

Spoken like a real military pilot who was could give a hoot about passenger comfort or the cost of brake wear and tear  
 
Max Q
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 7:03 am

Quoting A320FlyGuy (Reply 15):
Don't forget - the A380 only has 2 thrust reversers due to the capacity and engineering of the aircrarft brake system.

No, it was due to Airbus's desperate need to save weight, ask the Captain of the Qantas A380 who experienced the uncontained engine failure that left him with one operating reverser if he'd like to have had three instead.



They barely managed to stop on the runway, anyone who thinks reverse is superfluous has not operated jet transports in all weather conditions on limiting runways. You can have the best braking system made but they are useless if your tires are hydroplaning and / or can't get a grip on the runway.



Reversers are priceless and they're not going away.
The best contribution to safety is a competent Pilot.


GGg
 
mmo
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 7:22 am

Quoting FlyHossD (Reply 17):
FYI, as I recall, the 737NGs do use reverse thrust as part of the normal landing distance calculations.

No commercial aircraft takes into account T/Rs as part of the landing calculations.

Quoting ZaphodHarkonnen (Reply 1):
If they aren't really used the vast majority of the time and braking certification doesn't take them into account then why fit them?

Most airlines have SOPs that require at least minimum T/R operation. What that is is selecting reverse thrust and leaving the thrust levers in the idle position rather than raising the T/R levers and using above idle reverse. The thought being you have reverse thrust engaged and if needed it will be available. If it's not needed there is no increase in engine wear and accompanying increase in the noise level. I am not sure where you are getting your data about not being used but it is wrong.
If we weren't all crazy we'd all go insane!
 
INFINITI329
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 7:24 am

Quoting Max Q (Reply 21):

They barely managed to stop on the runway, anyone who thinks reverse is superfluous has not operated jet transports in all weather conditions on limiting runways. You can have the best braking system made but they are useless if your tires are hydroplaning and / or can't get a grip on the runway.



Reversers are priceless and they're not going away.

I agree with you 100%. I dont understand why the KC-46 is designed without them
 
Max Q
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 11:12 am

Quoting MMO (Reply 22):
Most airlines have SOPs that require at least minimum T/R operation. What that is is selecting reverse thrust and leaving the thrust levers in the idle position rather than raising the T/R levers and using above idle reverse. The thought being you have reverse thrust engaged and if needed it will be available. If it's not needed there is no increase in engine wear and accompanying increase in the noise level. I am not sure where you are getting your data about not being used but it is wrong.

Actually it's to cancel out any forward thrust.
The best contribution to safety is a competent Pilot.


GGg
 
BravoOne
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 12:51 pm

Quoting MMO (Reply 22):
No commercial aircraft takes into account T/Rs as part of the landing calculations.

Not so sure about that? I think Boeing / FAA have done something different with the NG. I can check it out but it might take awhile.

Here is a preview.

http://www.ntsb.gov/news/press-relea...er_Credit_in_Determining_Runway_St

[Edited 2015-12-05 04:56:04]

Just Google this subject if this link does not work.


[Edited 2015-12-05 04:58:17]
 
PITrules
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 1:23 pm

Quoting flyDTW1992 (Reply 8):

What are you basing that on? I don't remember the last time I saw a transport-category aircraft land without using TR.

Other than at BUR, JetBlue doesn't use reverse thrust above idle unless conditions warrant it.

Quoting MMO (Reply 22):
No commercial aircraft takes into account T/Rs as part of the landing calculations.

After years and years of not taking T/Rs in to account for landing calculations, my carrier just changed landing data tables and T/R's are now taken in to account. No T/Rs means a performance data hit - seemingly against industry norm.
FLYi
 
mmo
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 3:13 pm

Quoting Max Q (Reply 24):
Actually it's to cancel out any forward thrust.

Really, since most aircraft reversers only deal with fan thrust, what about the thrust from the turbine? I would say that's more of a "old wives tale". It's actually to provide almost instantaneous reverse thrust should you need it.

Quoting PITrules (Reply 26):

After years and years of not taking T/Rs in to account for landing calculations, my carrier just changed landing data tables and T/R's are now taken in to account. No T/Rs means a performance data hit - seemingly against industry no

What type of aircraft? And that seems counter to the NTSB's position vis a vis the MDW accident and their recommendations.

Quoting BravoOne (Reply 25):
Not so sure about that? I think Boeing / FAA have done something different with the NG. I can check it out but it might take awhile.

I don't fly "light twins" and on the aircraft I have flown, reverse thrust was never taken into for normal landing configurations.
If we weren't all crazy we'd all go insane!
 
PITrules
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 3:24 pm

Quoting MMO (Reply 27):
What type of aircraft?

B-744
FLYi
 
mmo
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 7:13 pm

Quoting PITrules (Reply 28):
B-744

Flew the 744 since it was introduced and 747 (all series) and never once had landing date calculated with T/R considered. Also always used wet V1 speeds. Both of those assumptions are much more conservative than computation with T/R considered. Again, it's counter to what the NTSB recommended in the MDW accident.
If we weren't all crazy we'd all go insane!
 
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CALTECH
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 7:15 pm

Quoting MMO (Reply 22):

Quoting FlyHossD (Reply 17):
FYI, as I recall, the 737NGs do use reverse thrust as part of the normal landing distance calculations.

No commercial aircraft takes into account T/Rs as part of the landing calculations.

Throw it out there. rom the QRH, 737-7/-8/-9

"FLIGHT PLANNING RESTRICTIONS:
A. CAT I, NO AUTOLAND.
B. THE WET RUNWAY / OBSTACLE LIMITED WEIGHT AND ASSOCIATED
V1 MUST BE REDUCED TO ACCOUNT FOR THE INOPERATIVE
THRUST REVERSER.

FLIGHT CREW:
A. REMAINING THRUST REVERSE SYSTEM MUST OPERATE
NORMALLY.
B. ADJUST LANDING DISTANCE FOR ONE REVERSER INOPERATIVE.
REFER TO FM PERFORMANCE / APPROACH AND LANDING /
NORMAL LANDING DISTANCE TABLES."
You are here.
 
PITrules
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 9:35 pm

Quoting MMO (Reply 29):
Flew the 744 since it was introduced and 747 (all series) and never once had landing date calculated with T/R considered. Also always used wet V1 speeds. Both of those assumptions are much more conservative than computation with T/R considered. Again, it's counter to what the NTSB recommended in the MDW accident.

Ok? I did say "my carrier" and "just changed". I didn't say I think it is a good idea.
FLYi
 
Pihero
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RE: A Future With No Thrust Reversers?

Sat Dec 05, 2015 10:34 pm

Quoting Max Q (Reply 21):
it was due to Airbus's desperate need to save weight, ask the Captain of the Qantas A380 who experienced the uncontained engine failure

Your usual hyperbole and anti A bias, Max ?
Please cite the passage where Captain de Crespigny said that.

Quoting Max Q (Reply 21):

They barely managed to stop on the runway

Bull ! They computed that with only 2/3 of their braking available, most of the spoilers gone, the ailerons fixed, 42 tons over MLW, and one T/R inop, they could land withing the LDA, which they did - T/R was cancelled at above 100 kt -.
Only one brake was overheating enoiugh to be a concern.
Another gooss anti-A exaggeration, I'm afraid.

Quoting MMO (Reply 22):
No commercial aircraft takes into account T/Rs as part of the landing calculations.

That is incorrect :
The T/Rs are used for landing performance calculations on all runway conditions except DRY. Both the FAA and the EASA agree on that matter.
In fact the regs have the same reference : JAR / FAR 25.125 subpart B

Computing landing distances w/o T/R albeit using them is no longer an accepted airline practice.
Contrail designer
 
FlyHossD
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RE: A Future With No Thrust Reversers?

Sun Dec 06, 2015 2:53 am

Quoting FlyHossD (Reply 17):
FYI, as I recall, the 737NGs do use reverse thrust as part of the normal landing distance calculations.
Quoting MMO (Reply 22):
No commercial aircraft takes into account T/Rs as part of the landing calculations.
Quoting MMO (Reply 27):
What type of aircraft? And that seems counter to the NTSB's position vis a vis the MDW accident and their recommendations.
Quoting FlyHossD (Reply 17):
FYI, as I recall, the 737NGs do use reverse thrust as part of the normal landing distance calculations.

MMO - Just checked my old 737NG manuals and Boeing did use TR in normal landing distance calculations. There is an additive (added distance) if a TR is inop.
My statements do not represent my former employer or my current employer and are my opinions only.
 
Max Q
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RE: A Future With No Thrust Reversers?

Sun Dec 06, 2015 7:09 am

Quoting MMO (Reply 27):
Really, since most aircraft reversers only deal with fan thrust

Where most of the thrust is derived on a modern high bypass turbofan so deploying idle reverse
will cancel out net forward thrust.

Quoting MMO (Reply 27):
I would say that's more of a "old wives tale". It's actually to provide almost instantaneous reverse thrust should you need it.

You have that backwards, waiting to use reverse thrust until 'you need it' is self defeating, it's only at its most effective at the higher touchdown speeds. Waiting until later in the rollout to use it at lower speeds is not recommended or effective.


If you're running out of runway and you have not initiated reverse yet it may well be too late.
The best contribution to safety is a competent Pilot.


GGg
 
mmo
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RE: A Future With No Thrust Reversers?

Sun Dec 06, 2015 7:21 am

Quoting Max Q (Reply 24):
Actually it's to cancel out any forward thrust.
Quoting Max Q (Reply 34):

Quoting MMO (Reply 27):
Really, since most aircraft reversers only deal with fan thrust

Where most of the thrust is derived on a modern high bypass turbofan so deploying idle reverse
will cancel out net forward thrust.

I think you need to work on how you quote people. Your initial statement was about cancelling out any forward thrust. I pointed out you still have the residual thrust from the turbine. I never said anything about fan thrust at all. I am very much aware of the amount of fan thrust produced and while you do reverse the fan thrust, depending on the engine and reverse set up it might not be all of the fan thrust. But you do not cancel out "net forward thrust" as you write. There is still forward thrust being produced.

Quoting Max Q (Reply 34):
You have that backwards, waiting to use reverse thrust until 'you need it' is self defeating, it's only at its most effective at the higher touchdown speeds. Waiting until later in the rollout to use it at lower speeds is not recommended or effective.


If you're running out of runway and you have not initiated reverse yet it may well be too late.

Reverse thrust is effective down to 50-70 knots and I never did say "until you need it". What I wrote was

Quoting MMO (Reply 27):
reverse thrust should you need it.

I never said anything about later in the rollout and using at lower speeds. Reverse thrust is much more effective at higher speeds, I have no disagreement there. But please don't misquote what I write trying to justify what you write.
If we weren't all crazy we'd all go insane!
 
Max Q
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RE: A Future With No Thrust Reversers?

Sun Dec 06, 2015 8:09 am

Quoting MMO (Reply 35):
I never said anything about fan thrust at all.
Quoting MMO (Reply 27):
Really, since most aircraft reversers only deal with fan thrust,

You certainly did.

Quoting MMO (Reply 35):
But you do not cancel out "net forward thrust" as you write. There is still forward thrust being produced.

Yes there is, however the reversed fan flow does cancel out net forward thrust.

Quoting MMO (Reply 35):
Reverse thrust is effective down to 50-70 knots and I never did say "until you need it". What I wrote was
Quoting MMO (Reply 35):
reverse thrust should you need it.

Perhaps you need to work out how you quote people and what you're trying to say.

[Edited 2015-12-06 00:13:12]
The best contribution to safety is a competent Pilot.


GGg
 
OldAeroGuy
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RE: A Future With No Thrust Reversers?

Sun Dec 06, 2015 7:16 pm

Quoting ZaphodHarkonnen (Reply 1):
braking certification doesn't take them into account

Actually, certification takeoff distance as defined under the current rule set does include the use of reverse thrust.

Dry certification landing distance does not include reverse thrust. Operational landing distance calculations on contaminated (wet, slush, ice) runways do include reverse thrust.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
mmo
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RE: A Future With No Thrust Reversers?

Sun Dec 06, 2015 7:40 pm

Quoting Max Q (Reply 36):
Perhaps you need to work out how you quote people and what you're trying to say.

I think you are the one who has trouble quoting people and mis-quoting them. Your "statements" you attribute to me are just plain wrong! In my reply, I quoted my text verbatim and you have quoted me wrong. Worst of all, you then tell me I have a problem. You really need to do better!
If we weren't all crazy we'd all go insane!
 
Max Q
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RE: A Future With No Thrust Reversers?

Mon Dec 07, 2015 8:05 am

You stated you never mentioned 'fan thrust' yet you directly referred to it in reply 27:

Quoting MMO (Reply 27):
Really, since most aircraft reversers only deal with fan thrust,

You are avoiding the main point of contention here, you have this mistaken belief that idle reverse
is initiated so:

Quoting MMO (Reply 22):
you have reverse thrust engaged and if needed it will be available.

That is simply incorrect, the main reason for deploying idle reverse is to cancel out net forward thrust.
No question there is still forward thrust from the turbine but the reversed fan flow still provides
a net reverse effect.



You could deploy reverse at lower speeds 'if needed' but as you conceed its not very effective, with
modern carbon brakes and noise abatement restrictions reverse above idle is not used that often
but it does at least cancel out net forward thrust.



Deploying reverse so you 'have it available' means by definition you are waiting to see if its needed,
you can't tell this until later in the rollout, by that time its usefulness is very limited.
The best contribution to safety is a competent Pilot.


GGg
 
mmo
Posts: 2059
Joined: Thu Apr 18, 2013 3:04 pm

RE: A Future With No Thrust Reversers?

Mon Dec 07, 2015 10:14 am

Quoting Max Q (Reply 39):
Deploying reverse so you 'have it available' means by definition you are waiting to see if its needed,
you can't tell this until later in the rollout, by that time its usefulness is very limited

Ok, so let me get this straight. You are approaching the end of the runway at a speed that will not let you turn off., let's say 90 KIAS. You are also entering an area with packed snow/ice. You are also applying max braking. Using your logic, you will not deploy reverse thrust because of your "usefulness is very limited"? After all, that is what you wrote!

Come on, don't be ridiculous!!!!

Quoting Max Q (Reply 39):
You could deploy reverse at lower speeds 'if needed' but as you concede its not very effective, with
modern carbon brakes and noise abatement restrictions reverse above idle is not used that often
but it does at least cancel out net forward thrust.

So, you are saying every aircraft that is in commercial service has "modern carbon brakes"? Again, you are just being ridiculous!!

Quoting Max Q (Reply 39):
You stated you never mentioned 'fan thrust' yet you directly referred to it in reply 27:

Quoting MMO (Reply 27):
Really, since most aircraft reversers only deal with fan thrust,

You are avoiding the main point of contention here, you have this mistaken belief that idle reverse
is initiated so:

Quoting MMO (Reply 22):
you have reverse thrust engaged and if needed it will be available.

That is simply incorrect, the main reason for deploying idle reverse is to cancel out net forward thrust.
No question there is still forward thrust from the turbine but the reversed fan flow still provides
a net reverse effect.

As I wrote previously, you like to pick and choose what you quote. I did mention fan thrust , but it was in the context of net thrust from the fan and turbine section. At idle reverse, the fan section reverse thrust component does NOT cancel out the turbine thrust component. In fact, at idle reverse, the fan reverse thrust is very limited and the idle turbine component is greater. You are assuming 100% of the fan thrust is reversed, which it isn't.

Having a discussion with you is like trying to hit a moving target. You skip all over the place and grasp at straws over and over again. Have fun!!
If we weren't all crazy we'd all go insane!
 
Max Q
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RE: A Future With No Thrust Reversers?

Tue Dec 08, 2015 12:26 am

Quoting MMO (Reply 40):
Ok, so let me get this straight. You are approaching the end of the runway at a speed that will not let you turn off., let's say 90 KIAS. You are also entering an area with packed snow/ice. You are also applying max braking. Using your logic, you will not deploy reverse thrust because of your "usefulness is very limited"? After all, that is what you wrote!

No, this is what I wrote:

Quoting Max Q (Reply 39):
You could deploy reverse at lower speeds 'if needed' but as you conceed its not very effective
Quoting Max Q (Reply 39):
Deploying reverse so you 'have it available' means by definition you are waiting to see if its needed,
you can't tell this until later in the rollout, by that time its usefulness is very limited.

Where in in those statements did I say I 'would not deploy reverse thrust' ?

Quoting MMO (Reply 40):
So, you are saying every aircraft that is in commercial service has "modern carbon brakes"? Again, you are just being ridiculous!!

Again, where did I say that ?

Quoting MMO (Reply 40):
As I wrote previously, you like to pick and choose what you quote. I did mention fan thrust , but it was in the context of net thrust from the fan and turbine section. At idle reverse, the fan section reverse thrust component does NOT cancel out the turbine thrust component. In fact, at idle reverse, the fan reverse thrust is very limited and the idle turbine component is greater. You are assuming 100% of the fan thrust is reversed, which it isn't.

The main reason for idle reverse is to cancel out forward thrust, it does provide a net reverse effect, granted you are in reverse already if you need to go above idle but if you have a contaminated surface and / or have braking issues you're far better going to max reverse on touchdown where its most effective rather than waiting till a lower speed where they are not.
The best contribution to safety is a competent Pilot.


GGg
 
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zeke
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RE: A Future With No Thrust Reversers?

Tue Dec 08, 2015 1:32 am

Quoting CALTECH (Reply 30):

As mentioned above there are two types of landing distance calculations, pre dispatch which is based upon certified data does not take into account thrust reverse. Then there is the "advisory" or "operational" landing distance (OLD) calculation which is based upon the actual runway conditions and actual aircraft landing capability. Most operators factor the OLD distance further.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
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CALTECH
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RE: A Future With No Thrust Reversers?

Tue Dec 08, 2015 2:18 am

A Future With No Thrust Reversers ? It would be a redundacy done away with. If braking becomes poor at the destination on arrival...............

Looking through the MEL, only one thrust reverser is allowed to be deferred on the Airbus A-319/-320, Boeing B-737, 747, 757, 767, 777 and 787. The other, or the other 3 on the 747, thrust reverser(s) must be operative.

737s landing in the snow. Some with gravel kits installed.

http://www.youtube.com/watch?v=Rxatv329aY4

http://www.youtube.com/watch?v=-Ht8nToKXfY

http://www.youtube.com/watch?v=EY9AZlnyF64
You are here.
 
kcrwflyer
Posts: 2616
Joined: Tue May 18, 2004 11:57 am

RE: A Future With No Thrust Reversers?

Tue Dec 08, 2015 3:06 am

Quoting CALTECH (Reply 43):

A Future With No Thrust Reversers ? It would be a redundacy done away with. If braking becomes poor at the destination on arrival...............

Looking through the MEL, only one thrust reverser is allowed to be deferred on the Airbus A-319/-320, Boeing B-737, 747, 757, 767, 777 and 787. The other, or the other 3 on the 747, thrust reverser(s) must be operative.

737s landing in the snow. Some with gravel kits installed.

http://www.youtube.com/watch?v=Rxatv329aY4

http://www.youtube.com/watch?v=-Ht8nToKXfY

http://www.youtube.com/watch?v=EY9AZlnyF64

Yeah none of those guys needed those reversers. Especially the pilot that re-deployed them while making the turn off


Those made my evening.
 
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7BOEING7
Posts: 3039
Joined: Fri Oct 12, 2012 5:28 pm

RE: A Future With No Thrust Reversers?

Tue Dec 08, 2015 6:02 am

Quoting kcrwflyer (Reply 44):

http://www.youtube.com/watch?v=-Ht8nToKXfY

http://www.youtube.com/watch?v=EY9AZ...nyF64

Nice to see the airplane I flew on its first flight (03MAR83) -- before heading to Royal Air Maroc as their first convertible -- has left the desert heat after 24 years for the artic cold.
 
OldAeroGuy
Posts: 3926
Joined: Sun Dec 05, 2004 6:50 am

RE: A Future With No Thrust Reversers?

Wed Dec 09, 2015 1:48 am

Now those are reversers! Nothing beats the reverse capability of a 732Adv.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
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Starlionblue
Posts: 20037
Joined: Fri Feb 27, 2004 9:54 pm

RE: A Future With No Thrust Reversers?

Wed Dec 09, 2015 2:06 am

Quoting OldAeroGuy (Reply 46):
Now those are reversers! Nothing beats the reverse capability of a 732Adv.

As well known by Steve Dumas... http://www.youtube.com/watch?v=yz3AC93DvDo
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
ZaphodHarkonnen
Topic Author
Posts: 1035
Joined: Sun Jan 04, 2015 10:20 am

RE: A Future With No Thrust Reversers?

Thu Dec 10, 2015 6:38 am

Thanks to everyone for the replies. Looks like they could be made an option for airlines. But that most airlines would go for such an option if they want to keep the pilot unions happy.

And I'm not being derogatory to pilot unions. :p They have a purpose.  
 
OldAeroGuy
Posts: 3926
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RE: A Future With No Thrust Reversers?

Thu Dec 10, 2015 2:02 pm

I think that most airlines will go for the reverse option since it helps to keep their airplanes on the runway in adverse conditions. There is a considerable economic benefit for doing that.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis

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