Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Why The Airbus A380 Has Only Two Thrust Reverser?  
User currently offline747400sp From United States of America, joined Aug 2003, 3758 posts, RR: 2
Posted (8 years 6 months 9 hours ago) and read 32767 times:

I been told that the Airbus A380 has only two trust reverser, I also just saw a photos of an A380 with it's trust reversers deployed an see that it just has two trust reversers. So is Airbus crazy!!! this plane at landing, has the weight of a DC-10-30 also what if an A380 has to abort take off, how or the pilots going to stop a 1,200,000 lb plane on a takeoff roll with only two trust reversers. 707, DC-8, 747 and A340 has trust reversers on all four of there engines, an A380 is much heavier than these aircraft, so I would think it would be a safe ideal to have the out board engines fitted with trust reverser also. Do not get me wrong an A380 looks cool at landing but safe out rules cool.

Just my Two Cents

PS: Please do not trun this into an A vs B topic I like all four engines airliners.

102 replies: All unread, showing first 25:
 
User currently offlineZeke From Hong Kong, joined Dec 2006, 9243 posts, RR: 76
Reply 1, posted (8 years 6 months 9 hours ago) and read 32767 times:

Quoting 747400sp (Thread starter):
I been told that the Airbus A380 has only two trust reverser, I also just saw a photos of an A380 with it's trust reversers deployed an see that it just has two trust reversers.

A couple of reasons, firstly its does not need them, a 146 does not have reverse thrust either. It has a lot of brakes.

Second reason is FOD, on most runways the outer engines will pick up FOD if reverse is deployed.

Reverse does not decrease stopping distance on landing with any of the newer airbus aircraft, they decelerate at pre-programmed rates. If you were to use reverse, less brake pressure would be applied to achieve the same deceleration rate without the use of reverse thrust.

Quoting 747400sp (Thread starter):
how or the pilots going to stop a 1,200,000 lb plane on a takeoff roll with only two trust reversers.

Aircraft are certified for normal stopping with NO REVERSE. Reverse is only considered operable for some specific takeoff scenarios, like a wet (not damp) runway.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineFr8Mech From United States of America, joined Sep 2005, 5660 posts, RR: 15
Reply 2, posted (8 years 6 months 8 hours ago) and read 32767 times:

Weight savings would be my guess.


When seconds count...the police are minutes away.
User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 3, posted (8 years 6 months 7 hours ago) and read 32767 times:

OH MY GOD!!!!! a huge design flaw by the Airbus engineers there, they'd better go back and re-design the whole aircraft!!!!!  Yeah sure

i mean seriously......do you not think they thought about this when designing the aircraft? do you seriously think they would let it fly if it was going to be a problem?

whats a trust reverser anyway? some kind of unit to reverse somebody's trust?  Wink


User currently offlineBohica From United States of America, joined Feb 2004, 2751 posts, RR: 0
Reply 4, posted (8 years 5 months 4 weeks 1 day 19 hours ago) and read 32767 times:

Quoting Matt72033 (Reply 5):
OH MY GOD!!!!! a huge design flaw by the Airbus engineers there, they'd better go back and re-design the whole aircraft!!!!!

There's another production delay.  duck   duck   duck   biggrin   biggrin   biggrin 


User currently offlineN8076U From United States of America, joined Jun 2006, 425 posts, RR: 9
Reply 5, posted (8 years 5 months 4 weeks 1 day 14 hours ago) and read 32767 times:

Apparently, Airbus has faith in the brakes the A380 is equipped with, and feels that two reversers are all it needs, besides any FOD/weight issues.

Chris



Don't blame me, I don't work here...
User currently offlineNZ8800 From New Zealand, joined May 2006, 425 posts, RR: 2
Reply 6, posted (8 years 5 months 4 weeks 1 day 14 hours ago) and read 32767 times:

80% or more of an airliner's stopping power - including the A380 - is in the brakes. If the pilots jam them on full, they could put the passengers through the seat in front of them  Wink
They can land completely without the thrust reversers. As for safety - it will have been checked, and re-checked, the prototype has flown, and they are now into the production run (however delayed that is!) - if it were not safe, it would not have been certificated.
Also technology has improved - we may see the 747-800 with only two thrust reversers as well, if that is all that is required.



MDZWTA ~ Mobile Disaster Zone When Travelling Abroad
User currently offlineTepidHalibut From Iceland, joined Dec 2004, 210 posts, RR: 6
Reply 7, posted (8 years 5 months 4 weeks 1 day 10 hours ago) and read 32767 times:

I believe that I read that the A380 was designed without any TRUs at all, but the FAA "recommended" that Airbus reconsider that plan. (Can't find a reference at the moment.)

I'm sure some folk are wondering why an airline would prefer to use brakes rather than TRU. My understanding is :

# Stopping with Brakes - Does result in wear of brake pads, which will eventually need replacing.

# Stopping with TRUs - Doesn't involve wear of the brake-pads, but unfortunately, an engine at idle doesn't produce much thrust (forward or reverse.) So the pilots have to apply RevThrust and accelerate the engine. This obviously used more fuel, and contributes to the Cyclic Life useage in the engines.

The decision on whether brakes or R/T is used comes down to economics. As brake technology and life improves, that options becomes more attractive.


User currently onlineStarlionblue From Greenland, joined Feb 2004, 17188 posts, RR: 66
Reply 8, posted (8 years 5 months 4 weeks 1 day 9 hours ago) and read 32767 times:

Quoting TepidHalibut (Reply 10):
I believe that I read that the A380 was designed without any TRUs at all, but the FAA "recommended" that Airbus reconsider that plan. (Can't find a reference at the moment.)

Also heard this rumor.

Quoting 747400sp (Thread starter):
I been told that the Airbus A380 has only two trust reverser, I also just saw a photos of an A380 with it's trust reversers deployed an see that it just has two trust reversers. So is Airbus crazy!!! this plane at landing, has the weight of a DC-10-30 also what if an A380 has to abort take off, how or the pilots going to stop a 1,200,000 lb plane on a takeoff roll with only two trust reversers. 707, DC-8, 747 and A340 has trust reversers on all four of there engines, an A380 is much heavier than these aircraft, so I would think it would be a safe ideal to have the out board engines fitted with trust reverser also. Do not get me wrong an A380 looks cool at landing but safe out rules cool.

To summarize:
- Weight savings.
- FOD problems on the outboards if they hang too close to the runway edges. Not so much a problem in forward thrust since small FOD would simply fly out the back. But in reverse gravel and other debris could potentially fly out of the reversers and hit the wing, the fuse, the other engines.
- Thrust reversers are a bonus. If the pilots use max braking, the pax would hang by the seatbelts. Landing calculations are made without thrust reversers and they have a 50% pad factor. Planes can come to a stop very very fast.

Quoting 747400sp (Thread starter):
707, DC-8, 747 and A340 has trust reversers on all four of there engines, an A380 is much heavier than these aircraft, so I would think it would be a safe ideal to have the out board engines fitted with trust reverser also.

You're making two logic errors here.
- You assume that the 747 and 340 could not be built with two reversers. They could, and inop thrust reversers do not preclude dispatch. It's a matter of economics (presumably, if those aircraft could be operated more efficiently with two thrust reversers, that's how they would have been build. Also, modern carbon brakes require less cooling time compared to older brakes. So the need for thrust reversers has decreased further.
- You assume that the enormous weight of the 380 is a problem in itself. The plane is large, but all other things (control surfaces, engines, etc...) are scaled up to match, including brakes.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineSpeedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0
Reply 9, posted (8 years 5 months 4 weeks 13 hours ago) and read 32767 times:

Quoting TepidHalibut (Reply 10):
The decision on whether brakes or R/T is used comes down to economics. As brake technology and life improves, that options becomes more attractive.

Your post suggests that engineers and airlines are faced with an "either-or" propostion; whether to use brakes, RT, or both. But as has been posted here already, and elsewhere, the decision to use RT or bakes is not a matter of economics. Brakes, in all airliners, provide the vast majority, and often, the entirety of braking. TR is a bonus, usually deployed as a matter of SOP to account for unexpected failures. It is never relied upon to provide the majority of deceleration unless there is some sort of incredible brake failure.
O



Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17188 posts, RR: 66
Reply 10, posted (8 years 5 months 4 weeks 6 hours ago) and read 32767 times:

Trust me on this one...  stirthepot 


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 11, posted (8 years 5 months 4 weeks 6 hours ago) and read 32767 times:

Quoting Speedracer1407 (Reply 12):
It is never relied upon to provide the majority of deceleration unless there is some sort of incredible brake failure.

Considering The Value of Engine Life.Brake Use seems a cheaper option.  Smile
Trust me its Thrust Reversers.
regds
MEL



Think of the brighter side!
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2577 posts, RR: 25
Reply 12, posted (8 years 5 months 3 weeks 6 days 8 hours ago) and read 32767 times:

Thrust reversers are installed particularly for operation on contaminated runways, where brakes might be useless. Usually they are only used in symmetric pairs on four engined aircraft. Certainly the BAe 146 and the Fokker F.28 have no reverse thrust, but they have very effective airbrakes.

Consider three things.

1. Either of the two inboard engines might be shutdown
2. A large engine running at idle produces significant forward thrust
3. Even at max reverse, the thrust produced is very much less than that produced in forward thrust.

So I wouldn't want to be onboard the first A380 which lands on an icy runway with an inboard engine out. No effective brakes, two engines still in forward thrust and only one asymmetrically in reverse.

Two outboard reversers would provide significant additional redundancy for a modest weight increase, and better spares commonality (operators will have to spare inboard and outboard engines separately). The FOD argument is spurious. 747 outboard engines are already very close to the runway edge. Why would there be more debris from the off tarmac areas anyway. I'd argue less, and then mainly dust and grass.

By the way, FOD stands for Foreign Object Damage, i.e. the damage done, not the stuff that does the damage. Sloppy usage has led it to come to mean the runway debris itself. I know the Boeing website talks about Foreign Object Debris, but why not just Debris, which by definition will be a foreign object for the engine.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 13, posted (8 years 5 months 3 weeks 6 days 1 hour ago) and read 32767 times:

Airbus Must have Def considered Alternatives,Prior to Deciding on No Outboard T/Rs.
regds
MEL



Think of the brighter side!
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17188 posts, RR: 66
Reply 14, posted (8 years 5 months 3 weeks 6 days ago) and read 32767 times:

Quoting Jetlagged (Reply 16):
Certainly the BAe 146 and the Fokker F.28 have no reverse thrust, but they have very effective airbrakes.

And they are an option on the ERJ. Some operators don't have them.

Quoting Jetlagged (Reply 16):

So I wouldn't want to be onboard the first A380 which lands on an icy runway with an inboard engine out. No effective brakes, two engines still in forward thrust and only one asymmetrically in reverse.

If there was a problem with this scenario, don't you think the FAA, the JAA and the operators would have insisted on 4 reversers? As Mel says, I'm sure Airbus has done the math.

On an icy runway, stopping distance is just calculated as longer. This calculation is not affected by the presence of reversers.

Also, two engines would certainly not "still be in forward thrust". They would be idle.

Quoting Jetlagged (Reply 16):
The FOD argument is spurious. 747 outboard engines are already very close to the runway edge. Why would there be more debris from the off tarmac areas anyway. I'd argue less, and then mainly dust and grass.

Maybe, maybe not. 747 outboards are several meters further inboard. Consider that the wingspan of the 380 is 8 meters more than the wingspan of the 747.

Quoting Jetlagged (Reply 16):

Two outboard reversers would provide significant additional redundancy for a modest weight increase,

Too much weight increase and not a lot of redundancy increase. And with current landing distance calculation methods, reversers are redundancy for brakes (which are redundant in themselves with multiple circuits and axles), not for each other. In essence, you could leave them off on most planes. They are "reaching desired turn-off" mechanisms unless the brakes are quite broken AND your runway is very short. Just popping the spoilers will brake the plane quite well in the speeds where reversers are effective.

Quoting Jetlagged (Reply 16):
and better spares commonality (operators will have to spare inboard and outboard engines separately).

On most large engines, the reversers are not part of the engine package in the way you describe. They are part of the nacelle. The engines themselves are all sans reversers.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineDavid L From United Kingdom, joined May 1999, 9546 posts, RR: 42
Reply 15, posted (8 years 5 months 3 weeks 6 days ago) and read 32767 times:

Quoting Jetlagged (Reply 16):
So I wouldn't want to be onboard the first A380 which lands on an icy runway with an inboard engine out

Do 747s often land on icy runways where reverse thrust can mean the difference between staying on the runway and over shooting? Not a loaded question, just curious.


User currently onlineStarlionblue From Greenland, joined Feb 2004, 17188 posts, RR: 66
Reply 16, posted (8 years 5 months 3 weeks 5 days 21 hours ago) and read 32749 times:

Quoting David L (Reply 19):
Quoting Jetlagged (Reply 16):
So I wouldn't want to be onboard the first A380 which lands on an icy runway with an inboard engine out

Do 747s often land on icy runways where reverse thrust can mean the difference between staying on the runway and over shooting? Not a loaded question, just curious.

I can hear SlamClick in my ear... "Why would you want to land an airliner with a failed thrust reverser on an icy runway when you can divert to somewhere with better traction?"

But in any case, I agree with what I think Mr. L is saying. If thrust reverse is needed to stop within the required distance on that icy runway, you won't be allowed to land there anyway, regardless of whether your reversers are in working order or not.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2577 posts, RR: 25
Reply 17, posted (8 years 5 months 3 weeks 5 days 7 hours ago) and read 32665 times:

Quoting Starlionblue (Reply 18):
If there was a problem with this scenario, don't you think the FAA, the JAA and the operators would have insisted on 4 reversers? As Mel says, I'm sure Airbus has done the math.

I'd love to share your confidence. History shows that sometimes "the math" is not done properly, and unforseen accident scenarios occur from time to time. It may not have been considered with an inboard engine failure wiping out half the reverse thrust and introducing asymmetry. I'm only speculating. I don't suppose the rules envisage a situation with only half the engines having reversers, normally it is either all or none.

Quoting Starlionblue (Reply 18):
On an icy runway, stopping distance is just calculated as longer. This calculation is not affected by the presence of reversers.

Much, much longer stopping distance for wheel brakes only on ice. On icy runways, the only really effective braking you have is aerodynamic and reverse thrust. Friction for wheel braking is minimal.

Quoting Starlionblue (Reply 18):
Also, two engines would certainly not "still be in forward thrust". They would be idle.

They certainly will be in forward thrust, at idle, which is a significant component of forward thrust nevertheless.

Quoting Starlionblue (Reply 18):
Maybe, maybe not. 747 outboards are several meters further inboard. Consider that the wingspan of the 380 is 8 meters more than the wingspan of the 747.

747 outboards are about 140 feet apart, centerline to centerline, which means the outer side of the nacelle will be roughly over the edge of a 150 foot wide runway. Apparently the FOD argument didn't also apply to the 747, which is why I think it is spurious.

Quoting Starlionblue (Reply 18):
Too much weight increase and not a lot of redundancy increase.

How much is too much? Do you know the reverser weight? Redundancy would be doubled by adding outboard reversers. What about the RTO scenario after an engine 2 or 3 failure for a very heavy A380? You will certainly want max reverse then, and I'd rather the outboards were not still producing forward thrust, even at idle.

Quoting Starlionblue (Reply 18):
On most large engines, the reversers are not part of the engine package in the way you describe. They are part of the nacelle. The engines themselves are all sans reversers.

Rolls Royce for one have always supplied complete engine/nacelle assemblies on their turbofans, including reversers. I confess to not knowing whether this is true for the A380 Trent engines, or the Engine Alliance equivalents.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineDavid L From United Kingdom, joined May 1999, 9546 posts, RR: 42
Reply 18, posted (8 years 5 months 3 weeks 5 days 5 hours ago) and read 32642 times:

Quoting Jetlagged (Reply 21):
It may not have been considered with an inboard engine failure wiping out half the reverse thrust and introducing asymmetry

I just can't see something as obvious as that being overlooked. Isn't it the same situation as you have with twins like the 737, 777, 320 and 330? If asymmetry is a problem, can't you just refrain from applying reverse on the other inboard?

Quoting Jetlagged (Reply 21):
On icy runways, the only really effective braking you have is aerodynamic and reverse thrust. Friction for wheel braking is minimal.

But then we get back to the question of landing on such a runway in any type.


User currently offline2H4 From United States of America, joined Oct 2004, 8956 posts, RR: 60
Reply 19, posted (8 years 5 months 3 weeks 5 days 5 hours ago) and read 32629 times:
AIRLINERS.NET CREW
DATABASE EDITOR




Quoting Jetlagged (Reply 21):
Quoting Starlionblue (Reply 18):
Too much weight increase and not a lot of redundancy increase.

How much is too much?

Well, to quote Bill Lear....

"I'd sell my grandmother to save a pound of weight"


 Wink



2H4





Intentionally Left Blank
User currently offlineBuckFifty From Canada, joined Oct 2001, 1316 posts, RR: 19
Reply 20, posted (8 years 5 months 3 weeks 5 days 1 hour ago) and read 32573 times:

If one engine has failed on either side of the aircraft, reverse is locked out on the coincidental engine on the other side. So asymetrical reverse will not happen, that's a given.

And as David L has said, this is not much different than a scenario with twins. Reverse, even in a contaminated runway condition, does not factor greatly with the stopping distance charts. Modern carbon brakes and anti-lock systems are quite capable of stopping an aircraft, even under the worst circumstances.

However, it is up to the pilot to avoid having the aircraft land in such conditions, and to make sure the aircraft performance is adequate enough to land on any runway dependent on the present condition, with thrust reversers or without. That's why we often check the runway condition when going into an airport where weather is a known factor.

I can seriously imagine the day when thrust reversers will be obsolete with the way braking technology is going. Most airports we fly into, we're only using a low autobrake setting, along with idle thrust reverse. As carbon brakes don't wear with pressure or heat (they wear only by the number of applications), this isn't a problem with brake wear.

However, in reference to turnaround times, heavy braking can cause high temps, which need to be sorted before the aircraft departs. But again, as materials research is advanced, I'm sure this problem will go away also.


User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 21, posted (8 years 5 months 3 weeks 5 days ago) and read 32567 times:

Quoting BuckFifty (Reply 24):
If one engine has failed on either side of the aircraft, reverse is locked out on the coincidental engine on the other side. So asymetrical reverse will not happen, that's a given.

not on our 747-400's! the MEL states that the aircraft can depart with one thrust reverser u/s, 2 u/s is a no go.....so if you have one go tits up and you lock out the corresponding engine on the other wing, your not going anywhere!


User currently offlineBuckFifty From Canada, joined Oct 2001, 1316 posts, RR: 19
Reply 22, posted (8 years 5 months 3 weeks 5 days ago) and read 32557 times:

I suppose I should have clarified my statement above.

I'm not sure what the 744's MEL states. However, on the 340, if we are to have a reverser locked out, for example on engine 1, then engine 4's reverser is unusable above idle, and is locked. Therefore we're only left with two reversers, on 2 and 3. If a reverser is inop on the inboard engines, the other can still be used, but may have to use differential braking to offset any directional stability issues.

And it is possible for us to dispatch a 340 without any reversers, as long as certain requirements are met.

[Edited 2006-07-06 23:17:14]

User currently offlineTepidHalibut From Iceland, joined Dec 2004, 210 posts, RR: 6
Reply 23, posted (8 years 5 months 3 weeks 5 days ago) and read 32559 times:

Quoting Jetlagged (Reply 21):
Rolls Royce for one have always supplied complete engine/nacelle assemblies on their turbofans, including reversers. I confess to not knowing whether this is true for the A380 Trent engines, or the Engine Alliance equivalents.

I'm going to have to call you on that. For example, the Trent 700. The TRU is the responsibility of Airbus / Aircell, and not part of the engine (as defined in DIS part 1.) I believe the Production engines are passed off with a slave C-Duct rather than a pukka TRU unit. The engine is shipped to Toulouse, where the engine is "podded", and that's where the engine gets it's fiirst sniff of a TRU.

On the older engines (RB211-535, 524 etc) the TRU was a Rolls-Royce supplied item, tho' I don't think they were DIS Pt 1 bits.


User currently onlineStarlionblue From Greenland, joined Feb 2004, 17188 posts, RR: 66
Reply 24, posted (8 years 5 months 3 weeks 5 days ago) and read 32550 times:

Quoting Jetlagged (Reply 21):
Quoting Starlionblue (Reply 18):
If there was a problem with this scenario, don't you think the FAA, the JAA and the operators would have insisted on 4 reversers? As Mel says, I'm sure Airbus has done the math.

I'd love to share your confidence. History shows that sometimes "the math" is not done properly, and unforseen accident scenarios occur from time to time. It may not have been considered with an inboard engine failure wiping out half the reverse thrust and introducing asymmetry. I'm only speculating. I don't suppose the rules envisage a situation with only half the engines having reversers, normally it is either all or none.

Even if the math were not done properly tests would uncover the deficiency. That's why they test.

Of course the rules envisage a situation with only half the engines having reversers. Otherwise the 380 would have no hope of certification.

Quoting Jetlagged (Reply 21):
Quoting Starlionblue (Reply 18):
On an icy runway, stopping distance is just calculated as longer. This calculation is not affected by the presence of reversers.

Much, much longer stopping distance for wheel brakes only on ice. On icy runways, the only really effective braking you have is aerodynamic and reverse thrust. Friction for wheel braking is minimal.

And why would you land on that short icy runway with an inoperative reverser? Your calculations will simply extend the runway requirement (and factor in friction) and you would have to find one long enough.

Also, anti-lock braking is pretty efficient. Avro 100s land on icy runways all winter long without skidding off the end.

Quoting Jetlagged (Reply 21):
Quoting Starlionblue (Reply 18):
Also, two engines would certainly not "still be in forward thrust". They would be idle.

They certainly will be in forward thrust, at idle, which is a significant component of forward thrust nevertheless.

Idle is idle. Means that the forward thrust is insignificant in this regard. Idle thrust is more than compensated by any form of braking..

Quoting Jetlagged (Reply 21):
Quoting Starlionblue (Reply 18):
Maybe, maybe not. 747 outboards are several meters further inboard. Consider that the wingspan of the 380 is 8 meters more than the wingspan of the 747.

747 outboards are about 140 feet apart, centerline to centerline, which means the outer side of the nacelle will be roughly over the edge of a 150 foot wide runway. Apparently the FOD argument didn't also apply to the 747, which is why I think it is spurious.

FOD is one of the stated reasons, but I don't really care since the reversers are a bonus anyway. Also your argument is a bit weak without a comparison to the 380. How far outboard are the 380 engines?

Quoting Jetlagged (Reply 21):
Quoting Starlionblue (Reply 18):
Too much weight increase and not a lot of redundancy increase.

How much is too much? Do you know the reverser weight? Redundancy would be doubled by adding outboard reversers. What about the RTO scenario after an engine 2 or 3 failure for a very heavy A380? You will certainly want max reverse then, and I'd rather the outboards were not still producing forward thrust, even at idle.

As I said, redundancy would not be doubled. Wheel brakes on a whooping 8 axles provide redundancy in themselves.



There are plenty of jets out there with no reversers and they seem to be doing just fine with just wheels and aerodynamic brakes, even in icy conditions. Sure, they tend to be smaller jets, but they have correspondingly smaller brake discs and airbrakes.

[Edited 2006-07-06 23:32:28]


"There are no stupid questions, but there are a lot of inquisitive idiots."
25 Post contains images David L : Ahem... 10 axles?
26 2H4 : I agree with the point being made, but Avro flights are also cancelled from time to time due to their occasional inability to cope with shorter icy r
27 Post contains images David L : But aren't Avros more likely to fly into airports where the ice-removing infrastructure isn't as great? Whose turn is it now?
28 2H4 : I can't speak to the accuracy of that....I was just relaying what I've observed (and heard from some Mesaba friends) regarding AZO ops. 2H4
29 Post contains images Vikkyvik : So if one reverser is unusable, would the opposite reverser be deployed on landing or not? I don't really understand the logic behind having 2 unusab
30 2H4 : Would procedures not differ from one aircraft type to another? 2H4
31 Prebennorholm : With the wheel brakes. In many airports like my local CPH the use of thrust reversers is prohibited for environmental reasons - except in case of an
32 Vikkyvik : Sorry - I was referring specifically to Matt72033's statement regarding his company's B744s. ~Vik
33 Starlionblue : Oops... Indeed. Which is why I keep saying that if the landing distance is not enough (including friction considerations) the aircraft will divert an
34 2H4 : Ah. I guess I was under the impression that aircraft equipped with reversers, and with comparable runway length requirements were getting in and out,
35 N8076U : I can't really answer your question, as it never made that much sense to me either, but I can tell you that at UA, the MEL stated the same for our 74
36 Matt72033 : i'll check the MEL again at some point today, but i know ive definately locked out one reverser without locking out the opposite!
37 HAWK21M : I don't think opposite T/R deactivation would be called for. regds MEL
38 Starlionblue : No, I was unclear. I simply meant that reversers are hardly a necessity for airliner operation. No runway length comparison involved.
39 OldAeroGuy : Under today's takeoff performance rules, neither of these statements is correct. Current EASA/FAA rules (FAR 25 Adment. 98 for the FAA) allow the use
40 Starlionblue : Good point thanks. I will revise my statement: Reversers are not needed for safe operation, but if they don't exist required runway length is increas
41 Post contains images Boeing Nut : The major reason is for FOD ingestion prevention. The two pics make it obvious why this is the case. This was discussed a while back, and I was prett
42 AirA380 : you are funny but there is no need to take the p*ss out of him...he was just curious..he didn't say there was a design flaw
43 Jetlagged : All I'm saying is that having the outboards with reversers would increase the options, or reduce the diversions. Avro RJ 100s have additional air bra
44 Zeke : If they touched down in the correct speed in the zone that would have been a good start. On the A340, the reversers only reduce stopping distance by
45 2H4 : That sounds fairly significant. It would be interesting to examine a chart that compares this percentage for all reverser-equipped aircraft. 2H4
46 Zeke : On the 340 landing with a 10 kt of tailwind and full reverse should give you the same distance as nil wind and no reverse. The numbers in my previous
47 Starlionblue : Ok let's have a poll. Would any of our pilots such as Philsquares, SlamClick, Wing and so forth have any reservations about flying the 380 with only 2
48 HAWK21M : Very Nice Picture Examples.Clearly the Engines Extend Beyond the Runway Width. regds MEL
49 Prebennorholm : The A380 has only has two reversers. Yes and No! If we call Airbus and order an A380 with four reversers, then I'm pretty sure they will say "Thank yo
50 Starlionblue : I thought it was to keep the threads in polls_and_opinions going... Not when you're skydiving.
51 Post contains images Jetlagged : I doubt that. Life is much more complicated these days, compared to the days of the VC10 and Comet (both of which had two out of four reversers). The
52 Zeke : The wiring problems as far as I understand are in the cabin, not to do with flight controls or powerplants. In my view no additional wiring would be
53 Post contains images Prebennorholm : Okay, Always keep your number of landings equal to or greater than your number of take-offs
54 N8076U : I don't really buy the argument either, but I think I understand what he's trying to say. According to the theory, a 747 is also "less safe than it c
55 Starlionblue : N8076U. Thank you for the excellent example of the 8 engined 747 with 6 reversers. This reminds me of the joke about the B-52 declaring an emergency w
56 Prebennorholm : Dear N8076U, the number of reversers have nothing with safety to do. It is about operational parameters. Sure an A380 would be able to operate on shor
57 Jetlagged : Who said anything about 6 or 8 engines on a 747? That is not my contention (or "theory") and never was. I won't repeat the whole argument again, but
58 Post contains images Starlionblue : By this logic, zero out of four is better than the current two out of four. Kidding Seriously though, there's no specific reason why you need reverse
59 Pygmalion : I'm sure if a customer wanted to add a couple more reversers to the A380... Airbus would say yes... but it will cost you 30 million a copy (or more) I
60 N8076U : Sorry if I misunderstood what you were trying to say. I was just trying to make a point, that's all, and it had nothing to do with "extra engines", a
61 Jetlagged : Yes, but that's a big, pointless, hypothetical if. As I said, if you're going to have a reverse thrust system, have it on all engines you install, un
62 Starlionblue : I still don't see the logic behind this argument. What is the reason for having to mount reverse on all engines as opposed to only two if you can get
63 2H4 : I agree. The logic seems to be "If a feature exists to reduce landing distance, it should be used"....which suggests every airliner should be equippe
64 Starlionblue : More drag chutes! And cowbells! While we're at it, let's have retro-rockets and splitting control surfaces doubling as airbrakes (like on the Space S
65 777-200 : Heh, I'm pretty shure the Airbus engineers know alot more than your about the safety of the aircraft...
66 Post contains images 2H4 : Heck, according to the media, the global transport-category aircraft fleet is already equipped with "reverse thrusters", so we're halfway there! 2H4
67 Jetlagged : Once again, no that isn't the logic. Read the posts again. I said if an aircraft has a reverse thrust system, it probably should be fitted to all eng
68 Post contains images 2H4 : Well, as you specified: ...Doing so is not always practical. 2H4
69 Starlionblue : It may be economically wrong, AKA impractical. Also, if FOD ingestion is an issue, it may make operation LESS safe.
70 N8076U : I'm wondering if, like others have said, because the outboard engines on the A380 are so far out there, and put out roughly twice the thrust of a 747
71 Post contains images Starlionblue : Indeed. Also, if you blow crap straight back through the engines it only moves more or less along the runway or taxiway. No huge problem. If crap bou
72 Post contains images N8076U : And uses a period at the end of his question, rather than a question mark to mask that fact. Chris
73 Post contains images 2H4 : HAWK21M has since replied with a letter, questioning the charges brought upon him. The letter, however, was thrown out by the investigation team. Say
74 Post contains images N8076U : Oops, sorry!
75 Post contains images Bri2k1 : Wow...we went from 8 engines on a 744 to poking fun at HAWK21M??? (Not that I mind, of course ) This just goes to prove that "reverse trusters" make e
76 2H4 : Surely, it must somehow involve several thousand birds, as well.... 2H4
77 Starlionblue : If the birds are flying upstairs or downstairs in the 380, will it make a difference to lift. (
78 OldAeroGuy : See Reply 39. The rules have changed.
79 Post contains images HAWK21M : Thanks to the Lack of Support,HAWK21M was considering losing the Bet with 5 months to spare & type in the Forbidden Question Mark.But then since Hes
80 CSMUK : I think it makes sense the Airbus A380 only has two engines that engage into reverse thrust when so many Boeing 744 pilots in my company only seem to
81 HAWK21M : Is this common with Most B747 Pilots. regds MEL
82 Kaddyuk : On the B744, all four engines are reversed when landing but with only idle power and brakes doing most of the work. If then required reverse thrust i
83 Starlionblue : Correct. If the brakes are applied fully, pax would be bang their heads pretty hard on the seat in front of them.
84 Kaddyuk : You dont need to apply the brakes fully... on a 12000ft runway, touchdown 1000ft down, leaving you with 11000ft of useable tarmac... plenty of room f
85 Vikkyvik : I heard something about birds, so I thought I'd poke my head in here, and what do I see? A bunch of guys ragging on the poor Indian guy! I think he wa
86 Bri2k1 : Funny story...I asked about that, and my post got deleted! Guess no one cares about reverse trusters anymore. Sad...
87 Starlionblue : As Vik says, I was just trying to illustrate a point about the relative importance of breaks and reverse trusters. Ahem... I mean...
88 Post contains links N8076U : I found out something interesting in another post: A380 Main Landing Gear (by WingedMigrator Jul 17 2006 in Tech Ops) Not only does the A380 have only
89 Speedracer1407 : After reading this thread for a couple weeks now, it's this information that has me quite a bit more perplexed than the thrust reverse. Carbon brakes
90 Starlionblue : So is the center wheel pair on the 342/343. It's no biggie. Also, "ONLY 16 out of the 20" [my emphasis]. That's still 80%. Since landings are slower
91 Kaddyuk : The airbus has larger wheels than the boeing and so has larger brakes... Just accept that this aircraft has enough braking power to stop the airframe.
92 Starlionblue : I can see it in front of me. The first SQ landing at LHR. "Here she comes in for landing... Long roll... She is now thundering into the BA maintenanc
93 Post contains images Jetlagged : I said that to cover myself, but I can't think of a current airliner, with reverse thrust, that doesn't have it installed on every engine (except the
94 Bri2k1 : This problem will take care of itself. The first time an A380 overruns a runway, the fleet will be grounded until the outboards are reverse-equipped.
95 Starlionblue : The problems are more related to making the aircraft meet weight and production targets. It seems to have no problems flying around and landing. The
96 Speedracer1407 : No, and I should have included that I ASSUME airbus would have desinged the world's largest passenger transport aircraft to brake properly. I accept.
97 Starlionblue : Ok. I also accept. But here's the thing. I don't really really know. I just trust that the certification authorities and the operators wouldn't put t
98 Post contains images Vikkyvik : How about.....REVERSE trust??? I think you just brought the thread full circle
99 Post contains images Klaus : I'd expect the MLG to have been designed with a) the forthcoming cargo version and b) the full-sized version (-900) in mind (although the latter migh
100 Starlionblue : Since most pax have no idea about these things they might well panic if you apply full brakes on all 10 axles at once. If nothing else, smashing your
101 Jetlagged : Not as designed. As I said, there are no current or even recently obsolete airliners with this configuration. At least Speedracer1407 has got the poi
102 Starlionblue : Handle it as in "get the pax off in a reasonable amount of time" no. But there are plenty of runways available if need be. Most larger airports have
Top Of Page
Forum Index

Reply To This Topic Why The Airbus A380 Has Only Two 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...
Is The A380 Having Only Two Mains? posted Mon May 31 2004 05:08:24 by Bio15
Do You Know Why The 737 Engine Has A Wierd Shape? posted Mon Dec 29 2003 21:53:29 by Captain777
Why The Airbus Yoke? posted Thu Oct 9 2003 02:33:00 by Tarzanboy
The Best Thrust Reverser? posted Thu Dec 22 2005 21:38:06 by Lockheed
Why The Up-Curve Of Windows On Airbus Widebodies? posted Mon Aug 29 2005 04:16:58 by Web
Why One Thrust Reverser On This Plane posted Fri Mar 14 2003 00:58:45 by BR715-A1-30
Thrust Reverser Styles On Certain Engines...why? posted Mon Dec 30 2002 23:32:52 by GotAirbus
Thrust Reverser Controls On The A320 posted Thu Apr 4 2002 06:37:28 by TWAMD-80
Why Are Airbus Aircraft Ugly At The Back?! posted Tue Aug 28 2001 14:25:14 by Singapore_Air
Dassault Falcon Thrust Reverser posted Sat Oct 21 2006 16:24:55 by Corsair2
Why The Airbus Yoke? posted Thu Oct 9 2003 02:33:00 by Tarzanboy
Why Does A380 Have Only One Vert Stablizer? posted Mon Jan 12 2009 21:03:18 by BOACVC10
Why Doesn't Airbus Put Winglets On The A306? posted Sat May 24 2008 18:50:29 by FalconBird
Why Do Airbus Tails Have A Bump On The Bottom? posted Sun Apr 29 2007 18:49:29 by Kaitak744
The Best Thrust Reverser? posted Thu Dec 22 2005 21:38:06 by Lockheed
Why The Up-Curve Of Windows On Airbus Widebodies? posted Mon Aug 29 2005 04:16:58 by Web
Why One Thrust Reverser On This Plane posted Fri Mar 14 2003 00:58:45 by BR715-A1-30
Why Do Airbus Test A380 Unpainted Before Delivery posted Thu Aug 4 2011 15:57:30 by 747400sp
Why The A332F Has A Short Tail Than The A332? posted Sun Feb 20 2011 15:39:31 by 747400sp
Why Does A380 Have Only One Vert Stablizer? posted Mon Jan 12 2009 21:03:18 by BOACVC10
Why Doesn't Airbus Put Winglets On The A306? posted Sat May 24 2008 18:50:29 by FalconBird
Why Do Airbus Tails Have A Bump On The Bottom? posted Sun Apr 29 2007 18:49:29 by Kaitak744

Sponsor Message:
Printer friendly format