Take the 2-minute tour ×
Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It's 100% free, no registration required.

One thing I noticed with the A380 is that it only seems to use the inboard thrust reversers while landing. I suspect it relates to FOD ingestion or perhaps damaging the runway. This is strange though, because the 747-8 (which also has a large wingspan and very large engines), does use all of its thrust reversers during landing. Does anyone have an official answer on why this is?

enter image description here

enter image description here

enter image description here

share|improve this question

1 Answer 1

up vote 7 down vote accepted

Why doesn't the A380 use its outboard thrust reversers?

Because it doesn't have (or need) any.


The A380 has reverse thrust on the inboard engines only. This saves weight and since the outboards are often way out over the edge of runways, decreases the risk of FOD.

From Airliners.net

The A380 apparently has 10 braked axles. It can stop from V1 on brakes alone with disks worn to minimum.

enter image description here

I've read that most airliners are allowed to take off even when all reverse-thrusters are inoperative. Most of the deceleration is handled by the brakes normally.


With the Airbus A380 weighing in fully loaded at 1,265,000 pounds, you might think stopping it within a reasonable distance after landing would require a Phalanx of Heavy-duty thrust reversers.

Truth be told, in the megaliner’s braking system, thrust reversers are the least critical components. Airliners are not required to have thrust reversers, and only the two inboard engines on the A380 are equipped with them. The decision not to install reversers on the A380’s two outboard engines saved weight and lowered the chances that those engines, which sometimes hang over runway edges, would be damaged by ingesting foreign objects.

The two reversers do help slow the A380—but not by much. In fact, unlike the thrust reversers on most airliners, including the Boeing 747 jumbo, they do not stop the aircraft in a shorter distance than brakes and spoilers alone. They do, however, take some of the strain off the brakes and are useful if water or snow makes the runway slippery.

From Airspace Magazine

share|improve this answer
    
If most deceleration is handled by the brakes, then why even have thrust reversers in the first place? I find it hard to believe that millions of man-hours (and dollars) went into designing, optimizing, and engineering entirely unnecessary equipment. –  Bryson S. Jun 18 at 13:53
2  
Millions of man-hours and dollars are spent on duplicate, triplicate (or more) redundant heterogeneous systems on aircraft. See Perdue University, College of Engineering –  RedGrittyBrick Jun 18 at 14:06
    
So does the difference ultimately boil down solely to the number of braked axles? –  Bryson S. Jun 18 at 14:31
1  
" It can stop from V1 on brakes alone with disks worn to minimum." - All aircraft can do this, it's a certification requirement and (partly) used to determine the runway requirements. But it's really bad for the hardware. White-hot brakes can (and do) set tires on fire, and replacing half of your undercarriage every time the pilot tries to exit on Charlie instead of Delta gets rather expensive. –  paul Jun 18 at 21:23
1  
@PhilPerry doesn't apply on takeoff because the jet blast is behind the engine, and it's accelerating away from the debris. Point your exhaust forward while slowing down, and you will at some point inhale any debris you kick up. Some small bizjets do use sideways "reversers" but they are more "thrust cancellers" as they do not slow the aircraft in any way. –  paul Jun 18 at 21:27

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.