The Airbus A380 gets brought up a lot in these forums, but has anybody here actually flown on one? I'd be interested to hear a passenger's perspective on the double-decker.

I have never had such a misfortune! I heaven't been on a 747...yet.

I've been on a 747 before (from Los Angeles to Amsterdam), and as much as I love the 747, that may be the worst plane I've ever flown on in terms of passenger experience. We had a seat right next to the engines. It was all I could manage to get to sleep (the seats were cramped and uncomfortable), and the roar of engines made it so you had to speak fairly loudly to talk to somebody right next to you. The 777 I flew on the way back, on the other hand, was great.

The KLM 747-400's are the loudest, because the ones used from KLAX-EHAM, are 747-400M's, 'aka' combis. This means the rear area is situated for cargo, and has a door there, hence, insulation is worse. But then again, most things from the 1980's weren't the best!

I've been on a 747-400 3 times each. BA twice, roundtrip, and Lufthansa.  The video screens on the Lufthansa are still on the roof! BA otherwise has personal screens. I've also been on 737(southwest), A-320's (BAW), 777-200er's(BAW) and a 767-300 twice(BAW), A320 a4 times37-300 on America West 3 or 4 times.

I didn't fly on her yet. But in the future who knows? Emirates will begin a daily non-stop A380 flight between Dubai/Sao Paulo (SBGR)/Dubai at the end of current year. Presently are used Boeing 777-300ER to fly the long route (flight time +/- 15hr).

I'm not much of an Airbus fan, but I'd be pretty excited if I could fly on an A380--it'd be a whole new flying experience. (Sorry, Peter  ;))

Well, I've been parked next to the AirFrance A380, Qantas, and Singapore, Emirates, and all of them are HUGE.  The Engines are ridiculously giant, and loud to move the oversize aircraft.

I've seen the A380s parked at CDG, but I have never heard them with engines on. Are they really pretty loud?

StephenL wrote on Oct 11^th, 2011 at 2:59pm:

Well, I've been parked next to the AirFrance A380, Qantas, and Singapore, Emirates, and all of them are HUGE.  The Engines are ridiculously giant, and loud to move the oversize aircraft.

Smaller however, than the General Electric GE90 on the Boeing 777, they're between the size of a GE90 and a GEnx, they put aout around 85,000lbf. For some reason, only inboard engines have reverse thrust.

The engines are too far apart to have all revesers.

StephenL wrote on Oct 12^th, 2011 at 2:55am:

The engines are too far apart to have all revesers.

All four-engined jet aircraft have had reversers, Boeing 707, 747, DC-8, VC10, Tu-144, Concorde, Tu-104, Convair 880/900, Airbus A340, Lockheed Jetstar, An-124, C-5, C-17, YC-15, An-225 (6 engines), all have ha reversers, maybe some didn't, but for a large aircraft such as the A380, it seems all teh more logical to have that extra stopping power. And no, the engines aren't too far apart, the spacing between them is almost on-par (by scale) to the A340, and the 707 had them farther apartat its scale. Yeah, they say that its too heavy, whatever, it makes sense that you should, it could stop much shorter.

One main reason why the A380 has no reverser on the outboard engines are that they are too far over the non-paved strip of standard runways.
'Stopping power' is managed on that plane and incorporates a "brake to vacate" feature for example, as a world's first. So while reverse thrust is a way to decelerate, it's not the only one. But they of course use the inboard engines for it.

All certification stuff regarding the fitting of a brake system onto a plane is done with the wheel brakes only, so they have to be able to handle the plane within a certain distance and time, which takes usual available runway length for that plane's category into account.


As a side note, please be aware that real pilots usually avoid landing downwind.  ::)  :P
This helps the stopping distance significantly as the amount of kinetic energy is reduced. So chose your landing runway wisely and you don't have to develop big concerns about stopping power.  8-)


And regarding 'loud', I don't know. If you can point me to a jet engine being 'quiet' in the way people relate the word quiet, this would actually be a first.
However, the inflight noise and also the one on the flyby is very low for the A380 and should be at the lowest noise to MTOW value among all currently flying aircraft.

However, boing247's thread question is a good one.
Me says that every new plane will somehow please the passengers since the interior is updated to modern or even future standards, which of course always aims at your 'it's nice here, I will come back' mood.  :)

On a big ship like the A380, this will even be more stressed since it receives a small negative impact from the sheer amount of people around you.
So while the business class guy may be happy at most places, the economy flyer is more critical in that aspect.
I think the plane's camera views are a nice feature for everyone though.

CoolP wrote on Oct 12^th, 2011 at 9:08am:

One main reason why the A380 has no reverser on the outboard engines are that they are too far over the non-paved strip of standard runways. 'Stopping power' is managed on that plane and incorporates a "brake to vacate" feature for example, as a world's first. So while reverse thrust is a way to decelerate, it's not the only one. But they of course use the inboard engines for it. All certification stuff regarding the fitting of a brake system onto a plane is done with the wheel brakes only, so they have to be able to handle the plane within a certain distance and time, which takes usual available runway length for that plane's category into account. As a side note, please be aware that real pilots usually avoid landing downwind.  ::)  :P This helps the stopping distance significantly as the amount of kinetic energy is reduced. So chose your landing runway wisely and you don't have to develop big concerns about stopping power.  8-) And regarding 'loud', I don't know. If you can point me to a jet engine being 'quiet' in the way people relate the word quiet, this would actually be a first. However, the inflight noise and also the one on the flyby is very low for the A380 and should be at the lowest noise to MTOW value among all currently flying aircraft. However, boing247's thread question is a good one. Me says that every new plane will somehow please the passengers since the interior is updated to modern or even future standards, which of course always aims at your 'it's nice here, I will come back' mood.  :) On a big ship like the A380, this will even be more stressed since it receives a small negative impact from the sheer amount of people around you. So while the business class guy may be happy at most places, the economy flyer is more critical in that aspect. I think the plane's camera views are a nice feature for everyone though.

Why would it matter if the engines are over the paved part of the runways?

That's mainly a thing of avoiding foreign object damage on the engines.
Since the reverse thrust airflow cycle with the "brutally" separated airflow of the bypass stream behaves differently to the normal thrust one, this is a thing to be taken into account when running those large engines above unpaved surfaces.

I think a video of a landing on a wet runway pretty much shows the way the airflow tends to blow things in front of the engine where it partially gets sucked in again.
So while you can keep a runway surface rather clean, the unpaved strips are a more unsafe factor.

As said, it's not much of a problem for the plane to use those two engines only or even go spoiler + brakes only.
With the spoiler's increased angle the weight on the wheels increases and therefore you can increase the break pressure too. I wouldn't call breaking this thing an easy job, but if you have plenty of big wheels and plenty of weight forcing them on the ground, the only limits you may run into are temperature based ones, since the break apparatus itself can take the load and also provide enough deceleration then.
The brake to vacate feature then takes care that you are using the runway up to the predicted taxiway for leaving it, so it adjusts the brake pressure to match that point.

The other avoidance from the Airbus side was a cost and weight factor I think.
The first years of promoting the big wale even had concepts where no reversers at all were fitted.

The cost factor was one for the airlines too and is always connected to the expected higher break wear of course, so one could see the '2 out of 4' reverser outcome as a tradeoff solution.

Once again the man from down under is spot on with his understanding of the use of reverse thrust.

As CoolP described honking hard on the reverse thrust levers will cause grief.

http://img213.imageshack.us/img213/1521/800pxc17reversethrust.jpg

Here is just a look at the engine at idle on a moist day. You can imagine what a good Dyson cleaner these big fan engines can be.
Reverse thrust is not used for certification. Reverse thrust is most effective at high airspeed and most operators require moving towards forward thrust by 80 knots to avoid ingesting exhaust gasses and possible engine compressor stalls.

You all remember this beauty!  :o

http://img842.imageshack.us/img842/6185/cartp.jpg



Uploaded with ImageShack.us

The reversing thrust on the C-17 goes back through the engine...

LOU wrote on Oct 12^th, 2011 at 9:29pm:

Once again the man from down under is spot on with his understanding of the use of reverse thrust.

CoolP is from "Down Under"?


LOU wrote on Oct 12^th, 2011 at 9:29pm:

You all remember this beauty!  :o http://img842.imageshack.us/img842/6185/cartp.jpg

That Delta aircraft looks like it wanted to take some "extra" cargo!!!!  ;D ;D ;D

But in all seriousness. OUCH! :o

Mark

It was a great PR stunt within the airline...

701151 wrote on Oct 13^th, 2011 at 2:27am:

It was a great PR stunt within the airline...

Hmmmm. Interesting way of explaining an incident. ;D

pj747 said: The reversing thrust on the C-17 goes back through the engine...

Peter, is that a statement or a question?  :-/

---

That is NOT what you are looking at in the picture of the C-17.

The tornado going into the inlet on the C-17 is a very common sight on all jet engines in high humidity conditions. The suction of the fan causes a low pressure area at the inlet and a resulting drop in temperature which produces the visible vortex much in the same way the vortex formed at the wing tip causes the air to become filled with condensation and thus visible.

The Boeing 737 had a kit to prevent stones and gravel from entering the inlet. This device was designed to break up this suction vortex.

http://img585.imageshack.us/img585/1322/gravelprotect.jpg

http://img696.imageshack.us/img696/2809/vortexdissipator.jpg

Bleed air was used through a spray bar to dissipate the vortex.

---

As for the P.R. stunt I wonder if you would say the same thing if the airline was say Southwest?  :o

Lou

Uploaded with ImageShack.us

Its a statement, unrealted to the picture, other than the fact the topic in indeed about the C-17 Globemaster III

Speaking of that vortex, I remember seeing something similar when I flew on a pilot's retirement flight. As I mentioned before in another topic, two LAX fire department trucks sprayed the MD-80 with arcs of water, dousing it. I was seated just in front  of the engines, and noticed that the water was being sucked off the plane in a spiral--slightly different than what you're mentioning, but similar.

And just how does getting a luggage cart jammed in an engine improve public relations?  :-? (Or is it just the comedy  :))

And Lou-- did many propliners have reverse thrust? I know the C-130 does, and I think the Twin Otter does, too, but how about some older planes such as the Constellation or the Stratocruiser.

Markoz wrote on Oct 13^th, 2011 at 1:47am:

LOU wrote on Oct 12th, 2011 at 9:29pm: Once again the man from down under is spot on with his understanding of the use of reverse thrust. CoolP is from "Down Under"?

Remember, Moth Air has all the routes.  8-) Wanna join?  :P

We are thinking about Peter being our PR guy.  :) We just have to make sure there are enough engines and baggage carts available.


The vortex picture is a great one!


Boeing247, that Stratocruiser in the sim has the reverse thrust modelled, but keep in mind that a prop reverses differently than the current hi-bypass jet engines.
They really "flip" the blades to an angle producing thrust in another direction. You can even see that happening on the torque meter as it goes down first and up again as the new direction has established and the engine then has to put power on the shaft again. The sound is very different too.
The whole prop reverse process is way more efficient than the methods used on the jet planes since you get a large amount of the currently produced engine power acting in the now braking direction, except for the exhaust gases.
With the smaller intakes or even very "automotive" ones, the danger of foreign object damage (to the engine itself) also acts in another regime.

The jets don't alter any blade angles (=fixed blades), but more or less try to redirect the airflow they produce. Sir Newton would love that method.
The older ones had those moving buckets, the newer hibypass ones are mostly running with the 'reversed' bypass airflow only while the core still produces 'unreversed' forward thrust.
The amount of the contents differs though, so the bypass part is (by far) the dominant one, in every direction.


Hey, look at the other pictures from Lou, that's the 'Gravel Kit' of the old 737s. I would love to see that modelled in the sim.
Together with a sort of deflector on the front wheel it's really approved to run the jets on the nasty gravel strips, like he says.
Here are some more details. Nice page by the way. http://www.b737.org.uk/unpavedstripkit.htm

CoolP wrote on Oct 13^th, 2011 at 9:04am:

Markoz wrote on Oct 13th, 2011 at 1:47am: LOU wrote on Oct 12th, 2011 at 9:29pm: Once again the man from down under is spot on with his understanding of the use of reverse thrust. CoolP is from "Down Under"? Remember, Moth Air has all the routes.  8-) Wanna join?  :P We are thinking about Peter being our PR guy.  :) We just have to make sure there are enough engines and baggage carts available. The vortex picture is a great one! Boeing247, that Stratocruiser in the sim has the reverse thrust modelled, but keep in mind that a prop reverses differently than the current hi-bypass jet engines. They really "flip" the blades to an angle producing thrust in another direction. You can even see that happening on the torque meter as it goes down first and up again as the new direction has established and the engine then has to put power on the shaft again. The sound is very different too. The whole prop reverse process is way more efficient than the methods used on the jet planes since you get a large amount of the currently produced engine power acting in the now braking direction, except for the exhaust gases. With the smaller intakes or even very "automotive" ones, the danger of foreign object damage (to the engine itself) also acts in another regime. The jets don't alter any blade angles (=fixed blades), but more or less try to redirect the airflow they produce. Sir Newton would love that method. The older ones had those moving buckets, the newer hibypass ones are mostly running with the 'reversed' bypass airflow only while the core still produces 'unreversed' forward thrust. The amount of the contents differs though, so the bypass part is (by far) the dominant one, in every direction. Hey, look at the other pictures from Lou, that's the 'Gravel Kit' of the old 737s. I would love to see that modelled in the sim. Together with a sort of deflector on the front wheel it's really approved to run the jets on the nasty gravel strips, like he says. Here are some more details. Nice page by the way. http://www.b737.org.uk/unpavedstripkit.htm

Does moth air have an MD-11 or L-1011? I can try to get the baggage box tuck in teh center engine.

The main question will then be: how does this actually help our PR?  :-?
By the way, me no likes full quotes.  ::)

CoolP wrote on Oct 13^th, 2011 at 12:42pm:

The main question will then be: how does this actually help our PR?  :-?

Mu cuidadosamente

Is it me? I'm never sure if Peter really means what he says.

pj747 said: The reversing thrust on the C-17 goes back through the engine... ???

pj747 then said: Its a statement, unrealted to the picture, other than the fact the topic in indeed about the C-17 Globemaster III

Hummmmmm???  :-/

Peter,

The air from the reverse thrust does not go through the engine. If it did, in any great quantity, it could cause the engine to compressor stall. Most modern large-fan jet engines only reverse (deflect) the fan air, the bulk of the thrust. Smaller engines and older large fan's reversed the fan and the turbine air. This caused too many problems with stalls and unbalanced air flow through the engine. Pilots are instructed to be at idle thrust by 80 knots, so the deflected air is not brought back into the inlet, along with other stuff like dirt or stones that could get sucked into the inlet - not to mention baggage bins!  :P

---

boeing247 asked: Lou-- did many propliners have reverse thrust?

All of the turboprops alter the blades pitch to control the thrust of the "disk." There is a position called beta where the thrust is about zero. In flight beta can produce a lot of drag since the diameter of the propeller (disk) produces drag equivalent to a solid disk. You can hear the sound produced by the spinning disk as it goes through this phase. The C-130, DHC-6 and most turboprops can use this ability to rapidly alter the blade angle for fine control of the thrust including reverse to back up the plane. Older prop planes also had the ability to change the blade angle and produce reverse thrust. Planes like the Boeing 337 with the P&W-4360 had to be treated with kid gloves when using a lot of reverse so as not to fry the engine or foul the plugs.

Here is a video of a C-17 backing up after landing at an airshow. The C-17 reverse is deflected up and to the side so as to avoid sucking-up stuff off the runway.  In the airline industry doing something like this would cause the CEO to have a heart attack since the chance of engine damage doing this is very high. Wait a minute, CEO don't have a heart so that could not happen!  ;D

C-17 backing up after landing...
http://www.youtube.com/watch?v=T9rdzqOgNrA

A few related videos...
C-17 landing in Afghanistan on a dirt runway. What do you think the descent rate was on touchdown?
http://www.youtube.com/watch?v=diX3x6ffvSA&feature=related
Boeing 737 taxing in snow. You can see the area in front of the engine where stuff is sucked into the inlet.
http://www.youtube.com/watch?v=L1DkUOOfDFk&feature=related
Short video showing the fan blocker doors in operation on a large fan engine.
http://www.youtube.com/watch?v=92ixq3iHFxQ&feature=related

Lou

I'll add this one to your already nice collection. Watch the airflow acting on the runway surface.
747 reverse thrust http://youtu.be/eqQcg7e8eYc?t=23s



Quote:

C-17 backing up after landing... http://www.youtube.com/watch?v=T9rdzqOgNrA

Sorry, Lou, you were fooled there, the video just runs backwards.  ;D And then forward again .. wait a minute.  :-?

CoolP wrote on Oct 13^th, 2011 at 3:42pm:

Quote: C-17 backing up after landing... http://www.youtube.com/watch?v=T9rdzqOgNrA Sorry, Lou, you were fooled there, the video just runs backwards.  ;D And then forward again .. wait a minute.  :-?

CoolP. I was actually at that air show at Avalon to see it do that. I'll have to dig up the photos my sin took at Avalon 2009. ;)

There is a rumour that, when reverse thrust is applied, the pilots also talk reversed (or like those spambots).  :-? Kinda creepy, huh?

Are you making fun of spambots???  


captainsim.comBUY CAPTAINSIM!!!captainsim.com

701151 wrote on Oct 12^th, 2011 at 1:54am:

StephenL wrote on Oct 11th, 2011 at 2:59pm: Well, I've been parked next to the AirFrance A380, Qantas, and Singapore, Emirates, and all of them are HUGE.  The Engines are ridiculously giant, and loud to move the oversize aircraft. Smaller however, than the General Electric GE90 on the Boeing 777, they're between the size of a GE90 and a GEnx, they put aout around 85,000lbf. For some reason, only inboard engines have reverse thrust.

It's only inboard because of weight*, however some addons have all 4 engines with reversers.
But then those addons were mostly released before the aircraft was rolled out, so they didn't know that much about it then.

*Evidence from book 'A380: Super Jumbo' by Nigel Wagner.

Razordraac wrote on Nov 11^th, 2011 at 8:09pm:

701151 wrote on Oct 12th, 2011 at 1:54am: StephenL wrote on Oct 11th, 2011 at 2:59pm: Well, I've been parked next to the AirFrance A380, Qantas, and Singapore, Emirates, and all of them are HUGE.  The Engines are ridiculously giant, and loud to move the oversize aircraft. Smaller however, than the General Electric GE90 on the Boeing 777, they're between the size of a GE90 and a GEnx, they put aout around 85,000lbf. For some reason, only inboard engines have reverse thrust. It's only inboard because of weight*, however some addons have all 4 engines with reversers. But then those addons were mostly released before the aircraft was rolled out, so they didn't know that much about it then. *Evidence from book 'A380: Super Jumbo' by Nigel Wagner.

I know their stupid reasons for everything...