Brake dust?

[Typhoon1244]

Okay, so I don't know everything. Somebody tell me, what the hell is coming off the wheels of this 747?

 

[DCitrus9]

It appears to be a malfunctioning chemgoo dispenser, or perhaps outdated chemgoo. Those dam dirty dutch are always trying to cut corners...

 

[POKEY]

I thnik this belongs in the Chemtrails thread

 

[Typhoon1244]

Can anybody just answer the friggin' question?

Is that really brake dust? I've never seen a pic like this before.

 

[skyking1976]

I too would like to know what that is. It looks like they might be hot brakes but that doesn't make much sense because they just took off. Curious...

 

[TX_DFW]

I'm not really sure but i would have my doubts.

 

[Buffettpilot]

Ok, before everyone kills my answer, my thoughts are:

cooling effects of the tires (just heat exchange off hot wheels burning down the runway and the cool air now on them)....

So go ahead and tell me the real answer, cause this is just a guess

 

[Wankel7]

Well, rubber burns black so it most likely tires. Isn't brake smoke white?

Maybe they went a little past V1 and there was an extreme crosswind on takeoff? Causing the tires to over heat?

Thats my guess

James

 

[pilot141]

Well here is another photo by that same guy on the same day of a Delta 777 taking off.

They are both taken at Amsterdam, so my guess is that both airplanes ran through a bunch of deposited rubber on the departure end of the runway on takeoff. There might have been a shower that loosened the rubber, or some poor bastard locked up the brakes on landing before these two aircraft took off.

 

[avbug]

In a shadow, it's almost impossible to tell the color of smoke. White smoke looks black. This doesn't appear to be smoke to me, but probably moisture (water) on the wheel assemblies. Departing off a wet runway, or through standing water on the runway, may produce a spray as appears in those pictures. If the gear is shadowed by the fuselage, against any light background (eg, sky, cloud, etc), the appearance will be dark.

You've probably seen the same thing in a contrail that appears dark from one angle, but is really just plain jane old ice crystals, and appears white from another angle.

 

[GCD]

You don't believe that you can have hot brakes after takeoff? Just try taxiing at 850,000 lbs (-400) or 830,000lbs (-200). Ever wonder why the whales look like they are taxiing so slowly? It's simple; because they are. The weight on the tires causes a greater friction and heat transfer from the ground through the tires. Add a little brake friction and it makes a wonderful combination of heat. If a whale taxis slowly, there is less friction heat transfer and less need to apply brakes, which will increase heat.

As a matter of fact, tire manufacturers recommend that for every 5,000' of taxi distance, a five minute cool off period is needed for the tires. Also, remember, heat build up reaches the peak maximum 15 - 20 minutes after takeoff or landing. That is one reason we practice the blown tire on takeoff routine in the simulator.

I'm sure SWA guys hate to get behind us. We use INS ground speed to taxi by. We use a maximum of 20 knots on a straight taxiway, and 10 knots maximum for a turn. It is not unusual for us, on a hot day, to delay gear retraction to cool off the Dunlops.

Now, for the original question: Amsterdam's elevation is -11' MSL. On a cool, humid day, the heat from the tires and brakes could possibly give the same visual effect that hot exhaust gasses give (not smoke, but bending the prism from heat).

 

[EOpilot]

Well someone made the point that any color would look dark when in shadow against a light background. I would agree with that statement although it doesn't seem to be the case here. If you look at the wheels, they are cast in sunlight. So whatever that trail is, it is not in shadow.

Now even if the brakes are extremely hot from taxiing, the smoke from hot brakes wouldn't appear that thick when travelling at 200 MPH unless they were on fire. (Doubtful.)

But on most larger aircraft (and some smaller ones) when the gear is retracting the brakes are automatically applied on the main gear to stop wheel rotation from interferring with the retraction. If you notice, both pictures are taken early in the retract cycle and the trail of particulates is short and abrupt (more obvious on the 777 picture).

The brakes were being applies on very fast spinning tires. This would dislodge a fair amount of brake dust in a short period.

Alright Typhoon, whaddya think?

 

[Eagleflip]

While I understand that most large aircraft apply brakes during gear retraction (at least I know for sure that the A320 does), it doesn't make sense that this is brake dust.

Why? I've hardly ever seen anything like this before. Of the hundreds and hundreds of takeoffs I've observed, I have never noted any consistent "brake dust" flowing behind an aircraft.

Using my Sherlock Holmesian logic, I therefore conclude that these jets rolled through some sort of water near their liftoff point. That water would then spin off the tires, creating this stream. In addition, that water near near the brakes would probably vaporize from the heat as the gear retract.

Or, to satisfy Denver, it could be a case of PGE...(Premature Goo Ejaculation).

 

[El Duderino]

Obviously Chemicals leaking out early. That is prior to chemtrail release. God Bless Oliver Stone.

 

[SennaP1]

Carbon Fibre dust

Don't most transport category a/c have carbon fibre brakes? I'm willing to bet its the dust off of those that is blowing off. If you're ever seen a F1 car under braking, or in the pits when they change tires same kind of effect.

 

[Typhoon1244]

The brakes were being applies on very fast spinning tires. This would dislodge a fair amount of brake dust in a short period.

Alright Typhoon, whaddya think?

Well, I suppose that could explain it. But why the exact same thing on two departing aircraft...the 747 and the 777?

You know, I just remembered something. My dad and I were watching Frasier one night. It was the one where Lilith had come to visit, and Daphne developed a mysterious headache that persisted until Lilith left town...but I digress.

During the closing credits, there's a ten second clip of an A300 taking off from SEA. Right as the gear started to retract, there was a puff of black smoke from (I thought) each engine. "A double compressor stall?" I asked. Dad's answer was that the "smoke" had probably come from the mainwheels, caused by the brakes being applied as part of the retraction cycle.

So I guess I was wrong when I said I've never seen that before. However, these two pictures show massive streams of smoke/dust, not the little "puffs" I saw.

Originally posted by Eagleflip
...to satisfy Denver, it could be a case of PGE...(Premature Goo Ejaculation).

I used to have that problem. Now I just think about baseball.

 

[EOpilot]

In the photos it looks like massive streams of smoke because the picture was taken in "mid puff". If you looked at the same takeoff in motion from the same angle you'd see that the smoke would end abruptly as the wheels came to a stop before they made their way to the wheel wells, within a second after the photo was taken.

To those who say this is unusual to this airport, wet runway, time of day, phase of the moon or just this photographer, this seems to happen to Australians too.

Like this one,
this one,
and this one.

Please note the explanations given by the photographers who've seen this a few times before (not that they are experts), and the cloudless skies in all photos. (Not that there couldn't be standing water, but water doesn't look black in sunlight..... Except at the Jersey shore.)

Oh yeah. Another photographer in Amsterdam caught the effect on a different day.

Am I bored today? Oh you bet your sweet bippy.

 

[Typhoon1244]

Well, you learn something new every day, don't you? Thanks EOpilot. You're boredom has caused me to be further educated.

Originally posted by EOpilot
Oh you bet your sweet bippy.

Deja vu...my economic geography professor at U. Tenn. used to say that all the time.

 

[GCD]

If it was water on the runway, why isn't the nosewheel trailing the same effect?

Yes, the main wheel brakes are applied as the gear retracts, and you do often see the "puff" from the mains.