http://www.liveleak.com/view?i=921_1179536523

I know this is kind of off topic, but I figured that in a forum where we all appreciate brakes that perform under incredible duress, I'd say that this counts. Pretty amazing footage.

wow. that was awsome.

@3:33 look at the heat waves coming off.

damn $375,000 how many sets of brembos would that buy.

Brakes are actually not the problem, its developing the best aggregate compound and tire to allow the brakes to be able to work.

Its easy to forget, even with the best components on earth on a car, the tires are the determining factor for how the car brakes, accelerates, and turns.

Impressive how they glowed for a prolonged period of time ! I'm surprised there is no onboard extinguishing system for the brakes

Impressive how they glowed for a prolonged period of time ! I'm surprised there is no onboard extinguishing system for the brakes
Looked more like fire to me :eek: . I think they said the temps were at high as 3000*C which is 5432*F !!!

wow. that was awsome.

@3:33 look at the heat waves coming off.

damn $375,000 how many sets of brembos would that buy.

He said "Three Quarters Of A Million", which is equal to $750,000.

I clean aircraft for a living and even hours after touchdown some aircraft wheels are still uncomfortably warm when I am trying to clean them.

9.7 million ft/lb of energy :eyecrazy

Wow. I'm assuming the nose wheel has brakes too, are they just biased waaaaay to the rear?

Actually, the figure is off by a factor of 10...on the low side. The total airplane brake energy is on the order of 900 million ft/lbs, divided by 12 brakes. Brakes aren't installed on the nose gear since there is insufficient vertical load to make it worth the added weight. The airplane weight is very biased to the rear in general, but placed at its forward limit for this test.

You should see what happens when things go bad. Having the pilot apply the brakes just a few knots too fast can get ugly, with wheels exploding and major fires happening as the hydraulic fluid fuels the fire. Carbon brakes however are pretty robust. The typical fire source now is all the little metal rotor clips melting out and igniting the deflated tires.

Rich

wow. that was awsome.

@3:33 look at the heat waves coming off.

damn $375,000 how many sets of brembos would that buy.

Actually the tires are what cost 3/4 of a million dollars...they said, "All twelve wheels were destroyed at a cost of 3/4 of a million dollars"

The tires, wheels, and brakes are destroyed in the test. The fire crews are there to protect the airplane and cool the axles so they don't get over heated. Having to replace the axles is a pain.

Rich

I wonder why it is all so expensive? Low volume, expensive materials and lots of QC and certification would be my guess

What were the brakes made of?

Steel is liquid at 3000F aluminum is only 1200F.... so 5400F is either a mistake, or they're made of... what?

What were the brakes made of?

Steel is liquid at 3000F aluminum is only 1200F.... so 5400F is either a mistake, or they're made of... what?
Unobtanium of course ;) .

I wonder why it is all so expensive? Low volume, expensive materials and lots of QC and certification would be my guess
All of the above, all aircraft parts have to be certified and that costs $$$!
On small General Aviation aircraft a normal "FAA Certified" alternator can costs $300 and above, while the same exact uncertified alternator for a car costs $50.

Impressive how they glowed for a prolonged period of time ! I'm surprised there is no onboard extinguishing system for the brakes
The brakes were on fire, and the test was to see if they make a maximum brake test without the rest of the airplane catching fire for 5 minutes, since that was the average time it would take the Crash/Rescue people to get to it.

Brakes aren't installed on the nose gear since there is insufficient vertical load to make it worth the added weight. The airplane weight is very biased to the rear in general, but placed at its forward limit for this test.

You should see what happens when things go bad. Having the pilot apply the brakes just a few knots too fast can get ugly, with wheels exploding and major fires happening as the hydraulic fluid fuels the fire. Carbon brakes however are pretty robust. The typical fire source now is all the little metal rotor clips melting out and igniting the deflated tires.

Rich

Somewhat incorrect, transport aircraft like the Boeing 777 in this test most definetely have brakes on the nose gear. However, lots of General Aviation airplanes, like Cessna 172's, Piper Archer's, and so forth don't.

And applying the brakes when you've landed a few knots to fast won't lead to tires exploding and cataclysmic fires, unless you lock them down.....which as this test fotage shows still isn't that bad.

M III Pilot, thanks for your YouTube link. Watching the ///M Power press video now. Never seen it before!

Yeah man, no problem.

I like that M Power video alot, just wish I had a cleaner version.

wow thats hot!

Somewhat incorrect, transport aircraft like the Boeing 777 in this test most definetely have brakes on the nose gear. However, lots of General Aviation airplanes, like Cessna 172's, Piper Archer's, and so forth don't.

And applying the brakes when you've landed a few knots to fast won't lead to tires exploding and cataclysmic fires, unless you lock them down.....which as this test fotage shows still isn't that bad.

Being a Boeing landing gear system engineer and having partipated in that test I can tell you that large civil transports from Boeing or Airbus do not have brakes in the nose wheels. It's not worth the weight and running the systems up to the nose for the small increase in braking efficiency.

Refused takeoffs (RTOs) are much higher energy stops than landings. Energy being a velocity squared function and airframers trying to get the maximum performance out of the brakes (read light weight), a few knots difference at 185 knots is a significant energy difference. With most new aircraft now using carbon brakes that don't melt, these tests are generally more successful than shorter range planes that use steel brakes. However, there have been some recent exceptions with carbon-braked airplanes with wheels exploding during these tests (not Boeing). There is some spectacular footage around, but it's not generally available to the public. It was because a DC-10 burned up after an RTO that now all max energy RTO tests are done with fully worn brakes.

Also, commercial aircraft all have sophisticated anti-skid systems that prevent any wheel lockup. They control wheel speed very closely to maximum efficiency slip angles. Typical braking efficiencies are on the order of 95% of available friction.

Rich

Being a Boeing landing gear system engineer and having partipated in that test I can tell you that large civil transports from Boeing or Airbus do not have brakes in the nose wheels. It's not worth the weight and running the systems up to the nose for the small increase in braking efficiency.

Refused takeoffs (RTOs) are much higher energy stops than landings. Energy being a velocity squared function and airframers trying to get the maximum performance out of the brakes (read light weight), a few knots difference at 185 knots is a significant energy difference. With most new aircraft now using carbon brakes that don't melt, these tests are generally more successful than shorter range planes that use steel brakes. However, there have been some recent exceptions with carbon-braked airplanes with wheels exploding during these tests (not Boeing). There is some spectacular footage around, but it's not generally available to the public. It was because a DC-10 burned up after an RTO that now all max energy RTO tests are done with fully worn brakes.

Also, commercial aircraft all have sophisticated anti-skid systems that prevent any wheel lockup. They control wheel speed very closely to maximum efficiency slip angles. Typical braking efficiencies are on the order of 95% of available friction.

Rich

OK, let me remove my foot from my mouth.

I stand corrected, I asked a buddy of mine if there were brakes on the nose gear instead of going to check myself since I didn't remember offhand.
I used to supervise the loading of air cargo and do the weight and balance, so the nose gear is not something I looked at in detail everyday.
I'm at work, so I just looked at the nose gear of the A310 sitting out back, and your right, my mistake.:(

The DC10's are also a bit older than the 777 so that doesn't surprise me.

And if your talking purely RTO brake applications then yeah, a few knots would make a difference.

worst video ever! :shifty

Unobtanium of course ;) .

:lol

Thats a pretty cool video thanks for posting it.

Impressive how they glowed for a prolonged period of time ! I'm surprised there is no onboard extinguishing system for the brakes

Not needed, that's what the fire trucks are for. This could never happen in a scenario where the aircraft would be airborne.

Refused T/offs are harder on brakes than landings because the civilian planes are always heavier on T/off than on landing due to fuel burn.

Refused T/offs are harder on brakes than landings because the civilian planes are always heavier on T/off than on landing due to fuel burn.

also can't they use the thrust reversers on landings? I assume that that test was without thrust reversers on to simulate what would happen if the engines went out on takeoff, hence causing the abort.

Actually that's when you use the thrust reversers, on landings as they help to slow the airplane down.

Lots of things cause aborted takeoffs, engine failure can certainly be one of them but not necessarily.


RichH, maybe you could clue me in on this question that I've been wondering about.

You know how after you've been hot lapping on the track with a car how your not supposed to keep the pads pressed against the rotors, so you don't get pad deposits on the rotors, thereby possibly inducing vibrations.

After an airplane lands and blocks in and the crew then applies the parking brake, does this not happen on the airplane's brakes?
If not, why?

Or does it, but since there is already so much vibration during a landing and roll out, that it doesn't really matter.

They don't set the brakes, that's why they use chocks on the wheels.

also can't they use the thrust reversers on landings? I assume that that test was without thrust reversers on to simulate what would happen if the engines went out on takeoff, hence causing the abort.

Yes they would normally use thrust reversers but this test was to simulate the worst case scenario and they did not deploy the TR. TRs would be used both on landing and in the case of a rejected takeoff if both TRs were operating nomally.

RichH, maybe you could clue me in on this question that I've been wondering about.

You know how after you've been hot lapping on the track with a car how your not supposed to keep the pads pressed against the rotors, so you don't get pad deposits on the rotors, thereby possibly inducing vibrations.

After an airplane lands and blocks in and the crew then applies the parking brake, does this not happen on the airplane's brakes?
If not, why?

Or does it, but since there is already so much vibration during a landing and roll out, that it doesn't really matter.

The brakes are typically carbon rotors on carbon stators (referred to as carbon brakes), or steel rotors on composite metal stators (referred to as steel brakes). The rotors and stators are complete disks being clamped together with brakes typically having four or five rotors. There is always one more stator an rotor alternating stator, rotor, stator, etc. The stators are keyed to the axle, effectively, and the rotors are keyed to the wheel. With the steel brakes I guess the complete circumferential contact eliminates having a deposit on only part of the contact surface.

The typical parking procedure is to stop, set the park brake, place the chocks, and release the park brake. This minimizes the heat transfer into the metal components in the brakes. Otherwise they can stretch (creep) under long term load.

Rich