The Brakes That Stop a 1,000 MPH Bloodhound SSC

cartechboy writes: "The problem: How do you stop the 1,000 mph Bloodhound SSC? The solution: Apparently you use steel rotors from AP Racing, which managed to absorb 4.6 kilowatts of energy on a test stand without failing although the Bloodhound team hasn't spun them up to the full 10,000 rpm just yet. During testing, a set of carbon rotors from a jet fighter shattered under the stress during a half-speed, 5,000-rpm test, thus the team switched to steel rotors. It's like stopping a bus from 160 mph on a wet road. That's how the engineers behind the Bloodhound SSC—the British land-speed record car designed to break the 1,000-mph barrier—described the task of stopping their creation once it's finished breaking the sound barrier. We'll have to wait to see if the steel rotors can handle the full 10,000 rpm run, but until then, it looks like steel is stronger than carbon when it comes to some instances."

not a car

[deadweight]

IMHO these are not cars and the records are fairly meaningless. It is a low flying aircraft being precisely controlled to keep the landing gear down on the runway. Don't believe me - watch what happens if the design is wrong. it will definitely be flying and not in a good way.

Red Lectroids drool!

[Thud457]

pish, the obvious design is to dump the energy into the oscillation overthruster. That way you don't have sudden deceleration when you collide with the mountain.

you know not what you speak of

[SuperBanana]

Steel bends, and bends back. Aluminum is the best example, being about three times lighter, but incredibly brittle. Carbon is also very brittle, just at the microscopic level. It'll fray, and slowly degrade until it comes a part -- like most fabrics.

I'm sorry, but you know not what you speak. Aluminum is used on millions of planes for, what, almost a century? There are very malleable forms of steel (like the springs in your car) and very brittle forms of steel (like some kitchen knives.) Go and look at the carbon fiber wings on thousands upon thousands of aircraft.

Go look at the carbon fiber rear seat/chain stays and front forks on millions of bicycles.

People commonly attribute specific qualities to broad material categories like "steel" or "aluminum" like you just did, which is completely ignorant of the fact that all these materials can be engineered for different properties.

Carbon fiber is the most engineer-able material available, just about. Choosing a fighter jet part was pretty stupid, given it was engineered for weight, very occasional use, and lots of airflow, etc. They could almost certainly have a proper ceramic rotor designed for them, but it's probably too expensive or they got sponsorship with AP (given the article etc. this seems likely.)

Re:Stronger?

[AK Marc]

Putting magnets into the wheels and slowing the wheels through inductive forces would solve the rotor issue (though introduce its own). I think that was the core of the suggestion.

Re:Killowatts are power, not energy

[AK Marc]

I would have considered something in the axle, though no idea what they used for it. To better spread the stresses, longer than minimum axles are generally used, and putting small magnets embedded into them with copper wire around would have minimal effect on rotating mass and be able to provide non-contact stopping power. The other option I though of was putting the same thing in the wheel, but even the smallest weight in the wheel could have large knock-on effects.

Or what about going with friction braking. Have a roller come down on the top of the wheel, and generate resistance. Use the wheel itself as the braking surface. There are 100 ways I can think of for stopping a car without having brake disks. Drum brakes started out by having the calipers work from the outside in, before it was reversed to make the "drum" appearance style widely called drum brakes. Putting them in a drum increased performance, but increased cost and complexity. Going back to the basics and re-inventing automotive brakes could give them something better than adapting current brakes to a special situation. The precursers to drum brakes were lighter and cheaper than their replacement, but were bad for wear and wet weather performance, but something tells me they won't be taking their runs in the rain (but may need to consider the large amount of cast-off of the ground surface that could pollute the braking surface in them.

This article is devoid of scientific and engineering details. It's "ooh look, this car is so fast that it breaks fighter-jet brake rotors before even trying to use them." Yeah, cool. So if it's so hard, why didn't you try other ways? What are the pads, as regular pads will no work at the temperatures given. Also, I noted the rotors were vented, but not slotted or drilled. Is this because survivability is more important than effectiveness?