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  • Writer's pictureNed Patton

How do Airplanes Stop When They Land?

I recently went up to Spokane, WA for a memorial for my cousin. If you remember, I wrote a post about his passing in December of last year. But, that’s not the subject of this post. When we were walking through the Spokane Airport on the way home, we happened on a display of an aircraft brake that was sectioned so that you can see how it works. And, lo and behold, the brake material is a carbon/carbon composite.

These pics are of a carbon/carbon composite brake for a 737. They are part of a display from Collins Aerospace, which has a major manufacturing center in Spokane where they make brakes and landing gear for commercial and private aircraft.

What you see in the pics above are cutaways of an actual 737 landing gear brake. Notice that the brake is embedded in the wheel itself rather than being separate like it is on a car. The pic on the right shows the hydraulic pistons that apply pressure to the stators and rotors (brake pads) with their carbon-carbon friction material on them and that make the aircraft slow down from landing speed of about 130 to 150 knots to a taxi speed more in the neighborhood of about 20 knots. And for those of you unfamiliar with nautical terms, a knot is a nautical mile per hour which is about 1.15 MPH. I find it interesting that airplanes use the same speed measurement as boats and ships, so large transport aircraft are really air ships 😊.

A better pic of the brake assembly is shown here in more diagrammatic form. This pic is a

schematic of a Gulfstream G450 which of course is quite a bit smaller than a Boeing 737, and the brakes are not as large, but they are the same basic construction, and they are carbon-carbon as well. But on this pic at least the different pieces and parts of a common aircraft brake are labeled so you can see how the brake works. The stators – the stationary part of the brake that is attached to the axle itself – consists of the disks that you see in the pic above that are between the rotors – the part that moves with the wheel – which you can see in the pic above and to the right that has those things that stick out with metal surrounding a carbon-carbon center. The metal part is apparently attached to the wheel itself which starts rotating as soon as the tires hit the runway – at something like 150 MPH. Your normal brake pads that you have in your modern car, which are not made of a carbon-carbon composite would never survive even one landing of a modern transport aircraft like a Boeing 737. Just the heat generated from the friction of slowing down an aircraft the weight of a 737 from 150 MPH to around 20 is enough to disintegrate most other materials. And, on top of this, these things last a long time. There are wear indicators just like on the disc brakes on your car, and they don’t get changed out for wear all that often. Commercial jet aircraft don’t make money if they aren’t carrying passengers from one place to another after all.

Such is the magic of the carbon atom. I have talked about carbon extensively in this newsletter/blog, so those of you that have read my posts understand why I pay so much attention to this very common atom – the fourth most common element in the universe after hydrogen, helium, and oxygen. And, of course, carbon is the stuff of life – all organic life is based on the chemistry of this stuff – so it is one of the most important elements to us as living beings. And, it just so happens that it has incredibly interesting properties. It does not melt, it is a solid at an enormous range of temperatures, and the covalent bonds that it makes with itself and other atoms are some of the strongest bonds known. Of course, I could go on about carbon for several pages here, but that is really not the point of this – other than to point out that here is another very interesting application of carbon composites. Pretty amazing if you ask me. But then that is why I have been interested in these wonderful materials most of my professional career.

That’s about enough for this week. I am going to be reminding everyone right here each week that I will be presenting two papers toward the end of this year. Both of them are about sustainability of composites – a subject that all of you that have read my posts know is a passion of mine. The first one is a paper about sustainability efforts for composites in general, with a focus on what to do with wind turbine blades. That one is going to be at the International Mechanical Engineering Congress and Exhibition in New Orleans October 29 to November 2 ( The second one will be at the Carbon Fiber Conference in Salt Lake City being put on by Composites World ( In that presentation I will focus on current work in sustainability of carbon fiber in particular. I’m of course going to talk about new fibers and fiber precursors made from plants, so again, focusing on closing the circle.

And, finally, for those of you that have not heard, my book has been published and is for sale. The best place to get one is to go to my website and buy one. I will send you a signed copy for the same price you would get charged on Amazon, except that I charge $8 shipping. Anyway, here’s the link to get your signed copy: And as usual, here’s a picture of the book, for those of you just tuning in.

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Sep 28, 2023
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Thanks, Ned! Very interesting!!!

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