The Controversy Behind Nike’s Vaporfly Running Shoe, Explained | WSJ

Anything more than totally naked sporting competition is essentially a materials question.

Wooden tennis racquets gave way (briefly) to aluminum and then to composite racquets.

Wooden baseball bats became aluminum then composites.

Similar progressions took place for pole vaulting and nearly every other sport.

In running, however, the materials question mostly shows up in the running shoes, and Nike's Vaporfly is the current materials leader in that realm.

More videos after the jump...

Can We Throw Satellites to Space? - SpinLaunch

This is another overly long video that is filled with a massive amount of science in all sorts of disciplines: physics, material science, chemistry, engineering, mechanics.

The video sees the Real Engineering host, Brian McManus, visit SpinLaunch's centrifuge being built to launch satellites into space primarily via kinetic energy rather than through rocket fuel combustion...which sounds totally bonkers but might work out.

One of the main technologies here involves a carbon fiber-reinforced polymer tether. At 3:00 that concept is explored with a laminated carbon fiber reinforcement mock-up of the thickness that they need the tether to be to hold the millions of pounds of force that would be necessary.

Then - 8:00 - they look at the need to spin up that tether in a vacuum chamber so that it doesn't melt the carbon fiber from the friction due to air resistance. They also describe how truly low pressure vacuum chamber pumps work and why the SpinLaunch people don't need a vacuum chamber with quite that low a pressure. The idea of outgassing from the metallic parts - 10:25 - was amazing to me. It makes sense to me that there would be small amounts of oxygen gas 'dissolved' in any steel parts, but I had certainly never thought about it before. It's an equilibrium problem, I guess, as oxygen is removed from the atmosphere around the part.

At 16:20 they take a look at the challenges of opening a low pressure chamber at near vacuum to the atmospheric pressure outside without destroying the chamber inside when the air rushes in. They've used a pairing of mylar layers that are broken through and two incredibly quick closing doors.

From 21:30 they explain how they address and minimize vibrations - especially once the payload is let go, leaving a highly unbalanced weight on the arm.

The next section - from 26:45 - they look into the ballistic coefficient of the projectile and why a heavier vehicle might be better for their launch process - something that is very well against the traditional method of launch's goals. With rockets, lighter is better. With the SpinLaunch, heavier and denser is somewhat better because it allows the projectile to gain more momentum without corresponding drag and heating due to friction with the lower atmosphere.

The whole process is fascinating, and I'm hopeful that it turns out to be feasible because I would love to see a full scale SpinLaunch facility built and functioning - for the science and novelty if for nothing else.

Carbon Fiber - The Materials Of The Future?

The rocket animation shown around 1:00 looks pretty hokey to me, though the concept is pretty outstanding.

I was speaking to a former student of mine who now works as an engineer in the aircraft industry. She said that one of the major issues with the carbon fiber laminates being used in airplane bodies nowadays is going to be the lack of recyclability after the plane's usable lifespan.

In this video we get a brief history of how carbon fibers are made, the initial uses of and driving forces for development carbon fibers, an explanation of the directional strength of the composite material, the general procedure of curing the laminate, and a quick look at SpaceX's use of carbon fiber composite laminate in its reusable fuel tank.

It lacks a bit in the 'how it's made' first steps, but it's a great overview of how carbon fiber works, its strengths and weaknesses.

Pinkbike vists the Santa Cruz Test Lab Video

Edit: Looks like the video has been taken down from YouTube. It's still available (but not embedable sadly) on this webpage which includes a lot of analysis of the tests.

break it!

Break it!

BREAK IT!

Joe Graney might want to talk to somebody about how to look like he's actually enjoying his hosting duties, because he's lucky enough to be standing there and breaking the snot out of both aluminum and carbon fiber bike frames (with a screw drive at 0:47 and then with dropped weights at 2:45).

Interestingly, the sudden breaks (from dropped weights) don't look all that different, but the slow breaks look very different.

Thanks, by the way, to Frank Marks, Director of Engineering for Utah Test and Training Range, who showed this at our graduation in Salt Lake City last week.