STEM101, a national non-profit dedicated to improving STEM literacy for all students, has teamed up with cart, cabinet and storage builder CTech Manufacturing to launch the next generation of the CO2 Car Challenge.
This time around, though, instead of CO2 cartridge-powered balsa wood vehicles, participants use 3D-printed cars propelled by compressed air.
Its founders are calling it the Air Drag Challenge, …
I remember our high school racing CO2-powered cars, but I don't recall participating. So either I didn't take the right class at the right time or it was just a dream.
I built CO2-powered cars in wood shop. The first one was a more standard design, aerodynamic curved wedge shape. I didn't win, but the car wasn't terrible.
The next year, I built one a bit differently. I made it twice as wide, and painstakingly carved it into the shape of my favorite real-life car at the time: a 1995 Mustang Cobra R. Including the double-ridged hood scoop shape, and the telltale Mustang sides. It was scaled so that the standard CO2 car plastic wheels we were supplied would look right on it. It was badass.
It was also so heavy that it couldn't get the whole way down the track.
I was in the TSA (Technology Students of America) and participated in CO2 dragsters. I still have my last car hanging out in the garage.
In reply to slowbird :
Pics of the Cobra R? 
This is very cool.
Speaking as a shop teacher:
Freaking cool; I love it.
The problem is going to be the bottle-neck of the printer(s). I don't have a class set of printers, and at maybe an hour (plus) per print, it would take a month of classes at least to puke out all the bodies. The kids will lose interest in the project by the time we have the class printed, whereas with wood (or soldered 1/16" metal frame dragsters), the actual "production" comes from the students themselves.
But still very cool, and I want to do it.
The shop teacher at my home town high school has been doing a similar program for his kids, although they're still making the cars out of wood (which I approve of, the whole point of shop class is to teach kids woodworking skills.)
Looks a bit slower and less dangerous than CO2 dragsters, which is going to make them a bit less interesting.
The launch box looks like you could copy it with some plumbing and an industrial solenoid valve.
Seems like friction in the wheels/axles would be the limiting factor and not aero. Same issue as back when I did a balsa wood racer gravity racer in the Cub Scouts.
Maybe polish up the nozzle for smoother air/more focused air release.
They don't seem to be going so fast that aero would make a difference. Taking the wing off would help because the car would be lighter.
David S. Wallens said:In reply to slowbird :
Pics of the Cobra R?
I'm pretty sure I still have it in a box of junk somewhere. If I ever find it I'll be sure to share.
Weight is the biggest enemy, but aero certainly does make a difference. The wings are dumb since you don't need downforce, but they sure look cool.
I know some schools have done air cars vs the CO2 cars. It's less expensive, as the CO2 canisters get pricey. Compressed Air Rockets are another one that's popular - the solid fuel rocket engines are pricey too.
And we always have to collect the CO2 empties so we aren't "DIY bong" parts suppliers....
As someone who was building pinewood derby racers with a couple of excited little boys over the weekend - this looks like a very similar set of design challenges but with different tech for building the cars. More pixels, fewer wood shavings.
berkeley yeah I remember CO-2 powered drag cars. Wood Shop. Honest to God shop teachers name was Mr. Wood. My car won. There was one car that was faster by a lot but it snapped in half because it was too thin in the middle during my dragsters race with it. The finale was racing against Mr. Woods ringer car. My car beat his by about an inch. Best thing to happen to me in 8th grade. I've been waiting over 35 years for this story to be relevant.
In reply to SkinnyG (Forum Supporter) :
Hello, Max from CTech here. Really value your solid feedback on this project. The actual printing process has been a top concern of ours from the beginning. We've considered finding a 3D printing partner, supplying pre-made cars, anything to make that step more accessible... At the end of the day those designing/printing skills have a lot of relevance to the manufacturing climate we find ourselves in, so we don't want to take away from that. Any other feedback you have to share is more than appreciated!
In reply to jharry3 :
The sky is the limit when it comes to finding more speed! The launch box was tested at 100psi (~25psi/car) with cars straight out of the box. The pressure can absolutely be adjusted to make it exciting for a wide range of track lengths. We actually shot these cars launching in slow-motion too, finding that the cars spent A LOT of time in the air as they make it down the track, with only the string tension keeping them from really taking off. This was most likely due to imperfections in the plastic wheel, or on the ground.
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