Comments on: Bad Idea

By: Michael

Michael — Sat, 16 Feb 2013 18:01:39 +0000

I want one

By: Sliptonic

Sliptonic — Thu, 07 Feb 2013 03:10:52 +0000

I don’t have any objective measure of speed but it’s VERY fast. Times recorded on the finish line were just over two seconds. A typical car would run the track in about five.

By: Troy Thompson

Troy Thompson — Wed, 23 Jan 2013 15:33:38 +0000

what times are you getting or how fast is the car

By: dtspencer2320

dtspencer2320 — Wed, 28 Mar 2012 11:33:20 +0000

I would suggest using the needles from a turkey injector. They are sharp, durable, and have large center holes. Cool designs though guys!

By: DosDet

DosDet — Mon, 12 Mar 2012 16:26:31 +0000

I’ve had the same trouble with mine. With the force it takes to pierce the canisters, and the strength needed in the piercing pins, it does seem that there isn’t an answer to this – at least with this type of design. There have been designs that work but they leave the piercing apparatus on the track and the car goes down on it’s own. I think that’s tacky at best. I’ve come to the conclusion that the cylinders need to be pierced prior to setting down on the track and some kind if a valve system. I’m working on that one.
My son has a turbo-fan car (RC) that is hitting the finish line in less that a second so we are going to build the CO2 car and race them against each other. Keep a check on YouTube, when we get them done we’ll post a video “Pinewood Turbo Fan vs CO2 race”. Probably be summer or fall 2012, time permitting. Thanks for your great posts!

By: Sliptonic

Sliptonic — Sun, 20 Mar 2011 13:58:42 +0000

I hadn’t though of this. I examined the cartridges after each run and adjusted the screws to try to get the resulting holes about the same size. There was usually some variability. In two (out of four) runs, the car stayed on the track and ran perfect. In all four though, the back end came off the track momentarily at the start. My suspicion is still that the force of the hammer is causing the rear wheels to lift. If all four wheels stayed down, I don’t think uneven gas release would be a factor but with the rear in the air, it’s very likely.

By: Brandon

Brandon — Sun, 20 Mar 2011 00:55:18 +0000

Based on the nature of the two “spectacular crashes” shown, it looks like uneven gas release causing a yawing moment (remember that flat spin in Top Gun? Same problem with an SR-71 Blackbird when one engine flames out unexpectedly).

I think the easy fix would be to stack the two canisters top/bottom, so that uneven gas release wouldn’t have any negative effect. This might be tough to do within the height restrictions for a car, but if one were mounted very low (between the rear wheels) it would probably work.

By: Sliptonic

Sliptonic — Wed, 16 Mar 2011 13:57:38 +0000

That was my original idea and I still think it would be the ideal solution but I wasn’t able to make it work with the tools I have. I started by using screws as the piercing pins and drilling a small hole through the center. I was never able to get it to work. Besides hitting accurately, the piercing pins have to be sharp and durable and they have to produce a pretty large bore to let a lot of gas out quickly. I seemed to be able to get 2 out of 3 of those goals but never all three.

By: Kevin

Kevin — Wed, 16 Mar 2011 12:44:05 +0000

Very cool ides…

Would hollow spike like a syringe needle help by not needing to have the “back and forth” movement of the hammer? Just slams closed over the end of the CO2 cart and the gas could escape via the “jet nozzle”. Might even help with the power…

Kev

By: Jeff

Jeff — Tue, 15 Mar 2011 19:01:16 +0000

You might be able to have a scissors mechanism, where there is a second part (attached to the current lever arm) that moves opposite it and counteracting the force of the first arm on the lift of the car.