mentos diet-coke car record distance run

[dana_swift]

This is a car I collaborated on building. The wheels are the key to the success and as you might well expect they are shopbot made!

http://www.youtube.com/watch?v=JeH4f_RLVtk

Using the bot allowed the wheels to be balanced by design, rather than by adjustment. It also allowed the ball bearing pockets to fit with the desired snugness.

The results have been excellent. The contest the car was built for did not allow a guide line (it won there too). Now its being run for laughs, a steering mechanism is in the plans to make it follow a fishing line.

I will keep you posted with the results of that-

D

[jdervin]

Here's an over-the-top alternate version that would probably break all the rules you had to follow (and it has nothing to do with a ShopBot -- I think)...

http://www.youtube.com/watch?v=M-fyCskz3Fw

[navigator7]

Now its being run for laughs, a steering mechanism is in the plans to make it follow a fishing line.

D
"Accident are the cause of all Horseplay!"

I'm an air canon enthusiast. The pressure these plastic bottles can withstand are enormous. Some have made air cannons using the 2L bottles as chambers.
They will easily withstand 200 psi.
I see turbine applications if high pressure could be maintained in the bottle and the flow of the chemical reaction directed at an impeller with a variable belt drive.
Heck, a vane motor could work?

There is nothing I like better than making something that causes grown men to giggle!

http://www.youtube.com/watch?v=OgexaMVea-Q

[dana_swift]

John- That would be a hoot to ride. A bit expensive in terms of $/mi. 200feet for about 200 dollars! Then it got them nation wide publicity on Letterman.

Chuck- I loved that air cannon video, awesome! Where can I get more info?

I have seen a mentos/diet-coke car that used a turbine. I have video of it, but not the permission of the owners/builders to publish the video. It was fun to watch. The design was clever, and gave the car enough torque to handle very rough road, it didn't go nearly as far tho. Our car wants a smooth surface.

Update on the steering mechanism. Should cut the parts for the new mechanism on the bot this weekend. Then we will see how it goes.

The best part about botting, is work is fun, and fun is even more fun!

D

[navigator7]

Chuck- I loved that air cannon video, awesome! Where can I get more info?
What do you want to know?


I have seen a mentos/diet-coke car that used a turbine. I have video of it, but not the permission of the owners/builders to publish the video. It was fun to watch. The design was clever, and gave the car enough torque to handle very rough road, it didn't go nearly as far tho. Our car wants a smooth surface.

The best part about botting, is work is fun, and fun is even more fun!

D
Was thinking your wheels should be disks.....unless it is powered.
If powered...perhaps 4WD???

Does the Mentos injection system work well enough? Sure seems like a lot of starting power is lost just setting the car down???

[dana_swift]

What is the cannon made from? Did you use bottles only for the pressure? Is the barrel PVC or steel? What sort of valve did you use, any problem with opening it up fast enough? How many bottles?

Are there photos of this somewhere? Looks like a hoot to play with!

---

On your questions: "Does the Mentos injection system work well enough? Sure seems like a lot of starting power is lost just setting the car down???"

The half second or so of lost thrust is the time needed for the washers to pull the mentos to the bottom of the 2L of diet coke. If that is not done, they quickly follow the flow of the liquid back into the nozzle and clog it up.

I have plenty of video of great thrust, then a sudden loss when the mentos go back into the neck of the bottle where they block the exit. Loss of thrust=short run.

Losing about a second of thrust actually results in much greater available thrust as the clog problem is solved that way.

If the wheels are disks, the mass goes up, most significantly it becomes a sail and the wind can blow it around. Having the shopbot cut spokes made it light and wind transparent. Not only that but the screw holes for assembly mate exactly.

D