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Name: Frank 
Status: other 
Grade: other 
Location: MA
Country: USA
Date: Fall 2011
Question:
I am building a space derby rocket, which is powered by a rubber band motor. Many sources recommend lubricating the rubber bands - the main rationale for this is that they improve the elasticity of the rubber band and possibly reduces friction. I can see how reducing friction would be advantageous, but it seems to me that given a fixed number of winds, improving elasticity would reduce the actual kinetic energy of the motor. (I can see that improving elasticity may allow for a greater number of winds and >reduce the chance it breaks- but I am assuming the same number of winds.) Do you agree or disagree?


Replies:
Hi Frank,

Having built numerous rubber band powered models in my misspent youth, I have never once heard of the idea of lubricating the rubber band!

Lubrication will definitely not "improve" the elasticity of rubber. In fact, if you use oil to lubricate the elastic, depending on the type of rubber, it stands a good chance of attacking the rubber and damaging it with long term exposure.

The only possible benefit I can imagine of lubricating the rubber band, is to reduce binding as it unwinds. But since this is not a problem that I have ever encountered, I personally doubt that there is any benefit at all.

But since this is a Science Forum, why not try an experiment both ways to see if you can see any difference? By the way, a safe "lubricant" for rubber that will prevent binding, and not damage it, is talcum power. Regards,

Bob Wilson

Try using microcare ptfe dry film. It should reduce friction and not mess with elasticity

Vanesa Dabul

Would you agree that elasticity is related to the elasticity modulus which is related to how much a material extends under tension?

So given the same number of winds does the tension change? Or stay the same?

The result of your answer and given increased elasticity should lead to the next question: do you increase the winds or not?

-Alex Viray

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