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How do I propell a small foam rocket up a wire that goes through it? Answered

I'm working on robot model covered with foam core and I wanted to add a fun detail. The robot has a rocket launcher behind it's shoulders and I thought it would be a fun feature if it could actually shoot a small 2 1/4" tall by 1" diameter (1 1/2" with the fins) flat top (not pointed) rocket upward approx. 9 inches and over it's shoulders and down in front of it's body to hit another object on the ground. I made the mini rocket with 1/8" thick foam sheet circles and a straw that runs through the entire rocket (think barbell inserted into a foam cylinder) so I could thread the wire through the middle of the rocket. I was going to put a cylinder inside the rocket launcher area to help guide the rocket up and through the hole. The area inside the rocket launcher is tight, approx. 3" tall by 3" wide by 3" deep. The wire I'm using is a 9 gauge wire to guide the mini rocket up and out of the 1 3/4" launch hole and down the path.

The problem I've run into is getting the rocket upwards with enough thrust to the peak (at the shoulders) to where gravity will do the rest. I wanted to try to totally conceal the method I was using to achieve this and yet be able to reset it to shoot it multiple times easily. I've tried to do a blast of air by running 1/4" tubing, but with the hole in the middle, it won't move. I purchased a mini 50mm x 10mm fan that fits inside, but unfortunately it does work either. I thought about using rubber bands, a balloon, but the space is too confined. Any suggestions is greatly appreciated.


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Jack A Lopez
Jack A Lopez

1 year ago

I suggest using a compressed spring.

Have you ever seen the, uh, "snake nut can" gag? Wikipedia describes it here:


I am guessing some similar contrivance, also using a large, compressed spring, could be used to launch your robot's rocket.


Reply 1 year ago

I thought of this this morning as I was typing, great minds think alike, LOL. Was thinking of the best way to release the compressed spring. I'm thinking if I cover the launch hole as a way to hold the compressed spring, the spring will probably crush the foam rocket. Perhaps a trigger release is best from below the rocket. Now to figure out one that looks good and works easily to reset in the confine space. Thank You!