High school project to propel a toy rocket as high as possible

[Ian_Brooks]

My sister has a high school competition to make a miniature rocket that shoots up - where the highest reaching rocket wins.

The best Idea I can think of is using
* a two liter pepsi/coke bottle and have a system to drop a whole roll of mentos into it
* hopefully without tearing the container apart it should shoot up
* we can streamline the edges for descent aerodynamics and perhaps have a central weight on the bottom such that it will perhaps maintain a straight line path after the contents is emptied out.

any help / ideas

*apologies if this is in the wrong section*

 

[rl.bhat]

Fill up the bottle with water upto two third of its volume. Fix a valve tube, which is used in the cycle. Close the valve tube and fill the air with a hand pump as much as possible. Hold the bottle so that its mouth is in the downward direction. Now open the valve. And see what happens.

 

[Loren Booda]

rl.bhat,

How does one determine what "as much as possible" is?

 

[Count Iblis]

It works better with liquid nitrogen or liquid helium in a sealed metal cylinder with a high pressure valve that will open just before the cylinder would explode.

 

[Danger]

I suspect that you could launch a small rocket higher with a bungee cord slingshot than you could with Mentos.
Try experimenting with various ratios of aluminum powder, butyl rubber, and potassium nitrate... VERY CAREFULLY.
If you want to go with a flameless system, vinegar and baking soda work pretty well.

 

[rl.bhat]

How does one determine what "as much as possible" is?
How does one know when the air is full in the cycle tube? Usually when you find it hard to push the air in bottle you stop.

 

[Ian_Brooks]

wouldn't the mentos solution be cheaper to implement? the only problem is that all the other students will be drenched in pepsi. :P

 

[rl.bhat]

You can fill up the bottle with water which does not cost much. I don't know what is mentos solution.