Bottle+Rocket

4W list:
 * Who || What || When || Where ||
 * everyone || State Meet || March 17, 2012 || Assumption College ||
 * everyone || State Meet || March 17, 2012 || Assumption College ||

From SOSI (Science Olympiad Summer Institute):

The rocket towards the bottom of the picture spent the greatest time aloft. The bottle towards the top-right did not. :-)

SOME TIPS FROM SOSI:
1) Take off the bottle's label, and mark the sides of the bottle (in permanent marker) with various volumes (50 mL, 100 mL, 150 mL, etc.). 2) Try filling the bottle in various amounts between 250-500 mL of water; the ideal volume is almost always (if not always) within that range. 3) The "nose" of the cone is usually best if between 1-3 ft. 4) Ping-pong balls generally make the best tip (low-density, so the whole rocket does NOT get "tip-heavy"). 5) Plastic tubes work well for the base of the cone; alternatively, you could try using rolled-up paper (either cylinder- or cone-shaped). 6) TRIAL-AND-ERROR-FOR-BALANCE-ONLY: drop the rocket *sideways* off of the 2nd or 3rd floor of a building. If it falls tip-first, make the rocket's nose shorter. If it falls bottom-first, make the rocket's nose longer. 7) IF TRIAL-AND-ERROR-IS-GETTING-FRUSTRATING(-OR-IF-YOU-DON'T-MIND-INVESTING-SOME-TIME-BEFORE-YOU-START-LAUNCHING): for the rocket to descend sideways (a.k.a. be a "Backslider"), if you look at the side of the rocket, you should see an equal *area* on each side of the center of mass. a) **To find the center of mass:** find the point at which you can balance the rocket on a finger (like a balanced see-saw). b) **To test if you have equal areas on each side**: trace the outline of the bottle rocket onto some graph paper (maybe several sheets taped together). Then draw a line across the outline of the rocket where you found the center-of-gravity. Count the squares on each side of the line. If the side with the nose has more squares, make the nose shorter. If the side with the nose has fewer squares, make the nose longer. --DWJ