The StratoLauncher IV 8 inch stainless steel tube has a score mark about 1/2 inch from the top that indicates the optimum fill level, which is about 1 cup of water. Exceeding this score mark does not increase the launch altitude, but rather the extra water swirls around inside the bottle before exiting thus causing the rocket to be out of balance and it veers off rather than flying straight up. This is not a problem with a narrow rocket such as an FTC rocket, which is only about 1.5 inches wide.
- SS Tube 0.25 x 8 inch with 1/4-20 inch thread
