It was lost some 300 feet from the launch site on the roof of a building. A sketch with approximate dimensions follows. We got great amusement from the resulting shower of debris. More recent launch successes have involved smaller bottles, tubular fins or corrugated plastic fins inserted in the report cover spines, and a half tennis ball nose. They are elegant and effective.
Acceleration is almost immediate, and the rocket's flight is almost entirely ballistic.
With a tube launcher, the initial thrust takes place with very little loss of water, and lasts the length of the launch tube. At that point, not only the rocket but also it's considerably more massive fuel are already traveling at speed. Any loss of pressure up to this point is partially offset by air entering the rocket from the launch tube. An open nozzle launch uses the original dimensions of the bottle's mouth for the nozzle. This is not the only way to launch these rockets, nor is it going to result in the highest performance.