I can't really think of a reason why the piston returns to the original position!! any ideas?? I made a transparent QEV coaxial cannon out of the preform of a bottle. This was inspired by a Nighthawkinlight's project, although I added a transparent barrel and had to make everything work with a wooden piston and o-ring seal. The breech seal is just a piece of rubber from the inner tube of a bike tire. Thanks for watching!

Another shot of the Rokit water rocket. This time in slomo! Full time travel achieved right after the take off probably due to the rocket breaking the speed of light. Some friends disagree with this..

Volando el Rokit en el Juancarlos... Sólo 0,5L En otros lanzamientos con botellas de 2L tuvimos grandes problemas de estabilidad. El cuerpo estrecho de la botella de 0,5L parece funcionar mucho mejor. También se ha observado una mejor estabilidad de la botella de Fanta frente a la de Cocacola. Quiza debido a que el estrangulamiento evita que el agua trepe por las paredes, o quiza incluso por un efecto coanda (?)... Flying the Rokit on the Juan Carlos I park in Madrid. As previous flights with 2L bottles were highly unstable, we took here a narrower 0,5L Fanta bottle, wich performed much better. The performing has been observed to be better also against 0,5L Coke bottles, which could be due to the water not rising through the walls of the rocket because of the throat of the Fanta bottle, or maybe even (?) due to a coanda effect...

Boomerang hecho a ojo de buen cubero en cartón pluma de 5mm En el video se queda a la mitad, pero una posterior flexión en la mitad de la herradura lo hizo hacer un vuelo perfectamente circular. Alcance -6m. Boomerang made "at its own luck" on foam cardboard (dont know the exact name. It is a sandwich of soft light white foam between two thin sheets of paper) 5mm thick (a bit less than an airsoft bb) In the vid the boomerang doesn't finish the circle but a later bending on the middle made it return truly accurately to my hand on an aprox.6 yard circle...