Launching the ball

[s_forbes]

Team 39's robot (as shown in the video, modified for prototyping purposes) does not violate any of this year's pneumatic rules that I can tell. The original design used several solenoids to feed one cylinder, but this is prohibited in the 2014 rule set.

The partially filled catapult cylinders + latch approach from 2008 was very dangerous, I cringed a lot when seeing these robots used at competitions.

Here is a shot of the NERDS (team 1726) catapult from that year. Due to the geometry, the weight of the ball allowed pressure to build up in the cylinders before they had enough force to get the ball moving. This is similar to the latch approach, but if it is dry fired there is not a massive amount of stored energy being released instantaneously.

Catapults are dangerous! Make your system as safe as possible if you take this approach.