Pneumatic flipper design guidance

Hello so, I'm building a featherweight robot for rampaging chariots. I'm planning on making a flipper which will be used to kick a ball at 45 degrees. I want to use pneumatics, which I never used before. Could someone tell me what parts am I going to need in order to build the most basic and easiest to assemble flipper ? and also what force should the piston exert to reach a high enough torque ?
from my probably faulty calculations, I will need about 6 newtons of force to kick the ball at the desired speed
(impulse calculation to get speed of flipper, then conservation of angular momentum)

here is everything you might need

the chasiss:
http://imgur.com/a/w7LYW

the flipper size: 21.61cm (length), 28.6cm (width), 8mm (depth) made from alluminum
flipper initial angle: 50 degrees (incline from horizontal)
flipper final angle: 45 degrees
flipper density:

2712 kg/m^3

ball radius: 0.06 m
b

all mass: 0.1 kg

ball required speed: 4 ms^-1

Is it better to use a single or double acting piston ? what pressure to use ? exact part specifications are very welcome