Quote:
Originally Posted by rytcd
hey, would a pneumatic pendulum style kicker be more powerful than a straight horizontal pneumatic punch? also, might it be better to use a kicker with a smaller surface area?
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That is a tough question to answer as there are many variables. Desired ball velocity, cylinder size, total air flow (Cv of valve or valves), mass of the kicker, etc. all interplay with each other.
With unlimited air flow, a horizontal punch would deliver the higher force. However, you may not need to deliver 100 pounds of force to the ball to get it to move the way you want. Speed may be more critical than force. If so, then the pendulum will give you more speed at the cost of some force.
Here are a few formulas:
1) (1/2)*acceleration*time^2 = Distance (assuming uniform acceleration and initial velocity of zero)
2) acceleration*time = velocity
Rewriting the second equation you get acceleration = velocity/time
Substituting that into the first equation and simplifying you get...
(1/2)*velocity*time = Distance
Rearranging you get to
3) Time = 2*Distance/Velocity
What speed do you want the ball to travel? (I'll assume 15 ft/s)
How much distance do you have to accelerate it? (Assume 3" inside frame + 3" under bumpers = 6" or 0.5 ft.
Plugging these numbers into equation 3 you find that time of acceleration should be close to 0.05 seconds. Putting this back into equation 2 and solving for acceleration you get acceleration = 15(ft/s)/0.05s or 300ft/s^2.
Divide the acceleration by 32.2 ft/s^2 (force of gravity) and you find the acceleration is 9.3G. Now the weight of a soccer ball is about 0.95 pounds. But to accelerate at 9.3G you have to multiply (0.95*9.3) and you find the force to accelerate the ball to 15 ft/s in 0.5 ft is averaged out to be just 8.9 pounds of force.
Of course I pulled the velocity off the top of my head and you may want to use less total distance. Actually, it would be safe to assume the ball does not stay in contact for the full stroke.
So use the equations, not the numbers and good luck!