Needing help in diagnosing catapult project. Project was to launch basketball (22oz) from the 3 point line (20ft) and through hoop (10ft). Ideal angle of entry would be 45 degrees. Launch height of approximate 2.5 feet, arm length of catapult is 2.5 feet, weight of arm is 3 pounds 10oz. Students used AMB Design spreadsheet to determine release velocity to be 9.4 m/s. Release angle to be 60 degrees.

They determined that approximate amount of force required for launch would be 250 newtons. The mass of the arm and ball is 2.26796 kg. The calculated acceleration was 110.45 m/s/s. (0 to 9.4 m/s over approx .4 meters.

From our collection of leftover parts we have four 3/4 inch pistons 7 inches long. Our calculations indicate that each piston should produce 117 Newtons of force at 60 psi. Pistons are 9 inches from fulcrum and are placed to be at 90 degrees to the arm at the midpoint of arm travel.

Each piston is on its own solenoid and is placed as close as possible to piston. Pistons have the output opened up to allow for better airflow. We have 2 tanks storing air at 60 psi so it doesnâ€™t have to go through regulator at shot. We have a latch system to hold the catapult arm momentarily from deployment of solenoids before shot.

The problem is projectile is only traveling about 12 feet and max height is about 8 feet. Does anybody see any problems with our math our other suggestions to help out?