Help with Launcher

[JamesCH95]

You want seemingly insane roller speeds to get good shots.

Squirrel has posted some really good videos and specs on his team's shooter. They're rocking about 4,000rpm axle speed with a single 8" wheel. That's about 42 m/s surface speed on their shooter.

Our shooter is substantially slower, around 6.4m/s and we're getting around 2.3m range with a high-arc shot (65deg from horizontal) with no roller slippage. This is about 70% of 'ideal'. Our range is very limited even though we have over twice the motor power of Squirrel's shooter. We are rebuilding our prototype for a much faster roller speed and using smaller, lighter, less powerful motors.

TL;DR notes:

-go for very fast roller speed
-ball-park 70% free speed for ideal trajectory calcs
-power/torque matters, but rollers/wheels will store lots of energy

[Cem8301]

Originally Posted by JamesCH95

You want seemingly insane roller speeds to get good shots.

Squirrel has posted some really good videos and specs on his team's shooter. They're rocking about 4,000rpm axle speed with a single 8" wheel. That's about 42 m/s surface speed on their shooter.

Should that be in ft/sec?

[JamesCH95]

Originally Posted by Cem8301

Should that be in ft/sec?

Nope. meters/second

Check out this thread: http://www.chiefdelphi.com/forums/sh...hreadid=100540

If they're indeed running a CIM geared up 22:15 with a 6" kit wheel they're rocking about 190ft/s or about 58m/s tangential speed.

I would theorize that nearly all of the imparted energy from most roller/wheel shooter systems comes from the kinetic energy stored in the rotating mechanisms.

[jeremy5561]

OK I'll talk to my team about using the planetary gearbox. We have more torque than we need.

[jeremy5561]

Ok well I made an excel spreadsheet to calculate this stuff and I figured that if we use the sprocket we're going to lost more speed, where if we use just the gearbox we could shoot at 10 m/s. Is there any way to directly connect the 8mm shaft to a wheel?

How would I attach two wheels to one axle and directly turn that axle from the output of the gearbox?