2-Speed Shooter Gearbox

[JVN]

Based on a post by Andy Baker, I started thinking about something.

Originally Posted by Andy Baker

The gears and the plates go together to make a 2 speed, shift-on-the-fly shooter. This is to optimize acceleration. They can start their flywheel in low gear, get up to a good rpm and then shift to high gear. With this shifter, they will be spinning at top speed faster than their opponents. Very nice.

Andy B.

Based on the motors we're dealing with, is a 2-speed shooter advantageous?
Andy is (of course) right about decreasing the acceleration of the system by using a 2-speed; I'm wondering, is it necessary?

Unfortunately, I haven't had a a chance this year to play around with the design of these systems. Who has more information about the acceleration time for a shooter in this year's game?

First set of questions--

• How long does your shooter take to reach top speed?
• Do you think this is an unreasonable time?
• What advantage do you think you'd gain by decreasing that time (by half or more)?

Second set of questions--

• If you had a 2-speed gearbox, how much time would it shave off your acceleration time?
• Would you be able to reduce the power applied to the shooter, and still have comparable acceleration time (using 1 motor, instead of 2)?
• Would a shifter weigh less than this 2nd motor?

[vadyr]

what about a shooter with a fully adjustable speed

[DjAlamose]

We have decided that there are better ways of doing this. You don't need to gear the shooter twice to get it to speed up faster. How about an adjustable flywheel instead? Plus there really isnt that much of a differance. Ours would go from 3 sec down to 2 sec. That really isn't that much of a differance when the shooter gets the shots off fine in 6 sec.

[Kevin Sevcik]

We're using a CIM through a Dewalt for the reasons stated in Andy's post. The math says it'll shave about a second off the spinup time. I think the more important feature is that it optimizes the power output to the shooter. Your motor is limited to 40 amps or so, after all. If you gear it low to start out, you can get out of the RPM range where you're drawing 80+ amps at 12V a whole lot quicker. And you only need to worry about the sequence once if you're keeping your wheel spun up the entire time. Although I really need to check on the current draw to see if we'll be doing that.

[Mark McLeod]

Our shooter reaches full operating speed in 0.6 second (due to good mechanical design coupled with software control), but we slowed it to ~ 2.0 seconds to reduce the stress on the mechanical system (to reduce the stress on our M.E. really).
I can't imagine needing to take less time than 0.6 sec. to come up to speed unless you only turn it on to fire. Not much energy gets burned simply maintaining speed though.

We use a single mini-bike motor, 3 gears, 4 pulleys and 2 timing belts, so a shifting transmission and piston would add weight.