292 views

# Catapult speeds

1. 3 weeks ago

### skate17

Dec 28

Hey everyone,

I was wondering if any of you had the chance to calculate the speed of your catapults. If so, would you mind sharing? We want to see how other teams are doing in terms of speed, so we have an idea of what speed to shoot for.

Thanks

2. ### Xenon

Dec 28 Long Beach, California 99999V

firing speed or loading speed? both are pretty fast. ours is fully drawn back in no more than 2 seconds. its a 2 393 motor 1:7 ratio.

3. ### 7517H

Dec 28 Malvern,PA 7517H

Ours is 2 200 rpm V5 Motors with a 1:7 gear ratio.

4. ### skate17

Dec 28

we are looking for the speed of the catapult arm as it fires. Is there a way to find the speed given gear ratio and motor type?

5. ### Xenon

Dec 28 Long Beach, California 99999V

@skate17 we are looking for the speed of the catapult arm as it fires. Is there a way to find the speed given gear ratio and motor type?

oh wow, well its quite fast. no measurements here, but it uses 4 rubber bands on each side, and goes really fast.

6. ### callen

Dec 29 Braintree, MA, USA

@skate17 we are looking for the speed of the catapult arm as it fires. Is there a way to find the speed given gear ratio and motor type?

No, there is no way to calculate from there. You could theoretically calculate from mass (including ball(s)), mass distribution (including ball(s)), elastics, behavior of the elastics, and the way the elastics are stretched. But that would be really hard.

Better would be to use it, film the projectile, and determine from the film.

7. ### terminalvelocity

Dec 29 Bloomfield Hills, Michigan 39X Terminal Velocity (formerl...

@callen Better would be to use it, film the projectile, and determine from the film.

+1

We are going to try this method out and will pm you with results.

8. ### skate17

Dec 29

We are going to try this method out and will pm you with results.

Ok thanks