360 Degree, Rotating post launcher

[purduephotog]

I have this idea....

So the paper model isn't the best, and I'm having trouble deciding how best to support the inner ring since I would expect a 1cm gap between the slick material and the rotating post.

Also the outer edges are rubber to increase traction. The unit is fed through the bottom (probable piston) and exits the top. The exit chute is angled slightly (which may be cut down depending on the effect of spin).

I originally was envisioning the unit as about 4 Frisbee thick (A new official unit?), in order to accommodate an unsupported inner gap from flexing. Obviously if the material is stiff enough it won't deflect under loading. Some sort of iso-beam bottom would suffice for that, so long as the outer rim is secure enough.

With a full 360 degrees of rotation to accelerate the Frisbee I've got to imagine this would be even more efficient and accurate than the 180 degree shooter.

Elevation and rotation can be centered about the rear axis.

Unfortunately I've exhausted my drawing capability. I failed stick art 101.

Comments?

[CalTran]

It's basically an Archimedes screw, but going faster in order to shoot, correct? I would definitely prototype something for this, but also keep in mind the *sheer size of the end result. Say you use a 2" inner post. That's going to be at least a 2' cylinder, not including outer thickness.

[purduephotog]

Originally Posted by CalTran

It's basically an Archimedes screw, but going faster in order to shoot, correct? I would definitely prototype something for this, but also keep in mind the sheet size of the end result. Say you use a 2" inner post. That's going to be at least a 2' cylinder, not including outer thickness.

Yup. A theoretical exit velocity of 15 mph at least, if the math holds. A larger post, 45mph, but that requires more space and exceeds the width requirement.

Of course it could be spun faster at a smaller size to take advantage of the additional contact and acceleration time.

Hrmm... interesting thoughts.

[CalTran]

Originally Posted by purduephotog

Yup. A theoretical exit velocity of 15 mph at least, if the math holds. A larger post, 45mph, but that requires more space and exceeds the width requirement.

Of course it could be spun faster at a smaller size to take advantage of the additional contact and acceleration time.

Hrmm... interesting thoughts.

Why 360 degrees of rotation and not 1440 degrees of rotation? The latter would make for a taller cylinder. Or, some amount of rotation between those two numbers. Funnily enough, if you want to pursue an Archimedes Screw, you can look at a couple of designs from 2009, Lunacy, and modify them from orbit balls to frisbees.

[Jeffy]

If the rotation is increased, then I could see this being a very good storage and shooter-all-in-one type of mechanism. We played with an idea similar to this last year and called it a "dead stop shooter" because it accelerated from "dead stop" to full speed by the time the balls left the shooter.

The issue we had was that we inevitably still needed a loading roller to keep the balls in the robot and it ended up not being able to save us any complexity at the loss of range because the shooter was based much less on Ke.

Best of luck. Let us know how it goes.

-Jeff

Also wanted to add:
The designs used in 2009 (or 2006 for that matter) will provide good reference, but should not be emulated. Remember that in 2009 many teams ran 2-3 inches of compression throughout the system. It can be very difficult to create a spiral that can keep a constant 1/8-1/4 inch of compression (which is what seems to work for Frisbees)