Re: OT: Repeatably lobbing "projectiles"

On 11/21/2024 10:18 AM, bp@www.zefox.net wrote:

Martin Brown <'''newspam'''@nonad.co.uk> wrote:

>
One other thought you might be able to buy a tennis practice serve
machine off the shelf with high reproducibility.

 The tennis ball thrower seems promising if the projectile weight is
close to right.
 Another thought would be a crossbow-like mechanism with a motorized
winding mechanism. Range could be adjusted by moving the limbs to
vary the preload on the string. Bulk can be reduced by using a
reverse-draw layout.

The machine would have to move the limbs.  Once fabricated (and
"loaded" with a supply of projectiles), a human doesn't interact
with it.

[electronics content]
Many years ago I worked on a project to build a fast (microseconds)
opening gas valve. Introducing a flying weight (essentially a hammper)
between the first actuator and the rest of the control train improved
reproducibility by sharpening up the trigger impulse.  If you end up
using a pneumatic "gun" that would help regularize valve performance.
 We used a pulsed coil accelerating an aluminum ring which then hit
the valve poppet to drive it off of its seat.
\[electronics content
 A similar approach could be applied to a crossbow or catapult sear.

<frown>  This sounds complex.
What sort of performance did you see from "unassisted" valves?
I.e., what made it so important to have such a fast action?

Thanks for reading,
 bob prohaska