Re: OT: Repeatably lobbing "projectiles"

On 11/22/2024 10:57 PM, Don Y wrote:

On 11/22/2024 9:35 PM, Jasen Betts wrote:

On 2024-11-23, Don Y <blockedofcourse@foo.invalid> wrote:

On 11/22/2024 7:08 PM, Jasen Betts wrote:

On 2024-11-21, Don Y <blockedofcourse@foo.invalid> wrote:
>

Any other ideas, given latitude in the design of the projectile?

>
It seems that you are looking for a low friction (and thus repeatable) sear mechnism.
This is almost certainly a solved problem.
>
Possibly something involving an over-center mechanism and low friction
bearings will be suitable.

>
So, are you suggesting sticking with the initial compression/extension spring
approach and just "fixing" the release "catch"?

>
If that's the problem and not the temperature of the spring, or some
other uncontrolled property of the aperatus.
>
I haven't seen any suggestions yet that don't have the same release
friction problem, except perhaps the rotating arm in sleeve,

---^^^^^^^^^^^^^^^^

I used a linear actuator (from an electric wheelchair -- so it
could handle large forces, given that people weigh hundreds of
pounds) to move the *spring*.  I.e., the spring was attached to
the "carriage" that the actuator moved forward and back.
 A stationary "release" (catch) was mounted on the fixed portion of
the assembly adjacent to the moving carriage.  So, any connections
to it -- mechanical or otherwise -- wouldn't be "traveling".

What if I do this mechanism BACKWARDS?
I.e., use a spring in extension mode.  Let the "carriage" STRETCH
it to a desired length (storing energy).  HOLD the "free" end of
the spring in place ELECTROMAGNETICALLY (!).
When commanded, the magnet is switched off (no "moving parts"
to create friction in the release mechanism) allowing the spring
to return to its relaxed state.
In doing so, an attached "plunger" propels the projectile
outward.  (again, thinking in terms of pinball machines  :< )
To reset the mechanism, the carriage moves to allow the electromagnet
to reengage with the "back/innermost/moving" end of the spring, awaiting
instruction as to how much the spring should be extended for the
next cycle?
The problem with the catch (magnet) acting along the same axis as
the motion (instead of normal to it as in my prototypes) means it
would have to exert a strong enough force to overcome the maximum
tension on the spring.  Though the duration of that activity could
easily be limited by delaying it until immediately prior (and part
of) the "launch" command.  That maximum tension would define the
maximum payload (mass and acceleration).
So, this would limit how much the solution could (reasonably) be scaled.
If the mating surface of the "spring" is a permanent magnet, does
that improve the effectiveness of the electromagnet's "grip"?
And, drive the electromagnet "backwards" to actively push the
permanent magnet (and the spring to which it is attached) apart.