Re: OT: Repeatably lobbing "projectiles"

On 11/21/2024 2:53 AM, Liz Tuddenham wrote:

Bow and arrow?
 That was actually meant seriously as the geometric arrantement of the
string acts as a variable-ratio transformer between the movement of the
propelling spring (bow) and the increasing velocity of the load (arrow).
This means that if you charge the spring with a known amount of energy,
it will always be transferred with the same high efficiency into the
load.
 By varying the starting point of the arrow, and hence the spring
tension, you have an accurate repeatable energy input.

The "variable force constant launch angle" approach was
implemented on a similar principle:  pull a spring back to
a particular amount of compression and then release.
(This is how a pinball is launched, hence my inspiration)
The "release" seems to be a big problem -- getting a (home
brewed) mechanism that cleanly releases so the stored energy
can be transferred to the projectile as a step function.
A similar problem exists if STRETCHING the spring to a particular
amount of extension.
There is a bit of twisting moment on the release mechanism
from the tension in the spring mechanism.  So, any slop
in the "manufacture" results in a variable amount of binding.
And, you need a lot of (electromechanical) force to disengage
the release from the mechanism.
I've been trying to get a feel for what we could do pneumatically
or hydraulically in the belief that we could just buy premade
valves that are (hopefully?) more repeatable.  So, the controller
would simply monitor the pressure in the "launch chamber" and
open the release valve when the desired pressure had been achieved
(simultaneously disabling the source of said pressure).
Ideally, we want to be able to say "lob this projectile X feet"
(along an azimuth that is separately selected).  And, at a high
enough angle that it ONLY impacts that location (none shorter
nor longer).