Re: OT: Repeatably lobbing "projectiles"

On 11/22/2024 4:41 PM, Don Y wrote:

I think I'm going to explore the air solution, next.

I actually skipped ahead to trying "skinless water balloons"
thinking that gating a chunk of water would be easier than
trying to control the release of pressurized air.

I figure I can use a surplus oxygen tank (they come in
smaller sizes for portability) so I know it will
handle any sort of pressure I might apply without
rupturing.  I can probably fashion an inlet port
and outlet valve to mate to it via the single
opening available (so I don't have to pierce the
vessel to allow for the introduction of pressurizing
air).

I opted for an "expansion tank", instead.  It's limited
to ~100psi but that's likely not a problem.

I'm *guessing* that a battery powered "inflator" that
one might use to fill tires could achieve whatever
pressure I need (?).  The chamber acting as a reservoir
to allow a larger volume of air to be expelled than
the inflator could supply in a short interval.

I plumbed the inflator to the "air" side of the tank.
I figured it would be easier to let water FLOW into the
"water" side instead of trying to force it in, under
pressure (most water pumps seem to want to move water,
not really develop much head -- unless used in a well)
I.e., deflate the air side, fill the water side, seal,
inflate air side to desired pressure, launch.

[The "reload time" may become an issue.  But, a larger
inflator -- or a real *compressor* -- should address
that shortcoming]

It is lengthened considerably in my approach!  <frown>

This then boils down to how repeatable a valve I can find.

And this is AGAIN the disappointment!  Fast valves for water
are often driven by pressurized air.
And, get expensive really quickly!
Next iteration is "inline magnetic catch" (suggested elsewhere).
I figure if I start with one of those that are designed to
hold "fire doors" open during normal business conditions
(and release them to close under external spring power)
that would likely be a sizeable mechanical load and yet
an OTS device (instead of trying to fashion an electromagnet
of suitable holding force)
Holiday week.  It will be hard to call in favors for equipment  :<