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From: Don Y <blockedofcourse@foo.invalid>
Newsgroups: sci.electronics.design
Subject: Re: OT: Repeatably lobbing "projectiles"
Date: Sun, 24 Nov 2024 05:01:30 -0700
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On 11/24/2024 4:30 AM, Liz Tuddenham wrote:
>> ... I had assumed "water" just because it "flows" once the bag has
> ruptured.
>> (the ruptured bags represent minimal litter and the water will
>> eventually evaporate.
> 
> Use ice for the projectile, there would be no litter at all.  If it were
> pointed and had the right aerodynamic properties it would embed
> point-first in the ground and not bounce - but it could be dangerous if
> it hit anything other than soft ground.

Or, make it *hollow* so it just shatters and leaves small, thin ice shards
behind!!

[The trouble would be storing them prior to launch so they don't
melt and stick together in the magazine!]

>> What if there was a "plunger" that provided the seal, with the "payload"
>> sitting ON the plunger, while loaded?  E.g., like a linear catapult.
> 
> Yes, that would work.  The critical point is that the air flow and
> maximum obstructed pressure are already established before the
> projectile enters the accelerating region, so there is no need for
> accurate valve timing.
> 
> How about a spherical bag (toy balloon?) full of water sitting in a
> polystyrene cup which maintained its shape as it was accelerated up the
> barrel.  The cup and balloon would separate in the air, with the cup
> falling near the launch point where it could be retrieved and re-used.

Couldn't the plunger be "polystyrene cup shaped" so it stays behind
for reuse, automatically?

>> Could a "gate" behind the ONE projectile not serve the purpose of the
>> second?  Or, the plunger I mentioned, above?
> 
> Yes.  I was following on from the 'row of peas' already stored in the
> barrel, but if you have a magazine on the side you could load one at a
> time.  That could get messy if the projectiles were water-filled bags.
> 
>