Re: OT: Repeatably lobbing "projectiles"

On 11/23/2024 4:10 AM, Liz Tuddenham wrote:

Don Y <blockedofcourse@foo.invalid> wrote:
 

Engineering is not just about solving problems but, rather, about identifying
the problem to be solved.

 We have been told the range is about 20ft (but no accuracy limits) and

Exactly.  Repeatability is the first criteria.  Accuracy can be
addressed thereafter.

there have been hints about what the projectile must not do (bounce or
injure bystanders) but the main constraints on the projectile were not
known at the outset and this was mainly what was making the problem more
difficult than it needed to be.

There are no real constraints on it that can't be fuzzed.
If you want to toss watermelons, then I suspect there is
a way to downsize the mechanism to toss oranges.
Buckshot would probably be too small.  Basketballs would
border on too large -- but mainly because they would be
hard to dispose of after firing.

The sorts of properties that make a huge difference to the design are:
 Rigid , flexible, floppy or completely shapeless like a bag of water?

Again, flexible.  Tell me you can do it easier with bags of
Ramen noodles and I'll figure out a way to use Ramen noodles!
The point is to "place" any number of objects at particular locations,
"blind" and unassisted.  Not being able to see how well your previous
shot has performed means your mechanism has to be able to ensure
consistent results.
I mentioned a basketball player as "launcher".  Imagine if he was
blindfolded and not told whether or not he had made his shot...
because he was *supposed* to make it, unconditionally!

If fairly rigid: spherical, cylindrical or some other shape?

I think in terms of balls simply because they seem easier
to move around the launcher.  But, clay pigeons aren't balls
and they can be loaded easily/rapidly...

Approximate range of mass?

Again, any value I specify limits how you would approach the problem.
I can make a 24" diameter ping-pong ball that weighs as much as
a 1" diameter steel ball.  The mechanisms for each would be radically
different, as would their aerodynamic characteristics.

Homogenous or made from bits of widely differing density?

If there is a perceived advantage to either approach, then
exploit it.  E.g., a "nerf dart" is made of different
materials and is nonsymmetrical -- yet they seem to be
easily launchable.  Kites have tails for stability.  If
a particular projectile design might need such stabilizing
(to avoid tumbling as it flies), then that's acceptable.
As long as any complications from that shape can be accommodated
in the *loader*.

There is a vast difference between trying project a
quarter-inch-diameter lead ball 20ft and trying to do the same with a
bucketfull of cows guts.

So, by NOT specifying either of these, I've given you the freedom
to pick whichever is easiest.  Presumably, some identifiable
characteristic of your choice will be a hint as to other "compatible"
projectiles to exploit your design.
E.g., the potatoes used in a potato gun could probably be replaced
by plastic/rubber spheres or ellipsoids of comparable size and mass
(if potatoes were objectionable).
Or, the design could be downsized to use small rubber/plastic balls.
Or, badminton shuttlecocks.  Or...