Re: OT: Repeatably lobbing "projectiles"

On 11/21/2024 4:46 AM, Martin Brown wrote:

On 21/11/2024 07:04, Don Y wrote:

We're trying to make a mechanism that will allow for the
REPEATABLE lobbing of small projectiles over short (0-20 ft)
distances.
>
We've tried using a constant force with a variable launch angle
(higher for shorter).
>
And, a variable force with a constant launch angle (push harder
to throw farther).

 Trebuchet is probably the method of choice. There is a bloke round here with one big enough to lob a watermelon about 100m. It is an impressive beast and flat packs into his pickup traler.
 https://en.wikipedia.org/wiki/Trebuchet
 He takes it around rural summer fetes to raise money for charity (and buying more water melons). They land with a very satisfying splat!)
 One to throw a tennis ball 20ft would be a bit dangerous close to but very reproducible if that is what you want.

But how do you RELIABLY adjust the length of throw?
I.e., "I want THIS (repeatable object) to be tossed in a high arc
to land X (not Y or Z) feet from the launcher"
It is permissible to store "calibration factors" -- including
in *tabular* form.  But, you should be able to use any of those
specified ranges with a reasonable guarantee that you'll strike
at the correct distance (the launcher won't be able to verify the
*actual* distance achieved)
The entire sequence has to happen without human intervention
(and, ideally, in a short enough time span that one can repeatedly
"get off rounds" without long delays)