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From: Don Y <blockedofcourse@foo.invalid>
Newsgroups: sci.electronics.design
Subject: Re: OT: Repeatably lobbing "projectiles"
Date: Thu, 21 Nov 2024 05:06:59 -0700
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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)