[chbot] OT ping pong balls at mach 1.2

[Paul Davey]

I wouldn't be surprised if they serve the ball with a pair of rotating
wheels and have a slight difference in speed between them to introduce spin.

Next we should build one that uses hydrogen to propel the ball and
something else to propel the hydrogen :)


On Tue, Feb 12, 2013 at 10:27 PM, Helmut Walle <helmut.walle at gmail.com>wrote:

> On 02/12/2013 08:21 PM, Mark Atherton wrote:
>
>> Kerry just found this :
>>
>> http://www.gizmag.com/how-to-**build-a-supersonic-ping-pong-**
>> gun/26082/pictures#3<http://www.gizmag.com/how-to-build-a-supersonic-ping-pong-gun/26082/pictures#3>
>>
>> or is this Off Topic ?
>>
>> -Mark
>>
>>
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>
> Did I calculate it right that the kinetic energy is 218 J at the muzzle
> (at the standard mass of 2.7 g for the ball)? Pretty impressive... however,
> due to its low ballistic coefficient, the ball would slow down rapidly. I
> wonder, though, whether a reduced-speed version of this would make a nice
> commercial product - after all, there is quite a range of table tennis
> robots available on the market, which brings it back on topic. I have never
> bothered finding out how they work internally, but as they produce spin as
> well, they probably really "hit" the ball with something like a racket. But
> this is not to say that spin couldn't be produced by a pneumatic gun like
> this one here. It might be sufficient to provide a transverse pressure
> gradient, although this could lead to issues with the ball touching the
> barrel wall. Sounds like something worthwhile further experimentation!
> (Given time...)
>
> Kind regards,
>
> Helmut.
>
>
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