A Little Penetration...

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A Little Penetration...

Postby Nerva on Thu May 21, 2009 9:35 pm

Salvete Omnes!

Well we finally had a chance to dust off the Cheiro and loose a few bolts this evening (in between the downpours :roll: ). Anyway, we were trying to set up the ballistic radar and distance measuring equipment so we could begin to get some meaningful results. Unfortunately the ballistic radar did "just as it says on the tin" and went ballistic so we have no precise velocities. The old odeometer and timer did ok. The machine is torsioned to 526 lb's at full draw for these tests.

So here's the first pic. The target is at 30m and consists of a crappy old shield, 9mm ply, that should have been put down ages ago...

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Here's the Cheiro primed and ready to loose...

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The first bolt was loosed on the 3rd last stop, I have no idea what the draw weight was other than something less than 526 lb's. It hit the umbo perfectly. The umbo on this shield was just light aluminium, about 1mm thick at most...

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And another

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And again...

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Now here's one from the inside of the umbo...Ouch! :shock:

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And...

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And here's the hole...

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Here's a bolt loosed on the same setting but this one hit the wood...

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And...

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And from the inside...

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Now here's a bolt fired on the last stop, 526 lb's or so, right through the shield, but would it have done any harm to the person weilding it? Probably not...

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And...

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And from the inside...

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And...

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And the hole...

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This is one fired on the second last stop...

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And from the inside...

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We finally decided to loose one off on the second stop. It travelled 98m. Here's a pic looking back at the Cheiro from the bolt's final position...

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And then at the last stop. It travelled 162m...Time of flight was 4sec approx (give or take 10sec or so :) ) which works out at an average velocity of 40.5 m/sec or 133 ft/sec, but, until we get the ballistic radar working that figure is approximate. (actually it's not a radar at all. It's a laser device based on two beams at known distance).

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And here's the bolt...now you know why we paint the bolt's ass red...

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It's worth noting that at 520 lb's or so our machine is wound far less than maximum. Len Morgan and Alan Wilkins experimented with a machine torqued up to 680lb's.

Valete

Nerva
Last edited by Nerva on Fri May 22, 2009 10:19 am, edited 1 time in total.
Vale

Marcvs Vlpius Nerva

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Re: A Little Penetration...

Postby museumtom on Fri May 22, 2009 6:15 am

Great pictures and commentary.Well done!!.
Regards.
Tom.
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Re: A Little Penetration...

Postby brendan on Fri May 22, 2009 5:29 pm

i suppose i could set it up on the balcony of my apartment and lob bolts towards sheriff street...
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Re: A Little Penetration...

Postby lordedward on Sun May 24, 2009 6:48 pm

Can I just point out that it went farther thru the metal bit than the wood :shock:
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Re: A Little Penetration...

Postby Nerva on Mon May 25, 2009 4:00 pm

Salve Barry

The umbo is just thin aluminium, I think it may have been an ash tray in a former life. Tonight we're experimenting with a leg of lamb though!
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