A Little Penatration... (testing a cheiroballista)

[Nerva]

Salvete Omnes!

Well we finally had a chance to dust off the Cheiro and loose a few bolts this evening (in between the downpours ). 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...




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




This 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...



And another




And again...




Now here's one from the inside of the umbo...Ouch! He wont be doing DIY for a while!



And...



And here's the hole...



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



And...



And from the inside...



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...



And...



And from the inside...



And...



And the hole...



This is one fired on the second last stop...This was actually the first bolt we shot.



And from the inside...



We finally decided to loose one off on the second stop at about 35 Deg's.. It travelled 98m. Here's a pic looking back at the Cheiro from the bolt's final position...



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).



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



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. We calibrated ours earlier in the day using an electronic strain gauge in the weight room of a local gym.

Valete

Nerva

[D B Campbell]

The target is at 30m ...

There are some who claim that catapults were used over a range of 300m. Hmmm, makes you wonder ...

(btw Love the bolts, Martin! )

[Robert Vermaat]

Hi Nerva,

Great test!

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...

Any idea of the force with which that bolt hit? It might perhaps have toppled the person over?

[Magnus]

Very cool!

[barcid]

Very cool!

ditto may just prompt a chap here to build his 8)

[M. Demetrius]

I'd suggest that if a bolt like that hit an unarmored part of anybody, there would be serious harm done. Good to be overly careful, isn't it?

[Nerva]

Salvete Omnes!

Salve Duncan, even to wind the machine back full at that draw weight was frightening, lots of creeks and cracks and if anything breaks at that pressure bits could go anywhere hock: . I think operating over 300m may well be possible but you better have spare parts at the ready. I know that the maximum distance achieved by Len and Alan was 206m, well short of 300m. One of the problems I had was that the 'bow' string kept slipping out through the small gap between the claw and the base, only a few mm wide. I had to use cardboard wedges to keep the claw down. I think it is possible to get into the 200m-220m range but I'll build up to that slowly else I might damage my little darling :oops:

Salve Vortigern, sorry but no idea what the force was at the target D

[Nerva]

Salve Duncan

Sorry, just noticed your comment on the bolts. We tell people that they're 'tracer' rounds :lol: But do you know whats even funnier? They believe us :lol: :lol: :lol:

[Titus Juventius Tertius]

I'm going to come out and say I know nothing about that contraption of yours (which is a beauty I might add). So my question... how historically accurate are those bolts? They seem rather thick and short for what they're being used for.

[A_Volpe]

Oooh! great stuff!!

Glad the work went well.

Although the bolt didn't go through, I know I would've been scared out of my wits if all of a sudden this little bolt head poked through the shield!

I like your bolts, too, and clever idea to paint the 'butt' bright red.

[Nerva]

I'm going to come out and say I know nothing about that contraption of yours (which is a beauty I might add).

Salve Titus, you just made my day :lol: Your honesty is just brilliantly refreshing :wink:

So my question... how historically accurate are those bolts? They seem rather thick and short for what they're being used for.

Oh, you've completely caught me off guard with that one :? //www.comititatus.net">www.comititatus.net ) has done experiments with 3 span bolts as well, see his post here <!-- l <a class="postlink-local" href="http://www.romanarmytalk.com/rat/viewtopic.php?f=20&t=26257&start=20">viewtopic.php?f=20&t=26257&start=20<!-- l

Valete

Nerva

[sulla felix]

Some examples from Dura Europos:

[dave budd]

something that struck me about that little test is just how effective a thin bit of plywood is against incoming missiles

it's always good fun shooting at things just to see what will happen. all in the name of research

[Titus Juventius Tertius]

Some examples from Dura Europos:

So the bolt would normally be about 12 inches long? By the photos? I don't know what the context of the image is and what each photo represents. How long was the one tested? Or did I miss that?

[D B Campbell]

Salve Duncan, even to wind the machine back full at that draw weight was frightening, lots of creeks and cracks and if anything breaks at that pressure bits could go anywhere hock: . I think operating over 300m may well be possible but you better have spare parts at the ready. I know that the maximum distance achieved by Len and Alan was 206m, well short of 300m.

Lost track of this thread for some reason. I simply meant that you must've set up your target at 30m for a reason -- presumably so that you could see it. I think it highly unlikely that catapults were used at much over 100m for the same reason -- so that you can see the flippin' target as it comes thundering towards you.

But your comment about creaks and groans is interesting -- presumably artillerymen would not want to operate their machines at such a (self-)destructive level, but would want to keep them well within their operational capabilities. After all, you presumably want your machine to perform steadily throughout the battle, rather than bursting apart after a few record shots.