Who makes Artillery ??

[P. Clodius Secundus]

To keep things cheap during the R&D phase of the build I've been using pine for the base and case. I figure that if it holds up through field trials it will be that much stronger/safer when made with better wood. The finished weapon will probably be a mix of oak and ash. I will be consulting some friends who are much better wood workers about proper joinery techniques and the best wood for each application. This is proving to be a sound strategy since There are already aspects of my base design that I can improve upon. With the metal components I'm working on, price and ease of construction are more impotrant for now. Eventually I will have a blacksmith recreate them. Better yet, by then I may have my own forge set up and running.

[AuxArcher]

Sorry, guys, I haven't been on RAT since I last posted.

Randi, thanks! I will be bringing the little beast with me to Higgins this Saturday.

Duncan, thanks to you too. I did craft the bow arms using the 7x formula, and they seem just fine. I made up some el-quickie rope springs out of jute just so the machine will look more complete for the upcoming event, and the length is fine on the arms. I was totally surprised at how powerful the springs are with just heavy jute, and could only put about an 8th of a twist in each end of each spring with just finger power. This little machine is going to be as lethal as it is cute.

[P. Clodius Secundus]

Dane,
Looking forward to seeing your new baby at Higgins Armory this Saturday. If possible I'd like to try stringing it with the two lengths of brown 550 paracord I bought, to see if that stuff might be any good for the larger engines. With it's high strength and small diameter you could really put a lot of windings on it. Which way did you put the crescent? have you tried using it as a brace on your thigh when latching the bowstring?

[AuxArcher]

Hi Randi.

The only way to find out how parachute cord would work would be to try it out, eh? We would than need to rewind new springs out of another type of material to compare performance, and I’m not sure what criteria to use in that kind of test. Let’s talk about it Saturday. And, remember the larger scorpion is hot on the heels of this manuballista, though the manu will be completed sooner, pretty soon after I cast the various metal parts and incorporate them into the machine. I am also planning to build a second almost identical manuballista (I’ll explain that plan when I see you, and why – getting a thickness planer today to cut down on a lot of hand work!), so maybe we can wind one with horsehair rope and the other with para cord?

I can see now you can fit a LOT of cord into the spring holes!

The machine is at home, resting against my desk, and I can’t recall this second which way I twisted the springs (it was past midnight when I finished), but you will see for yourself.

And, last, I haven’t yet made a bowstring, or cut the bow sting notches in the ends of the arms. I am thinking I may need to make a bastard string to facilitate stringing the machine, such as used for heavy crossbows. Part of the stored energy of course is in the unspanned string under tension before cocking, and the string, among other things, will prevent the arms from slamming into the frame’s outer uprights upon firing. However I make the string, it has to be very, very strong.

[Gaius Julius Caesar]

Could you not string it before you wind up the springs?

[Crispvs]

"We would than need to rewind new springs out of another type of material to compare performance, and I’m not sure what criteria to use in that kind of test."

I would recommend measuring the draw weight at full draw. When we did this on our manubalista (which is sprung with nylon rope) a few years ago we found it had a draw weight of 732lb at full draw. The distance a bolt shot at this draw weight travelled was then measured. These two figures (the measurement of the maximum draw weight and the distance achieved at that draw weight) are the figures we alway quote for our machines. We then performed penetration tests on lorica segmentata at a lowered draw weight (which was also measured) on the basis that being sprung at the maximum tension for too long would put too much pressure on the springs. If you have access to a copy of JRMES 11 check out our findings in Len Morgan and Alan Wilkins' article 'Scorpio and Cheiroballistra'.

Crispvs

[AuxArcher]

That does seem obvious, Gaius. However, I am taking this one step at at time, and wonder if have it strung before tightening the springs to get even tension on each side would help or hinder?

That is one of the many reasons for building this thing.

[AuxArcher]

"We would than need to rewind new springs out of another type of material to compare performance, and I’m not sure what criteria to use in that kind of test."

I would recommend measuring the draw weight at full draw. When we did this on our manubalista (which is sprung with nylon rope) a few years ago we found it had a draw weight of 732lb at full draw. The distance a bolt shot at this draw weight travelled was then measured. These two figures (the measurement of the maximum draw weight and the distance achieved at that draw weight) are the figures we alway quote for our machines. We then performed penetration tests on lorica segmentata at a lowered draw weight (which was also measured) on the basis that being sprung at the maximum tension for too long would put too much pressure on the springs. If you have access to a copy of JRMES 11 check out our findings in Len Morgan and Alan Wilkins' article 'Scorpio and Cheiroballistra'.

Crispvs

Excellent suggestions, and thank you very much.

How, if I can ask, did you measure draw weight? For bows, I have a 110 pound scale, which is sufficient for that kind of work, pulled down using a pully and rope and a hook on the string (a tillering rack bolted to my workshop wall). How does one measure for a rope tension machine?

What angle did you have the manuballista on when you fired for distance? War bow guys fire in a high arc. Did you use a relatively flat trajectory?

Having the doppler radar setup they have at Sandhurst (I believe it is, saw that bit on a documentary on the English long bow) would be fantastic, eh?

Last, did you measure bolt speed using a chronograph?

[Crispvs]

Aha, you have me there - I wasn't actually present when the cheiroballistra was tested. I am pretty sure though that the bolt would have been shot at a fairly level trajectory. That is how we would expect such a machine to have been used much of the time. I will have a look at the relevant copy of JRMES over the weekend to see what was actually done (it's about three years since I last had a look at it). I know that measuring instruments have been used with our machines to check the speed of the bolts but I don't know what the results were. I believe that that was during the filming we did for 'What the Romans did for us'.

Crispvs

[Gaius Julius Caesar]

That does seem obvious, Gaius. However, I am taking this one step at at time, and wonder if have it strung before tightening the springs to get even tension on each side would help or hinder?

That is one of the many reasons for building this thing.

Just my opinion, but I would imagine it was important to have it strung for that very reason? So you can guage the balance of the tension?

I have a cross bow that looks to be centered when I tighten the lock screw, but as soon as I string it it goes a little wonky, not the same but I can imagine similar issues of tension altering things when you change the parameters a little, or something like that!

[AuxArcher]

Aha, you have me there - I wasn't actually present when the cheiroballistra was tested. I am pretty sure though that the bolt would have been shot at a fairly level trajectory. That is how we would expect such a machine to have been used much of the time. I will have a look at the relevant copy of JRMES over the weekend to see what was actually done (it's about three years since I last had a look at it). I know that measuring instruments have been used with our machines to check the speed of the bolts but I don't know what the results were. I believe that that was during the filming we did for 'What the Romans did for us'.

Crispvs

Thanks for looking that up, but don't rush on my behalf.

The testing phase is what I am really looking forward to, and with horsehair ropes, it should perform well. I do want to put the little beast through a number of tests, and hump it around a bit in the field to get an idea of how handy a machine like this performs on campaign.

Today is it's public debut, even in it's unfinished state. More picture coming this weekend, as well, so you can all see how it is turning out.

[AuxArcher]

That does seem obvious, Gaius. However, I am taking this one step at at time, and wonder if have it strung before tightening the springs to get even tension on each side would help or hinder?

That is one of the many reasons for building this thing.

Just my opinion, but I would imagine it was important to have it strung for that very reason? So you can guage the balance of the tension?

I have a cross bow that looks to be centered when I tighten the lock screw, but as soon as I string it it goes a little wonky, not the same but I can imagine similar issues of tension altering things when you change the parameters a little, or something like that!

I am glad I can admit I don't know everything yet! Thanks for the feedback and comments. Considering it more, stringing it before tensioning the springs seems the way to go.

I'll let you know what happens, of course, and will post as the journey continues for this thing.

I still have to name the weapon, too. I tend to name my bows, so why not the manuballista?

[Crispvs]

Alan Wilkins' own Cheiroballistra / Manuballista is sprung with horsehair cord. Unfortunately, as far as I know, this particular machine has not been tested for draw weight and distance. However, from our own experience of using all five of our artillery pieces (including Alan's two personally owned pieces) in the same place at the same time, we are pretty sure that the horse hair is a more powerful springing material than the nylon rope on our own machines. It is worth noting at this point that ancients considered horsehair to be an absolute last resort material, coming well behind sinew and even behind cord made from women's hair in order of preference.

Crispvs

[AuxArcher]

Crispvs, thanks for that bit of info. I do realize sinew would be the ideal material, and to do that, I need to access a whole lot of dead animals. Local slaugherhouses would probably be a good source, but I's be required to wade in there with a knife and extact the leg sinew (maybe backstrap sinew, but I seem to recall hearing that that stuff is eradicated in modern slaughering methods). I also understand cattle sinew is greasy, but can't say if that is true or not.

As for women's hair, can you convince that many women to give us thier locks? Actually, there are Asian dealers in real human hair, but I have no idea how expensive that would be, nor how much human hair I would need. And, it would be perhaps a bit macabre if the hair came from dead folk. But maybe kind of cool too. So, that is an avenue to think about for later.

Horsehair is by far the most economical and least finicky of the ancient materials easily available to us moderns.

[P. Clodius Secundus]

Dudicus (gratis frater!) has forwarded to me a link to a youtube file on the firing of a Medieval Springald. For those unfamilliar with this type of weapon it is an updated version of a Roman torsion ballista. It doesn't prove anything as far as our timeframe goes, but I thought some of my fellow ballistriarii might be interested. I really like the way they've incorporated a screw winch.
I'm not sure how to transfer the link, so you may have to search it, sorry
http://www.youtube.com/watch?v=s4qQreFFniY