Hi, Its Tod from Tods
Workshop and Tod Cutler here and I'm back with the catapulta again and this is the second part of a
two-part series and now we're right at the point where we're going to put the tension up. We're
going to put the power up because in the last film that I did, I managed to get to I think it
was 122 kilos at 45 centimeters / 18 inches. So that's about 250 pounds at 18 inches. Now
that's powerful, but it's not super powerful. I mean it's going to drive an arrow a long way,
but it's not going to drive it the 660 yards the Romans said these things could do. Whether I ever
get there I doubt, but you know, I want to get 350/400 yards that would be lovely, that's my aim
with this machine and I've built it well enough and constructed it accurately enough. I should be
able to achieve that, but that's for another film. But this one now we're going to start putting the
power up and I have to do exactly what they did, which is I need to find a way of really getting
some serious torque on the spanner that does this. The spanner is 1.8 meters/six foot long,
I need to resist it in a frame. You could see from the last film, I wasn't able to hold it,
I couldn't get somebody to hold it well enough for me to tension this up, so it's really a simple
thing. I've got a steel frame here that I made years ago and I just put the clamps on it and now
I can get my spanner on it and really crank It up. I'm going to start tensioning it up now,
but you're going to see something interesting happening so I'm going to crank that in
just a little bit at the moment. So first of all the whole frame's moving which is really
annoying. I made this 10 years ago I must have been more stupid then than I am now. I'm going to
clamp some crossbars on it, but the other thing is just watch the movement of that arm and that arm.
It's kind of obvious, but what I'm doing is I'm increasing the power on this side, so it's pushing
the arm around more and turning that one. What that means is that you have to balance the system;
you turn that one a little bit, you turn that bit. Ideally of course again both going to be exactly
the same. Realistically in a handmade object they're not. So you turn that one until the
string is straight, turn that one a bit more and just keep going until you've tightened them a bit,
straighten it then you flip the whole thing over and you have to do the bottom bundles as well.
So it's you know, it's all a bit of a process this, none of it is very quick. I've got my two
crossbars in now and I can finally start winding up the power on this thing, really giving it some
effort. That's Basil by the way, we thought she was a boy, anyway that's another story.
I'm looking for the balance on this now, I felt that that was getting relatively
tight so I'm just going to back this one off a little bit, the first one
because of course I have to tighten the bottom ones as well. What I'm going to do next is to
flip this over and tension on the other side so that we can try and get the top and the bottom
of these coils reasonably balanced. But before I do that, I mentioned before that it's really
important that these things are tight. Now the reason that you want them to be tight is if you
just put twist after twist after twist, when you pull the arms back the outsides of the bundles
i.e some of the ropes are doing work, but the inside are not really under much tension at all,
so basically you get a very lazy machine. So what you want to do to get an efficient
machine and the Romans were just fabulous at this, is that you pre-tension these things,
you absolutely pull them tight and you pull it until a Roman legionary can pluck it and hear a
particular note. He clips it off, he clamps it, we don't know how they did that, and then he winds it
on to the next one, pulls it tight until he gets a particular note. That tightness is critical,
absolutely critical and we don't know how they did it so I had to invent a device for doing it, so
I'll show you that. And this is the bar, the lever that I used to tension the cords on this. So that
goes on the bottom there, you tie off your cord on the first loop on the bar, you bring it up pass
it over this peg and then just lash it on these cleats here; makes the job a little bit quicker.
But then you push it forward and the relationship of these components stretches the cord, stretches
it as much as this wants to stretch and then you clamp It off. Like I said, we don't know how
they did it, I did it with a modified G clamp. You clamp it to keep that tension on and then
take all that off turn this up the other way thread the cord back through, go again. Took two
of us a day to do this very laborious process. So the headstock is now in the other way up
so I'm doing what were the bottom bundles. Process is exactly the same. Let's do that one first
Now this I'm guessing is going to be harder.
Okay
So what I'm going to do now twist this bundle
and I'm going to stop when the bow string is about parallel. Oh my goodness me.
No I'm not. I've lost courage. I'm going to undo that first one a little bit. I I'm sorry,
I'm just not brave enough to try and shoot that yet. I'm not familiar enough with it.
The string's parallel, everything's good. I've put it up obviously a lot of power,
now I'm just going to drop some pins into these holes, but let's just, let's just get a feel
for what I'm dealing with now. It's times like this where I really wonder why I'm doing this.
It's everything, I don't know what that is, but I can span
basically a 200 pound crossbow by hand so whatever that is going somewhere close to that.
Four inches/ 10 centimeters. Oh well that's gonna do something,
so we just need to get the headstock back on and then we'll weigh it and see what we got.
The last time I tensioned this thing up the whole thing was assembled. I tried to give
it as much as I could while it was here in this position, couldn't do it. Managed to
get 122 kilos at 45 centimeters so about 250/260 pounds at 18 inches let's see what we got now.
I
maybe some time. Right I can tell you right now my courage will be through the floor on this one.
Zero kilos. So that's our first mark there, same as it was before. Now I don't know if you can see
from there, but that's our 10 inch and our 18 inch so our 25 centimeters and 45 centimeters.
I don't think I'm even going to get there. I've been criticised about my safety in a couple of
films I've recently done. There was one about a trebuchet with multiple bolts, another about
dagger that I was pushing through armour. Now the thing is I have 25 years in special effects
before all of this and I have a danger radar that is really pretty good and you mustn't forget that
TV film special effects you can make things look dangerous and they're not. It's not my intention,
but you might have a different view of what it feels like. Those films I actually felt safe;
this one? This actually disturbs me, my only safety here is just being very
careful and very cautious. Interesting, six inches/15 centimeters, that is 118 kilos
which is what uh? 118... 240/250/260 pounds. I'm not going to go very much more today.
Well maybe I will I don't know, let's see how it feels. Doesn't make horrible noises.
So 153 kilos/320 pounds. so this is interesting because it begins to tell me a bit what kind of
weight we're dealing with. It's okay, significant that's okay, I built crossbows with a lot more.
Okay I'm just listening.
Okay we're not quite 18 inches right, 210 kilos that over that draw length is a lot. You know
what? I'm going to stop there. So we're on about 16 inches okay but also I've got more power left
in that winch, I can give this more but you know what today I'm nervous. We're gonna shoot this.
Let's load her up. Let's go. Well I'm back and we've already got a problem
I haven't even begun to shoot it but I just noticed while I was checking over the machine
this cord bundle here has slipped off the little ledge where it's supposed to stay,
so that means... Well good news I'm going to shoot it, I can shoot it once twice I'm sure it'll be
fine, fingers crossed. But it does mean I have to dismantle this machine again, these whole bundles
aren't going to come out, but that's another film, that's the next film that's what that'll be,
is stripping these arms out and changing them and getting it back together. Which is interesting
because I'll show you a bit of kit you haven't seen. So here you can see the left hand arm,
the coords are all where they're meant to be tucked away behind that wedge on the right hand
arm you can see now that few of these chords have started to slide up the wedge, this whole arm has
moved into the machine and that is no good at all. I'm going to have a couple of shots now with this,
I think it's safe enough to do that they're not going to be super powerful ones, but we're going
to get an idea. But what I really want to know is what kind of speed we're going to get out of this
because at the moment I'm going to take the short, go for short distances, but if I can get
over about 150, 150/160 feet per second something like that I will be very excited about what we're
going to get, because I do know that 160 feet per second is going to give you around about
uh 200/220 meters something like that. Sorry about all the mixed numbers but if you're into
bows you'll probably work it out. First problem of course is this string, is slightly too far forward
now because the arms moved and I can't get my teeth in so the crowbar comes back out again.
That's it. Gonna do it
yes
Bet the Romans didn't do this
What do we got there well that feels like it's going to do something. 250 gram bolt.
And honestly only a teensy a bit scared right. Don't want to take my chrono out either and loose!
Well disappointingly the chrono didn't register that. Means one of two things. It either wasn't
over 145 feet per second or the chrono just didn't pick it up, because of course that's
really meant for going on the front of guns and things. Anyway let's go again, we'll see
I've got to get a feel for this machine, I've got to learn it. Another thing that you learn,
you don't want to learn it when it's in its most dangerous state, you want to learn it
when it's not so dangerous. Loose! That sounded and felt more powerful and very good news! 166
feet per second! So I know that those numbers are going to be up in the 230/240 meter range now a
bit more than 150/160fps I originally said. But what that really means, what that really means, is
I know I can go up from here. That had plenty of drawback yet before we even hit the 18 inch mark,
the 45 centimeters and it's got more power that I could put in when I actually use the levers.
166 feet per second we're going to leave that one behind and that was on a 250 gram bolt.
And for those of you who want the numbers, 166 feet per second, I've just done a calculation,
55 meters a second and that is delivering 640 joules that's a whopper and we're going up from
there. So this is, I'll put money on it, we can get over a thousand joules with this bow which
is extraordinary for an a arrow type weapon. I'll see you again another time, but this
has excited me because it felt safe, it didn't have the.... obviously not totally safe, depends
which end you're on, but it didn't have that fear that when I was looking at the numbers that was
kind of in my heart, it felt good. As a final sign off, I'd just like to make a correction.
I originally called this a catapulta and in fact it is and I was adamant that it is not
a ballista. Well at the time that this machine was designed around about the birth of Christ,
it was a catapulta, but by the time we get to the 4th Century A.D they were referring
to bolt throwing machines like this as Ballista. And then of course we go to the medieval times
and ballistarii, Italian for crossbowmen and a catapult is something that shoots rocks and so
everything is thoroughly reversed, but at the time I did this; catapulta. But anyway, I think
the point being is let's not get too precious about whether it's a ballista or a catapulta,
kind of call it either really and it works. We all know what we're talking about. See ya. [Music]