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The shape of her wood is not quite there yet.  But close.

 

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Pretty darn fancy for something that’s mostly just a test bed.  Note how Phantom Advisor has particularly long ears — just the thing for detecting the patterns and echoes of a distant past.

 

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Tease that she is.

 

IMG_5148Click to enlarge.

 

Third wave feminists are encouraged to comment.

 

I finally got the balls to cut into that nice chunk of walnut.

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To my eye, her snout is still far too fat.  (I’m talking about the ballista now, not the German Sheppard.  Oona is a very sensitive and intelligent animal. I’d get a cold shoulder for sure if she thought I was making nose jokes at her expense.)

….And so, Phoenix’s forend will revisit the band saw for a little more trimming as soon as I get my nerve up again.  In the meantime, there are washers to ponder.

Also, any sharp eyed AP’s scrutinizing the above photo will be sure to object to the square-headed nuts bolting everything together.  They are just simple analogs.  Rivets are too permanent if there are changes to be made.

The corollary to this is, with a performance focused reconstruction, there are always changes to be made…

 


 

 

28 hours have elapsed since the above cuts were made.  With my chutzpah restored, the band saw has done it’s deed.

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And remembering for a moment, that inspiration from Trajan’s column: a double perspective, ancient rendition of an inswinger’s forend, outlined with little yellow markers.

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Uncommonly similar snouts, don’t ya think?  At least when this ancient art work is given the side view interpretation.  I have often thought that as a subject, “History” is the most cherry laden of disciplines.  As R says,  “It is better to know that you believe, than to believe that you know.”  We all choose the truths we care to inhabit.  Making sand castles with the evidence is the most common of traits and I’m as guilty of that as anyone.  With ancient history, the interesting propositions usually deal with hints and traces.  The “definitive” ones are often just banal.

And just because I can’t make up my mind on this whole flash bulb thing, here is Phoenix again with enhanced photons present.

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It must be admitted that Firefly’s trigger and catch assembly looks a trifle dorky stuck on a smaller machine like Phoenix.  Someday I’ll make the little dear a new one, just her size.  Now I have to dream up some softening scallops for her forend.  All very artsy, I am sure.

For newcomers, here is my five part strategy for squeezing the most performance out of Phoenix’s new torsion springs:

(1)  Pre-stretch the nylon spring cord to within an inch of it’s life.  Less hyperbolically, that means:  perform a vigorous vertical stretch of an anchored bundle of spring cord with the shop crane.   The spring cord should be in a bundle maybe eight feet long for this stretch.  The idea is to cause all the cord to elongate about 10% (maybe more) and stay under tension this way for quite a while, probably about 24 hours.   –Must research again  what’s ideal.–   Or do by feel.  “Feel” usually trumps calculation when dealing with something as amorphous as fresh spring cord.  The dynanometer can measure the amount of force being applied for this linear stretch.  Adjustments can be made throughout the duration of this pre-stretching period to keep the pressure on.

(See how useful blogs are.  I didn’t remember that long bundle, dynanometer monitored,  stretch thing, until just now when the writing took me there.)

(2)  Reform the pre-stretched spring cord into the final bundles and install in the field frames, along with the limbs. Make sure all areas that contact the springs are as smooth and pleasing and as soft and cuddly as possible. This means: nice fat radii anyplace the spring cord actually touches.  If deemed helpful, padding and pillows would be acceptable to help prevent chaffing.  Strictly the red carpet treatment for the little dears — perhaps breakfast in bed, hourly massages, that sort of thing.   In short, lull the springs into a state of blase complacency by how nice you are treating them.

(3)  After installing the springs in the field frames, and with all due ceremony and respect, drive shallow angled wedges along the top of the flat crossbars to really stretch out all of the spring’s fibers with many hundred of pounds of force.  How many hundreds?  Well that all depends …. how big is a hammer?   In any event, drive the wedges in deep. Make the springs beg for mercy, all the while utilizing the wedges to balance their power output.  When they get through gripeing at all this fiddling around, do a final round of wedge smacking and low power shooting to confirm the balance.  Then get ready to twist baby!

….. And the springs thought they were stressed out enduring all that linear stretching and power balancing from the wedges.  What comes next will really make them howl! …..

(4)  With great solemnity,  rotate all the washers equally.  (Probably about 180 degrees.  Haven’t quite decided yet.)   Now, if all goes as planned, the balance of power between the two sets of springs should transfer intact right through the twisting operation.  I have every hope that it will because Firefly herself has shown she can stay balanced through 75 degrees of universal washer rotation.  Also, it is expected that the stress will become more evenly disposed throughout the spring. Every tiny bubble of slackness will be wrung out.  All the fibers will do their part, no slackers allowed.  The springs should feel rock hard to the touch.

(5) Fire for effect.  ?????????   Here lies the great unknown in this lengthy wedge machine experiment. Hopefully it is the point at which the games can really begin.  Probably there will  be several repetitions of steps 3 and 4.  The springs need to understand that there is no escape from our training regimen.  They are going to have to work for a living.

But not to worry.  If they are evenly strained, and the chaffing trolls can be kept at bay, rope torsion springs can take a tremendous amount of stress before they fail.

Anyway, that’s the basic plan and what we will be working towards over the next couple of months.

 


 

 

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The above photo is of one of Firefly’s torsion springs that has been fully developed into a powerful source of propulsion.  If you take a closer look at it you can sense the strain that is contained within it.  (Click to enlarge.)    Note how all the cords have a smooth and even appearance.

Firefly was not fired in two years, and her springs held this high level of strain while sitting in the uncocked position for all that time.  When she was taken out of mothballs and fired again, Firefly’s velocity was exactly the same as when she had been put into storage, 316 fps with a 521 gram bolt.  And I do mean exactly the same, 316 feet per second, which astonished me to no end.  Such is the consistency of a properly developed rope torsion spring made from 3-strand nylon.  My experiments with braided nylon were short lived because it quickly became apparent that the braided material was essentially dead as a spring.  The 3-strand twisted rope was far superior to the braided.  I figure all those intersecting crossover points in the braided material just killed its performance.

Of course, Nylon ain’t Sinew.  Dismissing physical experimentation on reconstructions of ancient torsion engines because they are not powered by authentic materials neglects the fact that there is more going on in the design and development of these devices than the springs that power them.  Given firsthand accounts of ancient ballista performance (e.g. the Lightning as described by Anonymous)  it is no great stretch to conclude that however they were made, sinew springs were reliable power generators.  Our modern nylon analogs can only seek to emulate this.  If an authentic Dura bolt fired from a modern reconstruction can be cast 800 yards or more, the springs that performed the act must bear some measure of equivalency to the originals.

It is this high level of consistent power generation that has helped Firefly shoot with such amazing precision over the years.  It is no great trick to take rope torsion springs to this level, it’s just more fiddling around than most novice catapult makers can conceive of.  Which is probably a good thing.  This is potentially a very dangerous game we are playing.

Phoenix is getting her struts fitted.

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The ends of the struts that are resting on the kamarion still need to be trimmed so that they will drop down and position themselves in the center of the yokes.  After that, welding them to the yokes should be easy.  Keys will be made to drop through the slots in the yokes to secure the lock around the kamarion.  My conjecture is that the two holes evident on Orsova kamarion were for crosspins to lock the keys in place, and also prevent any lateral movement of the yokes.  Pins that pass through the projecting studs on the sideplates should retain the rear of the struts nicely.

All this fancy, just to claim the title of “take-apart”.  Such is the price of extending the design themes apparent in the artifacts.


 

And the welding goes fine.  We do TIG welding as an analog for forge welding.  I never weld things together with modern techniques that could not also be done with ancient ones.  An analog is an analog is an analog.

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Now for clean-up and finish work.  And a stout key and pin.  All in a day’s work at the little catapult factory.


 

As usual, I ran out of sanding discs.  Later, ye pesky burnishing bug!

 

IMG_5111Click to enlarge.   Rebecca says it’s worth it!

There are just the keys and cross pins left to do and then the struts will be done.  I left the sagma (saddle) deliberately long to help stabilize the stock sans the lower struts.  We’ll see how well that all works out.


 

And finally, the keys and their pins are installed.

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I must admit, those cotter pins are making the authenticity gremlins that ricochet around inside my skull, a tad analeptic.  Solid pins of somewhat larger diameter will be the thing.

That will be for another time. Next we move on to the washers and vernier plates.


 

Okay!  I can’t stand it any longer. Now is another time.

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A modern 20 penny nail, non-galvanized of course, gets the job done in the role of analog for the Roman version.  Good enough for our purposes, anyway.

And that, ballista fans, is my explanation for those two little holes seen in the kamarion of the Orsova artifacts.  Maybe the Romans did it some other way.  But not for my money.

 

 

 

Glory be! it looks like the electric winch has plenty of room to operate when mounted directly on m’lady’s tail.

(Click to enlarge.)

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I will have to make a special hook and pulley combo for the winch rope; easy-peasey compared to the rest of this journey so far.

Not so simple will be the hand winch.  Something plausibly Roman will have to be dreamed up.  Any old hand winch, just won’t do.  It will need to include a functional duplicate of the original crank handle from the Elenovo horde, seen below.

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Photo is from the Kayumov/Minchev paper about the Elenovo horde.

For now, however, the electric Warn winch will get us going.  Authenticy patrols have agreed to give us a temporary pass on the electrics due to my intermittently bad back.  Sensibility is inversely proportional to necessity.

 

So many chalk scribbles trying to figure Phoenix’s proboscis!

 

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Rectilinearists will have to forgive us our curvy parts. This is the part where catapult-makers get to be all artsy; a chance to reveal our finely extruded sensibilities regarding shape and form. It’s a small role, so we have to make the most of it.

Next:  From the great cherry tree that is the historical record, I’ll mix me metaphorical fruit and pick this fat little plum.

 

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A twisted piece of logic to be sure.  Much like the twisted double perspective prevalent elsewhere on Mr. T’s phallic offering.  Blue is the nosepiece.  Red is the trace of an inswinger limb….   (wink, wink, nod, nod, etc.)

According to my phantom adviser:  for obvious reasons, inswinger technology was a closely guarded military secret by the Romans.  Outright public depictions of it could result in severe penalties for the artists involved.  He muses how it has always been a black-robed technology.

Phantom advisors are so helpful.

 

When you finally see the light and give up on all this outswinger silliness,  you will have learned the irrefutable mechanical logic of the inswinger design.  (Tongue in cheek alert.)

 

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You might like to try clicking on these photos to enlarge them.  Perhaps let your eye root around inside the design a bit.  If you cannot sense how this geometry oozes with pent up kinetics, just waiting to be exploited after 1700 years of being buried, then perhaps this game is not for you.

 

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Honestly, I don’t know why I try, if you are going to be so bloody-minded all the time.   By any practical judgement, isn’t it obvious that something along these lines is how the artifacts were meant to be put together?  Why can’t you submit to the logic of how neatly the Elenovo and Orsova artifacts reveal themselves as inswinger’s?   Compact! Accurate! Powerful! Deadly! Let them out of your ivory closet already yet!

And if that doesn’t do it for you, stay tuned as we get this baby strung and kitted out for action.

 

I have been looking forward to implementing this plan for connecting the struts to the kamarion for some time now.

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I have not the slightest doubt that certain fellowes I know will be rolling their eyes, and wonder why I don’t just rivet the strut to the kamarion by utilizing those two little holes evident on the Orsova artifact.  Other than the need to make these parts thematically consistent with the take-apart strategy implied by the loops of the kambestrion and the tangs of the kamarion seen in the artifact record, I do not believe the rivet size suggested by the aforementioned holes would be adequate to handle the stresses that occur as the machine vibrates at the moment of firing.  Just my opinion, of course, but one I stand by having seen Firefly jiggle around with so much enthusiasm as she is fired.

Those two little holes for connecting the strut to the kamarion seen on the Orsova, are huge clues if you know how to read them.  I defy anyone to come up with a stronger and simpler take-apart design for connecting the strut to the kamarion than the one I’m about to implement.  Flat plate with a projecting pin? Relying on the rearward bend of the kamarion to hold it all in place?  Not so much, I think.  Think mil-spec reliability and you’ll understand where I’m coming from.

After a bit of finish work on her metal parts, I assembled Phoenix today to take a look at some possible stock profiles.

(Click to enlarge.)

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Naturally Oona thinks all the fuss is about her.  Fashion models! ….waddayagonnado?

Because for some folks, linguistic ambience is everything, I’ve decided to call this hunky brute: the “Sagma”.  According to the Google, that’s Latin for saddle.  All very erudite and tickety-boo, I am sure.

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The sagma joins the stock and the ladder together with great strength.  Note how the tight inside corners of our new sagmae, mimic the sharp rectilinear lines of these exact duplicates of the Elenovo kambestrion, seen below.

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That’s thematic extension, Baby!  I will sandblast my sagmam to get a matte finish as seen on these kambestrions.  (Or is that kambestrium?)

Ain’t Latin the shiz, though.

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