And here is what happens when Mr. Man goes one clickity-click too many. (Note the depressions cut into the limb that were to be used to mechanically anchor the nock whippings.)

Fortunately I had a spare piece of ash. So, all was not lost. Eventually, a couple of usable limbs appeared out of this catasrophe.

A smallish whipping on the very end of the tip locked in the tension from the braided cable until additional epoxy soaked whippings could be added to form the nocks. Happily this cordage style nock forms a couple of high-tension compression rings that also protect the end grain on the ash. One day it would be intersting to try a similar binding rendered in sinew and hoof glue, or something.

…. Anyway, past experience has shown that inswingers can get away with minimal nocks so long as there is an additional retaining strap connecting the limb tip to the bowsrtring. More on that later.

These Mk IX limbs are all finished, save for a bit of rasp work and some sanding. They weigh exactly 8 pounds each, and are 3″ longer than the previous Mk VIII’s. Those previous limbs were a chunky 10 1/2 pounds each and are the ones responsible for all the data generated in the last year or so. We are hopeful that this new design of limb will develop much higher velocities.

Here is a photo of that locking pin and some of the handy-dandy ferrule cement that holds it in place.

The 1″ deep hole for this 3/8″ pin should pick up enough ash to form an effective lock. The hole in the limb is only .002″ larger than the pin, and when installed that gap is filled with the marvelously sticky ferrule cement. Application of a hot iron to the flattened tip of the pin will allow for its removal.

While the sum of all the forces in the firing cycle always seems to propel the limb aggressively forward into the taper of the limb iron, it is well to guard against any backward forces that might be encountered when applying the old heave-ho to the tension strap. It is imperative that the tension strap remain unbudgeably anchored at either end of a non-compessible limb.

The splice that forms that eye has a tapered core inside it. This taper makes for a neat and easy application of strength where strength is needed, over the length of the strap.

Our current strategy relies on inducing tension into that strap, and then locking that tension into the limb by means of corrugated whippings out on the extreme tip. And yes, we love to cheat by using epoxy now and then. (The Roman’s probably had some pretty good heat activated resins. Think of ferrule cement, blobs of pine pitch, rosin, etc.)

If ever one day this investigator is lucky enough to encounter a good quantity of sinew, he figures it would behoove mission sucess to have all the basic cordage designs modelled in modern fibers first. In short, enough refined sinew to power a machine of Firefly’s size would be a fairly precious, labor intensive outing for whoever came up with it. Not the sort of thing you’d want to entrust to a machine that wasn’t already up to snuff.

And hence the reasoning behind using modern cordage for the springs, strings and other little wingy-dings. At this stage, it’s all just an exercise.

A cunning plan has taken root wherein we start testing with the new limbs at the full length seen here. At 31″ OAL, that is 4″ longer than the previous set. By utilizing a set of whipped on nocks, we can shorten the limbs at will. Or, for that matter, return them to full length. When an optimum length is established they can have any excess removed then.

Compared with that old Mk VIII in the photo, it’s clear we are going into new and dangerous territory with Firefly.

The square hole is 1/2″ X 5/8″. It is intended to anchor a tension strap made of Dacron strands. Not only will this new arrangement be lighter, the strap should also be stronger. While it is true the previous strap was made from kevlar, it is also true that it was in the form of webbing. I imagine webbing to be less strong of a format because so many of its fibers run crosswise to the strain. Our new attempt will have all the fibers running lengthwise. And quite incidentally, their whitey/yellowish colour will do a fair job of mimicking sinew.

Not that we care about that, right?

My gut tells me to go all in here and thin out the tips. What’s the worst that can happen. Replacing the limbs in the event of failure is a minor chore compared to making the irons. A woody bit goes pop! So what? Maybe we learn something, eh?

Anything for speed.
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Don’t worry mother. Civilians are banned from the area during testing.

These beauties have been heat treated to 40 RC. If you hold them lightly and give them a sharp rap with a hammer, they’ll sing to you for a good twenty seconds.

While a couple of tapered tongues could have been neatly forge welded together to form the U-strap, here at the LCF we try to keep our standards of authentic portrayal within the bounds of certain key questions. Things such as: how accurate? how far? how fast? how powerful? And the like. The smaller niceties of metalworking are more useful to us as accomplished entities, rather than unaccomplished diadems sparkling with the promise of 4th century metal working techinique. It is enough that the designs chosen here would be as equally feasible with a well equipped and well staffed black smithing operation, as by yours truly with a bunch of whirling electrons and hard tipped carbide.

The horror of their fascination is a marvel to behold.