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I’m on the injured list with a cranky knee today.  Only managed three shots before retreating to the couch.

Stats as follows: 7191 grain bolt.  4900 lbs draw weight.  49″ of draw length.

Shot 1,    326.8  feet per second,   1705  foot pounds

Shot 2,    321.5  feet per second,   1650  foot pounds

Shot 3,    324.0  feet per second,  1675  foot pounds

Unfortunately, accuracy was spotty with these three shots.  It looks like I need to trim the fins down so they don’t interfere with the more acutely angled string that results from the longer draw length.  This 49″ draw puts the limbs at exactly 90 degrees to their at rest position  (i.e.  lined up  straight,  directly opposite each other when in the cocked position.)

These power levels are awesome to witness.  The sharp tipped bolts penetrate over five feet into the loose sand of my backstop.  Soon as I get mobile again I’ll fire up the video camera and punch holes in something challenging.   I wonder how much wattle and daub it would take to keep one of these bad boys out of your hut?

Firefly spread her wings today.  The happy little bisom  flew rings around her former self and started performing at the level I always knew she could.  5 shots in a 3″ circle at 50 yards.  298, 300, 303, 295, 303 feet per second respectively with a 6800 grain bolt.  Energy was very close to 1400 foot pounds for each shot.  Draw weight is around 4500 pounds.  She is performing at this level with only 42″ of draw length.  The previous set of springs took 52″ of draw length and 5,000 pounds of pull to achieve this much power.  The untapped reserve we have  in those ten extra inches of draw length will be something to explore tomorrow.

I am bone tired now.  This last little development stint has been a doozy, but it looks like the chaffing trolls have finally been smothered into submission by all that  swaddling.   I need to keep an eye out for them though.  Rope based torsion springs are delicate affairs and at these power levels should never be  allowed to rub on objects harder than they are.   Big sissies really.

Its looks like I am once again starting up a shooting phase for this project.  Stats and video are in the works.  Thank God! I was getting close to exasperation with this whole thing.  Journey over goal;  it’s a lesson I need to relearn every so often.

Sherlock.  Definitely Sherlock.

Mr. Wilton squeezed  a 1/2″ diameter piece of steel into three different test materials today.  Nylon rope was placed on the backside of the pad to simulate the spring.  When this test was tried with a piece of harness leather,  a hole was eventually cut in it by the concentrated pressure from the vise.   A  piece of oiled  rawhide was tried next.  Eventually, it too failed,  exploding in such a way as to propel the severed portion  upwards at high speed.  It bounced off the fifteen foot ceiling and ricocheted into my odds and ends box over in the corner.  ( Perfect place for it, by the way.)

The four layers of upholstery fabric  stood up to this  compression test just fine.  It would seem my analysis from the other day is correct.  The Sherlock Holmes fabric works fine under massive compression, just don’t pull on its ends while it’s under that kind of load.

It is starting to0 look as if  separate fabric pads that just fit over the crossbar and go no further, may be the answer to my continuing travails with the Chaffing Trolls.  Hate those little buggers.

Okay, okay.  Rawhide then.

I am getting the distinct feeling of being somewhat slow on the uptake here.

The wrap is still needed to protect the spring as it goes through the hole in the washer.   However, after carefully analyzing where the upholstery fabric (otherwise known as the Sherlock Holmes wrap)  actually ripped going over the crossbars, it is clear what is happening.  Lower down where it goes through the hole in the washer, the wrap gets twisted into the spiral of the spring.  This effectively anchors the bottom of the wrap in a vise grip.   The effect is a bit like having the hem of a full length dress become  stuck to the floor, and then having its inhabitant undergo a vertical growth spurt.  Things tend to rip at the shoulders;   or in our case, up by the crossbars.

The solution may be to have a separate anti chaffing pad that only extends far enough to cover the crossbar, and is not attached to the wrap.  That way it would only have to withstand the compression coming from the rope bundle, and not any linear strain.

I’m moving in treacle here.  Slow, so slow.  Got to get this right.

The trepidation evident in the last posting has blossomed a bit.   Chaffing trolls gobbled up Sherlock like he was a raw amateur.

Whatever it was that the Romans did to defeat these little bastards, it was good.  Very good.  It looks like I am going to have escalate to Kevlar and rawhide.  The kevlar would be a cloth wrap, similar to our last attempt.  (It is covered by special dispensation under rule three re: allowable modern cordage in times of crisis.)  The rawhide would be in the form of a special shoe that fits over the crossbar,  and is stitched into the kevlar.  At this stage it is more important to get up and shooting again, than it is to devise a period authentic solution.

The width of these crossbars is 1/2″ and they have a full 1/4″ radius on the top and bottom.   My old Gallwey ballista had crossbars that were 3/4″ in width with a full 3/8″ radius on them.   There never was a problem with the nylon springs abrading through with that old outswinger style machine.

… So many variables to consider, it’s making my head hurt.

Rawhide shoes may just get me through the door on this one.  Clearly I need to put my thinking cap on a little more askew.  Conventional approaches are not working.

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