This will be our fourth field trip in search of the performance  envelope of the elusive, Lightning class,  ballista.  The cast of characters in our afternoon adventure, were as follows:  The Rebecca, Brian & Kachi, an impishly good-natured Angela, the noddypoll doing the shooting, and, of course, our faithful reconstruction of the Orsova artifacts, Little-Miss Firefly.  In good “Lightning” fashion, we find Firefly thumping out her ancient war dance, on a flat plain a few miles West of town, early on a Sunday afternoon.   Click for Vid.    20121028141638 .   In that video, we heard Kachi’s reaction to the first shot of the day, which was performed with a 521 gram bolt from my matched set of extra heavy  bolts.  And now, for the discerning eye,  that same shot rendered in a better quality mpeg.  20121028141638(2)

In this next photo, that tiny diagonal fleck on your computer screen is one of our “heavies” rocketing skyward.  Click to enlarge.

And here is the video of the event that this still was clipped from.  Click for Vid.   20121028145328(3).    The camera location here is about 100 yards off of Firefly’s port side, and maybe 50 yards downrange of her firing line.   It is just possible to glimpse the flight of the bolt in the first two seconds, before it exits the field of view and climbs up the slope of  it’s nearly 1/2 mile parabola.   Although it can’t be seen in the video, the bolt  landed 50 yards short of the end of that grassy plain we are shooting down, just a sliver in front of where the sage meets the grass at the end of the field.

When they were standing on the rocky outcropping, off to the side,  my companions were able to confirm that there was a distinct whistle coming from all three of the Dura bolts that we fired.    In this next video, that whistle is clearly audible,  but unfortunately cut short by the bellowed exclamations of that big twit in the steel helmet. Witnessing such a stable launch with his first Dura Europos bolt, left the poor fellow unhinged with joy.  Click for vid.   20121028143301(1)

And finally for the videos, we have this launch moment of a “heavy”contrasted nicely against the overcast sky.    Click for Vid.   20121028142650(2)

……So anyway, that was the best of what we were able to do in the filming department.  Yeah! I know, it’s all a bit too elusive and hard to follow.   But who knows?  Maybe there is someone out there who will value the humble reality of it all…..

And now we move on to the data.

I suppose I’d better cop to it right from the git-go.  My intention to break 1,000 yards with the new Dura bolts was never given a fair chance to succeed because it found itself countered by another one of my intentions.  This latter involving a wooden wedge.

Long story short — I implemented this bright idea to tighten the lashing that binds Firefly’s tail to the counterstay with an oaken wedge driven between those two parts.   Clearly a “senior  moment” was having it’s way with me.   The effects of this little brush with senility ended up  changing the elevation of the machine; dropping her angle from an intended 44 degrees, down to 38 degrees. Naturally this caused all of the day’s shooting to fall short of it’s true potential.   Something I didn’t realize until I slapped the inclinometer on the deck for a quick check after the shooting  was finished.  Not my finest moment, and all that.

So whatever this field test is about, it is not about maximum distance shooting any more.   This scale chart shows an average range of 728 yards for the heavies, when we had something like 790 yards on  the previous trip.

Click to enlarge.

And when we include the firing line,  the chart looks like this when everything is to scale.

Despite the fact that these groups  are a good sixty yards short of the range achieved with our previous field tests (thanks to that pesky wedge),  the size of the groups is much improved over our previous attempts.  The three Dura bolts that we fired showed a perfectly stable flight pattern to the naked eye, and perhaps that is why they all fell inside a 30 foot circle at an average range of 854 yards.   There was virtually no wind for this field test, and this must also be why the groupings were so tight at this great a distance.  As for the heavies,  nine out of twelve shots fell inside a 60 foot circle at an average range of 728 yards.   Given the larger sample size of this particular test, this is a good indication of what these machines would have been capable of  in terms of indirect fire at maximum range.  More than enough precision to lob heavy pointy things into the ranks of  any close ordered enemy, threaten access to key thoroughfares and meeting places, or even dispense fire arrows into shipping at long range.  Just the kind of extended military capability a shrinking Empire is greedy for, as it topples towards it’s final destiny.

We also note, with some delight, that the case of wandering zero experienced in the previous field trip, seems to have resolved itself.   I am not even going to attempt a detailed explanation of why that might be so,  (probably the bundles finally settled in after the new MK X limbs were installed);   just thanking the CG’s for their beneficence.

The velocity for the 276 gram Dura bolts averaged 360 feet per second, while the 521  gram heavies were doing right around 300 fps.   It should be noted that in terms of tuning on the spring bundles, although we have monkeyed around with the rotation of the washers to improve the limb balance,  it has been done in a way that did not add any new torque into the system.  If one half of a bundle was tightened, then the other half was always loosened the same amount.  And it has been this way since the beginning of summer and for all the field tests we have done.

It may be time to up the ante, a bit.

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