Friday, 7 April 2017

More Flight Arrows

I've finished off a couple of flight arrows for my mate JT ready for a shoot on Sunday, he can compare them with a couple of his others which perform well.
I found an old one which I'd made for him which was a good performer so I used that as a reference, I've got the weight about the same, but got the spine a tad stiffer, up to about 60* from 55, the shafts are slightly thicker (cedar) but more barrelled. Brass being denser than steel allows a smaller diameter point with the same weight. Overall weight is 400gn and 480gn for the two new ones, the old one was 456gn.

Ruth who is a regular at the ILAA shoots asked if I could make her some arrows to help her get to 200 yards with her 40# bow. Making arrows isn't my fave' but I'm old school and don't like to refuse a lady, so I said I'd make a one off to see if she could get the 200 yards.
One of my flight arrows from last week had broken it's point off on impact, I also had the front end from another very light flight arrow (slightly smaller diameter). It didn't take too long to splice the two together and run the sesulting arrow in my arrow tapering jig to give an arrow with a very slim front end. The pic shows the splice which is near the point so won't be subject to much flexing. I've spliced many arrows this way and never had a failure. It still has the centre of balance a reasonable distance in front of the geometric centre so it should fly ok. I also filed down and tapered the nock end a bit more to help in that respect.
I tested the stability of the arrow by throwing it in the back garden like a javelin, it flew well and even when I threw it nock first, it righted itself and landed point first!
I've finished them with the bright yellow paint which certainly aids finding them.
Anyhow, I can't make the Sunday shoot, but I'll give all the arrows to JT later today and he can pass the one test arrow on to Ruth... hopefully she'll get to 200 or close.
The pic also shows I've found a good use for off-cuts of decking!

* Note:- These arrows are to be shot from a warbow of about 120#, but one needs to realise that poundage doesn't really correlate to the speed of the arrow or the acceleration if is subject to at loose.
So a 120# bow isn't going to accelerate an arrow 3 times more than a 40# bow.
A 60# flight bow can often kick the arrow harder than a 100# bow. The weight of the point is also a big factor, a light point present far less resistance to the acceleration than would a heavy field point or huge warbow head. The lower resistance creates less bending force and that's why a 60# spine flight arrow is fine from a warbow.
There is a similar problem with the gpp (grains per pound) rules of thumb applied to arrows to avoid a "dry loose", one has to remember the g force on the arrow is huge ( I think it is something daft like 300g) so even a very light arrow presents substantial inertia compared with a dry loose.
many of these guidelines, rules of thumb etc, are ok for average mid weight bows but the performance of a bow isn't linearly related to poundage.

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