More on speed

[DC]

I recently decided to drop to drop my draw weight. I was making bows in the 40-43# range but I wasn't getting full draw at that weight. Getting old I guess. Anyway I've made my last couple of bows at 35#. I was expecting the arrow speed to drop but at 10 gpp it's actually gone up a bit. These last bows are consistently in the high 170's with a few shots into the 180's. I was willing to kill to get into the 180's but I guess I dodged that bullet Was a higher speed at 10 gpp at a lower draw weight to be expected?

[bradsmith2010]

your form at the lower weight may be part of that,, and getting good full draw too,, or maybe you making a better bow now, since you are over the pyramid craze,,

[DC]

Don't like pyramids do we Brad .  I figured that improved form and draw would help but in the back of my mind there's something that says lighter bows are faster using 10 gpp. I think I read it somewhere but I wanted to check. If it's just my form and draw length then maybe I should just buff up a bit and my 40#'ers should be screamers. Yeah right. To me getting in shape means shifting my position in my recliner.

[bradsmith2010]

it does seem easier to make a lighter bow shoot harder,, really some of my bows look pyramidish ,, so no worries,,
i have not read that but have wondered about that

[stuckinthemud]

Part of me has wondered, from time to time, if people building heavy bows do not always feel the need to maximise bow performance in the same way as those building medium and light-weight bows do.  Equally, I think I read that more wood means more internal friction losses so 'big' bows are less efficient?

[Badger]

   First off how heavy are your arrows? The only way that a lighter bow will outshoot a heavier bow is if the lighter bow is made better. Speed without knowing arrow weight doesn't really mean anything. Are you talking 10 grains per pound? Your heavier bow may have been overstrained dropping performance. At 10 grains per pound high 170's is smoking fast. I have never seen that fast on a straight bow.

[Del the cat]

Try shooting the 350grain arrows from the 40# bow...
Del

[George Tsoukalas]

Full draw means a lot regarding speed. Jawge

[DC]

   First off how heavy are your arrows? The only way that a lighter bow will outshoot a heavier bow is if the lighter bow is made better. Speed without knowing arrow weight doesn't really mean anything. Are you talking 10 grains per pound? Your heavier bow may have been overstrained dropping performance. At 10 grains per pound high 170's is smoking fast. I have never seen that fast on a straight bow.

I always use 10 grains per pound(or as close as I can get) for chronoing. This arrow was 360gr and the bow is 37#. The arrows are 30" so I may be overdrawing a bit. It's amazing that dropping about 5# let me draw another 2". Some king of mental block I guess. It wasn't just one heavier bow. With the last ten bows or so I've been sneaking up on speed and draw weight. I was up to 44# two bows ago but my draw length had dropped by a couple of inches. Last two bows are about 37# but with them I can get 27" draw and both are in the high 170's. The Dogwood I just posted and a slightly recurved OS. I've always suspected my Chrony as being faulty but I've asked about it before and i think it was you that said he'd never seen one be out of calibration. They either work or they're broke. You suggested that I try for distance but I can't find a spot. I was going to use the beach but in the summer they are full of people and in the winter there are no low enough tide during the day to get to the sand. I'm bummed now because I'm back to suspecting that I have a faulty Chr.ono

[bradsmith2010]

if it is faulty, its the right way,,

[DC]

Try shooting the 350grain arrows from the 40# bow...
Del

I used my last "heavy" bow it's 43#. I got in about ten or so shots all around 185-187 with one at 192 but that's probably an error. Then I hit the plywood frame of my target and smashed the arrow. It was a hemlock arrow and they're a tad brittle. I'm gunna be some disappointed when I find out my Chorny is reading fast.

[joachimM]

In principle, any bow weight can shoot equally fast at 10 gpp.
The distance covered by each arrow, however, will be shorter for lighter bows. The reason being that air density (and friction to be overwon) remains te same: that is an externality we cannot scale up or down with bow and arrow weight. Since heavy arrows have more kinetic energy, a smaller proportion of their kinetic energy is lost to friction, hence they fly further.

At very short distances, like when chronoing a bow, friction differences between light and heavy arrows (10 gpp for a light and heavy bow) are negligible.

When talking 10 gpp and 28" draw (or actually, a 22" power stroke), 175 fps is exceptional for a straight bow. longer draws, however, can get you a few fps more. So maybe you're just drawing it a bit further at the lower draw weight.

[DC]

I've sent an e-mail off to Chrony asking about whether or not they go out of calibration and how much it cots to recalibrate. What with shipping both ways it may be better just to buy another one. If the two Chony's agree then I'm golden. See what they have to say.

[Stick Bender]

I'm not saying this is the case with your Chrono but if I'm just using natural light with mine I get some crazy fast eradic speeds  but when I use the led hoods I get much more consistent readings also I disregard the speeds I get tell the bow has at least 200 arrows threw it and keeped braced for 1 hour then I pull it to full draw 3 times before shooting arrows usaly gives me real numbers that's similar to how Tim Baker did it I read , I'm not saying your numbers are wrong just saying I get a lot faster numbers on a fresh bow ! Plus wrong spine arrows give me erratic numbers to. chronos can be real touchy some times !

[DC]

I actually get very consistent numbers. I read on a website a few weeks ago that painting the tips of the arrows flat black helps get more consistent results. I tried it and now I get nice repeating numbers. I still get errors when I screw up but by and large I get good repeatable numbers. It's whether they're accurate or not that's my problem. The test I did for Del's suggestion was nice and solid, 8 or 10 shots all within 3 or 4 fps except for the one at 192 but that was just 4-5 fps out of the range. That could have been me. I just ignore numbers like that, they get me too exited.