live2Draw

i would have to say the most efficiant bows out there are bows like the Equalizer elite fire/ice. Producing awsome KE and speed at low low draw weight.

Sylvan

In archery if all you do is go to a lighter arrow you actually wind up with less kinetic energy and less momentum than you had with the heavier arrow. The reason is that bowstransfer energy less efficiently to lighter arrows than they do to heavier arrows. Another way tosay it is that lighter arrows absorb less of the bows stored energy than do heavier arrows.

If you decide to shoot a lighter arrow to get more speed out of your bow but you want also to maintain the ke and momentum you had with the heavier arrow you would need to increase the amount of energy you store in the bow to compensate for the loss in efficiency. Now assuming you're not going to change cams or increase the draw length, the only way to compensate would be to increase the draw weight.

Arthur P

True, Sylvan, but the change in KE will be pretty negligible. Only a few foot pounds at most. But that truly is one of the biggestmisconceptions a whole lot of people have about archery, that switching to a light arrow in order to shootfaster will give you more energy. It just doesn't work that way.

Sylvan

Agreed the loss isn't great but the point was that there is not and increase as was suggested. It's amazing how many believe this myth.

Arthur P

That ain't no lie!

Sylvan

Actually Art I don't know that I'd agree that the loss in negligble. Kind of depends on how much you changeand how sensitive you are to increasing your draw weight. I ran some numbers ina computer model. I started with a bow at 60# throwing a 600 grain arrow 225 ft/sec at 125 grains virtual mass or 82.8% efficient. It generated 67.5 ft/lbs ke. The same bow with a 400 grain arrow had 62.1 ft/lbs ke or a 5.4 ft/lb loss. To make to up for the ke loss on the 400 grain arrow I had to raise the draw weight 5.2 lbs to 65.2 lbs. For me, a 5 pound increase in draw weight is not negligable.

Note: I used a pretty good cam with an sep of 1.36

Another note: By increasing the weight the lost ke was recovered but momentum of course wasnot. If fell from .6 to .49 pound seconds. I know that is know suprise to you!

MeanV2

My Allegiances I have hunted with produce over 68#KE
60# bow 28.5" draw
340 grain arrow shooting 301 fps
Sure I could get a couple more #'s KE shooting a heavier arrow,but do I need it? I have blown through every Deer I've shot with it and a 450# bear. Maybe I'd get more penetration in the dirtWith my setup I'll take a little loss in KE that is more than I need anyway to keep a flatter trajectory for the type of hunting I do with my Allegiance. On another note on my recent NE trip I knew ranges would be shorter and I'd be hunting out of my Double Bull so I built some FMJ's that weighed 500+ grains and had 20%+ FOC. They worked great! Will I change the setup on my Allegiance? Hardly! I hope I never get tunnel vision so narrow that I think one type of setup is a do-all, cure-all

Dan

Sylvan

MeanV2,

I agree with you 100%! Once you have enough energy/momentum to do the job properly worrying about tweaking to get a bit more is not worth it in my opinion.

The previous discussion about loosing energy when you go to a lighter arrow was more of a point of fact rather than an endorsement or lack of endorsement for the idea of shooting a lighter arrow. And of course the facts are that contrary to what a lot of people believe, you loose both kinetic energy and momentum when you simply go to a lighter arrow.

GMMAT

I hear ya, Dan.....but ya gotta admit....If you can handle the draw weight.....and your bow can handle the arrow weight (and still produce speeds of +/- 300fps)......THAT is a do-all/cure-all.

Questioning that bow's "efficiency" is kinda like asking the guy dating the new hottie.....if she can cook

Sylvan

So GMMAT, I have a rhetorical question for you.

Given2 bows,one that shoots a 350 grain arrow 320ft/sec and requires 70 ft/lbs of work to draw and one that shoots a 350 grain arrow 320 ft/sec and requires 80 ft/lbs of work to draw, and everything else between them is the same, which would you choose?