Building my arrow
 

If I go with an a/c/c 3-71 @ 27.5".....4" QS vanes....6" reflective wrap.....100gr muzzy brass weighted insert.....and a 100gr BH (TBD).....I'm getting an arrow in the 515gr. total weight.

Anyone have a program that can estimate arrow speed from a 2008 Bowtech allegiance (smooth mods), 60#'s DW @ 29" DL?

Thanks.

RE: Building my arrow
 

I don't exactlly recall what the IBO with smooth mods was for the ally.... but assuming it was in the 315 area, and assuming that you have about 10 grains added to the string in the form of a loop and peep, you'll have speed around 240-245fps.

Here is a link to a webpage that you can use to enter your set-ups information and get an approx arrow speed. In my experience its usually on the optimistic side by a few fps.... but it will give you an idea.

http://www.backcountrybowhunting.com/articles/tools.php

RE: Building my arrow
 

Calculated Speed:
241 fps


Kinetic Energy:
66.44


Source: http://bucklemke.com/ke/ke.php

RE: Building my arrow
 

Jeff,
Copy this link, it's as accurate as I've found in guestimating speeds and being CLOSE to a chrono.... http://thearcheryhut.com/calculators.php
Not sure what your "goal" is, but if you are trying to achieve the MAX KE, you're on your way, but you can actually achieve a little more KE with a 450-475 gr arrow, and possibly not have to use the weight adapter.

For what you've proposed, an ACC 3-49 will hit just right spine wise, while weighing in at roughly 515.9grains according to OT2. That should fill the bill pretty well, that 3-71 is REALLY stiff which may not help your tunability much. The 3-49 though will hit right in the middle of the GREEN on the spine selector. If I were setting that up, that's probably what I'd go with. And I get a little better speeds on my calculators (246), but it's usually within 5fps. so it should be CLOSE.

RE: Building my arrow
 

But I lose weight with the 3-49 (I assume you figured that in, though).

So....will the 3-49 have ENOUGH spine?

Also....when looking a tthe easton charts....it says to subtract for the insert weight. Why?

Thanks.

EDIT**

If I go with the 3-49 ....I can't seem to get my arrow weight over 450gr. (WITH the 100gr adaptor)

RE: Building my arrow
 

I had some 3-71's lying around from last year....and I pick up 35gr by simply going to them (now). Took a slight adjustment to my 30yd pin......but otherwise it's good to go for the afternoon.

If I can get to 500gr with the 3-49 (I don't see how) and have enough spine with the 200gr tip.....I'll look hard at that.

Tell me how.

RE: Building my arrow
 

I don't think you will have the correct spine with a 3-49. I think you'll need at least a 3-60, but a 3-71 like you have will be better.

I shot a 3-49 this spring, tinkering around. I'm shooting an Iron Mace... same cam system... granted a little harder... but I was shooting 100gr tips.... and I got a weak spine reaction.

Every bit of weight you add to the arrow will effect the spine... wraps... fletching weight, insert weight... you name it... more you add... more resistance there will be... weaker it will make your arrow spine.

RE: Building my arrow
 

I'm emailing back and forth with the tech from LAS right now. He's thinking 3-60, also.

If I can get them to the desired weight....I'm gonna pull the trigger.

RE: Building my arrow
 

Jeff,
How many GPI are a 3-49, OT2 is showing the shaft alone to be 277 at 27.5", add a nock at 13gr or so --> 290 + 200 in tip weight --> 490 and another 15 with Blazers or 21 with regular vaines, and you're 505-510. The 3-71 are showing to be EXTREMELY heavy spined, even with the 200gr tip weight. Now if you were dealing with a full length arrow, the spine would get close but still he heavy. If you're gonna shoot expandables, probably not as much of a problem, if you're shooting fixed BH's then it will make tuning more of a problem.

I looked at the Easton site, it does look like the arrows are going to weigh less than OT2 says they would, however, for the spining, it should be right, and a little under your prescribed weight will actually give you a little more KE from the numbers I'm punching. You are correct on the weight, OT2 gives you the weight of a full length shaft when you do shaft only. (MY BAD there.) You'd be looking at a roughly a 472-ish grain arrow, but it still appears that you'd have a better speed/kinetic enegy curve at this weight. It looks like you'd gain 1ft/# from 71 to 72 and 15fps from 247-263, with the numbers I'm seeing.

RE: Building my arrow
 

What is the goal here? And I am not asking to be a smart a**?

Is it that you are not getting passthroughs with the rage?

By throwing the numbers around you are going down in KE and FPS. You will gain momentum which will help, but is it going to make a big difference. The reason I am asking is because I was thinking along the same lines as you. I went from a 375 gr Maxima 350 to a 450 gr FMJ. I lost about 20 fps and couldn't tell any difference in penetration on my BLOCK target(which I realize isn't a perfect way to tell) I eventually went with Beman ICS's that are around 390 gr and they seem to fit the bill.