Is there a definite correlation between the speed of the arrow and the pounds the bow is set? Say 60 pounds draw to 70 pounds what would the graph look like assuming pounds vs. velocity assuming the same arrow. I have a Mathews FX set at 70 pounds what arrow velocity should I expect?

There is a relationship between poundage and arrow stiffness. Generally when increasing the poundage, a stiffer arrow will also mean one that weighs more and the velocity will be close to the same. When you turn up your bow you will find the need for a different arrow. The bow must be tuned for whatever arrow you have and I think you will find the velocity will be very close. There is no free lunch!
What is more important is the action of the bow itself, the way the power stroke is applied to the arrow, the efficiency of the bow and so on. Some very heavy bows are real slow. Some heavy bows can shoot a lighter arrow which will give more speed. Some heavy bows will shoot a heavy arrow very fast.
Some light arrows are being made much stiffer today and you might gain velocity by choosing the right one.

A higher draw weight means a larger amount of potential energy is stored in the bow at full draw. This can definately translate into more arrow speed but beware.

Know your total arrow weight. In general that total arrow weight/five gives you the max draw weight that arrow can be shot at.

Assuming you have a arrow w/ the proper stiffness. If the arrow is the same weight(same cams etc.), the bow will shoot the same arrow faster at 70 vs 60. Quite a bit faster in some bows.

To tell you how fast it will shoot is not something we could guess. A chrony will tell you the speed difference. If you don't have a chrony, usually the local archery shops will let you shoot over their's.

Good Luck

Reloader

So pretty much, in theory a higher poundage bow might not be faster cause you have to shoot a heavier weight arrow to not break the bow? I am referring to the minimum weight arrow rating that the bow MFGR gives you with the owner's manual, more than likely right next to the "Do not dry fire the bow" statement.

If that were the case, it is about KE moreso than faster flight. Theres the tradeoff. The same, maybe slower flight from heavier arrows with higher poundage, but you get higher KE.

Sound about right?

Think about what your're tring to accomplish.

My 60# recurve will shot a 510 gr. arrow @ 200 fps..

My 70# recurve will shoot a 595 gr. arrow @ 200fps.

My 85# recurve will shoot a 722gr. arrow at 200fps.

At that speed I'm point on to 35 yrds with all three bows. Basically my arrows are flying fairly flat to that distence with is 10 yrds farther than I've ever hunted too(My personal choice).

All three bows are the same model by the same bowyer. Other than the obvious wt. issue, I have little adjusting to do in my shooting if I switch bows.

I have consistency in my arrow trajectory and differant K.E/Momentium options to cover every thing from sub-freezing late season whitetails to Buffalo.

Gixxer and Boss, right on. You never want to shoot an arrow lighter in weight then the manufacturer recommends for his bow. It is always safer to go heavier and it will make the bow quieter also. Strings and cables last longer too.

I've found broadheads get real hinky at speeds over around 280, esp in less than ideal conditions (wind).

I've seen guys with usually good judgement lose their minds over chrono readings. Until one really fully understands that speed ain't all that, I strongly advise to avoid chronos like the plague. They have ruined many otherwise perfect matches.

Listen to your bow with different arrows and poundages. It will literally tell you what arrows it likes and how it likes to shoot them. 99% of the time, the setup that sounds the best (quiet) is the most accurate.

Thank-you for all the info. When I bought the bow it was set to 55 pounds, and I presume the guy who sold it to me gave me arrows which were for 55 pounds. Over the last 6 weeks or so I have increased the poundage to 70, using the same arrows - reading your comments this aint a good idea. What weight arrow should I be using for the FX set at 70 pounds?

ghundwan,

Different Companies make different weight arrows.

The arrows the guys gave you may be stiff enough for the 70 pounds. A good many Archers shoot arrows that are much heavier than needed for a given poundage. It's not a bad thing, but it will lower your speed considerably.

For instance, I had a Bowtech that would shoot 7.4 GPI .400 spine target arrows at over 300 fps but, it would only hit 255 w/ 11 GPI .340 spine arrows.

What arrow are you shooting? If you tell us that, we can tell you if it will handle the 70lb pull. I would say you need at least a .400 spine for the set-up you have. A .400 to .340 would work well.

Also, What game are you going to shoot w/ them?


Have a Good One

Reloader

This web site should help.You'll need to weigh your arrow and go to the Mathews web site and find out what the IBO speed of your bow is. Good luck
BT53

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

IBO STANDARD: Minimum Allowable Arrow Weight - Includes Tip Weight
80# Bow 400 gr min. 64# Bow 320 gr min. 48# Bow 240 gr min.
78# Bow 390 gr min. 62# Bow 310 gr min. 46# Bow 230 gr min.
76# Bow 380 gr min 60# Bow 300 gr min. 44# Bow 220 gr min.
74# Bow 370 gr min. 58# Bow 290 gr min. 42# Bow 210 gr min.
72# Bow 360 gr min. 56# Bow 280 gr min. 40# Bow 200 gr min.
70# Bow 350 gr min. 54# Bow 270 gr min. 38# Bow 190 gr min.
68# Bow 340 gr min. 52# Bow 260 gr min. 36# Bow 180 gr min.
66# Bow 330 gr min. 50# Bow 250 gr min. 34# Bow 170 gr min.

You need to understand a few things about arrows:

Spine is a term to discribe how much or little an Arrow will flex in flight, basically how stiff the arrow is. Spine is affected by the lenght of the arrow and the weight of the fieldpoint or broadhead.(Research Archer's Paridox)

Then there is the weight of an arrow.

BOTH have to concidered in your arrow selection, to have good arrow flight. Arrow manufatures have wt./spine charts to help.

go here: http://www.huntersfriend.com/arrowhelp/arrow-selection-3.htm

In fact read the whole thing. This will have you understanding archery faster than asking us. Have fun. BT53

quote:

Originally posted by Blacktail53:
go here: http://www.huntersfriend.com/arrowhelp/arrow-selection-3.htm

In fact read the whole thing. This will have you understanding archery faster than asking us. Have fun. BT53

great link,

thanks.

who knows, he might already have arrows spined for 70.

quote:

Originally posted by Blacktail53:
go here: http://www.huntersfriend.com/arrowhelp/arrow-selection-3.htm

In fact read the whole thing. This will have you understanding archery faster than asking us. Have fun. BT53

Thank-you for the great link - learned a lot !

I am currently using 2 types of arrows the Vapor by Blackhawk 5000 ACA and the Terminator 4560 both with 100gr broard heads. I plan to shoot Kudu, Impala and Warthog. Does this combination sound right?

ghundwan,

Your BH 5000 ACAs are plenty stiff enough for your bow, they are rated as being spined for bows in the 80-100 pound range. If they shoot accurately for you, they should work great for hunting. I'm pretty sure the 5000s weigh around 11 GPI.

The Terminators you have from Carbon Express are too weak for your set-up. You could have a recipe for disaster if you shoot them at 70 pounds. The are intended for lower poundage much like the number printed on them (45 lbs to 60 lbs if you will). They weight around 9.5 GPI.

Just a best guess, I would say if you shoot the BH 5000 ACAs w/ 100 grain tips and you have a 30" draw you are probably going to get 240-250 fps from them, if you have a 28" draw, you'll probably be a few fps slower.

Good Luck

Reloader

Thank-you for the info