[c_m_shooter]

95 heat index 119 here in illinois too hot.everything expands and contracts in extremes. Would have to affect bows somehow.

Sounds like a nice cool spring day. Waiting for it to drop to that again.

 

[Beendare]

Lets add this to the subject
Pressure to push a 2 blade thru an elk hide-2#
Pressure on a chisel point and mech head-20# plus with the arrow buckling

 

[Grizz67]

Yeah but why didn't he show the scale on the last one?

 

[1oldbuck]

All those formulas and equations etc. in the first post were way over my head.
BUT...I completely agree with Dales demonstration. THAT I can wrap my head around and why I shoot Zwickey No Mercy two blades out of my lighter bow.

 

[Beendare]

More science;

I recently picked up the book, titled “Archery the technical side”

. It’s a compilation of scientific tests done on bow and arrow by the original rocket scientists, Goddard, whom the NASA space center is named for, CN Hickman and others. Hickman was inducted into the archery Hall of Fame for his incredible scientific testing and contributions to the sport of archery.

The Hickman test on Center of Gravity, what we call FOC now is enlightening. He found that and arrow with a COG range between 10%-16% was the most efficient. By most efficient, he means flew the furthest which would indicate the arrow that carries its energy the longest.

Hickman comments that the further he got away from that range, the arrows had bad flight to the point he cut the testing of these off.

He also tested fletching and other factors.
He had an ingenious arrow that had a moveable weight….so everything is exactly the same except FOC.

in this chart, the far left number corresponded to weight location, central number is distance the arrow flew- a good way of calculating efficiency.

Tests show a bell curve for efficiency….with 10.92%-16% FOC being the sweet spot and the further down the curve you go….arrow flight deteriorates- a lot.

Fascinating book that backs the Easton recommendations and disproves the current internet hacks pushing very high FOC.
[edited for accuracy]

 

[Grizz67]

Always heard 5% foc target. 10%foc hunting

 

[Beendare]

Always heard 5% foc target. 10%foc hunting

I’ve never heard of anyone shooting an foc of 5….about the lowest is 7%. ..but could be.

We see a wide range of what works ( Easton states 8-16%) …and it shows in Hickmans chart though he states he stopped the test in the high teens as arrow flight was visually degrading and distance seriously deteriorated So he threw those and the very low COG results out.

 

[Grizz67]

Some of the old guys at the club, way back when, when I started. Shot aluminum with little glue in nibb points

 

[Carboniac]

Always heard 5% foc target. 10%foc hunting

Why are you always the guy putting forth ideas that almost no one agrees with as if they are widely accepted?

 

[Grizz67]

Why are you always the guy putting forth ideas that almost no one agrees with as if they are widely accepted?

Tryin to straighten people out.

 

[Carboniac]

??????

 

[c_m_shooter]

Some of the old guys at the club, way back when, when I started. Shot aluminum with little glue in nibb points

Some still do.

 

[pipcount]

I like this idea! I have a couple degrees in Physics, so natural I would I suppose.

Re arrow FoC: It seems possible, perhaps even likely, that FOC values for optimized arrow flight/range may be different than FOC optimized for hunting/penetration. I have not considered, so have no opinion personally, and would be interested in what folks think. I shoot targets mostly, and in past have tried for as close to 10-12% as I can get without doing weird stuff. But I dont worry overmuch about it, rather shoot for simplicity in my portfolio of arrows vs. perfection.

 

[Grizz67]

Back in the 80s everybody wanted lighter and lighter arrows, now days everybody wants heavy arrows... It's just funny to me

 

[Beendare]

I like this idea! I have a couple degrees in Physics, so natural I would I suppose.

Re arrow FoC: It seems possible, perhaps even likely, that FOC values for optimized arrow flight/range may be different than FOC optimized for hunting/penetration.

I will try to copy the pages of scientific testing done by Hickson and Goddard. Those tests were essentially which % of center of gravity makes an arrow fly furthest.

This would indicate which arrow carries its energy the most efficiently. To me, that would seem to indicate its the arrow with the best penetration.

 

[Grizz67]

Think the broadhead has more to do with penetrat

 

[Grantmac]

I'd be interested to see which FOC has the lowest standard deviation for distance flown with a finger release. Because that will tell you things about how easy they are to shoot.
In my experience, even in competition, higher FOC (within reason) will be easier to shoot.

 

[KPinWI]

Calculus equations, my, oh my. Only 1 in 100 here knows what an integral is or can perform the calculation. Think 3rd grade math, that is what trad shooters can relate to, same with their writing. Follow the EASTON arrow recommendations, they only have been involved with arrow flight for years.

 

[DDD]

Some time ago I gave a factor for finding the front node based off the Arrows FOC. The finding the node is to fixed that point against the plunger for better flight.
DDD

 

[bowwild]

Interesting information. I had never heard of that "ideal" FOC before. I followed the first video pretty well with a bunch of concentration. It did remind me of some unpleasant times in HS calculus. Aced it in college, but as a wildlife biologist I never used it.

I had only recently heard folks talk about momentum before on this site in the past three weeks. Now I'm going to have to make it through the second video to understand then what is (if) the best measure of penetration from a physics rather than imperial standpoint.

It would seem to me though that if momentum was different in two arrows and they struck the opposing force at the same angle the one the would penetrate that opposing force (deer hide, muscle, and bone) better than the lesser? Now why it might may not be called "momentum" but something else revealed in a later video?

I will have to say I'm concerned a bit about my Iron Will Broadheads now though - broad blade (double bevel) vs. narrow blade. I have lots of Helix Broadheads (single bevel) I could use instead.