FOC

[M.Hogan]

Was reading an issue of primative archer and it had an article on FOC.
Just wondering who bothers with FOC...and how important it is.

[DylanK]

I think you will find that most archers who know their stuff will aim for a certain FOC, just depends on what the individual wants.

[ed]

I use about 15% FOC and would rather have an overly heavy arrow and adjust for the trajectory than have a lighter arrow without the FOC

[M.Hogan]

Yer, the article said that arrows should be in the 10-15% range...with the higher 15% having better penertration and straighter flight.

[Coach]

I use a FOC of 23% . This came about because I had arrows that were too stiff and I had to add weight to the front to soften the spine . In doing that ,I found that they worked great . It also added weight to my overall arrow weight which needed to be done . I will never go back to the old recommendation of 10% FOC .

So , as you can see , a heavy FOC can help in fixing stiff arrows , add weight to the overall arrow , which helps in penetration while hunting . It also helped my accuracy as the arrow flew much better .
I have heard it being described as such ,, Imagine a piece of string with a pea tied to the front ,, try throwing that piece of string and you will see it doesnt fly very well . Now tie that same piece of string to a fishing sinker and see how well that piece of string flies , following the sinker . It will be much better
As in anything , there is an optimum point where it will fly well and after that , there will be a loss in performance . It is up to you to experiment to find out what works best for YOU .

[M.Hogan]

Coach, do you find the arrows drop rapidly after a certain distance, with that much FOC???

[Coach]

I wouldnt say that they drop a lot because of the FOC , but more due to the overall weight . You could have a really light arrow with a high FOC that would not drop a lot at longer distances due to the overall weight .

[M.Hogan]

Those arrows must pack a punch. whats there weight???

[Coach]

630 grains

[Stickbow Hunter]

Yes FOC is important for proper arrow flight.
Jeff

[Bill]

I found this and it may be of interest to those that would like to know a little bit more than just, Forward of Centre "FOC".

An arrow has to have a point that is made of material with a high density eg..metal, iron, flint or bone, as compared to the actual arrow weight, a nock which fits onto the bow string, and fletchings that will add drag at the rear of the arrow.

An arrow has a centre of mass (centre of gravity or balance point that is forward of the actual measured centre) and a centre of drag. The centre of drag MUST be behind the centre of mass, and the further behind the better, otherwise the arrow will be inherently unstable in flight. Indeed, if the centre of drag is in front of the centre of mass the arrow will have a tendency to turn round and fly "backwards".

Large fletchings and a heavy pile will increase the distance between the centre of mass and the centre of drag and make the arrow fly better, but sometimes at the expense of cast (arrow speed). So again, here is the trade off.

For a given mass of arrow + pile, a lower mass shaft will increase the distance between the centre of mass and the centre of drag.

I hope this has been of some help in understanding FOC

[Glenn]

9%-10% foc was a standard we all accepted but I have found over the years that for hunting I much prefer to have 20% and even more foc, my penetration on pigs has gone way up, I wish I had of known about heavy foc when I first started bowhunting. I shoot arrow weights of 14-16 grains per pound as well, over all results are much better...Glenn...

[longbowinfected]

I noticed the effct of the impact on plastic 3D targets when using 600 grain arrows with a 49# bow......it physically jolted and moved the target and penetrated better into the self healing material....so what Jeff and Glenn says makes sense to my simple mind.

Kevin

[GrahameA]

Morning Kevin

A rhetorical question. Is the effect you are noticing on 3D Targets due to the change in FOC or the change in Arrow Mass? I would suggest the latter.

[Glenn]

No doubt Grahame the extra mass helps a lot but not having the foc in the right spot will hinder arrow penetration. The further back towards the centre the balance point is on the shaft the more arrow weight that is coming through at the point of impact and the more the arrow will buckle on impact reducing penetration. Years ago I used heavy mass arrows and never paid much attention to foc and had average results but since I woke up to foc I have had fantastic results with penetration, infact some of it is unbelieveable. This is why I will always question peoples views on bow poundage for the game they hunt...Glenn...

[GrahameA]

Morning Glenn

No doubt Grahame the extra mass helps a lot but not having the foc in the right spot will hinder arrow penetration.

Yep.

Will have a chat tomorrow - looking forward to seeing you.

[Glenn]

Grahame, something has come up with my family now and I can't go to the shoot on Saturday but I will come early on Sunday to catch up with people...Glenn...

[Blinkybill]

This is all very interesting. Thanks for bringing it up, M.Hogan!
Does anyone have any links to any articles that deal with FOC?
Thanks,

Ben

[TomMcDonald]

There are lots here:
http://tradgang.com/cgi-bin/ultimatebb. ... forum;f=24

[clinton miller]

bill and glenn hit the nail on the head.
it is a myth that 10-15% is best, the laws of physics says so! the perfect arrow would have it's entire mass in the point and the shaft would weigh nothing, though that's not possible. more FOC the better. however i have found that arrows of high foc to be affected more by a crosswind than lower foc models. they don't drift as far off target but the tail end "sways" in the wind more because of what bill stated.
at what point crosswinds nulify the gains in penetration gained by EFOC by making the arrow fly slightly sideways, i don't know.

it is also a myth that EFOC arrows "nose dive". two physically identical arrows of the same mass but having the mass distributed differently will drop at the same rate.

[Len]

The proof is in the pudding, just read Dr Ashby's findings on arrow penatration v buffs and you'll want higher foc.

[Blinkybill]

Thanks for the link, Tom.

Ben

[TomMcDonald]

No worries Ben.
Yup, the higher FOC I go, the better my arrows are flying. I think I'm on about 27% but I feel it's the most I need to go for now.

[Troy D. Breeding]

New to the site and while lurking through the threads I found this one.

I've been working with Dr. Ed for the past several months, his and my findings of arrow flight with EFOC and UEFOC arrows will blow your mind.

Currently my hunting arrows have a UEFOC of 33.46%

I've managed to achieve 37.2% with one test arrow and wish I had found this setup before hunting season started.

I'll be helping Ed in late Jan. with his siminar he will be giving at the Kalamazoo, MI (USA) Trad Expo.

Hopefully by then I'll have a setup with 40% or more UEFOC.

Troy

[kimall]

Yer Troy Ed is a great bloke I probed his brain over lunch a few years ago and the real life experience he has was awsome.How are you getting such a high FOC mabey you could give us the list of the bits that make up your arrows.
Cheers KIM

[Macca]

Troy welcome, that is some serious weight up front. Keep us updated with the various studies that are in progress with you and the doc.

Cheers Macca.

[Troy D. Breeding]

I've known Ed for several years. When he was promoting the heavy weight shaft theory I worked with him on that. As a matter of fact I used to manufacture Hickory shafting. Ed used them in alot of his studies.

Super high FOC isn't hard to get.

1.) Carbon shafts are the only way to get this
2.) Use the lightest grain per inch shaft you can find
3.) Start with a full length shaft and bareshaft tune
4.) Use brass inserts and glue-on fieldpoints with steel adpters to produce heavier point weights.
5.) Do all your shaft trimming from the rear of the shaft.

Once you have the bare shaft shooting straight and clean it only takes a small fletch to guide the arrow.

My current setup uses a 190gr Grizzly single bevel broadhead set on a 125gr steel broadhead adpt. My inserts are the 100gr brass type and I also use an exterinal footing made from a 3" piece of 2117 aluminium shaft. This helps prevent the shaft from splitting if I hit something hard like heavy bone. The shaft I use is a Victory V Force HV 300. These shafts only weigh 6.9GPI. I finish all my shafts with three 3" fletching.

I've been making afew super heavy broadhead adpts from 250gr fieldpoints. I just ordered some of the 300gr fieldpoints in hopes of making a 275gr adpt.

Joe Furlong of Tuffhead Broadheads sent me some of his 225gr fieldpoints to see if I can up my point weight even futher.

The fieldpoint alone on the test arrow that had the 37.2% FOC weighed 454grs.

Troy

[kimall]

I am finding it hard with my set up shooting 350 CX Heritage shafts cut to my 29 inches I can only put about 225 grains up front before they spine too soft.What shaft are you useing to get them that stiff.
Cheers KIM

[Stickbow Hunter]

Very interesting information. I have followed Ed's studies since way back in the late 1980's when no American magazine would dare print his study findings (for fear of upsetting their broadhead advertisers). I got onto it via a friend in Canada who sent it to me and it was in the form of a hand typed document - I still have it filed away here. I got to meet Ed some years ago now when I was delivering a bow to him; very nice fella with HUGE hands.

I will never achieve such high FOC figures as I shoot woods.

The fieldpoint alone on the test arrow that had the 37.2% FOC weighed 454grs.

How do you measure your arrow to get your FOC figures?

I believe Ed uses the AMO method and I have never understood why he does this as it DOES NOT give you the FOC of the arrow; it just gives a false FOC percentage figure.

I say this because the AMO method measures the arrow length as that being ONLY to the back of the point and completely disregards how far the point sticks out past that. For example; if you use a 190 gr field point and a 190 gr Grizzly broadhead on two otherwise identical arrows the two WOULD NOT balance at the same point and therefore their FOC figures WOULD be different!!! Yet when using the AMO method the FOC figure would be said to be the same I believe which is just not right.

Jeff

[kimall]

Yer Jeff you just reminded me about his hands they are like a huge bunch of bananas that just swallow your hand when you shake it.So happy to talk about his studies though and answer questions I am sure he had been asked a million times.He even helped Maggie with her shooting a bit and told her he would take her fox hunting one day and she still remembers that even though she was very little.
Cheers KIM