Author Topic: Ultra EFOC - How? (Read 2431 times)

Ragnarok Forge · « **Reply #20 on:** October 31, 2009, 09:03:00 PM »

Ok, from what I can read on the web GT Ultralights have 7.4 gpi. With a 31 inch arrow, 300 grain tip, 125 grain insert, a 9 grain nock, and 4 - 2.25 inch fletchings at 9.6 grains with center of mass at 2.5 inches forward of the back of shaft for thde fletch I can hit 30% FOC on the head.

This will make an arrow that weighs 673 grains. This will crack the 650 grain bone breaking threshold and have what a few years ago would have been an insane FOC.

I am interested in finding out what shafts out there have a tapering shaft. I know about the Alaska Bowhunting Supply shafts and may look there for making something work to increase FOC. What other carbon shafts are available with a tapered shaft? Any?

I would prefer a shaft that is American made. The grizzly stiks are made in China.

2treks · « **Reply #21 on:** October 31, 2009, 09:15:00 PM »

Clay,ARROW DYNAMICS are made in Kansas if I am not mistaken. They have many options for shafts and we have more than a couple sposors on the gang that sell them. Raptor Archery is one and Badger Arrow is another.

Earl Jeff · « **Reply #22 on:** October 31, 2009, 09:17:00 PM »

Question: Clay will the GT Ultralights have enough spine to fly straight at that much FOC from say a 55 to 60# bow ?

artifaker1 · « **Reply #23 on:** October 31, 2009, 09:24:00 PM »

If you go around to wheel bow shops you can sometimes find the GTs with the flag on them. The only tapered that I know of are ACEs and maybe x10s which are very small and very spendy.
Lately I've been using Beman ICS and I've seen these arrows take some hits no others I have could. I don't think there that much heavier and last time I checked there made in Utah.
One has got to be careful about cheap arrows though as I've had some split at the noc on release from a very heavy setup with a fast heavyweight bow. It is very near a dry fire.

artifaker1 · « **Reply #24 on:** October 31, 2009, 09:29:00 PM »

Earl Jeff, I think they make GT ultralights all the way to 300s. Depends on how your riser is cut and how much weight you put up front.
Man I've gone thru a bunch of candy tonight! I'm going to run out. LOL

Ragnarok Forge · « **Reply #25 on:** October 31, 2009, 09:37:00 PM »

Earl,

Right now I do not know. From Dr Ashby's recent posts and some deductive reasoning, I think they will spine out stiff enough if I build my side plate up a fair amount. The questions is how much. I plan to try and see if they will spine stiff enough with the side plate build out. If I need a stiffer spine, then I plan to start fiddling with internal footings with 4 or 5 inches of the IF glued in place for stiffening.

If that fails then I will look to the Arrow Dynamics and see what I can do with them.

Right now it is all theoretical and field testing will be required to help determine the answers. I can say it is exceptionally helpful to have Dr. Ashby and the other experienced people posting and helping those of us new to the FOC game understand where to start and where to look for answers.

I can say they will not be stiff enough at all if I try and shoot them with my bow with it's 1/8 inch short of center cut out.

Earl Jeff · « **Reply #26 on:** October 31, 2009, 09:42:00 PM »

GT ultras 300 are 8.5gr per inch, 400 are 7.4

Ragnarok Forge · « **Reply #27 on:** October 31, 2009, 09:43:00 PM »

Two Tracks,

Who makes the Arrow Dynamics? Are they the arrows or the company?

Thanks

Earl Jeff · « **Reply #28 on:** October 31, 2009, 10:15:00 PM »

PSE X force 200 arrows are 7.5 gpi spine for 29" arrow is suppost to be good for up to 63#

Earl Jeff · « **Reply #29 on:** November 01, 2009, 12:16:00 AM »

checkout carbon express (line jammers) they are 7.6 gpi with a spine of .376 which means they should be good up to 70# with a 30" arrow. they are a little pricey but should be fantastic for EFOC setups.

onewhohasfun · « **Reply #30 on:** November 01, 2009, 04:23:00 AM »

Clay, Made up some 55/75 GT's and some AD trad lites, full lenght. 100 grn. brass, 275 tip. Both weighed same 742grn. with about 20% foc. To get 30% foc out of an AD I'm pretty sure you will end up way over 800 grn. Great shafts but hvy. to start with.

SlowBowke · « **Reply #31 on:** November 01, 2009, 05:33:00 AM »

Just for what it's worth. I picked up some Patriot carbon shafts. 45/60 spine, (.435)that are 6.98 PGI. I think Git-r-done is the only place I could find them and the website for the company is no longer there???

Ive heard some neg comments on them but still looking for some "trial" High Country (Pro?) shafts that are "up to 80 lbs" but am sure thats quoted with their also ultra light heads but the GPI is 5.5. I also don't know the deflection in inches.

They also are not cheap like some others mentioned and finding A FEW has proved impossible.

As yet Im not in the position to commit to even a half dozen of these. Unemployment stinks.

Ive two bow weights to shoot but curiousity has me wondering just what Ultra EFOC one could get with that GPI shaft.

The "alledged" brittleness reported by a few to me might dictate an IF would be needed and sooner or later Ill find a few to find out.

God bless.

2treks · « **Reply #32 on:** November 01, 2009, 08:02:00 AM »

The arrow dynamics(AD) shafts are the shafts and company. They make many size shafts that are all tapered. from very lite to the HAMMERHEAD That is already "FOOTED" from the factory. it is thicker and stronger by making it with more carbon on the busness end. I am not too savvy with all of this EFOC stuff but I wanted an AMERICAN made shaft and have had very good luck with the AD's for about 10-12 yrs. I shot them years ago and loved em then, took a brake from them but got into the heavy HAMMERHEADS this year and am well pleased. With very little thought and work I was well above 25% foc and remained under 800gn.(about 754gn). They are TUFF shafts. worth a look. Call Ted at Raptor or Paul at Badger Arrow. Ted had a large part in the developement of the HAMMERHEAD and is pretty up on all of the AD stuff.
P.S.
My HAMMERHEADS are cut to 31.25" from 100gn brass insert to nock throat. I mounted a 165gn ACE EXPRESS to a 100gn. steel adapter, added some lead shot and ended up with a 747gn arrow. and if I remember my foc was about 27.8%

vitalinvader · « **Reply #33 on:** November 01, 2009, 05:02:00 PM »

Dr. Ashby,
What about shat diameter, wouldn't you be better off with skinny Axis at 9 gpi than a fat shaft at 7.5 gpi?

Dr. Ed Ashby · « **Reply #34 on:** November 01, 2009, 08:08:00 PM »

Scott, when average penetrations are actually measured there's no difference in tissue penetration between a shaft that's 5% smaller than the broadhead's ferrule diameter and one that 25% smaller than the broadhead's ferrule diameter. In some materials, such as most foam targets, which are designed to stop arrows by shaft friction, the surface area of the shaft becomes very important in the penetration shown, with very skinny shafts out-penetrating shafts even slightly larger in diameter. That difference does not show up in the measured tissue penetration. Fresh tissues are a blood-suffused environment, with the blood acting as a lubricant, reducing the frictional coefficient.

As long as both shaft's have a daimeter at least 5% smaller than the broadhead's ferrule there will be no consistent, measurable difference in tissue penetration. On the other hand, the degree of FOC; once FOC reaches 19% or greater; has an enormous effect on measured tissue penetration, and the lighter the shaft, the easier it is to get higher amounts of FOC.

I hope I explained that clearly enough to be understandable.

Ed

vitalinvader · « **Reply #35 on:** November 01, 2009, 08:30:00 PM »

Ed, thanks for the explanation. I was thinking more along the line of splitting bone. I'm shooting 23% FOC now but would have to go to a larger diameter for more...bone really is my only concern with the bigger shaft. Any thoughts on bone hits?

Richie Nell · « **Reply #36 on:** November 01, 2009, 08:32:00 PM »

Dr. Ed....That makes perfect sense.

As I have mentioned before I am using the GT Big Game 100's at 10.6 gpi and .280 deflection. What arrow is available that is lighter per inch with a spine of .280 or less?

Earl Jeff · « **Reply #37 on:** November 01, 2009, 08:40:00 PM »

Hay guys I've been burning up the computer since yesterday the best weight to spine in a arrow I can find is the carbon express line jammers model 250 7.6gpi with a spine of 0.376 dia. is .386
http://dev.carbonexpressarrows.com/cms/content/linejammer

Ragnarok Forge · « **Reply #38 on:** November 01, 2009, 11:19:00 PM »

Ok, I have been crunching numbers, checking out arrow shafts and reading up on some things here on Trad Gang. Terry has some 29.5 inch Beman ICS 500 Bowhunter shafts at 7.3 gpi, with 350 grains up front and 4 -4 inch feather fletch that are pulling right at 29% FOC per his post.

Running this shaft for my 31 inch arrows gives me a 226.3 grain shaft, a 9 grain nock, 2-3 inch fletch and 2-2 inch fletch = 8.4 grains, 5 inch tape = 7 grains, 100 grain brass insert and 300 grain head gives me a 650.7 grain arrow with 28.77 EFOC. I am running out of options to crack the 30% UEFOC barrier with standard carbon shafts.

I will get a hold of Ted at Raptor. I may have to drive the hour he lives away from Vancouver, WA to chat with him on this. I am wondering what the lightest AD hammerhead shafts would weigh at 31 inches. I don't want to crack the 650 grain weight barrier for my arrows.

I am shooting 55 lbs and want to keep my arrow speed up as high as possible while finding my maximum FOC with a 160 FPS arrow. I am willing to drop to 150 fps but would prefer not to. I am also planning to fiddle around 8 strand strings this winter in the off season to pick up a little speed that I am loosing to extra arrow weight.

Richie Nell · « **Reply #39 on:** November 01, 2009, 11:39:00 PM »

Clay...If your arrow already bareshafts well with the 28% EFOC you should not need four feathers to stabilize it. If you cut back to 3-3 inch feathers that should increase FOC to maybe 29.??%.
It all depends on how well it flys without any feathers first. The already high FOC has alot to do with that arrow stabilization.


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Author Topic: Ultra EFOC - How? (Read 2431 times)

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