The Hunt for Performance & Penetration

[smj]

Feb 22, 2009 22:15:21 GMT -5 voodoofire1 said:

"the recurve adds more pre-draw tension. This gives higher energy, which can give a faster arrow"......Ummmm, that doesn't sound quite right to me, let me explain........ yes there is added tension, as you have to bend the limbs farther to connect the string than you do on a longbow, that creates tension, but not neccessarily the additional power needed for faster arrow speeds because of the thin limbs, what does create the power are the recurve tips.. .

Peace!

Withouth getting into limb dynamics, my point was just that there is typically higher preload. Which is often seen as starting at a more favorable point, energy wise. Recurved tips can create power, but if to much mass is left on them - it don't work out so good! Ultimately, it is all about having a great design.

Recurve - I found this to be interesting...

www.archery-engineering.co.za/conversions/forcedrawcurve.htm

They have a lot of rather interesting reads - find the list here:
www.archery-engineering.co.za/entrance.htm

And - here is my point, taken from yet another web site - adding in recurve/hybred to the longbow gets the highest energy - based on early draw performance -
www.acsbows.com/storedenergy.html

[voodoofire1]

I agree! peace!..Thanks for posting those links, I had never seen them before, I was just going by my own experiences in testing numerous bows, glad to see we're on the same page.

[BT]

Nice

[BT]

So anyway, I was hitting the mark very well with the Sitka shafts (with the 300grn. heads) and flight was Great.
But then I decided to try the 250grn. heads and to be honest, the flight was better.
Better than perfect?!...apparently so or at least the eye is telling me that.

So since I was drawing into the riser anyway and was planning on cutting up some more shafts which would be longer, I decided to go up to the Grizzly sticks and see what would happen.
As Ed always suggests, I started longer than I wanted (29") and then after seeing where the weakness in the shaft was, cut another 2" off and reattached the 300grn. head.
Awesome!....just as good as the others....maybe better....hard to tell.
Now I have a 700grn. arrow (grizzly w/Ashby) that is 12& FOC and a 800grn. that is 18% FOC (sitka stuffed with a Grizzly head)
When the weather permits, I will get out and set up a pail for each and see which combo gives me the best penetration.

[voodoofire1]

Ok I'm confused,or maybe just dense......... Are you testing these with and for the Mamba? and if so, would that be around 61#'s at 25"? and about the only problem I see is the bucket, if you don't hit each arrow exactly dead center of the curvature(90*), your results will be skewed.. how are you dealing with that?

[BT]

Feb 25, 2009 7:40:46 GMT -5 voodoofire1 said:

Ok I'm confused,or maybe just dense......... Are you testing these with and for the Mamba? and if so, would that be around 61#'s at 25"?

I scaled it at 64# yesterday.

about the only problem I see is the bucket, if you don't hit each arrow exactly dead center of the curvature(90*), your results will be skewed.. how are you dealing with that?

Thats what I did when I got to the end of the bucket test last time.
Before that I ended the first round by bridging the apex as close as I could get it ...which was pretty darn close.
If I missed to by too much I would have to lay the bucket on a flat, measure the distance of each hole and then add/subtract that variable.
Since the water is a minimal drag difference for a miss by one inch and the plastic gauge remains constant, it wouldn't matter beyond that unless we are cat whiskers away and then the results would be irrelevant to the modifications which produced those close results.
In other words...if it's that close why be bothered?.

[pastorfarley]

If your buckets are tight lay them on the side and shot at the lids, no curvature and longer arrow travel to the bottom.

[BT]

You right, but there is little give and that makes penetration easier and drag on the shaft lesser due to the lack of rebound on the stiffer ends.

[BT]

So here is what I have seen a few times since working with this set up....
The 2.75/1 Ratio head is showing signs of (potentially) being an issue as pertains to damages to the arrow on some impacts.
What I have seen would result in near Zero penetration were it to happen on bone)
This has only showed itself during glancing impacts that come from quartering shots.
The Alaska shafts that I am currently using are extremely tough and until now, I have not yet had occasion to break one on impact.
However, I have broken the inserts out of three to date and all occurred on impacts as outlined above.

I could not envision this being an potential issue on soft bone. However, bone which does not succumb easily to impact (such as the scapula) could have a more menacing effect.
Provided the broadheads tip is capable of acting as a skid stop, this would be unlikely to occur.
However, on a hard quartering shot, with the broadheads forward point entering ahead of the scapula's high center ridge, impact with that area (and lacking such a forward point) could easily result in similar damages to the arrow.

My experience tells me that a chisel tip would be a very poor choice in such an instance whereas a Trocar tip or such (which carries a 360 same surface point of contact) would be superior and defeat deflection.
As bow speed drops or rises, so does the odds of having such an incidence occur.
The ration of the broadhead also relates to the extent of abuse that the shaft that houses the insert will receive on such an impact.
As the ratio increases or decrease, so does the amount of force it can exert (while being pinch levered) on the shaft.
While the Alaska is unquestionable strong...a 2.75 chisel tip head may just be too much for it....as is the case with most shafts.
At some point (as speed increases) the ability for break out to occur would near impossible against a whitetail scapula...but for the speeds of a recurve, no such speed exists.

[voodoofire1]

Hey!....... put some feet on them arras BT, no carbon arrow is strong at the ends......and still smoke free I see.....