Rotational Flight... Energy Lost?

[BT]

Jan 1, 2009 10:42:41 GMT -5 smj said:

My take is simple: If the arrow is flexing at impact, I say that the flex in the shaft will become greater. - but the dynamic action is the same with or without the hand. This is why folks say stiffer shafts penetrate better - they give up less energy to the sides. A sharper tip goes in with less impact back up the shaft to cause deviations, hence better penetration. An arrow that is angled to one side at impact will want to bend over and slap the animal with the fletching

This is what happens when you do not have flat arrow travel.
This happened about three hours after I pointed out that the arrow was traveling nock high out of the bow.

The shot was at 45 degree's downward.

[Buckshot06]

BT I didn't think of that as well . If I can find correct blazer vanes for the test I will try it. I am still surprized at the 3/4+" difference with this setup. Like you said if I can find the correct vanes the difference would be even greater .

[BT]

Since you are doing this testing (thank you!) should I throw some 1.5" Blazers in an envelope (for the four fletch) and send them to you?.
If so....PM me your mailing address

[firenock]

To throw something a LOT more interesting in the group. Firenock's Aerovane II. It is about the same weight as a blazer. 5.9 grain compare to 6.05 grain. Now, added a few factors that I have found totally change the concept of arrow flight.
1) rotational lift
2) surface drag (vane to air friction)
3) delta vortex (angle of attack of vane to air turbulence on the leading edge)
4) 1st and 2nd stage turbulence after the air clear the vane
5) minimize back pressure vacuum (backward force as arrow moves through still air)
6) creation of micro turbulence to minimize back pressure
7) structure rigidity to better guide air (as air speed goes higher, the air flow management is significant as feather is not meant to handle of 95 fps, know of any bird flying faster than 80 mph while new bow we have flies over 250fps/238 mph)
8) reduce surface to air drag by using concave surface and decrease pressure to surface drag (lift pressure)
9) reduce energy lost via sound
10) ultra thin pyramid design to reduce harmonic vibration
I know this is a lot to sink in, I am also trying to take all this in too.

What I am trying to say, is imagine an arrow that actually flies with the air instead of against it. To give a good example. Same arrow with duravane 4" at 2 degree helical compare to Aerovane (not aerovaneII) at 25mph cross wind, at 20 yard, aerovane is 3/4" while duravane is over 4.5"out of a 260 fps bow with 420 grain arrow!

Picture of aerovane and aerovane II below
Aeorvane weighs 11.3 grains

[BT]

The Aerovane's stated construction (on the shaft) replicates what I have been doing with the four fletch ( to minimize drag ) but.... it employees rotation while minimizing drag.
Then, the Aerovane takes it one step further by eliminating drag on the vane itself.

This is why I said that I was anxious to try this new vane from Firenock

[BT]

But are we getting off topic?....MAYBE?
I never had a question about the effective differences between straight and offset/helical....I knew that one.
The question was ( I THINK ;D ) does rotation of the shaft have a negative on impact....which I contend that it does.

Not that I am complaining!! (don't get me wrong)....very good work being done here in regard to education!!.

I think that SMJ and I are on the same wave length in terms of rotational effect on impact and that we are agreed as to the detriment to performance that the majority of the bowhunting public lives with.

I think that what we need to do is to first find out if we are increasing penetration due to velocity gains or friction loss gains.
So...we have to chrono the arrows and then (after finding the difference) slowing the faster arrow without effecting rotation.
At that point, then we will know absolutely what effect the rotational drag losses are based on solely the rotation.

Everyone runs toward performance in terms of what the manufacturer can produce and then robs those gains away by the way they design and tune that very bow.
My contention has always been that the vast majority of bowhunters/archers do not know the wealth of performance gains losses out there and therefore they are always under performing.

Threads like this can be ignored (or) used to benefit.
Most people are not willing to reconsider what they think they know

This is such a typical thread here at the A/E....no shouting, pissing and moaning or name calling....just learning and teaching.

Great input everyone!....outstanding critical thinking on display

[BT]

Jan 1, 2009 12:05:19 GMT -5 Buckshot06 said:

BT I didn't think of that as well . If I can find correct blazer vanes for the test I will try it. I am still surprized at the 3/4+" difference with this setup. Like you said if I can find the correct vanes the difference would be even greater .

In the mail tomorrow.
Do you have a chrono?.
If not, I will do the speed differential effects with mine

[BT]

Jan 1, 2009 11:57:27 GMT -5 Buckshot06 said:

I did go and shoot the NIGHTMARES and ThunderHeads. The results was the same at 20 yardswith the four vanes out penetrating the three vanes by 3/4+" every time. Sorry no pics this time my batteries went dead in the camera.
Now SPIKER has me thinking on what the penetration difference would be out to 40 yards .

I doubt that you will see any significant performance changes at the distance.
Very possibly, you will see the 3 vane either same or increased in comparison.
At 30 yards....you should still see the 4 fletch having a distinct edge.

[royden]

excellent thread guys!!

I agree smj - downrange velocity needs to be the same for any theories to be drawn when looking at penetration loss due to rotation.


I used/tested the four razyr feather's last summer during the 3-d shoot and liked them. Impact was higher than vanetec 4" 3/offset 1deg by probably 6" at 40 yards. tight groups even out to 90-95 yards with field points. Soooooo.... I took some of both antelope hunting and planned to keep my shots less than 50 yards. Well, I got one chance at 40 yards with a side/quartering to me wind: I think with more fletch control my shot would have been good, but as it was I missed. It was a poor decision on my part to use the razyrs; but they had done well shooting broadheads out to 50 yards in the yard (and we have no wind here). It has been my practice to go out in the field and shoot in the wind before the season ... but I didn't.

I still need to test dorge's vanes - and his new mini vanes also (those look more promising to me)

Oh yeh BT, you can beat up on my thoughts all you want

[BT]

Jan 1, 2009 20:41:38 GMT -5 royden said:

excellent thread guys!!

I agree smj - downrange velocity needs to be the same for any theories to be drawn when looking at penetration loss due to rotation.

Thats gonna be very hard to do and thats why (at times) questions to be answered must be answered based on the physics rather than actual physical evidence.

I know how to do it and I can do it but it is going to require a days time and a day that makes me want to spend the time
( no cold and snow is what I think I am getting at ;D )