Spin
05-18-2004, 05:20 PM
#6
Thread Starter
Join Date: Sep 2003
Location:
Posts: 83
RE: Spin
After putting 4inch vanes on my arrows (straight) replacing the 4 in offset vanes speed went up big-time. After thinking about how the spin works on an arrow I do not think you need it. IMO. As far as I can tell the spin just gives the arrow tail drag, and does not work like a bullet because of the slow speeds of an arrow. A bullet spins so it will not tumble, and speed increases but an arrow spins it slows down because of the drag?
Please answer why this happens.
Also the bow is tuned good.
Please answer why this happens.
Also the bow is tuned good.
05-18-2004, 07:11 PM
#7
Typical Buck
Join Date: Mar 2004
Location: Norwalk, CT
Posts: 599
RE: Spin
The guy at my local shop, the way he explained it was that you dont need a helical but if your going to shoot fixed blade broadheads it best to just offset the fletching a couple degrees. Not alot but just enough to get it to go around once or twice. His thinking is this gives a little more drag but more importantly the broadhead will have less of a tendency to plane.
I cant say the guys an expert, although he certainly thinks he is, but I'll say I value his opinion. I'm thickheaded & usually dont listen right away if I think I already know what I'm doing.
Anyhow, I cant say how many times I ended up listning to him after many frustrating hours trying to make myself right.
In my very limited testing of straight & offset it seems that broad heads are easier to control with offset fletching & the offset seems a bit more forgiving regardless of point type.
I had some arrows that came with a right helical 5" vane installed & they grouped about the same as the offset fletched arrows but seemed to be a bit noisier & I couldnt get them thru my rest reliably.
They now wear offset 4" feathers, against the local shops advice but I like feathers on my arrows.[8D]
I cant say the guys an expert, although he certainly thinks he is, but I'll say I value his opinion. I'm thickheaded & usually dont listen right away if I think I already know what I'm doing.
Anyhow, I cant say how many times I ended up listning to him after many frustrating hours trying to make myself right.In my very limited testing of straight & offset it seems that broad heads are easier to control with offset fletching & the offset seems a bit more forgiving regardless of point type.
I had some arrows that came with a right helical 5" vane installed & they grouped about the same as the offset fletched arrows but seemed to be a bit noisier & I couldnt get them thru my rest reliably.
They now wear offset 4" feathers, against the local shops advice but I like feathers on my arrows.[8D]
05-18-2004, 10:12 PM
#8
Boone & Crockett
Join Date: Feb 2003
Posts: 10,679
RE: Spin
The more helical the fletch the quicker the arrow will be stabilized after it leaves the bow and the longer it will remain stable in flight. A long object will not be stable in the air unless there is something providing that stability be it spin or drag. A straight fletch arrow has only drag and very little of it since the fletching is making a straight "slice" through the air. A helical fletch arrow has more drag as well as the benefit of the gyroscopic effect of the spin created by the helical fletch.
When you add wings (broadhead) to the front of the arrow those blades tend to steer the arrow and the fletching has less control over the arrows flight. If the fletching is straight it allows the arrow to veer off course more before the fletching has sufficent drag to straighten out the arrow and overcome the effects of the broadhead. With a helical fletched arrow the fletching always has more control over the arrow than the broadhead does and it is much much harder for the broadhead to steer the arrow off course.
This in an extreme example but you will see the point.
Take an arrow with no fletching and shoot it at 30 yards. It will begin to tumble before it hith the target. Now take an arrow with helical fletch and see how straight it enters the target.
Another test you can do is to take a bow and set it up so that it has a heavy right or left tear in paper. Get someone else to shoot the bow and you watch the arrow go downrange. I will bet you dollars to doughnuts that the helical fletched arrow will recover much faster from the fishtailing than the straight fletched arrow will. You will probably have better groups with the helical fletched arrow than the straight flecthed arrow.
When you add wings (broadhead) to the front of the arrow those blades tend to steer the arrow and the fletching has less control over the arrows flight. If the fletching is straight it allows the arrow to veer off course more before the fletching has sufficent drag to straighten out the arrow and overcome the effects of the broadhead. With a helical fletched arrow the fletching always has more control over the arrow than the broadhead does and it is much much harder for the broadhead to steer the arrow off course.
This in an extreme example but you will see the point.
Take an arrow with no fletching and shoot it at 30 yards. It will begin to tumble before it hith the target. Now take an arrow with helical fletch and see how straight it enters the target.
Another test you can do is to take a bow and set it up so that it has a heavy right or left tear in paper. Get someone else to shoot the bow and you watch the arrow go downrange. I will bet you dollars to doughnuts that the helical fletched arrow will recover much faster from the fishtailing than the straight fletched arrow will. You will probably have better groups with the helical fletched arrow than the straight flecthed arrow.
