Fletching info

[Kuru]

When filling out the info on AS do different fletches make a difference, ie spinwings, bi delta vanes as there only seems to be the length of fletch that you put in.

[James Park]

The type of fletching will make a (very) small difference to the drag. However, my testing has convinced me that we can ignore it (the sight gap largely deals with it anyway). Hence, all I use in the calculation is the fletch area. From the fletch length, I assume a fletch height to calculate the fletch area.
In fact, the largest contributor to the arrow's drag is actually the shaft surface area. The fletch contribution is a smaller component. Consequently, from the point-of-view of the drag, I do allow for some arrow shafts being barreled.
I have checked my drag calculations reasonably carefully by comparing the calculated with the measured flight distances, and they match very well (I did refine them just slightly after the flight competition earlier this year).
Similarly, any error in the calculated arrow weight will only have a tiny impact on the calculated sight settings (a small change in the weight makes a very small change to the drag as well).

[Kuru]

Thanks for the James, out of interest what brand of fletch are your calculations based on ?

[James Park]

Gareth,
I have made measurements of FlexFletch, PSE vanes and Easton vanes, and taken an average for all of these (they are all reasonably similar).

[mike]

The only thing I've noticed Jim is that spin wings are heaps lighter than normal vanes and so I have always had to enter them in as the smallest size so as to get the mass right. Perhaps if you had the time, adding spin wings as an option would be good.

[James Park]

Mike,
It is more important to get the fletch length correct than the arrow weight.
However, if you do wish to enter the exact correct weight, simply type a different weight in for the point weight.
Reason: the fletch length affects the arrow's drag more than the arrow's weight.

[James Park]

Mike,
You have prompted me to make a change to the program! I will change it so that (if you want to) you can type in the exact weight of the arrow. As noted above, you can do this by changing the point weight, but this ammendment will make it more obvious.