Print Tapes based upon gathered data - not calculated..? [Archive] - Archery Forum

James Park

09-11-2002, 05:40 AM

Ian,
Yes, in Accurate Sights I do predict the shape of that curve from the geometry and the arrow ballistics, and I do assume that the target is at the same height as the release device. Accurate Sights does provide the amount to allow when you are shooting up or down hill, but you need to make that change for each target as the sight tape shows the settings for the target at release device height. The problem as I see it is that those very short targets can be at severe angles both up and down hill (I have shot at some that were so steep up hill that you had difficulty getting up to the target).
When I originally wrote Accurate Sights I did ask for more than two settings as input data and did a best match to those settings, however my experience was that archers were not able to get three or four settings of sufficient accuracy for the maths to work well. For example, the sight gap from 20-30 Metres will always be less than the sight gap from 40-50 Metres, but I found that archers would want to input data that was inconsistent with that. What I needed to do was then make judgements about where they had made errors and try to predict how best to fit the physics to poor data, and it was just not accurate enough. Hence I went to the system you now see.
Note that for distances less than the turnover the settings change very rapidly (the j curve is very steep). This means that the setting you mark for a particular distance depends very critically on knowing exactly what that distance is. If you are slightly out in the distance (say you think it is 6 Metres but it is actually 6.5 Metres) you will get the setting wrong by quite a bit. It is for this reason that I suggest that in selecting the two distances to use as input data you should have your short distance just a little longer than the turnover distance - I use 15 Metres. This ensures that even if you get the distance to the target slightly in error your setting will still be very good. It is sufficiently tolerant of errors here that when I use 15 Metres I do not bother to measure it - I just go to "about 15 Metres" to get that setting. For the long distance I generally use 70 Metres, and I am careful to stand at exactly that distance.