What's legal

[Aarleks]

Jim and others,
Of the various excellent features that one can print from Accurate Sights, what is allowed on the field course in competition? Are they all allowed?

[Flame]

only the normal target sight settings

no gauging or incline measurements

[Aarleks]

I had a quick look at the rules and didn't see much.

Flame, so no "Slopes" printout?

[toxic_rabbit]

I am a born-again Triples-with-pins shooter.
:D

till the pins start eating your bank balance again :lol:

[Flame]

I had a quick look at the rules and didn't see much.

Flame, so no "Slopes" printout?

NOPE


You are permitted to have just one set of sight marks plus the manufacturer's scale on the sight bar.
You are permitted to carry a set of written sight markings, a rule book, but not a set of settings for shooting up and down hills.
The "turnover" is where your sight starts to go down again as you go closer to the target (due to parallax). It will usually be about 10 to 12 Metres.
When you are shooting up or down hills, you (just about always) have to put your sight higher on the sight bar. Usually this means that your sight is effectively set to a shorter distance, and this is what Accurate Sights shows. However, if in having your sight higher on the sight bar it would be higher that the setting for the turnover distance, Accurate Sights cannot say "set your sight to a distance of X" because there are no sight markings abover the turnover setting. Instead, what I have done is to tell you how many millimetres above the turnover setting to set it, and Accurate Sights puts a minus sign in front of the number to indicate this. So, a setting of "-0.2" would mean set your sight 0.2 mm above the turnover mark.
For estimating distances, we use the amount of the target covered by the diameter of our sight ring, and this is also shown in Accurate Sights.

[Aarleks]

Thanks.

[coach]

O.K i,ve watched this thread for awhile and i have a question, Why do we need a computer program to "sight in our bow"? Wouldn,t it be better to do it for real? :o
I know, that was two questions! :D

[Flame]

You only need to get your 20 and 70 metre settings and the program will work out the rest

By doing only 2 you can make sure these are right. There could be a variation in your shooting technique doing all the distances and could give you false readings

it works well :D

[Kuru]

Coach, how AS works is you get say your 10 meter setting and then get a 70 meter setting, measure the distance and a few other things and the program gives you all your in between settings. It does other things as well but thats the barebones of it :D

[coach]

Wouldn,t it still be better to do it "for real" For form and practise?
And how "accurate" is it ?

[coach]

Nothing beats going and doing it!!! :o

[Kuru]

Saves a hell of alot of time and gives you exact settings for every meter so it's a life saver when shooting a hunter round

[DrRalph]

You only need to get your 20 and 70 metre settings and the program will work out the rest


Jim, why only two points for the fit? 3 points would determine the parabola (albeit a shallow one) more accurately, and presumably get a better estimate of the flight speeds, drag etc. Can you add say the 90m setting, get a better drag estimate and fit a quadratic?

[Rodger]

Jim, why only two points for the fit? 3 points would determine the parabola (albeit a shallow one) more accurately, and presumably get a better estimate of the flight speeds, drag etc. Can you add say the 90m setting, get a better drag estimate and fit a quadratic?

I just get 3 sight settings and plot them in excel. That works fine. ;)

But what if the speed of the bow was known? The curve could be worked out then?

Rodg

[DrRalph]

Yes,

There are two ways to do sight settings. One is purely empirical, you measure a bunch of sight settings, and interpolate the rest on the curve.

The other is to get a couple of points, to work out the angles/geometry and put in a flight model for the arrow flight. The you can work out uphill and downhill sight settings as well - all from a few level sight tests. I'd still prefer to fit more than just two points on the level before I extrapolated to other elevations, especially for long distances. But then most field and 3D stuff is all short range, and with high speed compounds the flight path isn't exactly complicated :)

[Juggs]

one benefit coach
is that it only takes3 or 4 ends at two distances and
you have pretty acurate settings.

where to get sights for every distance would take hours.

[Mark]

I have to agree with Juggs. As an AS user and someone with not that much time to spare between shoots, if I make a change to my setup II can grab a couple of sights and shoot any round when I show up late to a shoot. Always proven accurate at calculated settings.

One feature I have used is the tuning section to help with an arrow/rest contact issue. More to this app than just getting your sights.

Mark

[Archangel]

Jim, why only two points for the fit? 3 points would determine the parabola (albeit a shallow one) more accurately, and presumably get a better estimate of the flight speeds, drag etc. Can you add say the 90m setting, get a better drag estimate and fit a quadratic?

Well for a start.... it's not a parabola, since it curves back at close range. So you'd have to use a cubic and hence 4 points.
Of course, it's not one of those either, since there's a significant drag factor, and the curving back is a strange phenomenon at close range.

And the program isn't using just two points - it's got a bunch of other information about your eye>sight distance etc. So it can happily work out a complex curve by it's arcane methods - which is why we pay for it!

[James Park]

I agree with Archangel.
In addition: by using two points plus the various physical measurements I can much better avoid data entry errors from the user. If I let archers input three sight settings and they make a mistake in one of them we can get a situation where the data is impossible (things like negative drag, etc) which would then crash the calculations. The way I have done it is relatively immune from such things and will get a useable sight tape even when the archer makes gross errors in the data, so long as the sight gap is correct.

[Joe]

Dr Ralph Wrote:
Jim, why only two points for the fit? 3 points would determine the parabola (albeit a shallow one) more accurately,

Agree in principle but not in practice. Sight marks whether directly measured or estimated are only nominal values. Actual sight marks on the day will depend on environmental conditions etc. so no point in trying for high accuracy.

[Archangel]

Agree in principle but not in practice. Sight marks whether directly measured or estimated are only nominal values. Actual sight marks on the day will depend on environmental conditions etc. so no point in trying for high accuracy.

Fair enough, but you do need a fair amount of accuracy to use the right curve - the alteration on the day is generally fairly constant. Plus there's potentially a lot of extrapolation going on - if you use marks from say 20 & 40m then your 60m mark is going to be pretty sensitive to error.

[Joe]

if you use marks from say 20 & 40m then your 60m mark is going to be pretty sensitive to error.

Of course - don't think any pin tape vendor would recommend calibrating with 10 and 12 metre data points and then hope to be remotely close at 90m.

[Archangel]

Of course - don't think any pin tape vendor would recommend calibrating with 10 and 12 metre data points and then hope to be remotely close at 90m.

Lol! That'd be a little optimistic I think!
But I think the example I gave would be doable, if not terribly accurate. Some degree of extrapolation is okay, just so long as you don't carry it too far.

[James Park]

Agree in principle but not in practice. Sight marks whether directly measured or estimated are only nominal values. Actual sight marks on the day will depend on environmental conditions etc. so no point in trying for high accuracy.
I think accurate sight markings are quite important. For example, say you make 1/2 mm error in your 60M mark (which many archers certainly do when drawing them on a tape by hand), with the sight pin 750mm out from the peep you will get 0.5*60/0.75 = 40mm error on the target, which puts your group on the edge of the 5 ring of a FITA Field target. This is way too much error for my liking, and will almost certainly ensure you do not win a big tournament.
Similarly, I very definitely want to be in the 10 for the first shot at a new distance in a target round.
I find that my sight makings are quite stable, changing very little, if at all, from month to month.

[2Dogs]

I find my markings change quite often.

This is due to buying a new bow.......release.......arrows......sight......... .. every month :wink:

[Kuru]

Once a month :o and you call yourself a whore :roll: gotta change something at least every two weeks :lol:

[Clare Barnes]

This is due to buying a new bow.......release.......arrows......sight......... .. every month :wink:

So you're slowing down at last I gather? :roll:

[Flame]

Similarly, I very definitely want to be in the 10 for the first shot at a new distance in a target round.
I find that my sight makings are quite stable, changing very little, if at all, from month to month.

Agree with Jim

get the initial settings right and you don't have to worry about it again.

works well

[2Dogs]

I suppose a sight setting for Flame would consist of six "HITS" at 30m.......WhhoooHOOOO!...(AS Homer would say) :wink: :lol:

[Flame]

Shows its working then 2Mogs :D

[DrRalph]

Well for a start.... it's not a parabola, since it curves back at close range!

Neglecting the close range parallax error, my sight setting curve is almost a straight line, and it extremely well fit by a shallow parabola. Good from 70m down to 20m. At 90 I change my sight bar setting anyway. Drag matters of course, but the outcome in the end is very close to quadratic, just not the one you expect from ballistics in a vacuum. This works extremely well on a level target range.

I am however interested in the modelling approach for non-level shooting, ie field. I have a simulator I made to test the altitude effect (to include air viscosity and density changes with temperature and pressure) , but I'd like to have a go at this sight game and see if it comes close. But it means converting to actual archer coordinates....

Questions:
1) Initial height of the arrow - I presume this is the height of the tip from the ground at full draw, or is it the center of gravity, or is it the nock, which at least doesn't change with elevation.
2) x= 0? Again, if 50cm makes a difference in a long shot, where do you measure zero from? Nock, CG, tip?
3) Angles. The length from the eye to the sight pin, or the nock to the sight pin? I am assuming the nock is the pivot point, but then I need to know the nock to eye distance accurately? or not?
4) Sigh bars are generally flat, except for the copper john, I assume there is a sin(theta) correction, esp for larger angles with the slower recurve shots.

I'm hoping a lot comes out of the wash with measuring the two sight marks, but when I started to look at using my own program to try this game there seems to be some work to covert a simple initial condition of x= 0 theta = angle, v = v0 into an actual archer. ;) I think I'll be happier too with a least squares parabolic fit to three marks at 20, 50 and 70m, to get the gaps/angles etc. This can help to warn of any accidental errors, and it'll be good to compared to a two mark test.

[James Park]

I think I'll be happier too with a least squares parabolic fit to three marks at 20, 50 and 70m, to get the gaps/angles etc. This can help to warn of any accidental errors, and it'll be good to compared to a two mark test.
Dr Ralph,
When I first wrote my program I used three distances (typically 20M, 40M, 70M).
Then, I used the three distance settings to calculate both the arrow velocity and the drag, and then from those the rest of the sight settings.
The problem is that I found that archers simply did not measure the three sight settings sufficiently accurately and they then got crazy answers for the various parameters. I also found that the nature of the problems that this gives was not comprehendable to the majority of users (they typically did not recognise the nature of things like negative drags and velocities that were unreasonable).
I have found it much more reliable for the program to calculate the drag from first principles and then to use the sight gap to calculate the arrow velocity. Then, all the archer has to do is to get two accurate sight settings, use the program to print a sight tape and then check the printed settings on the range. In general, with this arrangement archers can make gross input data errors and still end up with quite useable sight tapes (so long as they get the sight gap correct, and this is easy to verify from the print out).

[2Dogs]

try this game there seems to be some work to covert a simple initial condition of x= 0 theta = angle, v = v0 into an actual archer. I think I'll be happier too with a least squares parabolic fit to three marks at 20, 50 and 70m, to get the gaps/angles etc. This can help to warn of any accidental errors, and it'll be good to compared to a two mark test.


I think you need to SHOOT more if you want to beat Arleks :wink:

[Flame]

You are a wicked man :D

[Aarleks]

8)

[DrRalph]

I think you need to SHOOT more if you want to beat Arleks :wink:

Nice one 2D. :) I need to beat him in my mind too!

Jim,

My test with Rodger as the archer went very well. I put in the speed measured from the 10m sound test, put in his arrow parameters (length, diameter, fletches), then used his 30m and 70m sight marks to calibrate the sight against the angles for the optimum model shots. By shooting three virtual shots around an initial estimate and interpolating the best shot angle and testing it, the code reproduced Rodger's level ground sight settings very well indeed, all the way a long from 20 - 90m

Now I just need to get it onto a palm pilot :)

We'll do some elevation tests when we get the chance.

See you Sunday Aarleks if you are coming to the ANZAC day shoot. I'm looking for some more shooting tips :)