Archery Demonstrator

Archery Demonstrator

It’s closing on a year since I uploaded my last project.  This one is a rare project that combines all three of the themes of this site.

Several of my projects have used Processing.  It’s a quick and fun way to prototype projects, and it can grow to be pretty powerful before needing to move to another platform for production (if ever).  In the meantime, Open Processing has started, which is a web platform for Processing.  This has its trade-offs, but it lets other folks quickly get access to project there.  Which brings us to today’s project:

The Archery Demonstrator

What is it?

This is effectively an interactive illustration of some of the important realities affecting a tournament archer.  Yes, it’s a nifty toy.  And it’s pretty nerdy.  But that also describes most tournament archery equipment, so it’s fitting.

The purpose of this toy is to show how an archer needs to move their bow when the target changes distance and/or elevation, or when the bow changes its parameters.  The archer’s aim is automatically calculated — this isn’t an archery-shooting game (although, perhaps in the future…).

This can be a tool for learning or teaching these concepts.  I built it to remind myself of these concepts, because I’m a visual learner.

Hopefully you like it.  Or don’t like it.  Like most things on this site — this is for my own amusement or education.  If other people get something out of it — that’s cool, too.

What do the parts mean?

The screen shows an archer on a podium, and a target that can be moved.  If the target is moved to a place where the bow cannot hit it, the arrow path will draw the miss, and a big red message will be shown.

The blue straight line is the line-of-sight between the archer’s eye and the center of the target.

The red arc is the arrow’s path from the bow to the target.  This arc is affected by the target distance & height, and the bow power.

There is a tiny bow sight on the bow, and an aperture circle showing where the line-of-sight crosses it.  If the line-of-sight cannot be on the bow sight, the aperture will turn red.

On the lower-left is a zoomed-in bow sight scale, showing where the aperture would be.  So I don’t have to squint at the tiny version on the main drawing.  When the line-of-sight moves, both sight apertures move to where they would need to be so that the archer can look directly at the target.

Obviously, there are situations you can create here that are insane or impossible for real archery.  The archer is frequently looking through his front hand.  This isn’t meant to be that accurate.  After all, the archer isn’t really even meeting the modern dress code…

How to use it?

There are only three things you can change.  And that’s plenty.

The Target.  On the bottom-right of the target is a green circle.  You can click-drag that green circle to move the target.  If you stop your drag while the green circle is off the screen, then you can’t move the target anymore.  Sorry.  You’ll have to reset the toy. (Move your mouse to the top-center of the site.  OpenProcessing has a swirly arrow button that will reset it.)

Bow Power.  In the top-left corner, there is a green slider you can click in to change the bow power from 1-99.  This isn’t mapped to any real world settings like limb poundage or arrow weight.  It generically means “arrow leaves the bow going slow/med/fast”.  1 is crazy slow. 99 is a railgun rifle.  70 acts like a tournament compound.  45 acts a bit like a tournament recurve bow.

Sight Bar extension distance.  In the top-left is a grey/gray slider you can click to change the sight bar extension distance from -50 to +50.  Only -25 to +25 are reasonable distances.  Beyond that is too extreme for real archery, but it can be useful to see why certain concepts happen.  Setting this to zero puts it exactly on the bow itself.

That’s it.  Nothing else you do will change it.  Well, I suppose it matters what size you make the web browser window.  Some parts try to adjust to the web page size.  Some parts don’t.  I wrote it using half a laptop screen, or the whole laptop screen.  Other sizes may break things.  Sorry.

Why to use it?

There are three main insights that you can see from this demonstrator:

  1. Higher bow power flattens out the path of the arrow.  And lower bow power causes the arrow path to arc higher.
  2. The further the bow sight is away from the archer, the narrower the range of distances is that the sight will have a valid setting for.  Pulling the sight closer to the archer will let the sight work on a wider range of distances.  Try some sight bar settings for close/medium/far, and try moving the target close and far.  The sight runs out of room much earlier when it’s far in front of the bow.  (This is easiest to see with a lower poundage bow — around 30)
  3. (This one is subtle).  Most of the time, the arrow path will cross the line-of-sight.  (Ideally, they -always- intersect at the target…).  But when the bow is medium-strong or higher, and the target is very close, the arrow path will not cross the eye line.  When the target is closer than this “crossover point”, the setting on the sight necessary to hit the target will correlate in an opposite way to the way it correlates when the target is beyond the crossover point.  Usually, for a longer distance shot, the sight aperture needs to be lower.  But when the bow is closer than this crossover point, the opposite happens — the aperture needs to be lower for a shorter distance.  This is due to a number of factors, but it is critical to be aware of for the tournament formats that include very short distance shots.
    To see this, set the bow power to 75 and the sight bar to 25.  Then move the target from the right side of the window to the left side, while keeping the elevation of the target as consistent as you can (it works well with the target at eye level or waist level).  You will see the giant aperture on the lower left move up to around “B” on the sight scale, then move back down the scale again.  If you look at the red and blue lines, you will see the real crossover point, where the red arc only touches the blue line, but doesn’t cross it anymore.
    (For low-poundage bows, this crossover point is very close (a few inches), so it’s never going to affect the archer.  )


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