Shooting Machine - Arrow velocity - Projectile motion

[gfugal]

Alright yall. I want to share with you my final physics project for my class last semester. My goal was to estimate arrow velocity using 4 different methods: chronograph, projectile motion, sound, and electric currents. Here is a link to a PDF of the poster as well as a picture of it.

https://drive.google.com/file/d/1sIaLNSEvLRSLbt6De_aokzuEgE4tHIuZ/view?usp=drivesdk



For this project, I built a shooting machine so I could get more consistent and accurate results. Here's a picture of it.



Here's a youtube video that shows it in use, and gives you a little picture of how it works. (https://www.youtube.com/watch?v=O18ZtynJ2Do). I designed it so that it was adjustable so I can shoot it at -15°, 0°, 15°, 30°, and 45°.

The project was a continuation of an experiment I started a while ago. http://www.primitivearcher.com/smf/index.php/topic,59214.msg821468.html#msg821468.
Where I used this article (https://arxiv.org/ftp/arxiv/papers/1511/1511.02250.pdf) on pg 19 that sparked my interest.

[gfugal]

Pardon the fact that the bows on it aren't primitive wood bows  . I didn't have one with me at the time that would have been suitable.

[willie]

very cool project, I would like to read more, as I am working on a similar one.

will hold off on too many questions until I can read the poster better
the link does not open for me.

[Badger]

  Cool Project, are you just looking for different ways to record speed?

[gfugal]

very cool project, I would like to read more, as I am working on a similar one.

will hold off on too many questions until I can read the poster better
the link does not open for me.

Yeah, I noticed that it wasn't working. I'll try to fix that by the end of the day. The poster doesn't go into how I built the shooting machine if that's what you're wondering. If so we could just discuss it.

[willie]

The poster doesn't go into how I built the shooting machine if that's what you're wondering. If so we could just discuss it.

Actually , my machine is a bit more of a fixture for take town limbs. The different speed measuring methods are something I am looking into at present. Trying to find a way to measure arrow speed down range, so that I can compare to speed readings at the bow. Alan posted a link to a company that is selling an pricey radar solution in a thread in the flight bow forum. I think I have to wait until that product matures some more or the price comes down.

I won' t be online for the afternoon/evening, so hope to post later. Thanks for offering.

[gfugal]

  Cool Project, are you just looking for different ways to record speed?

Well, when I first got into archery I was frustrated by how expensive chronographs are. I used this physics project to convince the wife to get one since it was "a school supply" haha. But the idea behind this project is to offer alternative methods for people to determine their arrow velocity. 

[Badger]

  I wish I could find a way to measure the speed of a flight arrow as it came out of the bow and at about 30 yards. The only thing I have noticed is that if I can see the arrow it is not a good shot, if I can't see the arrow it is usually a good shot.

[gfugal]

  I wish I could find a way to measure the speed of a flight arrow as it came out of the bow and at about 30 yards. The only thing I have noticed is that if I can see the arrow it is not a good shot, if I can't see the arrow it is usually a good shot.

Yeah, the projectile equations I had to use were pretty complex if you take into consideration air drag, even then it's not completely accurate cause you have wind and the rod-like nature of the arrow and its fletchings which have such an impact on its trajectory. But still, I was able to get pretty close estimations from it. Regardless you are going to have to measure the distance the arrow went, so that method at least requires some way of measuring distance. I used a measuring wheel which was about $30 (1/3 the price of a chronograph). You technically don't need a shooting machine. There are imaging editing apps you can download for free that let you determine an angle in an image. So if you take a side view picture of the release you should be able to get the angle with that.

[willie]

I wish I could find a way to measure the speed of a flight arrow as it came out of the bow and at about 30 yards.

Steve, do you think that a reading at thirty yards is all you need? I wonder just how far out a good shot needs to stabilized by?

[gfugal]

I wish I could find a way to measure the speed of a flight arrow as it came out of the bow and at about 30 yards.

Steve, do you think that a reading at thirty yards is all you need? I wonder just how far out a good shot needs to stabilized by?

there should be a sweet spot. The longer it is in the air the more it can be messed with by the wind and stuff. Too short of a distance and minor errors in measuring that distance will result in big differences, plus the first several yards, before the fletchings stabilize the flight, are the most turbulent. The compound bow in the video shot at 160 fps. I put the shooting machine at 30° and it shot in the 160 yard range (or maybe it was meters I can't remember). I'm not sure where that sweet spot it is, but I'm guessing even 160 yards is overkill.

[BowEd]

That's a great project Greg.I would'nt mind having one of those around sometime.A friend of mine made one here and we found out because of the less friction release or trigger release that the machine shot a good 10 to 15 fps faster or more than finger realease.Depending on how well a person can release.

[gfugal]

I think the link for the poster should work now. Since it's formatted as a poster you will have to zoom in on a column to read it.

[Hawkdancer]

Greg,
Nifty shooting machine!  But what's that funny looking contraption on the end with wheels? Lol!  Sounds like a neat project, how did it score?
Hawkdancer

[Badger]

 With practice a human can outshoot the machine fairly easily.