Slingshots Forum banner
1 - 20 of 56 Posts

·
Premium Member
Joined
·
7,905 Posts
Ok, here goes: my attempt at giving you all the info you need to get accurate, consistent readings from your Android smartphone chrony. Keep in mind, the app from ChronyConnect only works on Android phones. Sorry 'bout that but we're not going to have an "Apple vs Android" debate in this thread and all comments along those lines will be deleted.

Let's get the test envrionment set up first. You need a target that will make some pretty good noise when hit. A good thick piece of cardboard will work fine, a metal lid or somethinhg would work as well. You also need something to shoot through. This app is meant for airguns and needs that first "muzzle report" to time the shot and generate FPS numbers. I have a stand set up with a piece of newsprint to shoot through. It doesn't slow the shot down and makes enough of a "crack" to register. I stand right behind the paper and shoot through it into the target. Target and stand are 16' (192") apart.

Wood Packing materials Floor Flooring Gas


My phone is set on a tripod halfway between the newspaper and the target and as high up as I dare to set it. One of the measurements you'll need is "Device to pellet path", that's how close the ball will pass over the phone. It's about 6" in this case.

Camera accessory Amber Gadget Cameras & optics Font


On with it, then! FIrst thing's first, go to the Google Play store and search for Chrony Connect. Get the free version first and then go back for the paid one (like $3) if it works for you.

When you first open the app it will look like this:

Mobile phone Communication Device Portable communications device Telephony Gadget


Tap the "Menu" button indicated by my thumb in the pic and you will get this menu:

Mobile phone Mobile device Communication Device Gadget Gesture


This lets you set up all your distances and ammo weight (for power readings). Start with distance in the "Target Options" menu. Distances can be set in a variety of different units of measure, I'm using inches.

First up "Muzzle to target": 192"

Mobile phone Telephony Portable communications device Mobile device Telephone


Next is "Device to muzzle": 96"

Mobile phone Telephony Telephone Communication Device Portable communications device


Then, "Device to pellet path: 6"

Font Rectangle Gadget Display device Electronic device


After that you can go to the "Projectile Options" menu and input your ammo weight. This will give you stats for the energy in the shot in ft/lb. You can Google "steel bearing weight" for a chart, this pic has several sizes on it, as well. Weight can be in grains or grams, I'm using grams.

Handwriting Mobile phone Mobile device Communication Device Telephony


After your all set you take your shots (3 at a time for the free version), check and repeat :)

Mobile phone Telephony Portable communications device Mobile device Communication Device


If you have any more questions or if I've left anything out please don't hesitate to ask!

 

Attachments

·
Registered
Joined
·
303 Posts
Just beginning my renewed interests in slingshots and I was not going to get into this deeper technical aspects of chronograph speed measurements, however as a gadgeteer, tinkerer & DIY type, this looks intriguing & fun :)

So the muzzle measurement point is at the newspaper sheet, then you measure from sheet to target. Hmmmm, I do not trust my inconsistent marksmanship skills. Just in case, if I were to pursue this chrony adventure, I would maybe put some kind of quick & dirty cardboard or styrofoam shield around the smartphone to protect it, especially since I would be sort-of shooting blind through that box & newspaper sheet. Good tutorial, even a beginner can understand!
 

·
Member, Brotherhood of Slingshot Nutz
Joined
·
11,147 Posts
Thanks M_J. I don't have an android, but I think Henry said they have that app for the Ipod touch, which I do have. Even if this setup isn't real accurate, it's still a good way to compare different band/ammo combinations to see how much faster one ammo shoots over another.

Great video.
 

·
Super Moderator
Joined
·
5,278 Posts
Thanks M_J. I don't have an android, but I think Henry said they have that app for the Ipod touch, which I do have. Even if this setup isn't real accurate, it's still a good way to compare different band/ammo combinations to see how much faster one ammo shoots over another.

Great video.
Let me know how you make out with the iPod Touch app. I couldn't get consistent readings with mine.
 

·
Premium Member
Joined
·
7,905 Posts
Discussion Starter · #7 ·
Can someone try this please? Hold or tape a piece of paper on the fork,in the flight path.It may work and if so you will not be blind shooting may give confidence to some if it works.
You can make a stand for the paper that is much smaller than what I have and that you wouldn't have any trouble seeing around. I threw that together in a hurry to get the initial review and the tutorial up.
 

·
Registered
Joined
·
777 Posts
Can someone try this please? Hold or tape a piece of paper on the fork,in the flight path.It may work and if so you will not be blind shooting may give confidence to some if it works.
You can make a stand for the paper that is much smaller than what I have and that you wouldn't have any trouble seeing around. I threw that together in a hurry to get the initial review and the tutorial up.[/quote]
Yes of cause you can,thanks MJ BTW did you find the BC correct for 3/8 steel? Or will this have to be tweaked as more info comes in? Great job on this it will help many
 

·
Super Moderator
Joined
·
5,278 Posts
I just finished setting up step-by-step by your tutorial, and made enough shots to verify that the Android Chrono Connect app is accurate enough for membership in the SSF 300 Club. I may have been off a tiny bit in my setup because I did all the measurements alone. The Android was consistently a few fps faster than my Chrony by about 2%. Close enough!

Here's what my setup looks like. The sheet of paper attached to the Chrony rods is to generate a sound for the Android and the target is a cardboard box. The sheet of paper and the box are 192 inches (16 feet) apart. The phone is on the table half-way between the sheet and the target.

Plant Wood Window Flowerpot Grass
 

Attachments

·
Adirondack Kyle
Joined
·
1,018 Posts
Bill Hayes did a vid on the app as well, his first shot was right on!! The next two were a few fps off. The slap of the bands were loud enough for the app to pick it up , no paper, just have to use wood or something loud to set your target in front of.
I think it works better in an open area, also, i believe your phone quality has something to do with it. More sensitive the audio, the better.
As long as you calibrate the app every time you shoot, and measure your distances carefully, this app is very reliable.
 
G

·
The one observation I would make here is this. It seems to me that the phone could be anywhere along the path between the first target and the second target because sound travels at a constant velocity. What I am trying to say is that the sum of the sound travel time between the first shot and second shot is always equal to the sound travel time between the first target and second target. That would in fact be true even if the phone was not between the two targets. The reason I bring this up is that phones which get shot are probably going to quit working. You should test with the phone just behind and below the first (newspaper) target. I believe you will get the same accuracy that way. Also the distance below the pellet path will probably be more consistent if the phone is closer to the shooter. Just random thoughts.
 
G

·
The one observation I would make here is this. It seems to me that the phone could be anywhere along the path between the first target and the second target because sound travels at a constant velocity. What I am trying to say is that the sum of the sound travel time between the first shot and second shot is always equal to the sound travel time between the first target and second target. That would in fact be true even if the phone was not between the two targets. The reason I bring this up is that phones which get shot are probably going to quit working. You should test with the phone just behind and below the first (newspaper) target. I believe you will get the same accuracy that way. Also the distance below the pellet path will probably be more consistent if the phone is closer to the shooter. Just random thoughts.
In the above I should have said "the sum of the sound travel time between the first hit and second hit". The phone does not know where it is in the path. But it does need to know how far off the path it is because that changes the total length of the path the sound travels... I'm not explaining myself well =(
 
G

·
And yes, it will work better closer to the shooter, and, no need to shoot through something first like newspaper. The band slaps should set it off. Bill Hayes just did a vid on this.
Welp! That certainly beats shooting your phone or your chrony. I wish we had discovered this a week before instead of a week after I bought a new chrony =)
 

·
Adirondack Kyle
Joined
·
1,018 Posts
Sorry to re post too much, but i think that if you wanna test your bandsets, like me, or test diff types of ammo and elastics, then this is perfect, but i would understand if the forum wont allow them for speed badges, just for the fact that n order for it to be right on, your measurements have to be perfect, hard to verify, even a few steps to the side can throw your numbers off.
 

·
Premium Member
Joined
·
7,905 Posts
Discussion Starter · #19 ·
And yes, it will work better closer to the shooter, and, no need to shoot through something first like newspaper. The band slaps should set it off. Bill Hayes just did a vid on this.
I'm going to keep shooting through paper because I believe it cuts down on variables and gives a better chance at consistent readings. For one, the looped tubes I often use produce virtually no slap and for another, by the time the bands make that sound the ammo is already long gone.
Also, Henry has approved this app for the Speed Club :)
 

·
"Mighty Can Smiter"
Joined
·
4,250 Posts
Yeah the paper seems like you would get a consistant muzzle noise each time, not all of my set ups make band slaps, in fact, none of my butterfly shooting set ups make a band slap since I am afraid a set up that would would give the opportunity for a hand slap.

My wife is the one with the android, and I can't seem to find the apple app.. Henry?

LGD
 
1 - 20 of 56 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top