I'm making a trajectory app. Assistance please...

[dcliff]

Hi Guys,

 

OK, so I'm currently making a free trajectory app for iPhone and Android - first up, this is not an advert! I won't even mention it's name (not sure about the forums rules on that but let's play safe, yeah)

 

I'm billing it as "the most simple trajectory app on the internet" and it's looking pretty sweet so far...

 

Anyway, I'm just after a bit of help with calibration.

 

Can I ask anyone who has a VERY FIRM understanding of their own rifle trajectory and velocity to give me some figures... Any calibre.. air rifle to .308 - it doesn't matter. Although air rifle figure would be very useful. Specifically .22 can be very sensitive.

 

In particular:

 

Velocity (not packet claim, observed if possible)

Your zero range. and

Hold over / under figures you are SURE about either side of the zero range.

 

Honestly guys that would be a real help...! The app will be free but I can credit anyone with assistance on the website if you want! We've done A LOT of maths on this. And I've tested it on a .17 .308 and .22/250.

 

Thanks in advance.

[Billy.]

The combinations are just too many. Download Ballistic Advanced Edition and you'll see what a fully kitted App is like and the complexities of it. The catalogue that guy has pulled together is immense and covers pretty much every calibre I can throw at it.

 

I'm really not knocking the idea, but a bit of data here and a bit of data there is not much to go on. You're missing barrel lengths, bullet weights, powder weight, OAL measurements, scope height, shooting angle, wind.... - to name but a few.

 

The world of ballistics calculations is a precise thing and I personally would avoid a cheap and cheerful means of getting the answer, especially if it's built on the data of what some people shoot on their setup.

Edited March 27, 2014 by Billy.

[dcliff]

Hi Billy,

 

I think you've missed the point slightly - the app has been built - its the User Experience thats the simple part (I'm a designer) Not the maths behind it, which is brutally complex. I know what I'm doing with it :-)

 

And, I don't want to correlate my app against another calculator.

 

The type of response I'm looking for is:

 

"Yeah i've got a .22 rimfire shooting 1034fps cos I crono'd it. Zeroed at 60yds its does XX at 40yds and XX at 100yds"

 

No one needs to know what I'm doing with that data other than it's very useful to me :-)

[Billy.]

 

OK, so I'm currently making

 

 

the app has been built

 

That was quick.

 

 

Right, so you're just looking to check the numbers match the real world.

 

So if my .270 is shooting inch high at 100 yards, chrono checks out at 3600fps, what good are those figures to you if you don't know the bullet weight, ammo or load spec?

[seeker]

FWIW ... 6.5,123gn bullet @2745 (av.chrono over 1st 6 shots) and 3 shots at each distance.

with 200m zero = +6cm @ 100m, 0 @ 200m, -9.5" to -10.5" @ 300m

sorry about mixed units ... That's how I jotted them down (I was having a play with a new scope after setting it up).

[dcliff]

FWIW ... 6.5,123gn bullet @2745 (av.chrono over 1st 6 shots) and 3 shots at each distance.

with 200m zero = +6cm @ 100m, 0 @ 200m, -9.5" to -10.5" @ 300m

sorry about mixed units ... That's how I jotted them down (I was having a play with a new scope after setting it up).

 

Thanks - good response.

[dcliff]

Anyone else got any data...?

 

Just FYI you don't need to know bullet weight, barrel length, ammo, powder load, scope type or wind for a linear ballistic calculation.

 

Just muzzle velocity and zero range.

 

You might get slightly different values if you do take into account the bullet's cross sectional density, but I'm ignoring that for this app and I'm using a one size fits all drag figure. The difference is so minute no human could ever shoot that accurately to tell.

 

This app is all about simplicity - And it for people who like simplicity.

[dcliff]

So if my .270 is shooting inch high at 100 yards, chrono checks out at 3600fps, what good are those figures to you if you don't know the bullet weight, ammo or load spec?

 

Those figure are no good even if i DID know the weight, ammo, load... What I'd like, if possible, and I appreciate people are doing me a favour here, is those figures combined with a POI at say 60yds and 200yds.

 

Bullet weight, load spec and ammo (brand?) are irrelevant for this calculation.

[seeker]

you might get more volume data from the specialist rifle accuracy sites ... 6mmbr in the US .. uk varminting ... etc or one of the airgun sites?

might help to list the exact info in a table form?

[dcliff]

you might get more volume data from the specialist rifle accuracy sites ... 6mmbr in the US .. uk varminting ... etc or one of the airgun sites?

might help to list the exact info in a table form?

 

Good plan, thanks. I'm only a member of this forum so it was my default starting point! Thanks tho I'll try them.

[dcliff]

I really can't see how this is going to assist you, if you ask people for their real world data AND they actually send it to you it will be enormous volumes of data to process and correlate. Saying that, I'm not really sure what you are trying to offer as there are countless ballistic solutions out there already with relevance to all levels of experience and multiple operating platforms. Anything much simpler is pretty much `data on the back of an ammo` box from the manufacturer. You are opening a can of worms to those who believe a 1 degree temperature shift is there cause of a miss on a 75 yard rabbit and those who think it is easy to shoot a 400 yard rabbit as their trajectory is `flat`. Still, its your life.

 

I can see how you might think it's useless data. Realistically it's very useful and not an enormous volume of data - so far I've had one response containing three figures! 10 more of them and I'm happy.. that's not huge volumes and very easy for me to process.

 

Also, you have to understand, I'm not calibrating the app with these figures, I'm just checking to see if our mathematical formula works in the real world. I've checked it with my guns and so for all is correct. We're only using muzzle velocity and zero range remember, and approximating everything else as it's negligible. Because of this, I'd really like to see if that throws any problems.

 

As I've already mentioned, the SIMPLE part of this is the user experience - that is, how it looks and how you use it. There are countless calculators out there, correct. Mine offers different and more simple operation WHILE ALSO being mathematically accurate.

 

I suppose if you get chance to download it you'd understand. It's not a table or chart. It's not a re-skined Hawke BRC device. It's a slider, crosshairs and output figure.

 

I wasn't going to do this - as it's in development mode and requires tweaking, but this is what it looks like, currently: http://cloud.cliffdesign.co.uk/Ugyv

 

Still, this is great feedback. If the shooting community (you guys) don't "get" it. Then I'll pack it in!

 

80% of this post is to test peoples' reaction to it.

[dcliff]

1 degree temperature shift is there cause of a miss on a 75 yard rabbit - trajectory is `flat`

 

Oh, and I forgot to touch on these bit... You do not enter a temperature figure in this app

 

And to the guy who thinks their trajectory is flat: Any calculator shows that.. it isn't - not just mine!

[dcliff]

My point is being very wary of information given by shooters who often misunderstand the concepts involved.

 

Ahh OK - good point. I know that can happen and can filter it out! This stage isn't crucial to development... merely intriguing.

[rtaylor]

Personally I commend what you are doing. I could see it being quite a useful app. It would be pretty simple to check it against your rifle by taking a few test shots and where it is in relation to the app.

 

It's all well and good saying you need to cover every possible variation but when in the field how do you know there isn't a breath of wind 75 yards away even though it's still where you are? There are too many unknown variations in the field to make any major difference in an app that it misses it a few.

 

I doubt people who shoot 1000yard shots will download an app which doesn't cover everything they (think) they need to know.

 

There is a problem with this forum or maybe people in general which they instantly feel they need to put people down for trying to do something or ask for help/advice. I'm sorry I don't have a crono so can't really help with your figures.

[dcliff]

Personally I commend what you are doing. I could see it being quite a useful app. It would be pretty simple to check it against your rifle by taking a few test shots and where it is in relation to the app.

 

It's all well and good saying you need to cover every possible variation but when in the field how do you know there isn't a breath of wind 75 yards away even though it's still where you are? There are too many unknown variations in the field to make any major difference in an app that it misses it a few.

 

I doubt people who shoot 1000yard shots will download an app which doesn't cover everything they (think) they need to know.

 

There is a problem with this forum or maybe people in general which they instantly feel they need to put people down for trying to do something or ask for help/advice. I'm sorry I don't have a crono so can't really help with your figures.

 

Thanks :-)

 

I suppose the best thing to do would be to ask people why this is a BAD idea... In fact, I'll do that.

 

PEOPLE: Tell me why this is a bad idea?

 

FYI: This app doesn't do wind. Just trajectory. It's not intended to be a field aid for that 1000yd bunny. Just a quick and easy to use reference point.