Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Chronograph question
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Engineering101" data-source="post: 1321244" data-attributes="member: 63138"><p>DartonJager</p><p> </p><p>Ballistics Guy is sort of correct but not entirely. I designed and built my own Magneto Speed style chrono including 25,000 lines of assembly language programming and I've used an optical chrono for many years until I upgraded to the Lab Radar so I know a few things about chronos. The 8-bit processors referenced by BG don't effect accuracy but the clock rate at which they run sure does as this determines the error in responding to the optical inputs. In my chrono I used a 100 MHz clock (10 ns clock period) to minimize that error.</p><p> </p><p>Enough background - about your question, it is pretty easy to calculate the effect of misalignment on chrono error with some simple math. If your chrono is not aligned with the bullet path, the bullet has to travel further between sensors than the physical length of the chrono. So anything that causes such a misalignment be it static (you set it up crooked) or dynamic (the wind blew it momentarily crooked) will cause the chrono to read slow. A chrono can never read fast due to misalignment since it reads fastest when it is perfectly aligned and you can't get any more aligned than perfect. It takes about 10 degrees of misalignment in both pitch and yaw to make a 3,000 fps bullet read as a 2,900 fps bullet. The roll axis has no effect. Ten degrees is a lot of misalignment and is pretty easily spotted with the naked eye however 100 fps is a pretty big error so smaller errors would not be seen with the naked eye which is why I always used a laser bore sighter to align my rifles to my optical chrono. Bottom line - any misalignment will result in a slow reading no matter what caused the misalignment.</p></blockquote><p></p>
[QUOTE="Engineering101, post: 1321244, member: 63138"] DartonJager Ballistics Guy is sort of correct but not entirely. I designed and built my own Magneto Speed style chrono including 25,000 lines of assembly language programming and I've used an optical chrono for many years until I upgraded to the Lab Radar so I know a few things about chronos. The 8-bit processors referenced by BG don't effect accuracy but the clock rate at which they run sure does as this determines the error in responding to the optical inputs. In my chrono I used a 100 MHz clock (10 ns clock period) to minimize that error. Enough background - about your question, it is pretty easy to calculate the effect of misalignment on chrono error with some simple math. If your chrono is not aligned with the bullet path, the bullet has to travel further between sensors than the physical length of the chrono. So anything that causes such a misalignment be it static (you set it up crooked) or dynamic (the wind blew it momentarily crooked) will cause the chrono to read slow. A chrono can never read fast due to misalignment since it reads fastest when it is perfectly aligned and you can't get any more aligned than perfect. It takes about 10 degrees of misalignment in both pitch and yaw to make a 3,000 fps bullet read as a 2,900 fps bullet. The roll axis has no effect. Ten degrees is a lot of misalignment and is pretty easily spotted with the naked eye however 100 fps is a pretty big error so smaller errors would not be seen with the naked eye which is why I always used a laser bore sighter to align my rifles to my optical chrono. Bottom line - any misalignment will result in a slow reading no matter what caused the misalignment. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Chronograph question
Top