Here's a free-to-all idea and its implementation: Measuring MV Without a Chrony

[Steve_in_NC]

http://www.network54.com/Forum/79537/message/1459269386/Update+on+the+%26quot%3BPoor+Man%27s+Chrony%26quot%3B 

I'm trying an experiment - my first attempt to use the free Excel-Online as a more convenient way to access shared math than C&Ping into Excel. 

If you'd like to try it, click on the link below, then click on "download" and open on your PC...

https://onedrive.live.com/redir?resid=B6690884CDBAEC95!184&authkey=!ALNWwS9cf8dyZdk&ithint=file%2cxlsx

...then enter your own data

 

[Rami939]

Thanks Steve for bringing this to all of us .

 

[Alan]

Well, you might get close, but no cigar. The fallacy here is, the BC changes during its flight path. And, the published BCs for most pellets are grossly over stated.

One hundred years ago, most bullet velocities were measured using a graphing pendulum. Some of those old devices still exist, and have been proven accurate within 1%. I'd bet the aforementioned method doesn't get within 10%, and may indeed be less accurate than that. 

 

[chasdicapua]

Thanks for offering that Steve

 

[Steve_in_NC]

"I’d bet the aforementioned method doesn’t get within 10%, and may indeed be less accurate than that. "

Alas, it's true. Perfection is ever an elusive goal. But meanwhile, better keep that money in your pocket.

"So : Actual mv was 880 fps for the FX Elite with JSB Kings. 
Steve's paper prediction is 887.48 fps. "

887.48/880 = +0.85%

http://www.network54.com/Forum/79537/message/1459310803/NC+Steve%27s+paper+muzzle+velocity++calculator+put+to+the+sword+...

 

[Steve_in_NC]

"Alan"Well, you might get close, but no cigar. The fallacy here is, the BC changes during its flight path. And, the published BCs for most pellets are grossly over stated.

By the way, if you're interested in the general topic of airgun pellet BC calculation (e.g., the algorithm that was "close" to being successful in the 100yard real-world test cited above), you might find this thread interesting...

http://airgunnation.dev/topic/backyard-bc-for-22-cal/#post-79451

 

[fe7565]

@Alan...as far as accuracy of the method. I wish I understood all the facets of Steve's posted test....as often when it comes to math and physics it take me some time through the fog of my brain to reach some clarity, but at the end...it is physics and match. So not much left for interpretation. My understanding based on prior posts on the Yellow on this subject, even if the BC is off or changes during flight/distance it will not affect the overall results significantly in this setup. 

If you plug in the same data in Chairgun at various distances (i.e. 50 and 100), you should get the same results as long as you use the same parameters. That part does not change. What is the hard part of this method is to setup and execute a real-life test scenario to can measure accurately the parameters involved and execute in such way that it can be reliably and repeatedly measured. And since Yrrah setup and documented the actual real-life test, I feel pretty confident with the results.

 

[Steve_in_NC]

A reminder...whenever a Point of Impact prints below the Point of Aim, enter the distance as a negative number. This user forgot that (his numbers are on the left), resulting in the #NUM! error messages. Adding the "-" to the "Y" value cured the problem (righthand column).