ha ha, Vaalserberg (meaning "the mountain of Vaals, berg=mountain, Vaals is a dutch village") we share with two other countries - Germany and Belgium.

Recoil is certainly an issue because it determines with how much force and how long the rifle interacts with the body during the shot. With F-TR however there is not much choice in calibers.

The reason I won that f-class match in the Netherlands was, apart for the rifle,  because I was quite able in attaining the proper "zero position" and a consistent butt plate contact and head pressure, as well as the same (firm) grip.The result of small bore rifle shooting.   And, because of the ballistic calculations I knew wat max wind deflection would be.

More than a MoA penalty will be the result of not taking care of these things.

in the beginning bfc_c had an additional paramerter h for height. I dropped it because I thought it would be easier and accurater to measure the pressure and humidity at the shooting range. Is this theory from somebody living at +1 meter, the highest point in the area?

... we are curious ...

Ian,

with bfx_u you can also modify the units of the gyroscopic drift calculations. eg =bfx_u(outputunit, gyroscopic drift, "in")

You have them now fixed to inches.

I have added bfx_ax(distance, heigth) to calculate the angle e.g. =bfx_ax("moa";100;"yd";3;"in")
The gettingstarted workbook is adapted.

you can download the new addins.

I was't happy with my own match. I shot a mere 567 of 600. 30 shots with small bore, 30 with a big bore, both at 100m indoor, iron sights, shooting jacket. I am still puzzled how that could happen - a too busy week, causing a dimnished sharpness? My friend shot 585 - that is better.

Next week I'll shoot my service rifle - outdoors 100m, iron sight shooting jacket. Wind is no problem but the light is.

Thanks for putting some life in this forum!

After the match (60 shots; 100m small bore 30x and 30x big bore), this evening I will have a better look. With BfX_U you can use the unit also as input parameter - your ballistic calculator becomes unit independent.

Page on drag functions updated and given a more prominent place on the menu. The "physics graphic" will be worked on later, as soon as I have figured how to format texts in Mathematica nicely

Thx, I am flattered!

I saw your spreadsheet and found the formula =BfX_Zx("moa";$B$9;"fps";$B$12;"in";0;D5;"m";$B$13;"m";$B$10*BfX_C($B$5;$B$6;"inHg";$B$7/100);"g7")

In there you used BfX_C($B$5;$B$6;"inHg";$B$7/100)

This formula contains $B$7/100 because you expressed the humidity in %, for instance 50 and by default BfX_C expects a number from zero to 1. Hence you divided 50 by 100. However, I am not sure if you saw the "%H" qualifier that would have allowed you to write BfX_C($B$5;$B$6;"inHg";$B$7;"%H")

Robert.

Quote from: ThunderDownUnder on February 26, 2011, 04:42:53 AM
I'm looking forward to making up a range chart using these functions when you have the update available and checking them against Berger Bullets ballistic calculator. I guess if humidity does not make much difference then the existing functions should be very accurate already. I'll make up some tables and check! 

After the match, I will look!

I have updated bfx. BfX_C does now incorporate humidity. Furthermore the function BfX_AD has been added with which you can calculate air densities. Also, BfX can convert between more units - see BfX_help2.  The "getting started" spreadsheet shows it all.

In fact this is an early release, the getting started spreadsheet and the site will be worked upon further. Foremost it will discuss the effects of atmospheric conditions. Also a detailed comparision of BfX calculations with radar measurements on Lapua bullet trajectories will be made.

Indeed BfX_C is modified. I will put the update online immediately, then your weekend is still long enough to play with it.

Have also a look at gettingstarted. Furthermore look at bfx_ad.

I am in a hurry, one of the shooting friends is coming and we will go at a match at 10.00.

as a by product of my investigation of the atmospheric conditions for which various drag computations were done in the past I have constructed bfx_ad(temp, pressure, humidity) that computes air density and extended bfx_c to bfx_c(temperature, pressure, humidty). Formulas were taken from the article
"Revised formula for the density of moist air (CIPM-2007), A Picard1, R S Davis1, M Gl¨aser2 and K Fujii3, Metrologia 45 (2008) 149–155"

Release coming soon

I used several atmospheric density calculators on the net - they give different answers! It seemed that, in 2011, it is not clear how to compute the density of air! I know now also why people mention pressure, temperature and humidity and not density - it is not trivial to compute. I researched more and found an article called

"Revised formula for the density of moist air (CIPM-2007), Metrologia 45 (2008) 149–155"

I have a prototype implementation of it. Soon I will release a BfX function that calculates the air density and expand BfX_c to include humidity as an option. (humidity effects, however are very very small).

(CIPM = International Committee for Weights and Measures)

The calculations confirm the earlier calculations menitionned in this thread for the density for which Ingalls tables are valid, as well as its relative density to icao.

For BfX it was a day with improvements.

Now the calculation of drag based Pejsa's drag coeficients is also done at the standard ICAO pressure. I have used the opportunity - now that I know how Pejsa's drag function is based on Ingalls Mayevski's parametrizations of deacceleration - to introduce the Ingalss Mayevski drag function to BfX. Of course the associated drag is also calculated at ICAO conditions.

I have reproduced Ingalls table and will put the spreadsheet online soon. By doing so I found a bug in BfX_Xv (it didn't want to parse "fps") and repaired it. I encountered also a wrong conversion constant from inchHg to Pascals. Furthermore I introduced the PSI (pounds per square inch) to BfX.

These modifications had impact on the GettingStarted spreadsheet and hence I had to modify it a bit.

You can download the updates. Soon I will extend my site with a discussion on atmospheric conditions and drag calculations