Range Report BP, Station Presure and Elevation

[3gunF1guy]

I am going shooting at a range that is at 6800 feet. the airport closest to it is at 5951.
The airport data for bp is only in corected pressure(30.25) I want to know what the formula is to convert it to station pressure. Then I can figure the altitude adjustment for the range. I just need the altitude convertion factor to get back to station presure.

Scott

 

[ChadTRG42]

Re: BP, Station Presure and Elevation

Calling Lindy!!!

 

[Rafael]

Re: BP, Station Presure and Elevation

If what you are calling "corrected pressure" is really "sea level corrected pressure", then all you have to do is use that pressure as though it is from sea level(which is what it is corrected to act like)....and use your current altitude as the other variable.

30.25 and 6800'.

If you have station pressure.... then you use that pressure and the altitude differential between the station and you.
If you have sea level corrected pressure you use that and your altitude.

 

[Lindy]

Re: BP, Station Presure and Elevation

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">If you have sea level corrected pressure you use that and your altitude.</div></div>

That's what you get from an airport.

(Actually, not quite - what you get is a pressure which, when set in the Kollsman window of an altimeter, will cause the altimeter to read the official elevation of the airfield. Which is pretty much the same thing.)

I'm assuming that he's going to be putting this data into a ballistic program, so he needs to tell the program that the pressure is corrected to sea level, and then, as you indicate, enter his actual altitude.

That's not quite as accurate as entering the station pressure from a Kestrel or similar instrument, but it's close enough.

 

[Rafael]

Re: BP, Station Presure and Elevation

Thanks for clarifying, Lindy.
I am certainly no susbstitute for you.

FWIW...I read through one of your articles before answering the OP.
Thanks for making those available to all of us!

 

[Lindy]

Re: BP, Station Presure and Elevation

My pleasure!

 

[3gunF1guy]

Re: BP, Station Presure and Elevation

The reason I'm asking is that I always like the set the Ballistics Program to a zero elevation and read off the kestral what the bp is(station Pressure). So if I know what the station pressure is then I can adjust for my elevation change.

Scott

 

[Lindy]

Re: BP, Station Presure and Elevation

If you haven't read this, you might find it of interest: Barometric Pressure and Ballistic Software.

 

[ReaperDriver]

Re: BP, Station Presure and Elevation

Not to hijack - but I just wanted to say thanks again to Lindy for all the help in explaining station pressure and sea lvl pressure and how to use it. I got a chance to today to input station pressure right off of a friend's kestrel while doing some 1000 and 1300 yd shooting this morning. Using the correct station pressure and other variables and inputing into Ballistic FTE - I finally got the program to actually give me good settings. On a new load that I've never shot at 1K before, I had the mil settings dead on in the verticle on the 1st cold bore shot and only had a miss due to wind. 2nd shot was on after a good spotter call. From 400 out to 1300 yds today, the Ballistic FTE was very accurate and usually withing a tenth or two mils using the Kestrel data.

 

[3gunF1guy]

Re: BP, Station Presure and Elevation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">If you haven't read this, you might find it of interest: Barometric Pressure and Ballistic Software.
</div></div>

Yes I have, that is why I almost always use station pressure with a zero altitude. I guesse I'll just have to do it the other way this time.

Scott

 

[rmfield]

Re: BP, Station Presure and Elevation

Scott, I don't know if this helps, but here is a table that lets you use corrected station pressure to convert actual altitude to pressure altitude: