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Range Report iphone ballistic app that uses density altitude

distantfoe

Sergeant
Full Member
Minuteman
Mar 23, 2006
293
8
El Reno, Ok.
I've become extremely confident using density altitude and would like to have a iphone app that uses DA. After some research, I'm not 100% sure there's an app that uses souly temperature and DA, but hoping someone has an idea for me.
 
Re: iphone ballistic app that uses density altitude

Ballistics does... however with a computer there is really no point as it does the math for you using the Baro, Temp and Humidity anyway.

But Ballistics does you simply have to tell it in the settings under the General Tab.
 
Re: iphone ballistic app that uses density altitude

Barometer meaning station pressure not the local weather or altimeter pressure. Altitude = 0. Almost all the programs will allow you to enter the station pressure, temperature, and humidity. This is density altitude settings for a trajectory chart. DA sure is becoming popular.

http://www.crh.noaa.gov/bou/awebphp/definitions_pressure.php

What I did was find a chart like the one linked below that shows the average humidity and station pressure for my area over a period of decades. So, I keep station pressure at 26.28 and humidity at 37% and only key in the current temperature. But I have a Kestrel now so I might change the station pressure and humidity but I don't see any material difference.

http://www.wrcc.dri.edu/cgi-bin/clilcd.pl?nm23009

......

...

 
Re: iphone ballistic app that uses density altitude

I think I understand. So in FDE under atmospheric conditions, the following values apply??

enable atmoshere - should be on
altitude - set to 0
Barometric pressure - enter actual value
Pressure is absolute - should be on
Temperature - enter actual value
relative humidity - enter actual value

So this will duplicate DA calculations?
 
Re: iphone ballistic app that uses density altitude

You got it!

There are charts that show the typical station pressure based on 29.92 sea level pressure and altitude that can be used and calculators on the Internet that will convert the corrected (altimeter) pressure to station pressure for those that don't have a Kestrel and so forth.
 
Re: iphone ballistic app that uses density altitude

I assume you mean FTE. You have to go into settings and tell it to use DA.
Settings
Ballistic FTE
make sure simple mode is set to off
JBM Computor
Format = DA

Then you have to shut down JMB on your ipod or phone and restart it if you are on
a multi tasking ipod. Double click the home button. Touch the icon at the bottom until it wiggles. Touch the minus sign and it will shut down. If you don't do this your settings won't load. You now have to re enter your load using da.
 
Re: iphone ballistic app that uses density altitude

In DA mode will it still require barometric pressure, temperature, relative humidity? Also, enabled atmosphere set to on and pressure absolute set to on?
 
Re: iphone ballistic app that uses density altitude

DA is DA, you don't enter anything else.
 
Re: iphone ballistic app that uses density altitude

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigwheeler</div><div class="ubbcode-body"> I assume you mean FTE. You have to go into settings and tell it to use DA.
Settings
Ballistic FTE
make sure simple mode is set to off
JBM Computor
Format = DA

Then you have to shut down JMB on your ipod or phone and restart it if you are on
a multi tasking ipod. Double click the home button. Touch the icon at the bottom until it wiggles. Touch the minus sign and it will shut down. If you don't do this your settings won't load. You now have to re enter your load using da.</div></div>

When following the steps listed above this is what mine is showing. Is this correct? Now there is no need for temp, humidity, or Baro? Where is it getting the DA reading from?
ae3fc7fd.jpg

 
Re: iphone ballistic app that uses density altitude

Mine shows the same thing, I have to manually input the DA. I can't figure out how to get the program to auto-populate the DA. I've just about given up.
 
Re: iphone ballistic app that uses density altitude

I've not used the DA setting much, so I'm a not familiar with it. I found this calculator online. Does it look correct? This is my local info.

63550c76.jpg
 
Re: iphone ballistic app that uses density altitude

Yeah, the calculator is correct in as much it is the formula used to create charts. It is not going to match current conditions off your Kestrel for example. But it is close enough.


If the program has DA then that is fine but you get the same thing by setting the station pressure, temperature, and humidity with altitude set to zero. Keep it simple.

All you are doing is uncorrected altimeter pressure. Again, you get the same thing when you use altimeter setting with actual altitude (think of an algebra problem with the variables switched on the equal sign). Remember even when looking at a Kestrel using DA your actual altitude is not going to be correct. Example, you know you are standing at an altitude of 3633' but your Kestrel is showing 3425'. The DA is showing 5320'. That latter is what the bullet "thinks". You get the same trajectory either using uncorrected barometer without altitude as you would with corrected barometer with altitude.

The differences in pressure types:

http://www.crh.noaa.gov/bou/awebphp/definitions_pressure.php


All we are tying to do with DA is get a trajectory output based on the same premise pilots fly safely above the ground. The more accurate the pilot's instrument the safer he flies. DA is simply giving the bullet a better idea on its own altitude and conditions above the ground. The question remains is it really material for bullet flight as it relates to aircraft flight.
...
 
Re: iphone ballistic app that uses density altitude

You have to enter DA off a kestrel or from a program. DenAlt is a free download
on iTunes.
 
Re: iphone ballistic app that uses density altitude

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigwheeler</div><div class="ubbcode-body">You have to enter DA off a kestrel or from a program. DenAlt is a free download
on iTunes. </div></div>

That is a cool app. Thanks.
 
Re: iphone ballistic app that uses density altitude

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: distantfoe</div><div class="ubbcode-body">I think I understand. So in FTE under atmospheric conditions, the following values apply??

enable atmosphere - should be on
altitude - set to 0
Barometric pressure - enter actual value
Pressure is absolute - should be on
Temperature - enter actual value
relative humidity - enter actual value

So this will duplicate DA calculations?</div></div>

it should
 
Re: iphone ballistic app that uses density altitude

Shooter fot Iphone rocks!
 
Re: iphone ballistic app that uses density altitude

Where can I find an app to give me station pressure on my iphone?

shane
 
Re: iphone ballistic app that uses density altitude

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mkollman74</div><div class="ubbcode-body">Shooter fot Iphone rocks!</div></div>

this... shooter is my "go to"... i also have FTP and the full KAC app...