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Density Altitude w/a Ballistics Program

 
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  #1  
Old 11-20-2013, 11:03 AM
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Density Altitude w/a Ballistics Program

I have a Kestrel that I use to get my DA. I then put the DA into Ballistic AE which also asks me for the Temp or Mach.

Here's my question. DA is calculated as:
Pressure Altitude + [120 x (OAT - ISA Temp)]

OAT is local temperature from a thermometer.
ISA Temp is always 15 C at sea level.

From that formula, it looks like DA includes temperature already. Why is Ballistic AE asking for Temp. again?
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  #2  
Old 11-20-2013, 01:51 PM
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Re: Density Altitude w/a Ballistics Program

Quote:
Originally Posted by bill123 View Post
I have a Kestrel that I use to get my DA. I then put the DA into Ballistic AE which also asks me for the Temp or Mach.

Here's my question. DA is calculated as:
Pressure Altitude + [120 x (OAT - ISA Temp)]

OAT is local temperature from a thermometer.
ISA Temp is always 15 C at sea level.

From that formula, it looks like DA includes temperature already. Why is Ballistic AE asking for Temp. again?
Got the answer myself. The Atmosphere pages ask for Temp to calculate Mach. DA already takes Temp. into account.
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  #3  
Old 11-20-2013, 02:04 PM
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Location: Central MT
Posts: 745
Re: Density Altitude w/a Ballistics Program

Additionally,

If your ballistics program is using temperature regression for correcting MV according to powder temperature you will need the temperature. Another consideration when using DA requiring a separate temperature input.
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  #4  
Old 11-20-2013, 02:13 PM
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Join Date: Jun 2013
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Re: Density Altitude w/a Ballistics Program

Quote:
Originally Posted by MMERSS View Post
Additionally,

If your ballistics program is using temperature regression for correcting MV according to powder temperature you will need the temperature. Another consideration when using DA requiring a separate temperature input.
Thanks, I'll look into that as well.
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