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Calculating QFE, manually vs the kneeboard. Heatblur Simulations can you help?


OZthewizard42
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Dear Heatblur Simulations,

 

Recently I have been experimenting with calculating QFE for target engagement. I have been using the rule of thumb that 1mb = 30ft, it is OK for small elevation changes. However when I am dealing with larger elevation changes > 1000ft above mean sea level the small errors start to accumulate to produce a inaccurate QFE.

 

Also I believe that the 1mb=30ft rule is based on standard temperature of 273K (0 degrees celsius). So when large temperature changes from the standard are present, I believe that they are also contributing to the errors in the calculation.

 

Method I use:

Elevation above MSL / 30 = x

 

QNH - x = QFE

 

But the Kneeboard calculated QFE always seems to be very accurate to the true value of the actual QFE.

 

So all I wanted to ask is.

 

If you could please share with us the method you use in the calculation of the QFE for the kneeboard in DCS?

 

As well as show and explain the formula of the equation/s?

 

Many thanks.

 

Kind Regards,

 

OZthewizard.

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Dear Heatblur Simulations,

 

Recently I have been experimenting with calculating QFE for target engagement. I have been using the rule of thumb that 1mb = 30ft, it is OK for small elevation changes. However when I am dealing with larger elevation changes > 1000ft above mean sea level the small errors start to accumulate to produce a inaccurate QFE.

 

Also I believe that the 1mb=30ft rule is based on standard temperature of 273K (0 degrees celsius). So when large temperature changes from the standard are present, I believe that they are also contributing to the errors in the calculation.

 

Method I use:

Elevation above MSL / 30 = x

 

QNH - x = QFE

 

But the Kneeboard calculated QFE always seems to be very accurate to the true value of the actual QFE.

 

So all I wanted to ask is.

 

If you could please share with us the method you use in the calculation of the QFE for the kneeboard in DCS?

 

As well as show and explain the formula of the equation/s?

 

Many thanks.

 

Kind Regards,

 

OZthewizard.

 

Hello OZ,

 

As you said, the rule of thumb is valid only for elevations close to sea level. (And it is actually 27ft per mbar, to be a bit more precise). If it is of any interest to you, I have been developing a flight planning tool, which has the QFE calculations included in it. It can also generate a Viggen cartridge file, that you can load in-game, and gives you the option to generate kneeboard pages with navigation data (incl. the QFE).

 

See this post:

https://forums.eagle.ru/showpost.php?p=3315034&postcount=49

 

The whole thread is here:

https://forums.eagle.ru/showthread.php?t=195724

 

The app calculates the QFE for each waypoint. It uses the international standard atmosphere model, corrected for the actual QNH and temperature of the overall mission weather settings. That's actually the method used in RL.

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