Sporty's E6B density altitude disparity

My trusty Sporty's Electronic E6B does not agree with the Density Altitude
Chart. My instructor is at a loss to explain the difference. Can anybody
tell me what's going on?

Here's a sample problem:
Field Elevation: 1165
Altimeter Setting: 30.10
Temperatu 21°C
___________________

Using the standard chart:
http://pacificrimprinting.com/densalt.pdf

30.1 in. Hg Pressure Altitude Conversion Factor: -165
Pressure Altitude: 1000
Density Altitude: 2000
___________________

Sporty's E6B calculation:
Pressure Altitude: 985
Density Altitude: 1894

The Sporty's pressure altitude is off by -15 feet and the density altitude
is off by -106 feet. I can't imagine Sporty's marketing a flawed
E6B, which one is inaccurate?

--
Dallas

I entered the same numbers in my Sporty's E6B and got
PA: 998
DA: 1910

Which is about the same as on the chart.
Your reading of 2000 DA for 1000 PA is slightly off. You need at least
22 deg C for that.

- Tom

On Sun, 29 Apr 2007 17:20:43 GMT, "Dallas"
wrote:

My trusty Sporty's Electronic E6B does not agree with the Density Altitude
Chart. My instructor is at a loss to explain the difference. Can anybody
tell me what's going on?

Here's a sample problem:
Field Elevation: 1165
Altimeter Setting: 30.10
Temperatu 21°C
___________________

Using the standard chart:
http://pacificrimprinting.com/densalt.pdf

30.1 in. Hg Pressure Altitude Conversion Factor: -165
Pressure Altitude: 1000
Density Altitude: 2000
___________________

Sporty's E6B calculation:
Pressure Altitude: 985
Density Altitude: 1894

The Sporty's pressure altitude is off by -15 feet and the density altitude
is off by -106 feet. I can't imagine Sporty's marketing a flawed
E6B, which one is inaccurate?

On Sun, 29 Apr 2007 17:59:35 GMT, Tom L. wrote:

I entered the same numbers in my Sporty's E6B and got
PA: 998
DA: 1910

You entered the *same* numbers into your Sporty's E6B and got different
numbers than my Sporty's E6B?

What's going on here?

--
Dallas

On Sun, 29 Apr 2007 17:20:43 GMT, "Dallas"
wrote:
Here's a sample problem:
Field Elevation: 1165
Altimeter Setting: 30.10
Temperatu 21°C
___________________

I entered them on my WingX E6B software on my Axim and got PA=995 and
DA=1925

On Sun, 29 Apr 2007 17:59:35 GMT, Tom L. wrote:

I entered the same numbers in my Sporty's E6B and got
PA: 998
DA: 1910

Here's photo evidence of our discrepancy:
http://img.photobucket.com/albums/v1...SportysE6B.jpg

BTW, mine is fresh from Sporty's a month ago.


--
Dallas

On Sun, 29 Apr 2007 19:50:42 GMT, ArtP wrote:

I entered them on my WingX E6B software on my Axim and got PA=995 and
DA=1925

Chart:
PA: 1000
DA: 2000

Tom L's Sporty's E6B:
PA: 998
DA: 1910

Dallas' Sporty's E6B:
PA: 985
DA: 1894

ArtP's WingX E6B:
PA: 995
DA: 1925

Excuse me, I need to take a couple of aspirin and lay down.

--
Dallas

Ï "ArtP" Ýãñáøå óôï ìÞíõìá
...

On Sun, 29 Apr 2007 17:20:43 GMT, "Dallas"
wrote:
Here's a sample problem:
Field Elevation: 1165
Altimeter Setting: 30.10
Temperatu 21°C
___________________

I entered them on my WingX E6B software on my Axim and got PA=995 and
DA=1925


On my ASA CX-2 PA=999 DA=1929

Dallas wrote

Using the standard chart:
http://pacificrimprinting.com/densalt.pdf

30.1 in. Hg Pressure Altitude Conversion Factor: -165
Pressure Altitude: 1000
Density Altitude: 2000
___________________

My reading of the chart shows about 1800' density altitude.

Bob Moore

Bob Moore wrote:

Dallas wrote


Using the standard chart:
http://pacificrimprinting.com/densalt.pdf

30.1 in. Hg Pressure Altitude Conversion Factor: -165
Pressure Altitude: 1000
Density Altitude: 2000
___________________


My reading of the chart shows about 1800' density altitude.

Bob Moore

Haha, remember all those old Boeing performance charts, Bob? No two
people could ever get the same answer, and no one person could ever get
the same answer twice!

Happy Flying!
Scott Skylane

On Apr 29, 1:20 pm, "Dallas" wrote:
My trusty Sporty's Electronic E6B does not agree with the Density Altitude
Chart. My instructor is at a loss to explain the difference. Can anybody
tell me what's going on?

There are lots of ways to calculate density altitude. Most
calculators used by pilots, totally ignore humidity, for example,
which can make the DA off by a thousand feet. Then there's all the
ways of calculating standard temps, by table or other equations. Plus
different calculators might round differently. So it's no surprise
how different they can be.

Want your head to really explode? :-) See below, the most detailed
DA paper I've seen:

http://wahiduddin.net/calc/density_altitude.htm

Cheers, Kev