Sporty's E6B density altitude disparity

Hi,

ArtP, which version of WingX do you have? I just ran it on the latest
2.0.4.3 and WingX came up with PA=1000' and DA=1931'.

Interestingly with a dew point of 18C, WingX shows the DA going up to
2,213', that about a 300' difference not that much - would be interesting to
see how it affects the performance numbers though.

Keep well,

Hilton


"ArtP" wrote in message
...
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 Mon, 30 Apr 2007 03:39:14 GMT, "Hilton" wrote:

Hi,

ArtP, which version of WingX do you have? I just ran it on the latest
2.0.4.3 and WingX came up with PA=1000' and DA=1931'.

My mistake. I had field elevation at 1160. At 1165, I get PA=1000' and
DA=1932'. (2.0.4.3).

On Mon, 30 Apr 2007 16:23:19 GMT, ArtP
wrote:

On Mon, 30 Apr 2007 03:39:14 GMT, "Hilton" wrote:

Hi,

ArtP, which version of WingX do you have? I just ran it on the latest
2.0.4.3 and WingX came up with PA=1000' and DA=1931'.

My mistake. I had field elevation at 1160. At 1165, I get PA=1000' and
DA=1932'. (2.0.4.3).

And I can't type either. It should read: PA=1000' and DA=1931'.

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

Scott Skylane wrote
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!

That just meant that you always had a correct solution. :-)

Bob Moore

On 29 Apr 2007 20:43:21 GMT, Bob Moore wrote:

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

I noticed that too... I took the problem out of the Jeppesen Private Pilot
Manual and they came to the 2000' conclusion that I was using. 1800'
would make my Sporty's the most accurate.

*grumble*

But, that doesn't explain why none of the electronic calculators agree with
the 1000' pressure altitude on the chart.

--
Dallas

On Sun, 29 Apr 2007 22:36:55 GMT, Dallas
wrote:



But, that doesn't explain why none of the electronic calculators agree with
the 1000' pressure altitude on the chart.

Since moisture content of the air has a significant effect on the
calculation and I have never seen a specification for relative
humidity as part of the "standard day" it would seem that everyone is
free to pick their own value which would cause different results.

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

On 29 Apr 2007 14:11:56 -0700, Kev wrote:

So it's no surprise how different they can be.

That makes me feel a little better. My concern is that I'm taking this E6B
into the written and I'd hate to find out it's little brain is retarded -
after the test.

--
Dallas