Sporty's E6B density altitude disparity

[Dallas]

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
Temperature: 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

[Tom L.]

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
>Temperature: 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]

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

[ArtP]

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

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

[Dallas]

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/v101/Dallas52/Dallas/SportysE6B.jpg

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


--
Dallas

[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

[gpaleo]

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
>>Temperature: 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

[Bob Moore]

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

[Scott Skylane]

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

[Kev]

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

[Bob Moore]

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

[Blanche]

>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

Field Elev : 1165
Pressure Alt: 1000
Temp : 21 C

DSSCalc - DA = 1931
CoPilot 1931
Garmin GPS 1930

If you want me to dig out the software I wrote based on "Flight Theory
for Pilots", it's around here someplace...

[Tom L.]

Right here:

http://www.flickr.com/photos/8058120@N06/477406074/

Feel free to use the picture if you decide to call Sporty's.

BTW, mine is two or three years old. Yours must have the new and
improved algorithms. :)

On Sun, 29 Apr 2007 19:58:04 GMT, Dallas
> wrote:

>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/v101/Dallas52/Dallas/SportysE6B.jpg
>
>BTW, mine is fresh from Sporty's a month ago.

[Dallas]

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

[Dallas]

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

[Dallas]

On Sun, 29 Apr 2007 22:22:56 GMT, Tom L. wrote:

> BTW, mine is two or three years old. Yours must have the new and
> improved algorithms. :)

Indeed. :-)


--
Dallas

[ArtP]

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.

[ArtP]

On Sun, 29 Apr 2007 22:41:12 GMT, Dallas
> wrote:

>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.

Be afraid. The test is multiple choice so if only one answer is close
to the one you got with your E6B pick it. If your only alternative is
the wiz wheel stick with the E6B. However if they give you a chart you
are supposed to read then I would use the chart. Remember you are not
expected to give the "right" answer, you are expected to give the
answer they are looking for.

[Matt Whiting]

Dallas wrote:
> 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?
>

It is called tolerance. An E6B is a mechanical device. The
registration of the embossing on the various rings can be a little off.
The rivet may not be exactly centered on all of the disks, etc. It
doesn't take much to be off by a fair bit given the meager resolution of
the scales on the E6B. When I took my commercial written last year, I
could never get exactly the numbers in the study guide for the
computation problems, but I was close enough to know which answer was
correct.

Matt

[Matt Whiting]

Dallas wrote:
> 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/v101/Dallas52/Dallas/SportysE6B.jpg
>
> BTW, mine is fresh from Sporty's a month ago.
>
>

Ignore my last reply as I thought you had a real mechanical E6B, not
these fake electronic devices. It does appear that you got a bum unit.

Matt

[Matt Whiting]

Dallas wrote:
> 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.
>

Why? The reality is that these small variations really don't matter
much anyway.

Matt

[[email protected]]

On Apr 29, 4:16 pm, Blanche > wrote:
> >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
>
> Field Elev : 1165
> Pressure Alt: 1000
> Temp : 21 C
>
> DSSCalc - DA = 1931
> CoPilot 1931
> Garmin GPS 1930
>
> If you want me to dig out the software I wrote based on "Flight Theory
> for Pilots", it's around here someplace...

Blanche, my flight planning software AirPlan comes up with 1931 as
well...

Dean

[Marty Shapiro]

Blanche > wrote in
:

>>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
>
> Field Elev : 1165
> Pressure Alt: 1000
> Temp : 21 C
>
> DSSCalc - DA = 1931
> CoPilot 1931
> Garmin GPS 1930
>
> If you want me to dig out the software I wrote based on "Flight Theory
> for Pilots", it's around here someplace...
>

FWIW - My 13 year old Jeppesen TechStar for PA = 1000 and Temp = 21C also
gives DA of 1931'. Worked just fine on my instrument written.

--
Marty Shapiro
Silicon Rallye Inc.

(remove SPAMNOT to email me)

[Hilton]

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
>>Temperature: 21°C
>>___________________
>
> I entered them on my WingX E6B software on my Axim and got PA=995 and
> DA=1925

[ArtP]

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).

[ArtP]

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]

On Sun, 29 Apr 2007 22:22:56 GMT, Tom L. wrote:

> Feel free to use the picture if you decide to call Sporty's.

Here is the image I sent to Sporty's asking for an explanation:

http://img.photobucket.com/albums/v101/Dallas52/Dallas/BothSportysE6B.jpg

--
Dallas

[Jay B]

On Apr 29, 10:59 am, Tom L. > wrote:
> 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
> >Temperature: 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?- Hide quoted text -
>
> - Show quoted text -

I got exactly the same...

Jay Beckman
PP-ASEL <Lurking>
Chandler, AZ

[Dallas]

On 30 Apr 2007 14:44:24 -0700, Jay B wrote:

> I got exactly the same...

I assume you got the same as mine?

As I look at the photo of the 2 Sporty's that disagree I can see that the 3
year old one on the left doesn't have some of the menu items like Timer,
°C, Reqclimb, etc. It's pretty clear that they have created a new
version.

http://img.photobucket.com/albums/v101/Dallas52/Dallas/BothSportysE6B.jpg

--
Dallas

[Jay B]

On May 1, 11:12 am, Dallas > wrote:
> On 30 Apr 2007 14:44:24 -0700, Jay B wrote:
>
> > I got exactly the same...
>
> I assume you got the same as mine?
>
> As I look at the photo of the 2 Sporty's that disagree I can see that the 3
> year old one on the left doesn't have some of the menu items like Timer,
> °C, Reqclimb, etc. It's pretty clear that they have created a new
> version.
>
> http://img.photobucket.com/albums/v101/Dallas52/Dallas/BothSportysE6B...
>
> --
> Dallas

No, I got exactly the same as Tom, to whom I was replying...

DA = 1910...

Can't resolve your claim about new/old by the photos...too blurry.

Jay B

[Dallas]

On 1 May 2007 13:02:12 -0700, Jay B wrote:

> No, I got exactly the same as Tom, to whom I was replying...


Ugh.. groan.. [and other disparaging sounds].

I guess I'll wait to see if Sporty's answers my email.

Thanks :-)

--
Dallas