On 02/15/2007 04:55 PM, Alex Perry wrote:
> More generally: It is always very important to distinguish between the facts
> that arise from the
> simulation of the planet (such as SLP and variation), and the facts that
> arise from simulation of
> the airspace (such as QNH and VOR alignment).
From: John Denker <[EMAIL PROTECTED]>
> Please do not write to me saying that SLP must equal QNH
> when you are flying at sea level. That's true in that
> narrow special case, but not representative of the
> general case.
Supporting John's point:
In real world operations, even when flying at sea
Dave Perry wrote:
> On Mon, 2007-02-12 at 21:18 -0500, John Denker wrote:
>
>
>> > When will you put this in cvs?
>>
>> Ha, funny joke.
>>
>>
> If you want to do the one-for-all function, the sooner the better.
>
> I hope I did not offend by poking, reading, and questioning. I know I
>
On 02/13/2007 12:11 AM, Dave Perry wrote:
> I can see how you generate a table that gives PA and C(s) for
> layers with nonzero lapse rate. I assume you use equation (8) solved
> for h to generate the table when lamda = 0.
Yes, equation 8, but I don't even need to solve for h.
That's the
Hi John,
Thanks for answering my questions. I did not realize the interpolation
table was for the first three layers.
On Mon, 2007-02-12 at 21:18 -0500, John Denker wrote:
>
> The tabulated numbers come from a three-layer model, namely
> layers 0 through 2 as defined in the table at the front
On 02/12/2007 07:24 PM, Dave Perry wrote:
> This looks really slick,
:-)
> ... why is this patch good above the troposphere (> 100,000 ft.)? It
> should give the same answer as the last patch, only much more
> efficiently.
The tabulated numbers come from a three-layer model, namely
layers 0
On Mon, 2007-02-12 at 17:24 -0700, Dave Perry wrote:
> On Mon, 2007-02-12 at 11:33 -0500, John Denker wrote:
> > Overnight I thought of a non-disgusting way to optimize
> > the code. A new, muuuch better patch is now at:
> >http://www.av8n.com/fly/fgfs/altimeter.diff
> >
> > The new patch get
On Mon, 2007-02-12 at 11:33 -0500, John Denker wrote:
> Overnight I thought of a non-disgusting way to optimize
> the code. A new, muuuch better patch is now at:
>http://www.av8n.com/fly/fgfs/altimeter.diff
>
> The new patch gets the right answer without calling any
> transcendental functions
Overnight I thought of a non-disgusting way to optimize
the code. A new, muuuch better patch is now at:
http://www.av8n.com/fly/fgfs/altimeter.diff
The new patch gets the right answer without calling any
transcendental functions.
Also its range of validity has been extended to >100,000 feet.
On Mon, 2007-02-12 at 01:41 -0500, John Denker wrote:
> On 02/11/2007 11:29 PM, Dave Perry wrote:
>
> > By the way, I agree that the current algorithm in altimeter.cxx is
> > wrong. This evening, I had time to look at your posted patch and I
> > think it would give the right hi.
>
> It is, for
On 02/11/2007 11:29 PM, Dave Perry wrote:
> By the way, I agree that the current algorithm in altimeter.cxx is
> wrong. This evening, I had time to look at your posted patch and I
> think it would give the right hi.
It is, for now, restricted to the troposphere (36000 feet and below).
Extending
On Sun, 2007-02-11 at 13:42 -0500, John Denker wrote:
>On 02/11/2007 10:02 AM, Dave Perry wrote:
>
> > So the altimeter setting is the same thing as the mean-sea-level
> > barometric pressure.
>
> Huh? That does not follow at all. The quoted passage does not
> say that at all.
>
Your own paper i
Reference: Altimetry principles.
Lurid details including equations and derivations.
http://www.av8n.com/physics/altimetry.htm
-
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quick
On 02/11/2007 01:42 PM, I wrote:
> OK ... assuming by "altitude" they mean "pressure altitude" not "true
> altitude" or "absolute altitude" or ...
Typo: I meant "indicated altitude" instead of "pressure altitude".
Pressure altitude is something else yet again.
Sorry for any added confusion;
> On Sun, 2007-02-11 at 00:22 -0500, John Denker wrote:
>> Both the Weather Conditions popup and the atis.cxx code rely
>> on the "pressure-sea-level-inhg" property and use it in ways
>> that the altimeter setting should be used.
>> This is at least a misnomer, and probably a misconception.
On Sun, 2007-02-11 at 08:02 -0700, Dave Perry wrote:
> Have you looked for bugs?
I just looked at altimeter.cxx and altimeter.hxx. The
"indicated-altitude-ft" is the result of a LowPass (taking into account
the last altitude) of an iterpolation of a table created from an array
in altimeter.cxx.
On Sun, 2007-02-11 at 00:22 -0500, John Denker wrote:
> Both the Weather Conditions popup and the atis.cxx code rely
> on the "pressure-sea-level-inhg" property and use it in ways
> that the altimeter setting should be used.
>
> This is at least a misnomer, and probably a misconception.
> The alti
There is evidently at least one serious misconception in
the code that calculates atmospheric pressure, altimeter
settings, et cetera. This can be easily demonstrated:
Park at or near the threshold of runway 33 at Aspen
(KASE). Under standard conditions, observe that the
altimeter reads 7820 feet
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