[Milsurplus] High & Mighty SCR-718

[D C *Mac* Macdonald]

"Pressure Pattern Navigation" was obsoleted by
all the new stuff such as Doppler, INS, GPS, etc.
The changing difference between pressure and
absolute altitude gives you direction of drift (left
or right).  As I recall, the speed with which that
difference ocurred gave you an amount of drift.
When you apply the drift direction and velocity
vector to the TAS (True Airspeed) and true
heading vector, you developed a ded reckoning
or DR position (ded is short for deductive).  It is
NOT terrribly accurate, but far better than simple
DR.

As I previously said, all this is from memory from
1961, 44 years ago.  Details are fuzzy, but the
basic method is clear in my mind.

There is a big difference in using pressure patterns
as a positioning aid and using them for flight planning.

Mac, K2GKK/5

p.s.  It has  NOTHING  to do with RADAR.



----Original Message Follows----

From: Dan Arney <hankarn at pacbell.net>
To: D C *Mac* Macdonald <k2gkk at hotmail.com>
CC: whitaker at ieee.org, milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] High & Mighty SCR-718
Date: Sun, 31 Jul 2005 22:02:42 -0700

Well, first of all with all parties flying with a setting of 29.92 means 
that all aircraft are at the same altitude over land and water. so If I am 
flying over Greenland at FL350 and you are flying in your BFUF and at FL390 
you are telling me that your radio altimeter is going to tell you the 
direction of the wind when the icecap below is 10000 plus ASEL.

I always had a "HowGoZit" DR running and cross checked all of my positions 
and Checkpoints without benefit of the Stargazer (navigator) in DC-6, 
Connines, DC-8 and 707's. I still have my Periscopic, Mixmaster and astro 
compass which I used in the Canadian NWT using modified GRID navigation 
hauling fuel oil all over the Arctic. We hauled into the island where the 
magnetic north pole was a that time and while sitting on the ground the 
whiskey compass was moving back and forth 1180 degrees and tilting up and 
down.

While flying the No. Atlantic and No Pacific we were more interested in 
where the tight Isobars depending on our direction of flight. push or shove 
+/-.

There were are some some good stargazers out there but in a lot of cases I 
would prefer my DR/Howgozit.
I have used Consolan, LORAN, DECCA, Omega and INS along with GPS.
I have had 10 hour or longer flights with INS/OMEGA and pull up to the gate 
check along track and cross track error and be Zero/Zero and the Lat Long on 
the money for the published data.

In the airline industry our Radar altimeter only read from 2500 feet AGL to 
ground.

I have over 20,000 hours logged and do not understand how your radar info 
can tell you the wind direction
With Doppler and all of the computer run systems they all give you ground 
speed, wind direction and speed, crosswinds and have nothing to do with 
pressure altitude.

I am no longer flying but if you can provide me with your pressure pattern 
navigation 101 I have an open mind,
Hank
KN6DI

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