[Milsurplus] Altimeter

[Peter Gottlieb]

These are interesting devices.  Since they come in many different 
flavors I cannot exactly describe yours but from your description I can 
offer the following:

Large aircraft have many systems which require an altitude input and 
thus use a redundant series of sensors called "air data computers (ADC)" 
to process pitot static pressures and air temperature and convert this 
to data accessible on the ship's data bus.  This data is also fed to the 
altimeter as a synchro signal (there are digital to synchro converters 
in the ADC).  Thus the altimeter shows the data the ADC system is 
producing.  Now, to add another layer of redundancy, also to handle 
complete ADC system failure, the altimeter is also connected to the 
static port so that when the ADC driving it drops offline for whatever 
reason the altimeter itself can measure and show the altitude.  The 
altimeter has a knob to adjust the "Kollsman window" which shows the 
local barometric pressure as the altimeter relies on barometric pressure 
and known pressure change vs. altitude to determine altitude.  The ADC 
system does not use this setting, instead relying on the use of a 
standard reporting pressure of 29.92 (1013 mb) inches of mercury.

Peter


pete williams wrote:
> 
>  Not  radio but got a  RAF  Smiths  servo altimeter used in a
> Lightning.. seems it has a inbuilt  mechanism for  stabilising and
> turning the indicator/pointers on. It's got a  static port and a  12
> pin  connector on rear but all sealed (sodered) up.
> Q... anyone any info on  likely operational connexion... Clive in UK
> checking for me  but  since it came out of US. local  knowledge helps
> and or  reference.
> Tks
> Pete
> Pete D . Williams
> METUNG 3904
> Australia
> jupete at bigpond.net.au
> 
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