[Xastir] Airplanes, anyone an expert?

[John Goerzen]

You probably don't want to auto-switch at all.

Examples:

Ultralight and light-sport aircraft often have stall speeds as low as
25-30kt.  Keep in mind winds aloft can easily exceed this speed, so it
is possible to have ground speeds (which is what a GPS will measure) near 0.

APRS reports feet MSL (above Mean Sea Level) but that is not all that
helpful.  If you're in Colorado and your elevation is 6000ft, then
7000ft isn't that high.

There are things like pressurized Cessnas and other twins.

I think it probably doesn't make sense to auto-differentiate like this.

If you've got to, maybe if you have the tail number from ADS-B you can
look up its class that way.

Really, like anything else APRS, those categories are broad and not
specifically-defined.  I mean, obviously a 747 is a large aircraft and
an ultralight is a small airplane...  but what's a regional jet?  Or a
twin piston, or twin turboprop?  Just throw everything up as aircraft
and let it be.

John

On 02/23/2016 01:51 PM, Jason Godfrey wrote:
> I'm not sure about a 150, but a 152 can operate slower than that. Somewhere
> around 35-40 knots air speed.  (I once was able to hover over a city when
> practicing slow flight in really strong winds.)
>
> - Jason
>
> On Tue, Feb 23, 2016 at 1:21 PM Curt Mills <curt.we7u at gmail.com> wrote:
>
>> Does the below make sense, switching aircraft symbols based on
>> speed/altitude in the ads-b.pl script?
>>
>>     # Auto-switch the symbol based on speed/altitude.
>>     # Symbols:
>>     #   Small airplane = /'
>>     #       Helicopter = /X
>>     #   Large aircraft = /^
>>     #         Aircraft = \^ (Not used in this script)
>>     #
>>     #  Cessna 150:  57 knots minimum.
>>     # Twin Cessna: 215 knots maximum.
>>     #  UH-1N Huey: 110 knots maximum.
>>     # Landing speed Boeing 757: 126 knots.
>>     #
>>     # If <= 10000 feet and  1 -  56 knots: Helicopter
>>     # If <= 20000 feet and 57 - 125 knots: Small aircraft
>>     # If >  20000 feet                   : Large aircraft
>>     # if                      > 126 knots: Large aircraft
>>
>> --
>> Curt, WE7U
>> http://wetnet.net/~we7u
>> http://www.sarguydigital.com
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