1By Default systems are initialized by the Aircraft/generic/generic-system.xml
2This initializes the following:
3- The generic electrical system
4- 1 pitot system, index [0]
5- 1 static system index [0]
6- 2 vacuum systems [0] and [1], depending on engine rpm of engine[0] and
7  engine[1] respectfully
8
9If you want to define more systems, copy the generic-system file to your
10aircraft-name/Systems folder and rename it systems.xml
11
12In your aircraft -set file add the path to the system.xml file:
13<sim>
14    ....
15    <systems>
16        ....
17        <path>Aircraft/aircraft-name/Systems/systems.xml</path>
18        ....
19    </systems>
20    ....
21</sim>
22
23
24** Adding a second pitot system.
25In your systems.xml, you should already have
26
27  <pitot>
28    <name>pitot</name>
29    <number>0</number>
30    <stall-deg>60</stall-deg>           # optionnal, default to 60 degrees
31  </pitot>
32
33and you need to add for a pitot system with index 1:
34
35  <pitot>
36    <name>pitot</name>
37    <number>1</number>
38    <stall-deg>60</stall-deg>  #optionnal
39  </pitot>
40
41For the any pitot system except for the first (with index 0)
42add in the aircraft -set file (below for index 1):
43
44<systems>
45      <pitot n="1">
46                <serviceable>1</serviceable>
47      </pitot>
48</systems>
49
50Of course you can add a third or fourth etc.
51
52
53** Adding a second static system
54Absolutely analog with the pitot system. So add in systems.xml:
55
56  <static>
57    <name>static</name>
58    <number>1</number>
59    <tau>1</tau>
60    <type>0</type>                          #optionnal: 0,1 or 2 default is 0
61    <error-factor>0.5</error-factor>        #optionnal see below default = 0
62  </static>
63
64and in the aircraft -set file:
65
66<systems>
67      <static n="1">
68                <serviceable>1</serviceable>
69      </static>
70</systems>
71
72Now you can source your instrumentation relying on static and pitot
73pressure (airspeed, altimeter, vertical speed indicator) from different
74and independent systems
75
76
77** The PITOT System
78
79The pitot system measures impact pressure and is basically a tube pointing forward.
80Small aircraft have one, small IFR aircraft have one or two (of which at least
81one is heated) and larger commercial aircraft have three or even more. In those large
82aircraft the left pitot serves the pilot instruments, the right the co-pilot and
83the third system the back-up instruments. This might be different for each type
84of aircraft of course.
85In Flightgear the pitot system outputs the total pressure to the following property:
86/systems/pitot[n]/total-pressure-inhg and
87/systems/pitot[n]/measured-total-pressure-inhg
88which are the same except at supersonic speeds. For supersonic aircraft use the "measured"
89property. See also the README.airspeed-indicator.
90However it is advised for every aircraft to use the measured property. In future
91this will be the property where all the measurement faults are reflected.
92the following "measurement failures" are currently applied:
931) decrease of total and measured pressure due to side-slip and angle of attack
942) at 60 deg the pitot tube will stall and the value will fall back to static pressure
953) for the "measured" property only: at Mach>1, a shock wave is assumed in front of the
96  pitot tube, decreasing the total pressure.
97
98The stall angle may be (optionally) set to any angle between 0 and 90 deg
99(default = 60 deg) like so:
100  <pitot>
101    <name>pitot</name>
102    <number>0</number>
103    <stall-deg>45</stall-deg>
104  </pitot>
105
106Both the decrease of the pitot pressure and the default stall angle are based on a measurement
107on an AN5812 pitot tube.
108
109
110** The STATIC system
111
112The static system measures the static pressure. So all influences of airspeed are eliminated.
113In real life this is however not always easy. Effects from angle of attack, side-slip, flap defection,
114gear extension, engine power setting and airspeed are present and for the aircraft
115designer it is not alway easy to find a good position for the static port.
116Usually the number of static systems are equal to the number of pitot systems.
117In Flightgear there are 3 types of static systems modelled.
118Type 0 (default): the perfect sensor. No measurement failures.
119Type 1: Dual static ports on the fuselage sides. Side-slip angle influence only. this model the whole pair.
120Type 2: Static port on the pitot tube. Both angle of attack and side-slip influence.
121If you want to use type 1 or 2:
122  <static>
123    <name>static</name>
124    <number>0</number>
125    <tau>0.1</tau>
126    <type>1</type>
127    <error-factor>0.5</error-factor>
128  </static>
129The output property /systems/static[n]/pressure-inhg is filtered. Therefore, if you want to see
130the effect of the measurement failure, "tau" should be 0.1 or smaller.
131The "error-factor" should be between 0.2 and 0.7. Setting it to 0 equals a "perfect sensor".
132A setting of 1 means the whole (projected on static port face) impact pressure is applied.
133This is not realistic as usually there are more than one static pick-up points
134and so the pressure increase gets "flattened".
135