Engine updates.

Engine/XLR99.xml

@@ -1,12 +1,17 @@
-ROCKET
-  600.0
-    0.0
-    0.0
-    0.0
-    0.0
-51090.0
-59000.0
-  100.0
-   40.0
-   91.5
-  105.2
+<?xml version="1.0"?>
+<FG_ROCKET NAME="XLR-99">
+  <!--
+    SHR      = Specific Heat Ratio, for LOX/Ammonia this is 1.23
+    MAX_PC   = Maximum chamber pressure in psf
+    PROP_EFF = propulsive efficiency. This is largely a fudge factor.
+  -->
+  SHR              1.23
+  MAX_PC       86556.0
+  VARIANCE         0.10
+  PROP_EFF         0.80
+  MAXTHROTTLE      1.0
+  MINTHROTTLE      0.4
+  SLFUELFLOWMAX   91.5
+  SLOXIFLOWMAX   105.2
+</FG_ROCKET>
+

Engine/c172.xml

@@ -1,9 +1,17 @@
-PISTON
-  -19.7
-    0.0
-   26.6
-    0.0
-    0.0
+<FG_PISTON NAME="IO320">
+
+  <COMMENT>
+
+    BrakeHorsePower;
+    MaxThrottle;
+    MinThrottle;
+    SLFuelFlowMax;
+    SpeedSlope;
+    SpeedIntercept;
+    AltitudeSlope;
+
+  </COMMENT>
+
   160.0
   100.0
     0.0
@@ -11,4 +19,4 @@ PISTON
     0.00144
     0.546
    -1.6E-5
- 
+</FG_PISTON>

Engine/eng_io320.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0"?>
+<FG_PISTON NAME="IO320">
+
+  <COMMENT>
+
+  </COMMENT>
+
+  BRAKEHORSEPOWER 160.0
+  MAXTHROTTLE       1.0
+  MINTHROTTLE       0.2
+  SLFUELFLOWMAX     8.7
+  SPEEDSLOPE        0.00144
+  SPEEDINTERCEPT    0.546
+  ALTITUDESLOPE    -1.6E-5
+
+</FG_PISTON>
+

Engine/prop_generic2f.xml

@@ -0,0 +1,45 @@
+<?xml version="1.0"?>
+<FG_PROPELLER  NAME="generic2f">
+  IXX       5
+  DIAMETER  76
+  NUMBLADES  2
+  EFFICIENCY 12 1
+  0.0   0.00
+  0.1   0.08
+  0.2   0.33
+  0.3   0.50
+  0.4   0.61
+  0.5   0.70
+  0.6   0.76
+  0.7   0.83
+  0.8   0.85
+  0.9   0.84
+  1.0   0.64
+  1.04  0.00
+  C_THRUST 12 1
+  0.0   0.104
+  0.1   0.103
+  0.2   0.102
+  0.3   0.101
+  0.4   0.092
+  0.5   0.082
+  0.6   0.070
+  0.7   0.550
+  0.8   0.040
+  0.9   0.022
+  1.0   0.005
+  1.04 -0.010
+  C_POWER  12 1
+  0.0   0.066
+  0.1   0.065
+  0.2   0.064
+  0.3   0.062
+  0.4   0.060
+  0.5   0.055
+  0.6   0.058
+  0.7   0.055
+  0.8   0.047
+  0.9   0.025
+  1.0   0.010
+  1.04  0.000
+</FG_PROPELLER>

Engine/xlr99_nozzle.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<FG_NOZZLE NAME="X-15 XLR-99 Nozzle">
+  <!--
+    PE      = Nozzle exit pressure, psf.
+    EXPR    = Nozzle expansion ratio, Ae/At, sqft.
+    NZL_EFF = Nozzle efficiency, 0.0 - 1.0
+    DIAM    = Nozzle diameter, ft.
+  -->
+  PE     40
+  EXPR    9.8
+  NZL_EFF 0.80
+  DIAM    1.6
+</FG_NOZZLE>
+