<?xml version="1.0"?>
<!--

  Bristol Pegasus XC engine model for JSBSim.

    Copyright (C) 2008 - 2013  Anders Gidenstam  (anders(at)gidenstam.org)
    Copyright (C) 2008         Ron Jensen

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
  
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
  
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  
-->
<!--
  File:     eng_PegasusXc.xml
  Authors:  Ron Jensen, Anders Gidenstam

Selected informative quotes from

"Flying Empires  Short 'C' class Empire flying boats",
Brian Cassidy, Queens Parade Press, 1996-2004. ISBN 0-9529298-2-1
[Cassidy:2004:FE]
    
  "The Pegasus engine data plates were fixed on the port side panel
  below the fore and aft level. The information on the plates read:
  Take off 2475 rpm. maximum +4 1/4 lb. sq. in.
           Maximum rpm   Boost.   Cylinder temp.   Oil temp.deg.C.
  Take off     2475      +4 1/4   235 for 15 min.      ??
  Climbing     2250      +2 1/2   235                  80
  Cruising     2250      +2       190                  70
  All out      2600      +2       235                  90
  Oil pressure maximum 80 lb./sq. in. 5 minutes
               minimum 5 lb./sq. in."
  (pp.71)

  "The Pegasus XC was a 28.7 litre, civil-rated, medium
  supercharged, poppet-valved engine and equipped the S.23, S.33
  'boats and one of the S.30 aircraft - KZ CATHAY. The Bristol
  Perseus XIIC was 24.9 litre, civil rated, medium supercharged,
  sleeve-valve engine and was fitted to the eight S.30 'boats. Both
  types of engine were geared down to turn the airscrew at half
  crankshaft speed, through Farman type reduction gearing."
  (pp.91) 

  "The starters were Rotax-Eclipse E 160R direct-cranking starters, capable
  of turning the crankshaft over at 25 to 30 rev. per min."
  (pp.92)

  "The engines originally fitted to all the Mark I S.23 'boats, one
  of the S.30s and both the S.33 'boats were poppet valved Bristol
  Pegasus XCs. The engines developed 820/900 bhp. (589/611 kW.) at
  2250 rev. per min., at the rated altitude of 3500 ft. At sea
  level, the maximum power was 885/920 bhp.  (660/686 kW.) at 2250
  rev. per min. The maximum economy cruise power was 510 bhp. (380
  kW.).  The maximum engine speed for for the climb - with the
  airscrews in COARSE pitch - was 2250 rev.  per min. with +1 1/4
  lb. sq. in.. For continuous cruising the speed was 2500 rev. per
  min. up to 5000 ft. and 2100 rev. per min. over 5000
  ft. Maximum engine speed - all out - was 2600 rev. per min. with
  +2 1/2 lb. sq. in. for 5 minutes in level flight."
  (pp.167)

  "Fuel consumptions varied between individual aircraft. In practice, `normal'
  four engine fuel consumptions ranged from as little as 107.5 gal. per hr. 
  (484 litres per hr.), to 119.9 gal. per hr. (540 litre per hr.). A good
  average consumption was considered to be 115 gal. per hr. (518 litre per hr.).
  The upper limit of acceptable consumption was set at 141 gal. per hr. (631
  litre per hr.), and anything over this amount was considered to be excessive.
  These consumption figures appear to be better than the manufacturer's figure
  of a maximum of 0,67 pints (0.38 litres) per hhp. per hour. ...
  [Oil] Consumptions varied from 8 pints to 3 1/2 gal. per hour for a
  typical Pegasus"
  (pp.168)

Flight Magazine November 5, 1936:
  Pegasus Xc
    Gear ratio:                        0.5:1
    Rated height:                      5500 ft
    Maximum take off RPM:              2475
    International rated power:         740 BHP at 3500 ft
    Max power all out level flight:    830 BHP at 5500 ft
    Max speed for 5 min. level flight: 2600 RPM
    Max take-off power:                920 BHP
    (Dry?) Weight:                     1015 lbs

  "The Claudel-Hobson carburetter, of the A.V.T. 85E type, works in
  conjunction with a variable datum boost control, which protects the
  engine against excessive pressure in the induction pipe."

Flight Magazine November 12, 1936:
  Bore:                   146 mm
  Stroke:                 190.5 mm 
  Reduction gear:         0.5
  Normal crankshaft RPM:  2,250
  Rated altitude:         4,500 ft
  Normal output at rated altitude:    785/815 BHP
  Max output at full throttle height: 830 BHP
  Take-off power:                     920 BHP
  Dry weight:                         1,015 lbs
  Remark: Moderately supercharged. Max. power at 5,256ft

http://theflyingboatforum.forumlaunch.net/viewtopic.php?f=19&t=897
  "... British and Australian CofAs for these aircraft give the Pegasus Xc
  as 740 hp at 2,250 rpm at rated height of 4,500 ft and 815 hp at 2,475 rpm."

-->
<piston_engine name="PegasusXc">

 <displacement unit="IN3"> 1752.80 </displacement>
 <bore unit="IN">             5.75 </bore>
 <stroke unit="IN">           7.50 </stroke>
 <compression-ratio>          6.25 </compression-ratio> <!-- From Wikipedia. Pegasus XVIII. -->
 <cylinders>                  9.0  </cylinders>
 <cycles>                     4.0  </cycles>

 <maxhp unit="HP">          920.0 </maxhp> <!-- At take-off boost. -->
 <!-- bsfc unit="LBS/HP*HR"> 0.40 </bsfc -->
 <!--
     [Cassidy:2004:FE]: For Pegasus Xc:
                        0.500 LBS/HP/HR (max cruise + acceptable consumption)
                        0.605 LBS/HP/HR (manufacturer's figure)
     Wikipedia:         0.52  LBS/HP/HR for Pegasus XVIII.
 -->
 <volumetric-efficiency> 0.65 </volumetric-efficiency> <!-- Default 0.85 -->
 <idlerpm>      300.0 </idlerpm>
 <maxrpm>      2600.0 </maxrpm>

 <numboostspeeds> 1.0 </numboostspeeds>
 <boostoverride>  0 </boostoverride>
 <boost-loss-factor> 1.20 </boost-loss-factor>

 <!-- For use with a separate variable datum boost control system. -->
 <ratedboost1 unit="PSI">      4.25 </ratedboost1>
 <ratedpower1 unit="HP">     920.00 </ratedpower1>
 <ratedrpm1>                2475.00 </ratedrpm1>
 <ratedaltitude1 unit="FT">    0.00 </ratedaltitude1>

 <!-- Boost control is handled by the variable datum boost control system. -->
 <boostoverride>1</boostoverride>


 <!-- For use without a separate variable datum boost control system. -->
 <!-- ratedboost1 unit="PSI">      2.50 </ratedboost1>
 <ratedpower1 unit="HP">     815.00 </ratedpower1>
 <ratedrpm1>                2250.00 </ratedrpm1>
 <ratedaltitude1 unit="FT"> 3500.00 </ratedaltitude1>

 <takeoffboost unit="PSI">     4.25 </takeoffboost -->

 <sparkfaildrop>              0.10 </sparkfaildrop>

 <minmp unit="INHG">         10.00 </minmp>
 <maxmp unit="INHG">         38.57 </maxmp>
 <maxthrottle>                1.00 </maxthrottle>
 <minthrottle>                0.05 </minthrottle>

 <!--
      Engine starter system.
      Inputs:
        propulsion/engine[#]/starter-serviceable
        propulsion/engine[#]/starter-voltage-V
      Outputs:
        propulsion/engine[#]/starter-current-A
        propulsion/engine[#]/starter-running-norm
 -->
 <starter-torque unit="LB*FT">368</starter-torque>
 <starter-rpm>800</starter-rpm>            
 
 <function name="propulsion/engine[#]/starter-max-power-W">
  <product> 
   <max> <!-- k_torque -->
    <value>0.0</value>
    <difference>
     <value>1.0</value>
     <quotient>
      <property>propulsion/engine[#]/engine-rpm</property>
      <value>400</value>   <!-- Starter max RPM. -->
     </quotient>
    </difference>
   </max>
   <value>498.941</value> <!-- Starter max torque in Nm. -->
   <product>              <!-- Engine speed in radians/sec. -->
    <value>0.10471976</value>
    <property>propulsion/engine[#]/engine-rpm</property>
   </product>
  </product>
 </function>

 <function name="propulsion/engine[#]/starter-current-A">
  <!-- Guess: Set the max current to 120A and let it decrease with rpm. -->
  <!-- The C-46 POH states that a starter on that aircraft draws 120A.  -->
  <product>
   <value>120.0</value>
   <quotient>
    <property>propulsion/engine[#]/starter-voltage-V</property>
    <value>12.0</value>
   </quotient>
   <max>
    <value>0.0</value>
    <difference>
     <value>1.0</value>
     <quotient>
      <property>propulsion/engine[#]/engine-rpm</property>
      <value>1000</value>
     </quotient>
    </difference>
   </max>
  </product>
 </function>

 <function name="propulsion/engine[#]/starter-running-norm">
  <min>
   <value>1.0</value>
   <product>
    <property>propulsion/engine[#]/starter-serviceable</property>
    <quotient>
     <product> <!-- Power available in W. -->
      <property>propulsion/engine[#]/starter-voltage-V</property>
      <property>propulsion/engine[#]/starter-current-A</property>
     </product>
     <max>     <!-- Max power in W at the current RPM. -->
      <value>1.0</value>
      <property>propulsion/engine[#]/starter-max-power-W</property>
     </max>
    </quotient>
   </product>
  </min>
 </function>

</piston_engine>