Continental O-200

[bomber]

This is the bible we'll be using...

http://www.flugsportvereincelle.de/down ... erator.pdf

simon

[bomber]

and this is the current engine.xml

Code: Select all

<!--
  File:     Continental 0-200-A.xml
  Author:   Aero-Matic v 0.82
  Inputs:
    name:           Continental 0-200-A
    type:           piston
    power:          100 hp
    augmented?      no
    injected?       no
  Generated with Aeromatic, with further details added from:
  www.pilotfriend.com/aero_engines/engine_specs/Continental%200%20320.htm
-->

<piston_engine name="Continental 0-200-A">
  <air-intake-impedance-factor>0.1</air-intake-impedance-factor>
  <bore unit="IN">4.0625</bore>
  <bsfc>0.45</bsfc>
  <compression-ratio>7.0</compression-ratio>
  <cycles>4.0</cycles>
  <cylinders>4.0</cylinders>
  <cylinder-head-mass unit="LBS">170</cylinder-head-mass>
  <displacement unit="IN3">201</displacement>
  <idlerpm>400.0</idlerpm>
  <maxhp>100.00</maxhp>
  <maxmp unit="INHG">28.67</maxmp>
  <maxrpm>2800.0</maxrpm>
  <minmp unit="INHG">12.17</minmp>
  <ram-air-factor>0.25</ram-air-factor>
  <sparkfaildrop>0.1</sparkfaildrop>
  <stroke unit="IN">3.875</stroke>
  <starter-rpm>500</starter-rpm>
  <starter-torque>50</starter-torque>
  <volumetric-efficiency>0.82</volumetric-efficiency>
 </piston_engine>

ad this is a previous engine (Continental_O-300) I did for the Outerra cessna 172

Code: Select all

<?xml version="1.0"?>
<!--
  Author:   Bomber
  Version:    1.0

General characteristics
   Type: 6-cylinder air-cooled horizontally opposed aircraft piston engine
   Bore: 4.0625 in (103.2 mm)
   Stroke: 3.875 in (98.4 mm)
   Displacement: 301.4 in (4.94 L)
   Length: 39.75 in (101.0 cm)
   Width: 31.5 in (80.0 cm)
   Height: 23.25 in (59.0 cm)
   Dry weight: 268 lbs (121.5 kg) dry, without starter or generator
Components
   Cooling system: Air-cooled
Performance
   Power output: 145 hp (108 kW) at 2,700 rpm
   Specific power: 0.58 hp/in (26.5 kW/l)
   Compression ratio: 7.0:1
   Power-to-weight ratio: 0.54 hp/lb (0.89 kW/kg)
-->


<piston_engine name="Continental_O-300">
    <displacement unit="IN3"> 301.4 </displacement>
         <!-- this value is used to determine mass air and fuel flow which impacts engine power and cooling. -->
    <bore unit="IN"> 4.0625  </bore>
         <!-- cylinder bore is currently unused. -->
    <stroke unit="IN"> 3.875 </stroke>
         <!-- piston stroke is used to determine the mean piston speed.
         A longer stroke results in an engine that does not work as well at higher speeds -->
    <cylinders> 6 </cylinders>
         <!-- number of cylinders scales the cylinder head mass. -->
   <compression-ratio> 7.0 </compression-ratio>
         <!-- the compression ratio affects the change in volumetric efficiency with altitude.-->   
   <maxhp> 145 </maxhp>
         <!-- this value is the nominal power the engine creates at maxrpm.
         It will determine bsfc if that tag is not input. It also determines the starter motor power. -->   
   <cycles> 4 </cycles>
         <!-- Designate a 2 or 4 stroke engine. Currently only the 4 stroke engine is supported. -->
    <idlerpm> 800.00 </idlerpm>
         <!-- this value affects the throttle fall off and the engine stops running
         if it is slowed below 80% of this value. The engine starts running when it reaches 80% of this value. -->
    <maxrpm> 2700.0 </maxrpm>
         <!-- this value is used to calculate air-box resistance and BSFC.
         It also affects oil pressure among other things. -->
            

      <!-- AIR INTAKE -->
      
   <ram-air-factor> 0 </ram-air-factor>
         <!-- this number creates a pressure increase with an increase in dynamic pressure (aircraft speed).
            is the efficiency of the air scoop intake. 0 turns ram air off. Default is 1. -->
   <air-intake-impedance-factor> 0 </air-intake-impedance-factor>
         <!-- this number is the pressure drop across the intake system. Increasing it reduces available manifold pressure.
            It is determined by <maxmp> if not supplied. -->
            
      <!-- STARTER -->
      
   <starter-torque> 300.0 </starter-torque>
         <!-- A value specifing the zero RPM torque in lb*ft the starter motor provides.
         Current default value is 40% of the horse power value. -->         
    <starter-rpm> 800 </starter-rpm>
         <!-- A value specifing the maximum RPM the unloaded starter motor can achieve.
         Loads placed on the engine by the propeller and throttle will further limit RPM achieved in practice. -->
                     

      <!-- THROTTLE -->      
      
    <maxmp unit="INHG"> 29.96 </maxmp>
         <!-- this value is the nominal maximum manifold pressure at sea-level without boost.
         Along with maxrpm it determines the resistance of the aircraft's intake system.
         See air-intake-impedance-factor

         It is used for determining <BSFC> and <air-intake-impedance-factor> if a values are not supplied
         for those items. In a supercharged engine is always the pressure at sea level under standard
         conditions (29.9). -->

   <minmp unit="INHG"> 11.7 </minmp>
         <!-- this value is the nominal idle manifold pressure at sea-level without boost.
         Along with idlerpm, it determines the throttle response slope. -->

      <!-- POWER PRODUCTION -->

   <sparkfaildrop> 0.1 </sparkfaildrop>
         <!-- this is the percentage drop in horsepower for single magneto operation, try a value of 0.1 for 10%. -->   
    <volumetric-efficiency> 0.865 </volumetric-efficiency>
         <!-- controls how much mixture goes through the engine at sea level running at the rated RPM.
         Value of 1 for unboosted engines and values over 1 for boosted engines. -->
   <bsfc unit="LBS/HP*HR"> 0.457 </bsfc>
         <!-- Indicated Specific Fuel Consumption.
         The power produced per unit of fuel. Higher numbers give worse fuel economy.
         This number may need to be lowered slightly from actual BSFC numbers because some internal engine losses
         are modeled separately. -->

      <!-- COOLING -->

    <cylinder-head-mass unit="LBS"> 14 </cylinder-head-mass>
         <!-- the nominal mass of a cylinder head. A larger value slows changes in engine temperature.
         So if you have a '5-minute' limit on a power setting you can adjust this
         value so the engine just starts to overheat at the end of the given time frame.-->
   <cooling-factor> 0.54 </cooling-factor>
         <!-- this number models how efficient the aircraft cooling system is. Raising the value makes
         the engine run cooler. This value is exposed on the property tree so it may be
         altered at runtime to simulate cowl flaps, for example. -->
   
</piston_engine>

Not saying it's right not saying it's wrong just attempting to show that if we're serious about making the flight modeling intuitive and easy to re-use by those following us then we must make some concessions to writing it in a clearly logical and understandable way, including comments.

that's all, and how I intend to do it

no critisism intended.

[bomber]

Code: Select all

<?xml version="1.0"?>
<!--
  Author:   Bomber
  Version:    1.0

General characteristics
   Type: 4-cylinder air-cooled horizontally opposed aircraft piston engine
   Bore: 4.0625 in (103.2 mm)
   Stroke: 3.875 in (98.4 mm)
   Displacement: 200.91 in (3.29 L)
   Length: 28.53 in (72.47 cm)
   Width: 31.5 in (80.0 cm)
   Height: 23.25 in (59.0 cm)
   Dry weight: 170 lbs (77.19 kg) dry, without starter or generator
Components
   Cooling system: Air-cooled
Performance
   Power output: 100 hp (75 kW) at 2,275 rpm
   Specific power: 0.5 hp/in (23 kW/l)
   Compression ratio: 7.0:1
   Power-to-weight ratio: 0.56 hp/lb (0.92 kW/kg)
   
-->


<piston_engine name="Continental_O-200">
    <displacement unit="IN3"> 200.91 </displacement>
         <!-- this value is used to determine mass air and fuel flow which impacts engine power and cooling. -->
    <bore unit="IN"> 4.0625  </bore>
         <!-- cylinder bore is currently unused. -->
    <stroke unit="IN"> 3.875 </stroke>
         <!-- piston stroke is used to determine the mean piston speed.
         A longer stroke results in an engine that does not work as well at higher speeds -->
    <cylinders> 4 </cylinders>
         <!-- number of cylinders scales the cylinder head mass. -->
   <compression-ratio> 7.0 </compression-ratio>
         <!-- the compression ratio affects the change in volumetric efficiency with altitude.-->   
   <maxhp> 100 </maxhp>
         <!-- this value is the nominal power the engine creates at maxrpm.
         It will determine bsfc if that tag is not input. It also determines the starter motor power. -->   
   <cycles> 4 </cycles>
         <!-- Designate a 2 or 4 stroke engine. Currently only the 4 stroke engine is supported. -->
    <idlerpm> 800.0 </idlerpm>
         <!-- this value affects the throttle fall off and the engine stops running
         if it is slowed below 80% of this value. The engine starts running when it reaches 80% of this value. -->
    <maxrpm> 2750.0 </maxrpm>
         <!-- this value is used to calculate air-box resistance and BSFC.
         It also affects oil pressure among other things. -->
            

      <!-- AIR INTAKE -->
      
   <ram-air-factor> 0 </ram-air-factor>
         <!-- this number creates a pressure increase with an increase in dynamic pressure (aircraft speed).
            is the efficiency of the air scoop intake. 0 turns ram air off. Default is 1. -->
   <air-intake-impedance-factor> 0 </air-intake-impedance-factor>
         <!-- this number is the pressure drop across the intake system. Increasing it reduces available manifold pressure.
            It is determined by <maxmp> if not supplied. -->
   
      <!-- THROTTLE -->      
      
    <maxmp unit="INHG"> 29.96 </maxmp>
         <!-- this value is the nominal maximum manifold pressure at sea-level without boost.
         Along with maxrpm it determines the resistance of the aircraft's intake system.
         See air-intake-impedance-factor

         It is used for determining <BSFC> and <air-intake-impedance-factor> if a values are not supplied
         for those items. In a supercharged engine is always the pressure at sea level under standard
         conditions (29.9). -->

   <minmp unit="INHG"> 11.7 </minmp>
         <!-- this value is the nominal idle manifold pressure at sea-level without boost.
         Along with idlerpm, it determines the throttle response slope. -->

      <!-- POWER PRODUCTION -->

   <sparkfaildrop> 0.1 </sparkfaildrop>
         <!-- this is the percentage drop in horsepower for single magneto operation, try a value of 0.8 or so. -->   
    <volumetric-efficiency> 0.865 </volumetric-efficiency>
         <!-- controls how much mixture goes through the engine at sea level running at the rated RPM.
         Value of 1 for unboosted engines and values over 1 for boosted engines. -->
   <bsfc unit="LBS/HP*HR"> 0.457 </bsfc>
         <!-- Indicated Specific Fuel Consumption.
         The power produced per unit of fuel. Higher numbers give worse fuel economy.
         This number may need to be lowered slightly from actual BSFC numbers because some internal engine losses
         are modeled separately. -->

      <!-- COOLING -->

    <cylinder-head-mass unit="LBS"> 9.25 </cylinder-head-mass>
         <!-- the nominal mass of a cylinder head. A larger value slows changes in engine temperature.
         So if you have a '5-minute' limit on a power setting you can adjust this
         value so the engine just starts to overheat at the end of the given time frame.-->
   <cooling-factor> 0.54 </cooling-factor>
         <!-- this number models how efficient the aircraft cooling system is. Raising the value makes
         the engine run cooler. This value is exposed on the property tree so it may be
         altered at runtime to simulate cowl flaps, for example. -->
   
</piston_engine>

So here's my first stab converting the 300 to a 200.... a couple of adjustments here and there..

But that's not the end of it surley ?

it should be tested... within Flightgear.... not attached to a plane but as it would be in real life strapped to an engine test bed.

I've asked on many occations if it's an unrealistic expectation for engines to have been tested and come with test data to prove that they perform to the manufacturers data ?

So I have no proof at the moment of the engines performance, just a wild ase guess that it's close.... but if I attach a prop it'll screw it up somewhat cronic and if I attach it to a plane and fly it at different alts I might just as well pull the numbers out of the air.

The engine has to be tested on it's own.

So let's test this baby

Simon

[bomber]

http://www.flugsportvereincelle.de/down ... erator.pdf

ok tables of interest are on pages 14, 35 and 44/45 of the 76 page pdf document.

please ask for clarification if required.... because sometimes I look at them and think WTF.

[bomber]

So at sea level my engine pulls 56 ponies @ 1750rpm.... supposed to be 100, me thinks its a bit of a wimp.

<maxmp unit="INHG"> 29.96 </maxmp>

the graph on page 35 shows about 28.8...so we'll adjust that.

<bsfc unit="LBS/HP*HR"> 0.457 </bsfc>

also on that page the BSFC should be about 0.555 at that RPM ...so in for a penny in for pound we'll adjust that.

oh and fuel consumption...

http://www.teamkitfox.com/Forums/showthread.php?t=2146

real life experience seems to indicate 6gph

[bomber]

And the problem is none of the adjustments above will get you to the engine you want.... you'd think it would, but you'd be wrong.

Because you're not dealing with an engine, you're dealing with a computer program... and if you want 100hp @ 2750rpm using 6gph of fuel at sea level with that engine...

you need a file that looks like this....

Code: Select all

<?xml version="1.0"?>
<!--
  Author:   Bomber
  Version:    1.0

General characteristics
   Type: 4-cylinder air-cooled horizontally opposed aircraft piston engine
   Bore: 4.0625 in (103.2 mm)
   Stroke: 3.875 in (98.4 mm)
   Displacement: 200.91 in (3.29 L)
   Length: 28.53 in (72.47 cm)
   Width: 31.5 in (80.0 cm)
   Height: 23.25 in (59.0 cm)
   Dry weight: 170 lbs (77.19 kg) dry, without starter or generator
Components
   Cooling system: Air-cooled
Performance
   Power output: 100 hp (75 kW) at 2,275 rpm
   Specific power: 0.5 hp/in (23 kW/l)
   Compression ratio: 7.0:1
   Power-to-weight ratio: 0.56 hp/lb (0.92 kW/kg)
   
-->


<piston_engine name="Continental_O-200">
    <displacement unit="IN3"> 200.91 </displacement>
         <!-- this value is used to determine mass air and fuel flow which impacts engine power and cooling. -->
    <bore unit="IN"> 4.0625  </bore>
         <!-- cylinder bore is currently unused. -->
    <stroke unit="IN"> 3.875 </stroke>
         <!-- piston stroke is used to determine the mean piston speed.
         A longer stroke results in an engine that does not work as well at higher speeds -->
    <cylinders> 4 </cylinders>
         <!-- number of cylinders scales the cylinder head mass. -->
   <compression-ratio> 7.0 </compression-ratio>
         <!-- the compression ratio affects the change in volumetric efficiency with altitude.-->   
   <maxhp> 100 </maxhp>
         <!-- this value is the nominal power the engine creates at maxrpm.
         It will determine bsfc if that tag is not input. It also determines the starter motor power. -->   
   <cycles> 4 </cycles>
         <!-- Designate a 2 or 4 stroke engine. Currently only the 4 stroke engine is supported. -->
    <idlerpm> 800.0 </idlerpm>
         <!-- this value affects the throttle fall off and the engine stops running
         if it is slowed below 80% of this value. The engine starts running when it reaches 80% of this value. -->
    <maxrpm> 2750.0 </maxrpm>
         <!-- this value is used to calculate air-box resistance and BSFC.
         It also affects oil pressure among other things. -->
            

      <!-- AIR INTAKE -->
      
   <ram-air-factor> 0 </ram-air-factor>
         <!-- this number creates a pressure increase with an increase in dynamic pressure (aircraft speed).
            is the efficiency of the air scoop intake. 0 turns ram air off. Default is 1. -->
   <air-intake-impedance-factor> 0 </air-intake-impedance-factor>
         <!-- this number is the pressure drop across the intake system. Increasing it reduces available manifold pressure.
            It is determined by <maxmp> if not supplied. -->
   
      <!-- THROTTLE -->      
      
    <maxmp unit="INHG"> 28.8 </maxmp>
         <!-- this value is the nominal maximum manifold pressure at sea-level without boost.
         Along with maxrpm it determines the resistance of the aircraft's intake system.
         See air-intake-impedance-factor

         It is used for determining <BSFC> and <air-intake-impedance-factor> if a values are not supplied
         for those items. In a supercharged engine is always the pressure at sea level under standard
         conditions (29.9). -->

   <minmp unit="INHG"> 11.7 </minmp>
         <!-- this value is the nominal idle manifold pressure at sea-level without boost.
         Along with idlerpm, it determines the throttle response slope. -->

      <!-- POWER PRODUCTION -->

   <sparkfaildrop> 0.1 </sparkfaildrop>
         <!-- this is the percentage drop in horsepower for single magneto operation, try a value of 0.8 or so. -->   
    <volumetric-efficiency> 0.565 </volumetric-efficiency>
         <!-- controls how much mixture goes through the engine at sea level running at the rated RPM.
         Value of 1 for unboosted engines and values over 1 for boosted engines. -->
   <bsfc unit="LBS/HP*HR"> 0.265 </bsfc>
         <!-- Indicated Specific Fuel Consumption.
         The power produced per unit of fuel. Higher numbers give worse fuel economy.
         This number may need to be lowered slightly from actual BSFC numbers because some internal engine losses
         are modeled separately. -->

      <!-- COOLING -->

    <cylinder-head-mass unit="LBS"> 9.25 </cylinder-head-mass>
         <!-- the nominal mass of a cylinder head. A larger value slows changes in engine temperature.
         So if you have a '5-minute' limit on a power setting you can adjust this
         value so the engine just starts to overheat at the end of the given time frame.-->
   <cooling-factor> 0.54 </cooling-factor>
         <!-- this number models how efficient the aircraft cooling system is. Raising the value makes
         the engine run cooler. This value is exposed on the property tree so it may be
         altered at runtime to simulate cowl flaps, for example. -->
   
</piston_engine>

notice the bsfc and volumetric efficiency values.

[IAHM-COL]

Thanks Bomber

I am reading this eagerly, to see if maybe one day I wrap my mind around what these cryptic xmls are all about

First simple question:
Is this the nose-engine on a certain dog?

[bomber]

Yes but it's also the engine on a lot more planes besides

https://en.m.wikipedia.org/wiki/Continental_O-200

[jwocky]

There are two things to keep in mind:

1.) The engine simulation, while in many aspects more accurate than in other FDMs, it is not perfect in JSB either. Your fuel consumption for exmaple can be calculated either simply via a set BSFC or by engine specifics (especially volume, horsepower, rpm). Now, since you give both, your fuel consumption will be higher than expected because well, the simulator does some things double. Same with sparkfaildrop. you add sparkfaildrop and at the same time BSFC and you added a fuel loss to the bsfc while the manufacturer data usually already include that factor. So your numbers will look in the end differently because if you want to set those parameters all, you have to use something like BSFC-faildrop-(additional_loss_at_Engine_temp)) and this is already simplified.

2.) The propeller is the real big deal in this. See, you get hp for the engine. That is the engine, it doesn't say how much hp are really on the prop. And this will change with propeller pitch, number of blades, rpm for the propeller (which are not always the same as for the engine, depending on the gear). The other thing to keep in mind here is torque. You can basically get the p-factor high, but then you get a lot of torque. With light aircraft and the excessive torque, both, JSB and Yasim traditionally produce, you end up that you have to use half of your maximal rudder just for compensating for that torque. Which for a real aircraft of course has to be unacceptable because it would prevent planes from turns to one side because the rudder is already half there to compensate for the torque ... so, there is some gap between the goal to make it "realistic" by a lot of torque and reality.

So, a test bed is a nice idea, but since you can't test without propeller in JSB, not feasible in FG. A combination of engine and propeller is always hard connected here for a given plane.

[IAHM-COL]

[

So let's test this baby

Simon

In what particular plane?
A test-reference Beagle perhaps?