This entry is from ancient (closed) Dispersalfield Website. R.I.P.
it resides at FM Forum
Hope it helps, it's all greek to me
RLLAMASL wrote:
hi
I found this (complete descripction of fmd and emd files) and think it could be useful for people here ;)
Original link
http://dispersalfield.ru/main/index.php ... opic=595.0
Just copy &paste for clarity
BTW this may help - the detailed explainations of the EMD file structure that I have gathered from modders all over the web - I include also in this post the emd file of the Gnome&Rhgone Jupiter engine, so we can see that all the entries are now decrypted and explained:
[Generic]
//Entries in this section will apply to all engine subtypes mentioned in the emd unless otherwise specified in the subtype section;
On the first column you will have default parameters
Type Inline
//Type of engine: Inline; Radial; Jet; Rocket; Rocketboost; Tow; PVRD; Unidentified;
Autonomous 1
//Capacity of the engine to start autonomously in air:
0=disabled 1=enabled;
In most of the engines is set to 1 - not sure that this function always works as intended
In fact, autonomous 0 mean that plane can't restart his engine in air, but not sure that this function always works.
The autonomous 1 is also required for seaplanes to restart their engines on water. If you don't have it, they may start the first time (or sometimes may not) but they will NOT restart if you then shut them down. Making the 0 into 1 will ensure that they will restart.
Cylinders 12
//number of active cylinders in a piston engine
//Strangely enough also turbo-jet engines have cylinders in Il2!
Carburetor 0
//Type of carburetor:
Inline Suction=0 Carburetor=1 Injector=2 Float carburetor=3
Direction Right
//Propeller rotation direction: Right; Left;
TowFactor 1.0
//??? Unexplained yet, but in nearly all the emd it is set to 1.0.
PropMass 30.0
//Weight of propeller in Kgs
EngineI 1.0
//??? Unexplained yet
EngineAcceleration 1.0
//This determines how fast engine will increase RPM's when throttle is opened
Extinguishers 0
//1 = you have them,0 = you don't have them
CompressorType 0
// None = 0; Manualstep = 1; Wm_komandgerat = 2; Turbo = 3;
CompressorSteps 0
// Number of compressor stages. Normally 1; 2; 3;
CompressorPAt0 0.3
//Suspected explaination: Starting pressure of the compresseur in atmosphere
AfterburnerType 0
//Type of WEP System:
0 Generic
1 MW-50
2 GM.1
3 Afterburner Chamber (Firechamber)
4 Intercooler Water Injection
5 NO2 Injection System
6 C3/Fuel Feed @ Carburetor System (Fuel injection)
7 Fuel _ILA5
8 Fuel _ILA5Auto
9 WaterMethanol
10 P-51
11 Spit
MixerType 2
0 Generic
1 Rolls-Royce Automatic (Brit_FullAuto)
2 NII Carburetor @ Manifold Pressure Limits (limited_Pressure)
MixerAltitude 4500
// Upper limit of good performance of the mixer
cThrottle 1
// Activates throttle control: 0; 1;
cAfterburner 0
//Activates WEP control: 0; 1;
cProp 1
// Activates Variable Pitch control: 0; 1;
cMix 1
// Activates Mixer control: 0; 1;
cMagneto 0
// Activates Magnetos control: 0; 1;
cCompressor 0
//Activates Compressor stages control: 0; 1;
cFeather 0
//Activates Propeller Feathering: 0; 1;
cRadiator 1
//Activates Radiator flaps opening: 0; 1;
TESPEED 0.01
//Speed of mean temperature increase.
It is the increment use for temp increase.
If you raise this number (0.012 for example) temp increase faster.
TWATERMAXRPM 75
//Minimum (critical)water temp for max RPM in Celsius
TOILINMAXRPM 70
//Minimum (critical)Oil temp for max RPM in Celsius
TOILOUTMAXRPM 107
//Water temp out of the engine when Max RPM applied
MAXRPMTIME 240
//Max time you can run the engine at max RPM without overheating; time in seconds
It is also the time allowed for the engine to sustain overheating after this time, you will sustain engines damages and engine will die if you persist. So, when you overheat, you have to reduce temp to stop overheating before this time is spent. After this time, you will sustain engines damages.
MINRPMTIME 999
//This is underheat.Max time you can run the engine at max RPM when temperatures are under minimum allowed...
This seems to be a remain of Oleg’s original damage code: 999 = infinite time
TWATERMAX 115
// Max (critical)water temp
TWATERMIN 60
//Minimum (critical) water temperature to rev up the engine
TOILMAX 132
// Max (critical) oil temperature
TOILMIN 40
// Minimum (critical)Oil temperature to rev up engine
SoundName Fiat_Radial_A_74
//Name of the sound (prs) file
PropName middle
//Name of the propeller type file
StartStopName std_e
//Name of the start/stop prs file
[A30RAbis]
//Entries in this section are engine sub-type specific and will override the entries in the [Generic] section,
HorsePowers 600
//Horse power taken into consideration as a starting point before other factors are applied;
//It can end up in being much more or much less after il-2 engine calculations;
//Please note that what matters is the HP delivered to the propeller
BoostFactor 1.0
//Factor increasing power availability with 1 Power stays at 100%;
// This value is set at 1.1 in most of the engines (110% power available),but you can put any number you want
//Different from WEP (AfterBurner)
WEPBoostFactor 1.16
//Seems to be the multiplier for power when applying WEB,
//WEP with 110% throttle means 1.1*1.16*base HP
TowFactor 1.0
// ?? Still unexplained
Thrust 0
// for jet engines.Amount of thrust delivered by the engine (in Kgs).
//If this is used,HP is set to 0
RPMMin 200
// RPM when engine is idle (it may end up in being different as Il-2 will consider also the other parameters)
RPMNom 2000
//Nominal RPM values used in the base calcutations for the engine (it may end up in being very different as Il-2 engine will consider also the other parameters)
// A Smaller value here than that defined in RPMMax gives the engine more torque and power at the lower RPM needed in take-off with fixed pitch prop.
RPMMax 2600
//Max RPM that can be reached considering boost it is also subject to further calculations in Il2
// Optimal engine RPM with best power..
RPMMaxAllowed 2800
// Max (Critical) RPM allowed;
//If you pass this mark, the engine will progressively be damaged and ultimately die.
//Above this RPM, the engine starts to get overrevving damage, between this and RPMMax the engine just overheats quicker with higher RPM
Reductor 1.0
//Reduction gear ratio for prop
// engine RPM * reductor = prop RPM.
//This also this serves as prop efficiency coeficient.
//Engine HP * reductor = HP at the prop
// Some one must explain the following remark have found somewhere:
This si just used for rotation. So, you can have more HP at the propeller with something like 0.80 or 0.90. For example, the engine can have 1000 hp and the propeller 1100 hp with a little prop and reductor like 0.8 or other. Don't confuse rotation speed and efficiency that is only a side effect.
PropDiameter 3
// Diameter of propeller in meter
PropAnglerType 0
// Type of pitch control:
0 Fixed Prop
1 Retain RPM (1) Constant Speed
2 Retain RPM (2) Constant Speed
3 Retain AOA (1) Constant Speed
4 Retain AOA (2) Constant Speed
5 Friction to Throttle (E_prop_Friction)
6 Manual (Prop_Manualdriven)
7 Messerschmitt Komandgerat (Prop_WM_Komandgerat)
8 Focke Wulfe Komandgerat (Prop_FW_Komandgerat)
PropAnglerSpeed 0.08
// Speed of automatic prop angle adjustments
//Speed of changing the propeller blades angle in seconds
//Larger value means faster adjustments here, with 0.20 the Skyraider has an almost constant RPM, but with 0.04 it is easy to overrev the engine by opening throttle in fast dive
PropAnglerMinParam 1200.0
// miniumal rpm at which auto prop pitch starts to respond.
//It is miminum pitch below 1200rpm
PropAnglerMaxParam 2600.0
// maximal rpm at which auto prop pitch reaches max pitch angle
//The RPM of engine that a constant speed propellor tries to maintain at 100% prop pitch
PropAnglerAfterburnerParam 2900.0
//The RPM of engine that a constant speed propellor tries to maintain at 100% prop pitch when WEP is used
PropPhiMin 20.25
// min angle of prop blades in degrees
//Minimum angle of prop blades, larger value causes RPM drop at slow airspeed
PropPhiMax 20.25
// max angle of prop blades in degrees
//Maximum angle of prop blades, smaller value causes overrevving at high speed dives
PropAoA0 11.0
//Propeller Angle of Attack
CompressorPMax 1.18
//MAX gauge manifold pressure in ATA when WEP is used
// max pressure that compressor can deliver (ATA).
// This value is used when an afterburner is used
Voptimal 300.0
//Optimal Cruise speed (used by AI).
//It is the speed at which the propeller has the best efficiency
//It is really usefull to tweak acceleration capability of a plane.
//Lowest speed for good propellor efficiency, 0.0 gives best possible take-off acceleration
VmaxAllowed -
//speed at which Gear and Doors blow off.
//Then you're happy to survive with a belly landing after crossing the VmaxAllowed. //You usually lose control surfaces and even wings if you try to fly faster than VmaxAllowed.
CompressorAltitude0 2600.0
//Full throttle height.
//Max altitude at which compressor can deliver its max pressure.
//Theoretical most of the time - this parameter is further elaborated by Il2 engine and must be tested in game.
//FTH in meters for first supercharger gear without ram-air
CompressorMultiplier0 1.012
// compressor eficiency.
// A small multiplier will give a small speed difference between sea level and full throttle height.
// Increasing the multiplier increases that difference.
//multiplier for power at FTH compared to power at SL with first supercharger gear, higher value improves performance at all altitudes above SL
CompressorAltitude1 4400.0
//FTH in meters for second supercharger gear without ram-air
CompressorMultiplier1 0.755
//multiplier for power with second supercharger gear, smaller value reduces performance with second supercharger gear
CompressorRPMPMax 2600.0
//Engine rotations at which max compression is reached
//engine RPM that gives those FTHs, if engine runs with higher RPM when WEP is used, then the FTHs with WEP will be higher
CompressorMaxATARPM 1.18
// Manifold pressure at max rotation in Atmosphere
//MAX gauge manifold pressure in ATA at and below FTH without WEP
CompressorSpeedManifold 0.77
//Strength of ram-air effect
// Larger value will give more manifold pressure in high speed above FTH thanks to ram-air effect and thus make the altitude of top speed higher compared to FTH and the drop in climb performance above that. Thus larger value here increases the altitude difference between top speed and drop in climb performance abuve FTH.
CompressorRPM0 400
//Engine rotation at wich compressor start to work
CompressorATA0 0.65
// Manifold Pressure at minimum RPM in Atmosphere
CompressorRPM1 2400
// Setting that helps to finetune manifold pressure at different RPM
// It can be more than one
CompressorATA1 1.146
// Manifold Pressure at RPM1
DisP0x 2400
// Better rpm for propeller efficiency.
DisP0y 0
// The DisPLy are used to calculate compressor curves but the rules are still unexplained
DisP1x 0
// The DisPLy are used to calculate compressor curves but the rules are still unexplained
DisP1y 50
// The DisPLy are used to calculate compressor curves but the rules are still unexplained
FMD file data
[Mass] //Masses in kg
Empty //Empty weight of the aircraft
TakeOff //Take-off weight
It is the mass on takeoff used as reference to determine the envelope of flight. It should be known that this mass is probably different from the one you can have on a mission, because the latter is related not only to the empty weight, but also to the fuel mass, the mass of oil, weight of the pilots, weight of the armaments and carried ammunition, etc…
Oil //Oil capacity (in Kgs)
Fuel //Fuel capacity (in Kgs)
Nitro //WEP-fuel capacity (in Kgs)
[Controls] //Usually 1 when that is controllable, 0 if not
CUndercarriage 1 //0 for fixed landing gear
[Squares] //Surface areas of different plane parts in m2
It is important to enter here historically exact data, as the Il2 engine bases its calculation upon these basic data. The remaining entries in the FMD file (together with the engine parameters entered in the EMD file) will enable to refine the basic performances,
It is not recommended to tweak these entries in order to “change speed” or such. Obviously, modifying wing area results in modifying the lift of the aircraft. An increase or decrease wing area will result in more or less lift, and a plane flying respectively 'slower' or 'faster'. However increasing to much the wing area will result in a plane gliding over the ground and being unable to land.
Wing (in square meters) //Wing area of the aircraft
Wing area = (Wing_In area + Wing_Mid area + Wing_Out area) x 2
Aileron //aileron area
Flap // flap area
Stabilizer //stabilizer area
Elevator //elevator area
Keel //keel area
Rudder //rudder area
Wing_In //wing_in area
Wing_Mid //wing_mid area
Wing_Out //wing_out area
all these subsurfaces areas are best calculated/approximated on the 3ds model or the plans
FuselageCxS 0.0 //Additional drag for plane, nonzero for example in IL-2 perhaps to simulate radiator drag
AirbrakeCxS 0.0 //Drag created by airbrake
[Toughness] //Damage toughness of different parts
Numbers here are possibly not damage levels but rather part numbers (left and right keel of the tail, for example). Note that part size also affects the probability of hits. Vator means elevator like in mesh names.
[Arm] //Distances in meters from the center of plane for various parts, i.e. the moment arms of forces
Best measured on the 3D model or on the plans
Aileron //how far ailerons are from centerline
Flap //how far flaps are from centerline
Stabilizer //how far vertical stabilizer (stab) of tail is from plane center
Keel //how far horizontal stabilizer (keel) of tail is from plane center
Elevator //how far elevators are from plane center
Rudder //how far rudder is from plane center
Wing_In //how far inner wing is from centerline
Wing_Mid //how far midwing is from centerline
Wing_Out //how far outer wing is from centerline
GCenter 0.05 //This parameter possibly moves the aerodynamic center (action point of total aerodynamic force) relative to the center of gravity (should thus affect pitch)
– this need to be checked
GC_AOA_Shift 0.45 //possibly controls how much aerodynamic center moves forwards when angle of attack increases
– this need to be checked
GC_Flaps_Shift 0.15 //possibly controls how aerodynamic center moves when flaps are lowered, i.e. pitch change caused by flaps
– this need to be checked
GC_Gear_Shift -0.15 //possibly this controls how aerodynamic center moves when gear is lowered, i.e. pitch change caused by landing gear
– this need to be checked
[Engine] //emd file names and sections for each engine
[Params]
The various coefficients have a suffiix H_0 or H_1 and L_0 or L_1.
H indicates horizontal normal flight,
L indicates inverted flight
_0 means “without flaps (flaps closed)”
_1 means “flaps fully extended”
Pn min (hp) //Minimum Power required
V Pn min //Speed corresponding to Pn min
P_max //Maximal power delivered by the propellor
Vz or Vz_climb (m/s) //Maximum clim rate (in m/s)
V climb (km/h) //Maximum climb speed (in Km/h)
T_turn or T turn (s) //Mimimum time needed for a 360o turn
V_turn or V T turn (km/h) //Speed corresponding to T turn
R turn (m) //Mimimum Turn Radius
V R turn (km/h) //Speed corresponding to R Turn
Vmax (km/h) //max horizontal speed at Sea Level
//It is the maximum speed which the plane can reach, at altitude 0, by using the emergency power. This speed corresponds necessarily to a defined engine output (hp), therefore a traction on the propeller shaft (in Newton) which is calculated by the Il2 engine on the basis parameters related to the engine.
VmaxFLAPS (km/h) //Maximum speed at altitude 0 with flaps fully extended
//above this speed flaps will get jammed if kept extended beyond combat setting.
VmaxAllowed (km/h) //max dive speed. Above this speed wings and control surfaces will begin to be randomly lost
VmaxH (km/h) //max speed at altitude, however, actual speed is a result of complex FM calculations
HofVmax (m) //altitude of max speed, however, this is really defined by engine parameters
Vmin (km/h) //stall speed
VminFLAPS (km/h) //Minimum possible speed with extended flaps.
Under this speed, stall will occur.
CruiseSpeed //speed at which the plane is perfectly trimmed with neutral trim (“cruise speed”)
K_Max //It is the maximum Cy/Cx ratio.
This value is used by the Il2 engine as a control limit parameter – enabling to check that the value the ratio Cy/Cx remains in the range 0.6K_Max to 1.3K-Max.
V K_max //Speed corresponding to Kmax
AOACritH_0 //Maximum incidence angle corresponding to stall without flaps
(lift coefficient at that AoA is CyCritH_0)
AOACritH_1 //Maximum incidence angle corresponding to stall with flaps fully extended
AOA_land //Maximum incidence angle of stall at landing.
This value is hardcoded in Il2 and fixed at 12°
AOACritL_0 //Maximum angle of stall, without flaps, in inverted flight
This value is hardcoded in Il2 and fixed at -16°
(lift coefficient at that AoA is CyCritL_0)
FlapsAngSh //See AOACritL_1
AOACritL_1 //As AOACritH_0, but in inverted flight with flaps extended.
Calculation of this coefficient is based upon AOACritL_0 (hardcoded in Il2, with a fixed value of -16°) and upon FlapsAngSh.
The calculation uses a simple formula
AOACritL_1 = AOACritL_0 – FlapsAngSh
CriticalAOA //angle of attack for highest lift
[Polares]
Cy
//Coefficient of lift
The lift coefficient Cy is a straight line of slope lineCyCoeff and intercept coordonate Cy0_0 at x=0, and connects with two parabolas of coefficients parabCyCoeffH (positive incidence) and parabCyCoeffL (negative incidence = inverted flight)
Cy = Cy0_0 + lineCyCoeff*AoA
lineCyCoeff //slope of the Cy lift coefficient line
Cy = Cy0_0 + lineCyCoeff*AoA
CyCritH_0 //Coefficient of maximum lift Cy for altitude 0, in horizontal flight flat and without flaps. With this value (corresponding to stall), the incidence is maximum and speed is equal to Vmin.
CyCritH_1 //As CyCritH_0 but with flaps fully extended
Calculation of this parameter is based upon Cy0_1, AOACritH_1 et lineCyCoeff.
CyCritL_1 //As CyCritL_0, but with flaps fully extended.
Calculation culminates with a choice between two possible values (when the smaller value is chosen). Depending upon this chosen value, AOACritL_1 may be taken into account for further calculations by the Il2 engine. If AOACritL_1 is not taken into consideration, Il2 engine uses a default value of 0,7.
CriticalCy //biggest possible lift coefficient
- This needs to be checked
Cyo_max 0.15
//possibly the lift coefficient for zero angle of attack with landing flaps
- This needs to be checked
Cx //Coefficient of drag
The coefficient of drag Cx is schematized by a parabola of coefficient parabCxCoeff_0 positioned by two values Cy0_0 and AoAMinCx_Shift.
This parabola is replaced by a linear function (straight line or part of a sinusoid) beyond two critical values: AOAparabH and AOAparabL (symmetrical when compared to the top of the AOAMinCx parabola).
It should be noted that these two values (AOAparabH and AOAparabL) are hardcoded in Il2 and equal to +6 and -6° , for all aircraft.
Cx = CxMin_0 + parabCxCoeff_0*(AoA - AoA0 - AOAMinCx_Shift)2,
where AoA0 is AoA with Cy = 0, thus AoA0 = -Cy0_0/lineCyCoeff.
CxMin_0 //It is the minimum coefficient of drag Cx (without flaps) and corresponds to the top point of the parabola related to the ParabCxCoeff_0 coefficient.
This coefficient is calculated on the basis of P_Vmax, Vmax, Wing, ParabCxCoeff_0, AOAMinCx_Shift and also depends upon the position of the lift curve Cy.
//minimum profile drag coefficient for wings
CxMin_1 //As CxMin_0 but with flaps fully extended.
Its calcualtion is similar to the calculation of CxMin_0 but is based upon parameters for configuration with flaps extended (_1).
//affects flap drag
AOAMinCx_Shift //This parameter is used to position the coefficient of drag. In practice, it enables to set up the minimum coefficient of drag Cx by comparaison to the null value of the coefficient of lift Cy.
You can get more drag at high AoA with smaller AOAMinCx_Shift or with larger parabCxCoeff_0, but those also cause significantly more energy loss in turns.
The difference between those two parameters is that larger parabCxCoeff_0 makes also inverted flight slower, but smaller AOAMinCx_Shift makes inverted flight faster.
AOAMinCx_Shift and parabCxCoeff_0 seem to be useful parameters for adjusting turn performance and ceiling.
AOAMinCx_Shift possibly moves the increase of drag to higher AoA and parabCxCoeff_0 increases induced drag making the drag increase with AoA steeper.
Changing AOAMinCx_Shift from 0.8 to 0.0 causes a bit slower speed, climb and especially turn at all altitudes, and changing it to 2.0 improves turn performance and high-altitude speed significantly indicating less drag in high AoA situations.
A larger AOAMinCx_Shift causes less drag in normal flight and more drag in inverted flight.
ParabCxCoeff_0 //It is the coefficient of the parabola being used by Il2 to simulate the curve of the coefficient of drag Cx (without flaps).
An Higher parabCxCoeff_0 causes more drag in high AoA situations like tight turns and flying just below ceiling, thus ceiling is lowered a bit and turn time increases significantly, but SL speed stays almost the same.
Changing parabCxCoeff_0 doesn't affect performance with landing flaps, but for flaps there is parabCxCoeff_1.
parabCxCoeff_0 and parabCxCoeff_1 have direct influence on energy bleed in turns (loss of speed).
A larger parabCxCoeff means stronger drag increase when AoA increases to get more lift for turning. So, higher parabCxCoeff simply means more energy loss in turns and also worse high altitude performance because high AoA is needed to get enough lift in thin air at high altitude.
parabCxCoeff_0 and parabCxCoeff_1 have direct influence on energy bleed in turns (loss of speed).
Cy0_0 //First critical value of the Cx parabola
//the lift coefficient for AOA0 (zero angle of attack)
(AOA0 = -Cy0_0/lineCyCoeff.)
Cx = CxMin_0 + parabCxCoeff_0*(AoA - AoA0 - AOAMinCx_Shift)2,
where AoA0 is AoA with Cy = 0, thus AoA0 = -Cy0_0/lineCyCoeff.
Cy0_1 //As Cy0_0 but with flaps fully extended
Calculation of this parameter is based upon TakeOff, Wing, VminFlaps, lineCyCoeff et AOA_Land (this last parameter is hardcoded in Il2 and has a fixed value of 12°, no matter what aircraft is considered)
AoAMinCx_Shift //Second critical value of the Cx parabola
FlapsMult //It is a multiplication coefficient used for the calculation of the coefficient of the parabola used by Il2 to simulate the curve of the coefficient of drag Cx (without flaps).
ParabCxCoeff_1 //As ParabCxCoeff_0, but with flaps extended
Calculation of this coefficient is simple:
ParabCxCoeff_0 = ParabCxCoeff_0 x FlapsMult
CxCurvature 00.70
//possibly a coefficient for induced drag (if is that, then it should affect energy bleed in turns). A possible suitable equation may be
Cx = CxStraightness +( CxCurvature * Cy2) + wing profile drag as determined by the [Polares] parameters
CxStraightness 00.05
//possibly drag coefficient for drag caused by other parts than wings
CriticalAOAFlap 21.00
//angle of attack for highest lift with landing flaps
CriticalCyFlap 01.80
//biggest possible lift coefficient with landing flaps
SpinTailAlpha 17.00
//some parameter for spin, maybe affects difficulty of spin recovery
SpinCxLoss 0.10
// possibly drag loss for outer wing in spin, if that then it should adjust horizontal radius of spinning
– this need to be checked
SpinCyLoss 0.04
//possibly lift loss for inner wing in spin, it that then it should adjust how much inner wing drops in spin
– this need to be checked
parabAngle //parabAngle defines for how many degrees in AoA that quick drop of lift after AOACritH continues
// The parameters parabAngle, Decline and maxDistAng affect the deepness of stall.
Decline //Decline defines how quickly lift drops after AOACritH
// The parameters parabAngle, Decline and maxDistAng affect the deepness of stall.
maxDistAng //maxDistAng affects what happens for AoA larger than AOACritH
// The parameters parabAngle, Decline and maxDistAng affect the deepness of stall.
In lift coefficient function there is linear part for AoA close to 0 with slope lineCyCoeff and y-intersect Cy0.
Then for larger AoA that linear behaviour becomes non-linear so that maximum lift coefficient CyCritH is reached at AOACritH.
For more negative AoA in inverted flight that linear behaviour also becomes non-linear so that maximum lift coefficient CyCritL is reached at AOACritL.
Drag coefficient function is a parabola between AOACritL and AOACritH with a minimum drag coefficient CxMin at AoA = [zero lift AoA] + AOAMinCx_Shift.
Thus, larger AOAMinCx_Shift causes less drag in normal flight and more drag in inverted flight.
The curvature of drag coefficient parabola is parabCxCoeff, thus larger parabCxCoeff means stronger drag increase when AoA increases to get more lift for turning. So, higher parabCxCoeff simply means more energy loss in turns and also worse high altitude performance because high AoA is needed to get enough lift in thin air at high altitude. For AoA beyond critical values drag coefficient increases linearly and quickly with hardcoded slope.
Then there are still unknown parameters parabAngle, Decline and maxDistAng.
All those three unknown parameters affect the deepness of stall.
With AoA higher than AOACritH there seems to be three parabola parts that form continuous curve. First of those parabolas starts from point defined by AOACritH and CyCritH, continues up to AoA = AOACritH + parabAngle and has curvature defined by Decline. Last of those parts seems to be hardcoded and is used for AoA from maxDistAng to 90 degrees. The middle part is then fitted to the ends of those two other parts and is used for AoA from AOACritH + parabAngle to maxDistAng.
Thus, Decline defines how quickly lift drops after AOACritH, parabAngle defines for how many degrees in AoA that quick drop continues and maxDistAng affects what happens for AoA larger than that.
draw_graphs 0
// – this needs to be checked
Author
Topic: Variable pitch prop question (Read 417 times)
