Bf109E-3

[Hunin]

Unfortunatly I don't have time to dig my teeth into this right now but here is the relevant ingame data.

Quick first impressions:

1. Cl max seems too low for both retracted and fully extended flaps.
Should be 1.4 and 1.9 according to british testing, 1.3 and 1.62 ingame atm.

2. Turn time of 25 seconds corresponds with british testing but is significantly higher then the 18. something stated in the official Baubeschreibung.

3. 460 km/h on the deck corresponds with both german testing of Wrk.Nr. 1792
and swiss testing. The Baubeschreibung on the other hand gives 500 km/h.
Any ideas where that difference might come from Kurfy?

Anyway here are the cold hard facts:

;
; Messerschmitt Bf. 109 E-3 Flightmodel
;

;
[Aircraft]
;

Wingspan 9.867 m
Length 8.738 m

;
[Systems]
;

Propulsion Engine Daimler-Benz DB601A Propellor VDM Generic
Hydraulics Source Engine0 Pressure 100 bar Reservoir 8.5 pt
Electrics Source Engine0 Voltage 25.1 V BatteryCapacity 54 Ah GeneratorOutput 650 sW at 2000 RPM

LandingFlaps Mechanical Extends 25 sec
Undercarriage Retractable Hydraulic Extends 5.0 sec Folds Outwards OperatesThrough 320 kmh EmergencySystem PneumaticDischarge SafetyLock Nil SpringsStiffness Main 0.6 Tail 0.6 MaxDragEquivalentS 0.7 m2
WheelBrakes Hydraulic Efficiency 1.5
Fenster Mechanical Opens 0.5 sec
PitotHeater Electrical
LeadingEdgeSlats Mechanical Automatic Move 0.1 sec ResponseRange 15.0 to 15.01 deg

Hatch0 Mechanical Motion Type SwingingForward Time 2.0 sec Jettison Type Detachable Time 0.2 sec
Hatch1 Mechanical Motion Type Nil Time 0.0 sec Jettison Type Detachable Time 0.2 sec

;
[Controls]
;

Aileron Slider Threshold 340 kmh
Elevator Slider Threshold 400 kmh
Rudder Slider Threshold 400 kmh

AileronTrim Nil Default 0.017
ElevatorTrim Slider Range -0.5 to 0.5 Default 0.25
RudderTrim Nil Default 0.06

EngineThrottle Slider
EnginePitch Slider
EngineMagneto Switch M0 M1 M2 M12
EngineRadiator Rocker
EngineOilRadiator Slider
EngineMix Toggle
EngineWEP PushButton
EngineMix Toggle

LandingFlaps Rocker
Undercarriage Switch Up Neutral Down
UndercarriageEmergency ExpendableSwitch Close Open
WheelBrakes Slider
Fenster Toggle
AltimeterPinion Rocker Range 795 to 1040 Default 1000 mbar
Puppet0PriPitLight Slider
Puppet0SightLight Slider
NavSecFrequency Rocker
Timer0 CyclicSwitch
AcemakerSight Dimmer Toggle
TankSelector0 Toggle Off On Parked 0 Cruise 1 Selection 0 Flow FuelTank 1 to FuelTank 0 at 1 kg per second Selection 1 Flow FuelTank 1 to FuelTank 0 at 1 kg per second + FuelTank 0 to Engine 0
HydraulicsHandPump PushButton
PitotHeater Toggle
Timer0 CyclicSwitch

Puppet0Hatch Toggle Close Open Selection 0 Closes Hatch 0 Selection 1 Opens Hatch 0
Puppet0Jettison ExpendableSwitch Off On Selection 1 Sheds Hatch 0 Hatch 1

;
[Instruments]
;

EngineFuelPress Hydraulic Range 0 to 2 kgcm2
EngineOilPress Hydraulic Range 0 to 10 kgcm2
EngineOilTemp Electrical Range 0 to 120 C
EngineWaterTemp Electrical Range 0 to 120 C
EngineManifoldPress Mechanical Range 0.6 to 1.8 bar
EngineRPM Electrical Range 600 to 3600 RPM
EnginePropPitch Mechanical Range 0 to 12 hour
Speedometer Mechanical Range 0 to 800 kmh Pitot Kollsman
Altimeter Mechanical Dimension m
MagneticCompass Mechanical JamAngle 90.0 deg
SlipIndicator Mechanical Amplitude 12.0 deg
TurnIndicator Mechanical Source Primary NominalTurnTime 2 min
FuelReserve Electrical Range 0 to 400 litre
ArtificialHorizon Mechanical Source Primary Pitch Range -45 to 45 deg Roll Range -181 to 181 deg

GyroFeed Primary Electrical Secondary Nil

;
[Mass]
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Empty 2060 kg
TakeOff 2600 kg
Fuel 300 kg
FuelTanks Aluminum 100 kg Aluminum 200 kg
FuelFillingOrder Tank 0 Tank 1

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[Squares]
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Wing 16.4 m2
Aileron 1.1 m2
Flap 2.0 m2
Stabilizer 1.90 m2
Elevator 1.20 m2
Keel 1.00 m2
Rudder 1.10 m2

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[Arm]
;

Aileron 2.03 m
Flap 2.04 m
Stabilizer 5.15 m
Keel 5.18 m
Elevator 5.35 m
Rudder 5.45 m
Wing_In 1.25 m
Wing_Mid 2.50 m
Wing_Out 4.10 m
GCenter 0.05 m
GCenterZ 0.00 m
GC_AOA_Shift 0.45 m
GC_Flaps_Shift 0.20 m
GC_Gear_Shift 0.05 m
Wing_V 1.5

;
[Params]
;

SpinCxLoss 0.06
SpinCyLoss 0.03

Vmin 170.0 kmh
Vmax 470.0 kmh
VmaxAllowed 750.0 kmh
VmaxH 560.0 kmh at 4500.0 m
VminFLAPS 130.0 kmh
VmaxFLAPS 250.0 kmh
Vz_climb 20.0 ms
V_climb 270.0 kmh
T_turn 25.0 sec
V_turn 340.0 kmh
K_max 13.0
FlapsMult 1.0
FlapsAngSh 10.0

RangeAbility 480 km

SensYaw 0.6
SensPitch 0.7
SensRoll 0.32

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[Polares]
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lineCyCoeff 0.091
AOAMinCx_Shift 0.2
Cy0_0 0.15
AOACritH_0 18.0
AOACritL_0 -15.0
CyCritH_0 1.3
CyCritL_0 -0.64417434
CxMin_0 0.0275
parabCxCoeff_0 6.2E-4
Cy0_1 0.55
AOACritH_1 17.0
AOACritL_1 -19.0
CyCritH_1 1.62
CyCritL_1 -0.7
CxMin_1 0.11
parabCxCoeff_1 8.7E-4

slatAOACritHInc 3.0
slatCyCritHInc 1.3
slatParabCxCoeffInc 0.8E-4

parabAngle 5.0
Decline 0.010
maxDistAng 35.0

; ------------------------------------------------------------------------------
[DB601A]
; ------------------------------------------------------------------------------


General MaximalPower 1020 sPS DryWeight 590 kg Displacement 33.9 litre Cylinders 12 Bore 150 mm Stroke 160 mm Compression 6.9
Reliability Lifetime 100 h FailureProbability 0.0

RPM Minimal 500 Nominal 2200 Maximal 2326 Saturated 9999 Continuous 2326 Limiting 3000 Direction Right
Intake Ramming 0.5
Exhaust PlainBackpipe
Supercharger SingleStageHydroCoupling Efficiency 0.23 LimiterInput Manifold NominalPressure 1.35 bar ContinuousPressure 1.2 bar WEPPressure 1.45 bar NominalAltitude 4500 m
Valvetrain Generic SlowRunningEfficiency 0.1
FuelPump Pushrod NominalPressure 3 bar at 500 RPM
Carburettor GenericDirectInjection OrificeSlowFast 0.05 sec Dresser ThrottleDriven Input 0.75 to 1.0 Output 1.0 to 1.2
Starter Mechanical
Ignition DualMagneto FrontEfficiency 0.57

Throttle Slider Translation Linear Bore 7.9 cm IdleOpening 0.05 WEPType ClockworkWEPModeToggle OperatingTime 1 min CooldownTime 10 sec
Pitch Slider Angle Min 82 deg Max 26 deg WEP 40 deg Feathering Nil
Mix Slider Multiplier Range 0.7 to 1.0

CylinderHead Material CastIron Temperatures Min 120 C Nominal 140 C Max 160 C
AirRadiator Tunnel Louvre Nil FlowControl Nil
Water Material Glycol Reserve 75 kg Temperatures Min 40 C Nominal 94 C Max 115 C
WaterRadiator ThermostatedTunnel Pressurized Louvre Mechanical OpensAt 80 C FlowControl Manual ContinuousAt 0.25 MinimalDragAt 0.25 MaxDragEquivalentS 100 cm2
Oil Material Oil Reserve 8.5 gal Pressure 70 lbsqin at 600 RPM Temperatures Min 30 C Nominal 75 C Max 105 C
OilRadiator ThermostatedTunnel Louvre Mechanical OpensAt 20 C FlowControl Manual ContinuousAt 0.25 MinimalDragAt 0.25 MaxDragEquivalentS 100 cm2

Propellor Reductor 0.64516129 Governor VariablePitch BladeAngleSpeed 1 degsec

SoundName motor.merlin

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[Generic]
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Construction VisualModel VDM Diameter 3100 mm Blades 3 BladeBreadthK 0.8 Mass 140 kg AngleRange 26 deg to 82 deg
DeIcing Nil

lineCyCoeff 0.07
AOAMinCx_Shift 0.0
Cy0_0 0.0
AOACritH_0 24.0
AOACritL_0 -22.0
CyCritH_0 1.3
CyCritL_0 -0.8
CxMin_0 0.02
parabCxCoeff_0 3.8E-4

parabAngle 7.0
Decline 0.002
maxDistAng 40.0

;

[unreasonable]

If this data is from the game files it shows V climb as 270kmh. (I assume this is supposed to be Vy - speed for best rate of climb). Kurfurst's test used a start speed of 250kmh. This might explain why the slope is "wrong".

Retest? (I am nowhere near a good enough pilot to do it myself I am afraid).

[609_Huetz]

That still will leave us at the problem that the mixture is not working correctly on either side - red or blue.

My concern, the higher you get, the more your data will be off due to this.

[Hunin]

I suspect it has something to do with this:

Mix Slider Multiplier Range 0.7 to 1.0

If my guess is correct and the function is linear ( 1 beeing full rich and 0 beeing full lean ) a mixture of 70 % seems awefully rich for flight above 4000 meters.

[unreasonable]

If you open up one of the dreaded info windows and put in the engine data, you can see the mix shown as 100% irrespective of height - this might be showing only the position of the control, but it I agree it certainly looks as though auto mix is not working. I also get the wheezing and black smoke puffs after about 5km height.

[Viper2000]

The simplest demonstration is to fly in no cockpit mode and look at the exhaust flame turn from blue to yellow during the climb; you'll see the same problem in the Spitfire & Hurricane too.

I think they just forgot the "AUTO" part of AUTO RICH.

As an aside, the large yellow flame is the result of after-burning, which is the continuation of combustion outside of the cylinder. This term is generally misused, especially by Americans, as a surrogate for reheat in the context of gas turbines, but it actually has, or at least had, a quite specific meaning in the context of piston engines before the turbojet was even thought of (on which note, today is the 74th anniversary of the first run of Sir Frank Whittle's engine, the 50th anniversary of Gagarin's space flight, the 30th anniversary of the first Shuttle flight, and, somewhat less significantly for aviation, my 27th birthday).

[IvanK]

"....by Americans, as a surrogate for reheat in the context of gas turbines"

LOL only the Poms call it reheat the rest of the world settled on Afterburner ... as did CLOD.

[Kurfürst]

Originally Posted by Hunin

Quick first impressions:

1. Cl max seems too low for both retracted and fully extended flaps.
Should be 1.4 and 1.9 according to british testing, 1.3 and 1.62 ingame atm.

Possibly, I'd have to check the Kurvenwendigkeit der Me typen doc, perhaps I can some data for that..

What is behind it that they did a couple of stall speed trials with the Spit earlier, and from the stall speed they deducted Clmax (which in itself lends some room for error, recall those lenghty discussions about what 'stall speed' really is'?). Based on the date, they calculated a doghouse turn chart for the Spi.

When the 109E-3 was handed over by the French for testing, the British wanted a similiar graphical comparison made. They made a similiar test procedure to establish 109E stall speeds, based on that, the Clmax.

at http://www.kurfurst.org/Tactical_tri...ls/Morgan.html

Originally Posted by Hunin

2. Turn time of 25 seconds corresponds with british testing but is significantly higher then the 18. something stated in the official Baubeschreibung.

As noted above, there was no actual measurement of the 109E turn times by British; or if there were, the 25 seconds value was not derived from testing. The Kurwenwendigkeit der Me typen part I. report by Messerschmitt AG calculates the turn time with 990PS on the deck, using proper propellor effiency curves etc.

It gives the turn time for 109E as 18.92 secs on the deck, a fairly believable number IMHO. What complicates things that appearantly we have (ca. 50HP higher) DB 601Aa ratings present, not DB 601A the report assumes. Well say 18-18.5 secs in this case. Actually it should be possible to calculate it precisly using the report.

3. 460 km/h on the deck corresponds with both german testing of Wrk.Nr. 1792
and swiss testing. The Baubeschreibung on the other hand gives 500 km/h.
Any ideas where that difference might come from Kurfy?

I am not sure, but I and others have a very strong suspicion the 460-470ish values are either for the 30-min rating, or due for using the high altitude (2nd speed, FS gear etc.) blower at low level too.

The conditions of the Wrk.Nr. 1792 test are not known for certain, as the report aimed for relative speeds w. and w/o MG FF barrels in the wing, and not absolute figures. Even boost is uncertain, a the report mentions that the figures are not corrected for nominal engine output etc.

The Baubescreibung is the official performance specs for the 109E, which the manufacturer guaranteed to be met withon +/- 5% tolerenace. Those Emils that could not satisfy the specs were not accepted by BAL, the LW's quality control organisation. Even at the war's end!

Moreover the 500/570 specifications laid down in the Bbschr. 109E paper were confirmed with the detailed report of the Emil prototype:

http://www.kurfurst.org/Performance_...w_109V15a.html



and by French testing of Bf 109E-3 WNr. 1340 (same aircraft as tested by the Brits later) also seem to confirm that the level speed figures laid down in the in German specs can be confirmed:
http://www.kurfurst.org/Performance_...formanceT.html
(beware of the bewildering combination of open/closed raditors, RPMs and manifold pressures used.. its a bit of a pity that the French used Hgmm for boost instead of ata. Confusing..)

Besides if one uses simple common sense, its quite easy to see. If you look at the Spitfire and Bf 109E speeds and powers at rated altitude, you'll find that that both do around 570 km/h, but the Spit has actually quite a bit of more power at this altitude (as opposed to popular knowledge, the Merlin III was pretty good at alt). It follows that it has more drag. Now, at SL the Spit does, iirc some 282 mph at +6 1/4 boost, which is 890 HP. And the 109 there has 990 (601A-1) to 1050 HP (601Aa). It follows that should be a good deal faster than 282 mph (454 kph), with 150 HP extra in less draggy airframe..

Just as a side note: 5% of 500 kmh = 25 kmh, so a 475 kmh fast Emil would still have been accepted

Just wait and take a look again when mixture ratio is fixed. This might in fact lead to more nominal values when finally this parameter can be optimized.

When talking about drag one has to be a bit cautious when saying which airframe is less draggy when talking about flight operations as drag is composed of friction drag and induced drag. The former is due to friction over the skin and therefore mainly dependent on speed and altitude, the latter foremost dependent on angle of attack. So it might be (might be, I don't say that it should be but yet could be) that the spit just had to fly at an angle of attack at high altitude that went along with higher induced drag while it had to use less angle of attack at lower altitudes and therefore had less drag. Actually it is quite reasonable to assume that this is indeed the case. When the air density decreases the plane has to increase angle of attack for level flight but then can reduce angle of attack with tanks more empty. The behaviour could be very much different for the 109 and the Spit. I cannot tell in which ways.

[Kurfürst]

Originally Posted by 41Sqn_Stormcrow

Just as a side note: 5% of 500 kmh = 25 kmh, so a 475 kmh fast Emil would still have been accepted

Just wait and take a look again when mixture ratio is fixed. This might in fact lead to more nominal values when finally this parameter can be optimized.

Top speeds at SL and rated altitude are coded (ie. set by developer manually. Currently its 470 at SL (which is double wrong as I suspect it should be attainable only with the 1175 PS rating instead of the actual 1045 PS rating), and 560 at 4500 meter for the Emil). I guess the engine works out the rest of the graph from these figures (its pretty obvious between SL and FTH, the above probably follows the same rules for all planes, taking into account stall speed, which is also manually set.