Do-335 Cockpit Information

[Pfeil]

For the past few months I've been gathering information on the Dornier Do-335 "Pfeil", more specifically the cockpit and its functions.

The Aircraft Guide and especially the Cockpit Arrangement Guide do explain a number of things, but they're mostly limited to functional equipment in IL2.

I realize IL2 is not a study sim, nor do I expect it to be. However, while researching this aircraft I found a few discrepancies with the RL cockpit versus the one in IL2 I'd like to point out.

--Bugs--

-Both Do-335 carry the same amount of fuel in IL2.
The B-series, of which the V13 was the prototype, carried wing mounted MG103's. To make room for these, smaller wingtanks were fitted containing 220L instead of 310L.

-When the top rudder section is shot off, the aircraft handles as if there is no rudder present. I.E. the tail feels very "loose", and though the bottom rudder still moves, it has no effect.

-The prop pitch gauges are only partially lit at night. The gauge faces are lit but the needles are not. See this screenshot.

-The artificial horizon isn't correctly lit, the "bar" that indicates aircraft attitude remains dark, thus making it useless at night.

-Is the Fire Warning Panel(#39 on the panel) functional? I've had engine fires, but the lights don't seem to come on. This warning system was implemented because pilots couldn't see the rear engine from the cockpit. A legitimate problem in IL2 as well.

-When using the ejection seat, the aircraft can be controlled while the pilot has ejected. Up to the moment the pilot detaches from the ejection seat.
It's also possible to switch to cockpit view during this time.

-The pilot's feet stick though the floor and are visible in the nose gear bay.

--Animations--

-The main trigger intersects with the bar it's mounted on when depressed.
I believe this occurs because the bar is modeled rectangular to save polygons, rather than round.
Screenshots: Depressed, Released.

-The bomb release button on the "yoke" has a black spot when depressed.
Possibly because it intersects with the model geometry below it.
Screenshots: Depressed, Released.

-The trim indicator(#15 LH console) doesn't move, neither do the appropriate trim controls(#13, #14 and #16 LH console).

-Most of the switches are static and in a neutral position

-The flaps switch acts as an analog control.
I don't have information about this on the real aircraft, however I assume it was either a momentary (on)-off-(on) switch or a multi-position switch.

--Engine/Development Limitations--

-Later prototypes had mirrors
In early development, test pilots complained of poor rearward visibility.
Because of this, a new canopy was designed featuring bubbles on either side with mirrors fitted in them.
Edit: In fact, every model aside from the very first prototype had these bubbles.

-The ingame A-0 model is actually based on later prototypes.
It lacks the distinctive round landing gear covers as well as the chin mounted oil cooler, both seen in this picture.

-The B-series had a heavily armored windshield.
The IL2 V13(B-2 prototype) has the old A-series windshield.

-The wheels on the B-series (V13) had standardized larger tires.
This necessitated a 45 degree rotation of the nosewheel when retracted.

-The ventral fin of the tail section could be jettisoned in case of emergency (Switch #27 Left Panel).
When attempting a belly landing, the ventral fin would pitch the nose down, forcing it into the ground. This could prove fatal with landing speeds of over 200kph.

-The airspeed indicator in this aircraft is also used in the Me262 and a few others. The real aircraft had two sources on board to determine airspeed, when the aircraft reached 400 km/h it would switch to the second source.
The airspeed indicator has two needles with a cover in between, so only one needle is visible at a time. A photo of this instrument.
According to this, the second needle indicates TAS instead of IAS.

-The radio altimeter in the real aircraft can be set to two scales, one from 0-150m(50, 100 and 150 indicated) and one from 0-750 as implemented in IL2

-The oxygen equipment isn't functional, even with a mask on neither pressure or flow gauges move(the pilot doesn't choke either though).

-Because of its speed, the Do-335's controls could be set to be less sensitive. This was achieved by mechanically switching between a long and a short lever to actuate the controls. Thus reducing the angle of deflection for all control surfaces.
The pilot could flip a switch(controlling an electric pressure valve) to switch control modes. There is also an emergency valve(#42 panel) which switches back to the normal(longest lever) controls.
According to this source the "snelflug" mode reduced control surface actuation to half that of the normal mode

-There is a UV lighting system in the aircraft, I'm assuming for night flight. These were basically cockpit floodlights.

-The module with flaps, gear and dive brake indicators(This aircraft never had dive brakes, but the module was universal so its use is correct) is portrayed as a conventional system using lights to indicate flaps/gear status.
In the real aircraft, rollers with a white and black side were used that would rotate to display their status.
However, Hans-Werner Lerche states "the three small green lights on the instrument panel indicated that all was clear". This could possibly mean the module had lights for night operations.
According to the manual, there is a version of this module where the dive brake section was replaced with a bomb door indicator.

--Minor inaccuracies--

-The white light (#36 on the panel) is permanently illuminated.
IRL, this indicates a low fuel level in the main tank and serves to tell the pilot to pump fuel from the wing tanks into the main tank. This is done with the switch next to it(#35).

-The Deviation tables for either compass source are not visible.
IRL, plates(#8 and #9 on the LH console) with these tables are present, the left hand plate for the Backup compass and the right hand plate for the Main compass. These are both textured as Backup compass plates in IL2 without any data on them.

-The flaps indicator has 3 positions, in IL2 these are combat, takeoff and landing. In the real aircraft these are closed, center and open.


I do understand this is only one aircraft in a collection of many, and an experimental one that didn't really see action at that.



Below are all the functions I've managed to find. I don't speak german and I lack a complete manual, so some may not be correct.
If you have more information on these(or even better, have a manual), please help me complete this.


Left Hand Console

1: Starter switch(Push to spool flywheel, pull to engage flywheel to engine. Function deduced from these)
2: Starter Engine selector switch?
3:
4:
5: Engine 1/2 Radiator (Open - Closed/Auto)
6: Engine 2 Fire Extinguisher
7: Engine 1 Fire Extinguisher
8: Deviation Tables For Backup Compass (Not Included in IL2, table is not in texture)
9: Deviation Tables For Main Master/Slave Compass (Uses same texture as #8)
10: Engine 1/2 Fuel Supply(Off-Left Fuel Line-Right Fuel Line-Both)
11: Engine 1/2 Throttle
12: Throttle friction
13: Rudder Trim
14: Aileron Trim
15: Trim indicator
16: Elevator Trim wheel
17: Oxygen Valve
18: Backup Compass
19: Engine 1/2 Magnetos (Off - Mag 1 - Mag 2 - Both)
20: Emergency Power Cutoff(Presumably cuts power to all electrical systems to prevent shorts/fire)
21: Flight Control Sensitivity Setting (When speed is below 400 km/h normal setting is used, when above, switch is set to "snelflug" to reduce control surface actuation angle)
22/23: Engine 1/2 Auto/Manual Prop Pitch Switch
24: Engine 1/2 Manual Prop pitch controls
25: Flaps switch
26: Landing gear switch
27: Belly landing switch (Activates explosive bolts to jettison the ventral rudder)

Main Panel (V13/B-2 Prototype)

1: OAT (Outside Air Temperature)
2: UV Light Dimmer
3: Daughter Compass Master/Gyro Input selector (Sets source for daughter compass heading indication)
4: Additional Identification Lights
5: Landing Light Switch
6: Identification(Navigation) Lights
7: Instrument Lighting?
8: Pitot Heater
9: Master Arm (Enable On Board Weapons)
10: Clock
11: Radio Altimeter
12: Ammunition Counters (Left Wing - Left Nose - Center - Right Nose - Right Wing) with "Empty" warning lights
13/14/15: Flap Position Indicator (Combat, Takeoff, Landing)
16: Landing gear indicator
17/18/19: Dive Brake Position Indicator (Dive Brake not installed)
20: Compass Illumination Dimmer
21: Oxygen Pressure
22: Oxygen Flow indicator
23: Airspeed indicator
24: Artificial Horizon with Turn/Bank indicator
25: Variometer
26: Altimeter
27: Compass
28: AFN 2 Radio Direction Finder
29: Engine 1/2 Prop Pitch
30: Engine 1/2 RPM/Manifold Pressure Indicator
31: Engine 1/2 Coolant Temperature
32: Engine 1/2 Oil Temperature
33: Engine 1/2 Fuel Pressure
34: Engine 1/2 Oil Pressure
35: Fuel Pump Switch (Transfers fuel from wing to main tanks)
36: Main Tank Low Fuel Indicator (White if main tank nearly empty and fuel needs to be transferred from wing tanks)
37: Fuel Level warning light Aprox. 20 minutes flight time remaining when illuminated
38: Fuel Level
39: Fire Warning Lights
40: Landing Gear Emergency Release Valve
41: Flaps Emergency Release Valve
42: High Speed Control Setting Emergency Disengage Valve
43: Bomb Doors Emergency Closing Valve
44: Bomb Door Emergency Release Handle
45: Stall Warning Light(Illuminated under ±150kph TAS, even when not in a stall)

Yoke

1: Bomb Release Button
2:
3: PATIN Autopilot Engage Switch
4: Microphone Button
5: PATIN Autopilot Direction Dial
6: Cannon Trigger
7: MG 151 Trigger (Button on back, pressed by pivoting lever)

Floor

1: Hydraulic Pressure(Landing Gear/Brakes)
2: Pneumatic Pressure
3: Ejector Seat Pressure
4:
5:
6:
7:
8: Left Rudder Pedal Adjust
9: Right Rudder Pedal Adjust

Right Hand Console

1:
2:
3:
4: FuG25a IFF Mode Switch (Key 1, Off, Key 2)
5: FuG25a IFF Test Button
6: FuG25a IFF Operation Indicator Light(Send/receive?)
7: Emergency eject switch (Activates explosive bolts to jettison the aft propeller and dorsal rudder)
8: Navigation Lights Fuse?
9:
10:
11:
12: Automatic Prop. Pitch Fuse?
13: Automatic Prop. Pitch Fuse?
14: Fuel Pump Fuse?
15: Fuel Pump Fuse?
16/17: Auxiliary Fuses
18: #1 Engine Generator 1?
19: #1 Engine Generator 2?
20:
21:
22: #2 Engine Generator 1?
23: #2 Engine Generator 2?
24/25: Gunsight Fuses
26: Left MG151 Fuse
27: Right MG151 Fuse
28: FuG16 Receiver Dynamotor
29: FuG16 Transmitter Dynamotor
30:
31: Bomb Fuse Mode Dial (Lower round knob fuse time, upper rectangular knob fuse type)
32-46: Bomb Arming/Salvo panel?
47/48: Radio On/Off Switch
49: Receiver Frequency Indicator
50:
51: Receiver Frequency Preset Indicator
52: Receiver Frequency Preset Knob
53: Receiver Fine-tuning Knob
54: FuG16 Mounting Screw
55: Connector for receiver test equipment(Under screw locked cover)
56: Volume Knob with (Mute?) switch
57: Oscillation Indicator (Signal Strength Indicator?)
58: Fuse Cover(Main and reserve fuse)
59: Phase Adjustment Screw
60: Transmitter Frequency Indicator
61: Transmitter Frequency Preset Indicator
62:
63: Transmitter Frequency Preset Knob
64: Connector for transmitter test equipment(Under screw locked cover)
65:
66: FuG16 Mounting Screw


Most of the information not found in the manual came from this illustration:

Sadly, it doesn't include all of the cockpit as parts of the side consoles are missing. The biggest problem with this particular image however is the illegibility of the numbers. It appears the scanner didn't pick them up all that well. The low resolution of the image rendered my attempts at enhancing it futile.

What's driving me insane in particular are the two levers left of the throttle controls. This version of the aircraft does not have superchargers, though later models with them were developed. Does anyone know the function of these?
Edit: this topic by ZG15_FALKE gave me the information, the levers control fuel supply to each engine.

--General Do-335 Information--

-Neither of the guns eject shells or belt linkages. They are instead collected in boxes inside the fuselage for reuse. (A models only)

-The reservoir for the hydraulics, while armored, is vulnerable due to its position in the port(left) wing.
If the wing is damaged, especially if close to the root, check floor gauge #1.
If this gauge indicates zero, the landing gear must be extended manually.
Without hydraulic pressure, the brakes will not work either.

-The Messerschmitt P8 High Speed Reversible-Pitch Propeller was to be tested on model A-08
The propeller pitch could not only be feathered, but set to a negative angle to provide thrust reversing to brake in flight or on the taxiing run after landing. This reduced the landing rollout by 200m.(luchtoorlog.be, Monogram Close-Up #21)


TL;DR: The Do-335 could be even more awesome with some Dev love, and I'm looking for a manual detailing the cockpit and its operation.


Sources:
Monogram Close-Up 21 - Do 335
cockpitinstrumente.de
luchtoorlog.be
noding.com, RIP Jan-Martin Nøding
this topic by ZG15_FALKE
Luftwaffe Test Pilot - Hans-Werner Lerche

[EJGr.Ost_Caspar]

Hello Pfeil!

Impressive instant posting!
Thanks for the detailed report. Unfortunately many cockpits suffer from static switches and levers (where it could have been animated). This was some kind of simplification, that 1CM seem to have made to reduce workload/time, even the if the modeler had prepared the model for such features. If we start to fix such things in general, we would bring us into an impossible situation, that we would have to do it for all cockpits.

However, regarding the things, that you pointed out as bugs, we will take a look into it.
If your points are valuable, it will be fixed. Maybe in that process, we can care for some of other points too.

[Pfeil]

Thank you Caspar. I didn't expect a reply on such a niche subject this quickly.

The point about the switch animations was included to make the list as comprehensive as possible. I understand that time and budget constraints limit the detail on any one particular aircraft.

I'm very glad to see you would consider further developing both this aircraft and IL2 in general. I've greatly enjoyed your additions to the sim. They're what convinced me to dust off my joystick and return to flight simulation.

[Pfeil]

Please excuse the double post. As the information pertains to a number of aircraft I hope I'm allowed to bump the topic.


Something I've been thinking about, but couldn't remember when making the list, is the radio altimeter.
The principle behind the device is relatively simple: A transmitter uses an antenna in the wing of the aircraft to send a radio wave towards the ground, where the wave bounces back up towards the receiver antenna.
The time this takes is used used to calculate the distance.

The problem with this technology is its reliance on aircraft orientation. To get an accurate reading, straight and level flight is required.
This is because when the antennas are not pointing straight down, the distance the signal wave has to travel is longer.
Modern radio altimeter measurements are taken from the fuselage, so it's less of a problem there. Along with its centered mounting, some aircraft also have the antennas on a gimbal, so they're always pointed straight down(with limitations of course, usually 40° pitch/roll IIRC).

However, WWII era german aircraft with a radio altimeter have the antennas mounted in the wing(either left or right, depending on the aircraft). This means when the aircraft rolls left with the antennas mounted in the right wing, the distance measured increases, and vice versa.

In IL2, this isn't taken into account at all. Even when flying inverted(with the antennas pointed toward the sky, I.E. having nothing for the radio waves to bounce back off of) the exact distance to the ground is indicated.
One thing I haven't tested is whether the measurement is calculated from the bottom of the fuselage, either wing or even the center of the aircraft model.

This is not exclusive to the Do-335 by any means. I've tested a number of aircraft which in real life carry the FuG 101a radio altimeter(BF110, Ju88) in IL2 and all of them exhibit this behavior.


Another thing I've come across in multiple aircraft is the lack of lighting on the artificial horizon. Even though most of the instrument is lit, the "bar" indicating aircraft attitude is not.
This is very problematic on dark nights, especially if there's no moon.
I would argue the entire instrument is rendered useless in this situation, as the actual indicator becomes invisible.

The following screenshot illustrates this problem perfectly:

With quite a bit of effort you can still make out the indicator running diagonally trough the instrument. However in anything but a static screenshot it's pretty much unreadable.


A similar bug, relevant only to the Do-335 also exists with the prop pitch gauges. I've detailed this in the main post.

[IvanK]

Originally Posted by Pfeil

Another thing I've come across in multiple aircraft is the lack of lighting on the artificial horizon. Even though most of the instrument is lit, the "bar" indicating aircraft attitude is not.
This is very problematic on dark nights, especially if there's no moon.
I would argue the entire instrument is rendered useless in this situation, as the actual indicator becomes invisible.

The following screenshot illustrates this problem perfectly:

With quite a bit of effort you can still make out the indicator running diagonally trough the instrument. However in anything but a static screenshot it's pretty much unreadable.


A similar bug, relevant only to the Do-335 also exists with the prop pitch gauges. I've detailed this in the main post.

This subject on AH and general cockpit lighting is already under discussion in DT.

[Pfeil]

I've just found out what an utter moron I am. All 3 "bugs" related to manual settings are my own mistake: I had complex engine management turned off.

Prop pitch, feathering and radiator can all be set manually when this is enabled.

I sincerely apologize for wasting your time through my own incompetence.

[Pfeil]

Found another bug, a somewhat annoying one:

When the top rudder section is shot off/removed, the aircraft handles as if there is no rudder present. I.E. the tail feels very "loose", even though the bottom rudder is still present and moving, which has no effect.

As there are aircraft with multiple rudder sections(B25, PE-2/3, HE162, etc) I don't think this is an engine limitation.


There's also a graphical bug/inaccuracy when the top rudder section is removed, either by damage or jettisoning. The part of the fuselage where it was attached is smooth, with no skeleton visible.

Edit: Another damage related bug: When the aft section of the aircraft is missing(Shot/broken off) and the ejection procedure is started(ctrl-e), the read propeller appears where it would be if the tail section had still been in place(I.E. the animation does not take damage in to account). I'm not sure whether the top tail section reappears as well.

Edit #2: When hydraulic pressure is lost, the gear can be extended manually. In the sim, this is done by repeatedly pressing the control until the gear is down and locked. This behavior is correct for aircraft like the I-16, where the gear is extended and retracted with a crank. On the Do-335, emergency gear(and flap) extension is done by opening a valve(Main panel, #40 gear, #41 flaps). I'm not sure whether this uses gravity to drop the gear, or a separate pressure tank. I'm assuming the latter.

[Pursuivant]

Great stuff!

Sadly, anything related to life support (e.g., oxygen flow meters), radio communications (e.g., different radio channels) or intercom systems that you see in an IL2 aircraft cockpit is purely cosmetic. Those systems are extremely simplified and "automated" in the game.

Likewise, there are a number of other aircraft features, such as de-icing equipment switches, weapon arming switches, first aid kits, flares and hand-held fire extinguishers, which are just eye candy. None of those systems is modeled in the game.

[Pfeil]

While transcribing the flight manual, I came across a surprising mistake in the Do-335 cockpit, and possibly the damage model:


As you can see the manual states landing flaps and gear should not be extended over 270 kph, and takeoff flaps over 340 kph;
In the cockpit of the IL2 Do-335 however, the placard on the instrument panel states landing flaps should not be extended over 340 kph, while landing gear and takeoff flaps can be extended under 340 kph.

I would assume the flight manual is correct in this(the numbers also make more sense this way), and yet photos of the original machine actually show the same mistake in the actual cockpit!

I can only assume, working under immense pressure lead to mistakes, and whoever made the placard in the first place, got the values mixed up.
In fact, photos of VG+PH before its restoration show that placard without any text at all, so do illustrations in the manual(though it does say speed limits are noted in the cockpit), suggesting the mistake came from a single prototype.
Despite this, I have seen replica instrument panels duplicating this text, mistakes and all, which isn't that surprising considering the very small amount of reference material available.


The question I have for Team Daidalos is actually about the damage model:
Knowing that the placard is incorrect, is the gear too strong?
I have been extending it at 340 kph until now, and it doesn't get damaged at that speed(The aircraft does shake like it's about to fall apart though).

[KG26_Alpha]

I would trust whats indicated in the cockpit and not whats in the manual.

Manuals have printing errors usually corrected at the point of issue before a new run of corrected manuals are issued.












.