Avionics Bending: Radio Digital Distance Magnetic Indicator (RDDMI) (Analysis)

The RDDMI instrument used on the Lockheed L-1011 is a rather generic one. Many of the RDDMI units used on the L-1011 did not provide the capability to switch from VOR to ADF with the two switches to the bottom right and the bottom left of the unit.


The units I picked for my project are actually from two different aircraft. The one featured in the blog posting was flown on a Boeing 737 and the other one that I used on this project was flown on a Boeing 747. However, the same RDDMI instrument was also used on the Lockheed L-1011.

Here are the internals of the instrument:

1) Top View


2) Left side

3) Bottom view


4) Right side


The two needles on the front of the instrument are driven by two Synchro Receivers. They are arranged in a rather interesting way. The shaft of the receiver in the back runs through the synchro receiver in the front.

Original Flight Hardware: Throttle Quadrant

Thanks to Lee King and BONEYARD2U I am now a proud owner of a L-1011 Throttle Quadrant. The unit is in great shape except for a few missing parts, such as the parking brake handle. Once the throttle elements are repainted white it will look awesome again. The quadrant appears to be from L-1011 103P-1127.



There is also some damage to the plastic cover the throttles and underneath the Fuel and Ignition switches. However, all this will be fairly easy to fix.

Original Flight Hardware: Main Instrument Panel (MIP) - First Officer Side

Here is the current status of the right hand side main instrument panel. It is pretty much complete, except for one instrument missing (a small cabin altitude indicator) and the HSI control panel below it. The Control surface instrument will eventually be replaced with on that is original to the L-1011 (since the one in the picture is from a DC-10). But here are the instruments that I picked for the project (from top left to right):

• AFC Modes (as flown on the L-1011)
• AFC Warning (as flown on the L-1011)
• Instrument Comparator (as flown on the L-1011)
• Static Air Temperature - SAT (as flown on the L-1011)
• True Air Speed - TAS (as flown on the L-1011)
• Surface Position Indicator (as flown on the McDonald-Douglas DC-10)
• Airspeed Indicator (as flown on the L-1011)
• Attitude Direction Indicator ADI (as flown on the Airbus A300)
• Radar Altimeter Tape (as flown on a Boeing 747)
• Altimeter (as flown on the L-1011)
• Radio Digital Distance Magnetic Indicator (RDDMI) (originally flown on a Boeing 747)
• Horizontal Situation Indicator HSI (as flown on the Airbus A300)
• Vertical Speed Indicator VSI (as flown on the McDonald-Douglas DC-10)
• Chronograph (as flown on the L-1011)
• Instrument Source Select (as flown on the L-1011)

Again, it is a bit of a mix, but, potentially all these instruments could have flown on the Lockheed L-1011 given a specific customer configuration.

Original Flight Hardware: Heading/Pitch Mode Panel

I finally added the last panel for the autopilot of the Lockheed L-1011. The panel that completed my set is the HEADING/PITCH MODE panel. It's actually a really neat device, it has a vertical speed dial that is synchronized to the vertical speed of the aircraft and can also be overridden with the dial to the right of it. The idea is that in control wheel steering the pilot would pitch the aircraft to the correct vertical speed and then engage the autopilot. The panel also has the heading input for the automatic flight system.

Below is a picture of the complete autopilot of the Lockheed L-1011. This one is completely analog, the -500 models also had a digital version.


The other switch elements on the panel are:

• VS ... Vertical Speed (Hold)
• ALT ... Altitude (Arm / Hold)
• IAS ... Indicated Airspeed (Arm / Hold)
• MACH ... Mach Speed (Arm/Hold)
• HDG ... Heading (Arm/Hold0

The various modes will be indicated on the AFCS Mode Indicators.


Panel Location

Original Flight Hardware: Slat Monitor

The Slat Monitor panel can be found on the upper Flight Engineer panel of the Lockheed L-1011. The panel shows the status and degree extension of the leading edge lifting devices, aka. Slats. There are 3 1/2 indicators for each wing showing the status of Slat panels 1, 2, 3, 4, 5, 6 and 7. There is an ON switch for the Slat monitor and a guarded switch that will lock the slats in place.



The round gauge has a flag that indicates system state and an indicator for the right and the left wing that shows degree extension of the slats.



Panel Location

Original Flight Hardware: Electrical

The Electrical panel is one of the main components on the lower Flight Engineer Panel. It contains all the controls for the power generators, external power, battery and the associated cross-bar switching. The L-1011 has a considerable number of independent power buses and a very intricate tie-bar and sync-bar arrangement.



The picture below shows the grouping of the power sources by APU, Engine1, Engine2 and Engine3.



Each engine driven constant speed drive has an oil temperature gauge that measures the oil temperature of the drive and also has an option to show the temperature rise of the oil entering the drive compared to the oil exiting the drive. By the way, the CSD instruments in the picture, again, are from a Boeing 747. The constant speed drives on the L-1011 are actually called IDCs. I chose the Boeing 747 instruments because they are easier to interface with my electronics hardware.

The flow for the power generators is from the top to the bottom of the panel. On top we have the constant speed drive instrumentation, then the breakers for the generator fields and towards the bottom of them panel we have the generator output breakers and the AC and DC cross bars. The next picture shows the flow of generated power from the CSD(IDC)s to the bus ties.



The upper right hand side of the panel has gauges and measurement selectors for various AC and DC power sources. The AC instruments measure power source frequency and AC Volts (that instrument is still missing) and the DC instruments measure DC Volts and DC Amps (charge and discharge). I was always somewhat surprised that he L-1011 did not have an AC Amp meter, like the Boeing 747. The following shows the measurement selections for the non-engine driven power sources for AC and DC.



The image below shows the measurements for the engine driven AC generators and the Transformer/Rectifier components that link the 3 AC buses to the DC bus.



Panel Location


L-1011 flight station picture used with permission from Sam Chui. Retrieved from airliners.net

Original Flight Hardware: Fire Extinguisher Test

The Fire Extinguisher Test panel is part of the L-1011 fire warning and suppression system. The panel has indicators for each engine on the L-1011 and the Auxiliary Power Unit (APU). There are two fire extinguisher bottles for each of the monitored components. Hence, each annunciator has an indicator for MAIN and ALTN (alternate). There is a breaker on the panel that is labeled with SHORT and a test switch to activate the system test circuitry.



The panel is located in the upper section of the Flight Engineers panel. It is co-located with all the other fire warning and suppression test panels.

Panel Location


L-1011 flight station picture used with permission from Sam Chui. Retrieved from airliners.net

Original Flight Hardware: Wheel Well Fire Test

The Wheel Well Fire Test panel is part of the L-1011 fire warning and suppression system. The system has a switch for the "A" or "B" loop operation of the fire test system, as well as two push buttons to activate the "A" and "B" side tests. The annunciator on the panel gives a visual indication of the "A" or "B" side fire alert loop activation.



The panel can be found in the top section of the Flight Engineers Panel. It is part of a larger group of fire test panels in the L-1011 cockpit.

Original Flight Hardware: Engine Turb Cooling Air

The Engine Turb Cooling Air panel is part of the L-1011 fire warning system. The panel has OVHT indicators for Engine 1,2 and 3 and has two test switches for the fire warning loops "A" and "B". The panel would be used to test the "A" and the "B" loop for the Engine Turbo Cooling Air fire warning system.



The panel is located on the Upper Flight Engineer Panel at the very top. The very top of that panel basically has a collection of all the fire warning test systems.

Panel Cockpit Location

Original Flight Hardware: Fuel Jettison Panel

The Fuel Jettison panel is located on the Lower Flight Engineer Panel.



It is used to jettison fuel from the wing tanks and the center tank on the L-1011. Each switch encodes the dump valve position as DUMP and also has a blue valve in transit light. The master switch encodes OPEN and has two large indicators that illuminate blue during valve transit.

Panel Cockpit Location