L-1011 Cockpit Trainer - Light Controls Planning

There are a total of 20 discrete controllable light systems in the L-1011 cockpit. Any more, and you could probably put on a Las Vegas-style light show. Just kidding. The light system in the L-1011 cockpit is designed so to give maximum control over each flight station lighting conditions to each flight crew member. Replicating the lighting systems in the simulator will allow us to replicate this experience as well allow the cockpit to stay illuminated when it is not used for a guided flight discovery session.

Light Control Systems

1. Center Console Flood Light
2. Overhead Panel Background Lights
3. Cockpit Overhead Flood Lights
4. Captain's Glareshield Panel Lights
5. Captain's Utility Light
6. Captain's Instrument Panel Lights (Instruments and Backgrounds)
7. Captain's Instrument Panel Flood Lights (Left and Center)
8. Center Console Background Lights
9. Engine Instrument Light Controls
10. Magnetic Compass Light Control
11. Eyebrow Panel Light Control 
12. First Officer's Utility Light 
13. First Officer's Instrument Panel Lights (Instruments and Backgrounds)
14. First Officer's Instrument Panel Flood Lights (Right)
15. Second Officer's Instrument Lights
16. Second Officer's Panel Background Lights
17. Second Officer's Panel Flood Light 
18. Second Officer's Desk Utility Light 
19. Forward Circuit Breaker Board
20. Aft Circuit Breaker Board

Where possible we are replacing incandescent and fluorescent light sources with LEDs. The LEDs will give us a lot more hours of operation and will also cut down on the thermal output of the individual light system. Again, the idea is to allow the simulator to stay illuminated even when it is not in use so that museum visitors can still enjoy the cockpit as a display item.

Here is a more detailed discussion on each of the light systems in the L-1011 cockpit.

Center Console Flood Light

L-1011 Flight Station Light Control (From Delta Pilot's Reference Manual)

The Center Console Flood Light consists of a single light bulb located inside of a panel that is located on the the pilot's overhead panel. To cut down on the heat output from the light, we will replace it with a 12VDC LED spot light. The potentiometer for the intensity of the spotlight will be re-used to control the 12VDC LED light.

Pilot's Light Controls

The second light control on the pilot's overhead panel is located right above the first officer's station. It controls a number of different systems: a) it controls 5V lighting to the overhead panel light plates, b) there is an ON/OFF switch and a transformer that controls the overhead cockpit flood lights and c) there are also two switches to test all the Caution/Warning and Advisory annunciators and to toggle the annunciator illumination intensity between BRT (bright) and DIM.

L-1011 Flight Station Light Control (From Delta Pilot's Reference Manual)

The cockpit overhead flood light switch will actually be a two-way light switch between the overhead panel and a light switch located right next to the cockpit door entrance. This way the flood lights can be controlled from at least two different places in the cockpit. By the way, this is also how it is configured in the actual L-1011 cockpit.  Below is an image that shows the overhead lights highlighted in yellow:

L-1011 Flight Station Light Control (From Delta Pilot's Reference Manual)

Glare Shield and Main Instrument Panel Controls

The main light controls for the captain's and first officers lights are located on the right and left hand side of the glare shield. Each side has a similar controls for main instrument panel flood lighting, a work light as well as the main instrument illumination controls. Most of the controls are basically just potentiometers that control the 5V instrument lighting as well as the 12V flood lighting. On the captain's side there is an extra control for the autopilot back lighting on the glare shield.

L-1011 Flight Station Light Control (From Delta Pilot's Reference Manual)

L-1011 Flight Station Light Control (From Delta Pilot's Reference Manual)

The image below illustrates whit yellow lines the illumination of the main instrument panel with flood lighting. On the original sim this was done with fluorescent lights, however this will be done with 12V LED lights going forward. 

L-1011 Flight Station Light Control (From Delta Pilot's Reference Manual)

Center Console and Instrument Lighting Control

The two potentiometers located just aft of the throttle quadrant control the 5V back panel lighting of the center pedestal instruments and the engine instrument illumination, which is also 5V. 

L-1011 Flight Station Light Control (From Delta Pilot's Reference Manual)

Flight Engineers Panel and Circuit Breaker Panel

The light control located on the lower left hand side of the flight engineer's station. The panel controls a number of lights as well as the annunciator test and brightness for the warning/caution and alert lights on the flight engineer's station.

L-1011 Flight Station Light Control (From Delta Pilot's Reference Manual)

The instrument and panel lights for the flight engineers station and the circuit breaker panels are 5V. The flight engineers station utility light as well as the console flood light will be 12VDC LED lights. 

Simulator Integration Planning: ATA 21 - Air Conditioning and Pressurization (Label Assignments - Part 3)

L-1011 Air Cycle Machine Temperature Ranges

In order to program the AC behavior of the L-1011 correctly we will have to go a bit deep on the various parameters in the system. First, lets take a look at the normal temperature ranges we should observe on the ECS Monitor in cruise flight. The numbers in the table below correspond to the numbers in the image above:

• [1] Pack Inlet Bleed Air Temperature ... 160º-200ºC in cruise
• [2] Compressor Discharge Temperature ... 60º-80ºC in cruise (depending on Turbine bypass valve setting)
• [3] Turbine Inlet Temperature ... 15º-20ºC in cruise (will vary with RAM air setting)
• [4] ACM Discharge Temperature ... 15º-20ºC in cruise. The lowest possible ACM discharge temperature is 2ºC
• [5] Hot Air Manifold Output Temperature .... 110ºC

The normal Pack Flow outflow for Pack #2 and #3 is between 2000 and 2500 CFM (#1 has 300-400 less). The spring loaded valves for the Pack Flow Control and the Hot Air Manifold will not open if the duct pressure is below 15 PSI.

Warning Indicators

• Pack Flow Control Switch OVHT light illuminates when the Compressor Discharge Temperature [2] exceeds 200ºC or when the ACM Discharge [4] temperature exceeds 96ºC.
• DUCT OVHT ... illuminates when the Hot Air Manifold Duct temperature has reached 145ºC. This causes both Hot Air Isolation Valves to close until the temperature falls below 120ºC.
• Hot Air Isolation Switch OVHT ... illuminates when the respective valve has reached 135ºC

Valve Position Values

There are a number of default valve position values that the system simulator needs to take into account.

Turbine Bypass Indicator - The turbine bypass value is positioned full warm until the RAM AIR louvers have reached the full cool position as indicated on the RAM AIR indicator (9 o'clock  on the ground or 1 o'clock position in flight). Once this status has been reached, the turbine bypass valve will now be positioned to hold the required temperature. With the pack turned off, the turbine bypass valve will be set to the 11 o'clock position by default.

RAM Air Indicator - With the Pack turned off the the louvers are automatically set to the 9 o'clock position on the ground and the 1 o'clock position in flight.

Turbine and RAM Positions on Ground.

Turbine and RAM Positions in Flight.

In part 4 of this series we are going to start developing a model that will allow us to compute the approximate temperatures and cabin zone temperatures base on the relationships established in normal cruise flight. Again, the idea is the create a systems simulation of the L-1011 air conditioning and pressurization system that is as real-world as feasible for this project. 

Simulator Integration Planning: ATA 21 - Air Conditioning and Pressurization (Label Assignments - Part 2)

L-1011 AC Pack

Simulating the L-1011 Air Conditioning and Pressurization for the simulator will be a lot of fun. As you saw in part one of this posting, the basics of the pressurization system for the aircraft is realized in the Laminar Research x-plane simulator. However, the Air Conditioning system is not implemented at all. To make the simulation complete these systems need to be simulated in software as well

The image above shows a single AC PACK for the L-1011, there are 3 of them in the system. Each of them has a number of switch controllers. For simplicity of this blog posting I will only talk through one of the packs (pack 2) but the others work exactly the same way.

So we start from top to bottom:

1. Pack Flow Control Switch

Pack Flow control is a switch light that shows either a FLOW BAR or  OVHT (Overheat). Here are the two elements on the actual panel and in the schematic:

The schematic shows a small [S] next to the valve. This indicates that this valve is spring loaded to shut.  In other words, when pressure is coming from the bleed air system the valve will be pushed open by the pressure and the flow bar will illuminate. When the valve gets too hot (bleed air too hot) the OVHT warning illuminates. So why is it a switch if all it takes to illuminate the bar is pressure on the valve. When the switch is "latched" (in) the valve is in normal operation and does exactly what I just describe. When the switch is unlatched (out), however, the valve is permanently closed and will never open, even with bleed air pressure.

2. Hot Air Switch 

The hot air switch allows for bleed air to be directly fed to the hot air planum. The valve is spring loaded [S] and opens automatically with pressure from the bleed air. When the valve is pushed open, the flow bar will illuminate on the switch. This is the normal operation when the switch is latched. When the switch is unlatched the valve will remain closed even with bleed air pressure. When the switch is unlatched the OFF legend illuminates.

3. Temperature Control 

Bleed air from the pack flow control valve (1) is cooled through a primary and a secondary heat exchanger. The cooling provided by the heat exchangers is controlled by the position of the RAM AIR exhaust doors which determine the flow of ambient outside air across the heat exchangers. This is the primary way of cooling air. Additional cooling is provided as needed by the Air Cycle Machine (ACM).  The ACM is a combination compressor and turbine powered by the bleed air flowing through the pack. When the ACM is working primary air from the primary heat exchanger passes through it and is heated by compression, cooled again by the secondary heat exchanger and the rapidly expanded by the turning for additional cooling.

The amount of cooling provided by the ACM is controlled by the Turbine Bypass Valve.

The system either operates in an automatic or manual mode as selected by the switch-light. Latched (in) the mode is automatic and ram air outlet and turbine bypass are controlled by the planum temperature demand. When unlatched (out) the system is in manual mode and the WARM and COOL momentary switches drive the position logic for TURB BYP and RAM AIR.

4. System Monitoring

There are a number of controls and gauges that allow the monitoring of temperatures in the system. All monitoring happens on the the ECS Monitoring panel:

There are a total of 5 temperature parameters that can be monitored for each AC Pack (controlled by the PACK SELECT switch on the ECS Monitor panel). They are:

1. Pack Inlet Temperature taken right before the Pack Flow Control Valve
2. Compressor Discharge Temperature measured before air from the ACM enters the secondary heat exchanger.
3. Turbine Inlet Temperature measured after the secondary heat exchanger and prior to air entering the turbine 
4. Air Cycle Machine (ACM) Discharge Temperature is measured after the air leaves the pack and water separator and prior to it being mixed into the Cold Planum. 
5. Hot Manifold Temperature is taken prior to hot air entering the Hot Air Manifold. 

Lastly, the air flow in Cubic Feet per Minute is displayed on the PACK FLOW meter also on the ECS Monitor Panel.

Software Considerations

All in all the system seem pretty complicated, however, from a software perspective it should not be too bad to model a somewhat lifelike system. Each PACK will be an object with attributes and parameters. The code will not attempt to compute actual air flow or heat exchange but will simply roughly approximate what the system would do under certain ambient air and airspeed conditions.

Ambient outside air at altitude and airspeed we can both get from x-plane as a dataref:

sim/weather/temperature_ambient_c
sim/cockpit2/gauges/indicators/airspeed_kts_pilot

With these two I should be able to develop an approximation of cooling efficiency of the air at altitude and simulate the automatic or manual operation of the ACM systems. As mentioned earlier, many of the spring loaded valves open automatically with bleed air pressure in the system. For bleed air there are also a number of datarefs that will come in handy:

sim/cockpit2/annunciators/bleed_air_off ... for each engine
sim/cockpit/warnings/annunciators/bleed_air_fail ... for each engine