L-1011 - CPT Installation at the Museum - Pre-Installation

L-1011 Cockpit Layout

The L-1011 has a very spacious and open cockpit. As a matter of fact, the cockpit dimensions and the large windows are what many L-1011 pilots to the day remember about it the best. Here are the elements of the cockpit as they are labeled in the image above:

1. Captain's Seat
2. First Officer's Seat
3. Flight Engineer's Seat
4. First Observer's Seat
5. Second Observer's Seat
6. Pilots' Center Console
7. Flight Engineer's Console
8. Ruder Pedal Assembly
9. Forward Electronics Compartment Access
10. Flight Crew Oxygen Supply
11. Stowage for Jackets
12. Stowage for Hats and Coats

Yes, the L-1011 cockpit is massive. The trainer that we are installing at the museum however, does not implement the entire cockpit but only the elements that we need to make it a full simulation experience. In the image below you can see the outline of the simulator room (red) and the simulator platform  (yellow).

Here are the elements that the trainer at the museum will implement. You see that some of the observer stations are gone because they are not really relevant to what we are trying to do, and secondly because we would simply not have the space to do so:

1. Captain's Seat
2. First Officer's Seat
3. Flight Engineer's Seat
4. -
5. -
6. Pilots' Center Console
7. Flight Engineer's Console
8. - 
9. -
10. -
11. -
12. -

The forward section of the simulator room will receive a curved projection wall that will allow outside scenery to be projected at a 110º viewing angle. 

L-1011 - CPT Installation at the Museum - Component Assembly

L-1011 Flight Engineer (Second Officer) Station and CB3 Panel

Got a lot of work done at the museum today. We have started the assembly of the flight engineering station, as you can see in the image above. This is a really neat step in the process because after sitting forgotten in a warehouse for a long time, the L-1011 is suddenly taking shape again. What you see in the image above is the L-1011 Flight Engineer station on the left and the Circuit Breaker (CB) Panel number 3 (CB3). Unlike with many other trainers, the circuit breakers in the panel are all real and will be used to secure the flight instruments in the trainer. 

L-1011 Trainer - Room Dimension

We also took a moment to validate that the room dimensions are correct (just in case :) ) prior to use moving the very heavy simulator platforms into the room. The platform that the simulator sits on comes in two pieces; a forward piece that is roughly 18" tall and the main section that is 12 inches tall. The room under the platform will be used cabling and for the control column actuators.

Here are a few more images of the assembled Flight Engineer's station. The tank panel in the lower left of the panel is removed because I am currently working on it. All of the simulated hardware has been replaced with functioning real flight hardware.

L-1011 Flight Engineer Station - Detail

Below is an image of the outside of the station with all of its service covers removed. Most of the original cabling of the trainer will be reused, however, the entire system will be interfaced with National Instruments I/O cards and the V1 Avionics SIM42911 interface for ARINC 429 components.

L-1011 Trainer - Flight Engineer Station

The L-1011 cockpit has quite a few circuit breakers. Actually, there are a total of 3 circuit panels (forward, overhead and aft) that are loaded with several hundred circuit breakers. While not all of them are relevant to the type of flight simulation we are planning on doing, most of them are and will actually work. Below is an image of the Flight Engineer station with the CB3 panel (right) and with the CB2 (overhead).

L-1011 Flight Engineer Station, CB3 Panel Left, CB2 Panel Top

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

L-1011 Trainer Light Plate Replacement

L-1011 Trainer Instrumentation to Real Flight Hardware Comparison 

The panel front plates on the L-1011 Cockpit Procedure Trainer are not back illuminated. Not having light plates on a trainer is pretty typical. However, for the simulator we are building at the museum we do want to have back-lit light plates because it will make for a much more exciting and interesting experience in the simulator.

In the image above you can the see the trainer front plate for the Engine Anti-Ice panel as it was made by Singer/Link; on the right hand side you can see the original Engine Anti-Ice panel as removed from a BWIA L-1011. Besides the slightly mismatched font, the two plates look very similar. Lets take a closer look at the two.

The plate on the trainer is a machined metal plate that has a picture pasted on the front. The machined plate is exactly the same size and shape as the actual light plate, but is slightly thinner; see images below:

L-1011 Trainer Metal Face Plate with Laminated Picture

L-1011 Trainer Metal Face Plate - Backside

L-1011 Plate Thickness Comparison (L) Sim (R) Real Hardware

The metal plates are cool, however, as discussed earlier are not what we want for the sim. Hence. we will either use the actual flight hardware with the illuminated faceplates, or move the light-plate from the real flight hardware to the trainer component. The complication with moving the plate, however, is that we also need to drill the power connector for the light plate since there are no provisions made for the connector on the simulated components (see image below).

Again, the positive is that the drillings for the mounting hardware are in the exact right locations and with the right screw pitch. Below are two images that show what the actual Lockheed light plate for the Wing Anti Ice looks like:

The silver screw looking times are the actual lamp holders. This allows for the light-plate to be re-lamped without the need to pull the PCB off the backside of the light plate. 

Simulator Integration Planning: ATA 21 - Air Conditioning and Pressurization (Label Assignments - Part 1)

To integrate the L-1011 pressurization panels with Lamina Research x-plane we are able to us a number of datarefs that are already in place for aircraft pressurization. The datarefs are:

sim/cockpit2/pressurization/actuators/cabin_altitude_ft sim/cockpit2/pressurization/actuators/cabin_vvi_fpm sim/cockpit2/pressurization/actuators/dump_all_on sim/cockpit2/pressurization/actuators/dump_to_altitude_on
sim/cockpit2/pressurization/indicators/cabin_altitude_ft sim/cockpit2/pressurization/indicators/cabin_vvi_fpm sim/cockpit2/pressurization/indicators/pressure_diffential_psi

While the datarefs are not complete for the pressurization implementation they are a good starting point.   Lets take a closer look how each dataref that is already present in x-plane can be used and which system elements have to be created as a separate code element for the Air Conditioning and Pressurization subsystem:

1. actuators/cabin_altitude_ft

This dataref sets the cabin altitude that is command in feet. On the L-1011 pressurization panel we have an analog dial that computes the commanded altitude for a given flight level. 

L-1011 Pressurization Panel

The flight level is set with the ALT SET knob and the the cabin altitude is read on the right hand side of the dial. For example, we set FL330 and the L-1011 is capable of safely holing a cabin altitude of 5000ft. In order to set the commanded altitude in x-plane we need to read the analog value from a potentiometer attached to the dial and translate it into a flight level. 

2. actuators/cabin_vvi_fpm

The pressurization module on the L-1011 has several ways of setting the vertical speed for the cabin pressurization. typically any pressurization of 500ft/min in ascent and 300ft/min in descent will be experienced as uncomfortable by passengers. The L-1011 differentiates between a NORMAL and STBY MODE for pressurization. Normal is a fully automated mode and STBY is a somewhat manual mode. 

L-1011 Pressurization Panel - Mode and VVI Select

The mode is selected by the rotary switch on the left and. When the pressurization system is in NORMal mode the preset rates of 500fpm up and 300fpm down can be increased by moving the middle rotary switch to the right. When the system is switched to STBY then both the ascent as well as the descent rate for the system is set with the rotary switch on the right. In order to associate the VVI speeds of the L-1011 to the cabin_vvi_fpm dataref in x-plane we need to convert the analog data represented by a potentiometer in the device for either the NORM or the STBY switch to a number value. X-Plane does not understand VVI for NORM or for STBY ... so I need to create a piece of code that will read the switch position of the MODE SEL switch and then send the respective selected VVI rate from either the NORM RATE or the STBY RATE rotary switch to x-plane. 

3. indicators/cabin_altitude_ft

Depending on the panel configuration, the L-1011 has either two or three gauges relate to aircraft pressurization. Regardless of the number of instruments, the gauges show a) differential pressure, b) cabin vertical speed and c) cabin altitude. The first label to look at is the cabin altitude in feet:

L-1011 Cabin Altitude

Delta used the configuration of gauges as seen above, TWA used a 3 instrument configuration as seen below:

L-1011 Pressurization Panel - TWA

The altitude data needs to be send from x-plane to an ARINC 429 compatible altimeter or output as fine/coarse synchro signals. 

4. indicators/cabin_vvi_fpm

Typically the VVI for the pressurization system on the L-1011 is an actual pressure rate change instrument. In other words, it is fully analog. I will not be able to simulate an actual rate of pressure change with air and therefor will substitute this instrument with a servoed vertical speed indicator.

L-1011 Cabin Vertical Speed - TWA

Depending on the type of servoed instrument the x-plane computed Cabin Vertical Speed needs to be output as analog value between -10VDC to +10VDC.

5. indicators/pressure_diffential_psi

The third and last instrument for the pressurization system of the L-1011 is the Pressure differential indicator. The Laminar Research x-plane simulator computes pressure differential for the hull. 

L-1011 Differential Pressure - TWA

Just as with the Cabin Vertical Speed Indicator the Cabin Pressure Differential gauges is fully analog and will need to be replaced with a servoed version. The x-plane computed pressure differential the needs to be output as an analog value between -10VDC and 10VDC. 

The data value of the pressure differential will also drive a number of additional indicators on the L-1011 pressurization panel that are not covered by the x-plane and/or a x-plane dataref. When pressurization exceeds that maximum permissible pressure differential the SAFETY VALVEs on the aircraft will open to prevent he hull from over pressurizing. There are two annunciators on the L-1011 panel that will illuminate when the safety valves are open. 

L-1011 Pressurization - Alert Annunciators

Safety valve opening is also accompanied by an alarm sound that can be silenced with the HORN CUTOUT momentary switch. The SAFTEY VALVE annunciators are 24VDC relay outputs and the HORN CUTOUT momentary switch is a digtial I/O port. The HORN CUTOUT switch will also be used for an alert that sounds when rapid de-pressurization is sensed. 

Simulator Integration Planning: ATA 21 - Air Conditioning and Pressurization

ATA 21 is the Systems chapter for Air Conditioning and Pressurization (a complete listing of ATA chapter numbers can be found here). I decided to work through the simulator system integration according to the ATA chapters and that way everything stays in a somewhat logic order. The upper panel of the flight engineer console on the L-1011 is largely consumed by control and indicator elements for ATA 21 and ATA 36 (which is Pneumatic).

Below are images from the original documentation of the L-1011 simulator created by Singer Link Division in the 1980s.

Environmental Control System (ECS) Monitor Panel (*791/A9)

The simulator implements all component pieces of the ECS monitoring panel.

L-1011 Trainer - ECS Monitoring System (Component Labels)

Implemented Components

Gauges
M10 ... Pack Flow 
M11 ... ECS Temperature
M12 ... Cabin Temperature

Switches
S10 ... Pack Select 
S11 ... ECS Temperature Select 
S12 ... Cabin Zone Temperature Select    

Switch Lights
SDS26 . Cool Air Overboard
SDS27 . Cargo Heat Forward
SDS28 . Cargo Heat Mid
SDS29 . Cargo HEat Aft
SDS30 . Instrument Cooling

Annunciators
DS14 .. Avionic Air Forward
DS15 .. Avionic Air Mid

Cabin Pressurization (*791/A9)

Several of the gauges for the pressurization panel are photo simulations on the original Singer Link Division L-1011 simulator. These instruments will be replaced with the real flight hardware as part of the simulator outfit at the museum. However, several switch and annunciator elements are already fully implemented.

L-1011 Trainer - Pressurization (Component Labels)

Implemented Components

Gauges

M1  ... Forward Outflow Valve 

M2  ... Aft Outflow Valve

Switches

S1  ... Forward Outflow Valve Manual Control 

S2  ... Aft Outflow Valve Manual Control 

S9  ... Cabine Altitude Horn Cutout

Switch Lights

SDS1 .. Forward Outflow Valve Manual/Automatic

SDS2 .. Aft Outflow Valve Manual/Automatic

Annunciators

DS12 .. Forward Safety Valve 

DS13 .. Aft Safety Valve

Cabin Temp Control (*791/A9)

The Cabin Temperature and Engine Bleed Control panels are combined. The lower portion of the panel is the cabin temperature control panel. For the ATA 21 integration we will only cover the lower portion of the panel. 

Implemented Components

Gauges
M4  ... #1 Turbine Bypass Valve Position 
M5  ... #1 RAM AIR Valve Position
M6  ... #2 Turbine Bypass Valve Position 
M7  ... #2 RAM AIR Valve Position
M8  ... #3 Turbine Bypass Valve Position 
M9  ... #3 RAM AIR Valve Position

Switches
S1  ... #1 Valve Cool
S2  ... #1 Valve Warm
S3  ... #2 Valve Cool
S4  ... #2 Valve Warm

S5  ... #3 Valve Cool
S6  ... #3 Valve Warm

S7  ... Area Overheat

S8  ... Area Overheat Test

Switch Lights
SDS10 . #1 Pack Flow Control
SDS11 . #2 Pack Flow Control 
SDS12 . #3 Pack Flow Control
SDS13 . #1 Valve Control Auto and Manual
SDS14 . #2 Valve Control Auto and Manual
SDS15 . #3 Valve Control Auto and Manual
SDS16 . Left Hot Air 
SDS17 . Right Hot Air
SDS18 . Left Isolation Valve
SDS19 . Right Isolation Valve
SDS20 . Ground Cont
SDS21 . Flight Station Open Close
SDS22 . Forward Cabin Open Close
SDS23 . Mid Cabin Open Close
SDS24 . Aft Cabin Open Close
SDS25 . Galley Open Close

Annunciators
DS7 ... Area A Overheat
DS8 ... Area H Overheat
DS9 ... Area B Overheat 
DS10 .. Area C Overheat
DS11 .. Planum Duct Overheat

L-1011 - CPT Installation at the Museum - Pre-Installation

L-1011 Trainer - Pre-Installation Move (Overhead and SO Station)

Jay and I worked on moving simulator elements from the storage room to the museum today. We moved quite a few elements including the Flight Engineers station (aka. SO Station) as well as the Overhead Panel as well as the Overhead Breaker Panels. 

A number of the panels on the L-1011 procedure trainer are non-functional simulated panels and instruments. The overhead and first officer station has mostly functional elements, however, a few of them are non-functional. Below is an illustration of which elements of the overhead panel are non-functional. These non-functional panels will be replaced with panels from an actual L-1011 so that in the end-state the entire overhead and so-station will be fully functional.

L-1011 Overhead Panel for the Simulator at at the NMCA

 Below is an image illustrating the non-functional panels boxed in yellow:

L-1011 Trainer at the NMCA - Non-functional panels. 

Most of the non-functional panels above are elements of the navigation system, such as then INS as well as the HF radios. Both we already have and will be easily replaced with functional units. Lets take the same look at the first officer station. Here we will see that only a few of all elements are not functional:

L-1011 Flight Engineer Station

Below is an image illustrating the non-functional elements (boxed in yellow) of the L-1011 trainer that will soon be replaced with functional units from an actual L-1011.

L-1011 Trainer at the NMCA - SO Station Non-Functional Elements

L-1011 - CPT Installation at the Museum - Pre-Installation

L-1011 Procedure Trainer - Original Setup at Delta Airlines (photo Grant Wainscott)

The paint job on the sim-room is complete and we are getting ready to move the L-1011 procedure trainer back into the room. The idea will be to close the procedure trainer in some more with ceiling panels and other pieces to create a more "closed cockpit" like experience. Here are two images of the L-1011 CPT prior and during the de-installation of the device at the Delta Airlines training center here in Atlanta.

L-1011 CPT De-Install at Delta (photo Grant Wainscott)

What we are planning to add are the ceiling panes (see images below) and some of the window panes.

Ceiling Panels

Avionics Bending: Dual ADF Head

Gables Dual ADF Radio Controller

Been busy working on some additional pages for the Litton INS the last few days as well as working on the software for the SIM42911 interface we are building. However, here is a new addition to the L-1011 project - a Gables Engineering G6095A-1 ADF radio controller head.

The unit is very early digital and actually uses the standard 2 of 5 encoding on a mechanical drum and a digital decoder/display unit to show the frequency selection. Each side of the instrument is actually independent and has an independent set of controls and power source.

Once I am a bit further down the line withe work on the Litton LTN-72 INS simulation, we will do a 2 of 5 implementation together. They are fun to do and relatively easy to interface with the simulation.