L-1011 Trainer Installation: NAV and COM Radio Head Integration

L-1011 Trainer NAV and COM Radio Integration

Today we finished the VHF NAV and VHF COM Radio head integration with X-Plane. Ben Klang wrote the code for the VHF NAV radios. The VHF NAV radios use a 2 of 5 encoding method and we are reading them with National Instruments DIO cards. Ben wrote a program on a small Linux box that continuously reads the values and sends them on to X-Plane via a UDP DataRef.

We also completed the VHF COM Radio integration. Here, the radios use the ARINC 429 Labels 030 with different SDI numbers to differentiate the various COM channels. For now, we integrated COM1 and COM2 to directly interface with X-Plane. Just as with the VHF NAV tuning information, the VHF COM frequencies are passed to X-Plane via the network as UDP packets.

The video below shows the operation of the VHF COM and VHF NAV radios in our L-1011 cockpit.

L-1011 Trainer Installation: Glare Shield Replacement

L-1011 Trainer - Glare Shield - Autopilot

The L-1011 trainer that we got from Delta did not come with any real instrumentation. All of the instruments you have been seeing as part of the blog postings are instruments we replaced with real flight hardware used on actual L-1011s. Today, we replaced the last photo mock up on the simulator ... the glare shield autopilot and radio components. In the image below you can see the image that was pasted onto a plate and mounted in place of the autopilot under the glare shield. This has now been replaced with a custom made plate and with the actual control components:

Before

L-1011 Trainer - Original Autopilot Photo Replica

After

The glare shield is not only home to the autopilot components, but also holds the VHF NAV 1 and VHF NAV 2 radio as well as the RADIO/NAV selector for the HSIs, a ENGINE 2 warning light and a FIRE warning light.

L-1011 Glare Shield

L-1011 Navigation: HSI Location (34-3)

The primary navigation display in the L-1011 cockpit is the Horizontal Situation Indicator (HSI). Here are the basic function elements of the HSI:

• The deviation bar works the same as on other HSI's or CDI's
• The type of radios at a is displayed in the small windows (NAV data source indicators) which are VOR 1, VOR 2, ILS 1 and ILS 2
• The cursor arrow is controlled by the two course knobs on the autopilot NAV MODE panel. 
• Triangular VOR indications are provided when the HSI is in VOR mode. 
• Glideslope display is provided when turned to an ILS. While using VOR, the glideslope display is shuttered. 
• The ALERT 1 Minute from R-NAV Waypoint is also used in conjunction with the INS and NAV equipment.

L-1011 Navigation: VHF NAF (34-1/2)

The Lockheed L-1011 as two in depended VHF NAV systems. The control heads are not located as part of the center console, but are part of the glare shield (see image above). A four-position DME control switch is also provided (outlined). The DME control switch has the following functions:

1. STBY - permits audio reception but no search display 
2. NORM - permits reception of up to 200 NM 
3. OVRD - permits reception of up to 400 NM
4. TEST - provides the following interactions on the RDDMI within a 9 second period after pushing the spring loaded switch to TEST: a) DME fail flag, b) Four dashes followed by c) Four zeros 

Avionics Bending: VHF NAV Radio

Tonight, I fished the avionics bend for the first of the VHF NAV radio heads that I will use for the Lockheed L-1011 project. Yes, the head is one that is not typical for the L-1011, since the two NAV radios are to the right and left of the autopilot on the glare shield. However, these units are in such great shape that I could not resist.

As you can see from the image below, I used the same board that I designed earlier and used on the three (3) VHF COMM heads. If you want to see the details of the avionics bend, check out the postings I did earlier this month, there I show step by step how I arrived at the modified flight hardware.




Currently, the light plates still use incandescent bulbs, however, once I start the plate restorations, I will rework all instruments to LED lighting.

Design Specification: VHF COM/NAV Frequency Selector

I have written a design specification for the VHF NAV and VHF COM frequency selectors used on the Lockheed L-1011 Project. I call them "radio heads". I would like to get some input on the design document. You can see the document by following the link below:

Radio Head Design Specification

The electronics components selected for this initial design specification are the ATMEL 8bit ATmega32U4 MCU and a I2C controlled I/O chip made by NXT.

Original Fligth Hardware: NAV Radio Heads

The Lockheed L-1011 uses two VHF NAV radio heads that are mount to the left and to the right of the autopilot system on the glareshield (see location image at the end of the posting). The panel above shows a version of the VHF NAV panel that has "AUTO TUNE" capability. When the radio is in auto tune mode, the FMS can tune the NAV frequency, however the frequency will not be shown on the head the number will simply be overlaid by a flag labeled as "AUTO".

The image below, shows a dual NAV head that is used by Boeing aircraft, such as the Boeing 747. I am actually, contemplating using the B747 style head for my L-1011 project, because the head is easier to interface with.


Both, the single and the dual NAV heads cover a frequency range from 108.00 MHz to 117.95 MHz (which is the typical NAV radio frequency range used for at least the last 30+ years). Both heads have a rotary switch that switches the following functions:

• STBY ... Receiver operational but not transmitting. four dashes will appear on the RDDMI and shows that there is no computed data for distance.
• NORM ... enables the DME to be usable up to 200 NM
• OVRD ... enables the DME to be somewhat usable to 400 NM
• TEST ... DME fail flag followed by four dashes followed by four zeros in the RDDMI DME window.

The AUTO/MNL switch alternates the VHF NAV head been manual input made by the frequency selector as shown in the frequency window, or automatic tuning as instructed by the flight management system (FMS).


Panel Location