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F-5 HUD Optical Module

Technical Information

Catalogue No: C0803
Category: Head-Up Display [HUD]
Object Type: Module/Sub-Assembly/Component
Object Name: F-5 HUD Optical Module
Part No: 2501-00049
Serial No: K0656C0002
Manufacturer: Pilkington PE
Division: Unknown
Platform(s): F-5
Year of Manufacture: Unknown
Width (mm):
Height (mm):
Depth (mm):
Weight (g):
Location: Rack RAA13 (HUD DU Parts) [Mezzanine Store]

Part No. 2501-00049
Serial No.
Mfr Code K6111 PL2614
Mfr Part No. 039909
Cont No. F09603-84-G-1438/SA15
Optical Module Assy
S/N K0656C 0002
NSN - - -
A[zimuth] = 0.29
E[levation] = -2.14
A[zimuth] = 0.9940
E[levation] = -0.995
[Optics protective cover]
Pilkington P.E. Inspection


In 1989, the Indonesian Air Force began to take delivery of its first F-16s, and these were based alongside its F-5s. In March 1995, Belgium's SABCA was awarded a contract to upgrade the Indonesian F-5 fleet so that the planes could act as lead-in fighter trainers for the F-16. The 16 aircraft were fitted with the GEC-Marconi Avionics HUD/WAC and Sky Guardian RWR, new air data computer, stores management system, HOTAS controls, and a MIL-STD-1553B databus.
This is the Optical Module assembly from the F-5E/F HUD. The unit is attached to the Chassis and itself has a Control Panel and Video Camera located on it.

The HUDWAC consists of three line replaceable units; the Pilot’s Display Unit (PDU), an Electronics Unit (EU) and a Weapon Data Input Panel (WDIP).

The physical configuration of the HUDWAC was designed to be drop-in compatible with all known versions of the F-5E/F. Other than removal of the Lead Computing Optical Sight (LCOS) no rearrangement of existing systems nor structural modification was necessary; the new PDU mounts onto the same LCOS tray. The HUDWAC was made to be interchangeable between F-5E’s fitted with the APQ-153 radar and AHRS and those fitted with an APQ-159 radar and an INS without any modifications. The HUDWAC monitors the armament panel switch settings and the in-built software determines the required operating mode which overall makes the system easier to use than the original LCOS.

The PDU gives a field of view nearly twice that of the ASG-29 Lead Computing Optical Sight it replaces. The unit hosts a control panel with switches and a keypad through which mission data such as target elevation and barometric pressure can be loaded. A 16mm film camera or a colour video camera can be attached to the aft end of the PDU. In this aircraft the PDU is hard mounted to a pre-aligned mounting frame, rather than an adjustable Mounting Tray i.e. it is already boresighted to the airframe. The drawback to the installation is that the PDU has to be long and narrow which is reflected in the design of the circuit boards within the unit. The High Voltage Power Supply locates on the underside of the PDU and there would be a Gun Camera and an Up-Front Control Panel fitted to customer requirements.

The HUD therefore has to be a long thin design although in these upgrades as many as possible of the F-16 modules were employed.  The alternative involved a reconstruction of the PDU mount to allow a conventional variant of the F-16C/D PDU to be fitted and this was the approach in some of the upgrade projects.

The EU contains 15 circuit cards of which 13 are common to the F-16C/D EU; the two unique cards are for the interface to the F-5 avionic systems. The system software, also known as the Operational Flight Program (OFP) was written in Jovial J-73 language and the symbology was compliant with the Mil-Std-187 standard.

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