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F-16C/D EU Low Voltage Power Supply Unit (LVPSU)

Technical Information

Catalogue No: C0882
Category: Head-Up Display [HUD]
Object Type: Power Supply/Conditioner
Object Name: F-16C/D EU Low Voltage Power Supply Unit (LVPSU)
Part No: K0656SOCN7506-00079/B
Serial No: 1577-23
Manufacturer: Roband Electronics
Division: Unknown
Platform(s): F-16C/D Fighting Falcon
Year of Manufacture: circa 1985
Dimensions:
Width (mm):
41 
Height (mm):
178 
Depth (mm):
368 
Weight (g):
3,880 
Location: Rack RAA05 [Main Store]
Inscription(s):

L.V. Power Supply Unit
PN K0656SOCN7506-00079/B
Mfr. PN 0A3358-04
Ser No 1577-23
Mfr K1286
NSN
Contract No. F33657-80-C-0326

Notes:

The HUD EU has comprehensive video mixing and scan conversion and self contained weapon aiming capability.

The units were made by Roband in the UK and Eldec in the USA and were common for the F-16C/D and LANTIRN programmes.

The Low Voltage Power Supply was a major part of the F-16A/B and C/D Head Up Display systems Electronics Unit and variants of that design. The LVPSU takes in aircraft power at 115V 400Hz and 28VDC and conditions it to the voltages required by the internal electronics typically 5VDC and +/-20VDC. The box locates on the opposite side of the EU coldwall from the Circuit Boards such that heat is conducted into that coldwall and cooling is by means of filtered cold air blown through the wall. There were two suppliers of these Power supplies; the majority was made by Eldec in the USA but a number were second sourced from Roband in the UK. The unit has a large ‘D’ type Cannon connector into the EU and externally the Aircraft connector ‘J2’ and most units also have a Test connector ‘1J5’. A more shallow but wider LVPSU was fitted to the F-16A/B whereas that on the F-16C/D type goes the full height of the EU.

The F-16C (single seat) and F-16D (two seat) variants entered production in 1984. The first C/D version was the Block 25 with improved cockpit avionics and radar which added all-weather capability with Beyond Visual Range (BVR) AIM-7 and AIM-120 air-air missiles. Blocks 30/32, 40/42 and 50/52 were later C/D versions. The LANTIRN Diffractive optics HUD was designed for the new aircraft but development was delayed by the complexity of the manufacturing problems. As an interim the Company offered a wide angle conventional optic design.

The initial order was placed in 1984 and was valued at nearly $50 million (then about £30 million) to cover both development and production. Over 2300 HUD’s were delivered for the F-16 and the system has been the basis of equipment supplied for other programmes such as for the A-7D/K and F-5 adding another 1500 units to the family. In 1985 the F-16C/D design won the Queen’s Award for Technology Improvements to aircraft Head Up Display systems for the Company.

The HUD Pilot's Display Unit (PDU)

The HUD PDU has both a raster and a cursive capability with the first application of ‘cursive in flyback’ in which the same amount of symbology as in the daytime high brightness mode can be drawn on the CRT using the raster flyback period of the Night mode. A good grey scale was provided for sensor video and the system could operate in 525, 625, or 875-line standards. The system accuracy was enhanced by the ability to apply corrections for the windshield. The F-16 windshield in particular acts as a lens which modifies the focus of the system and this is compensated for in the optical module design but in addition there are linear distortions away from the centre of the field of view caused by the curvature of the one-piece canopy and manufacturing variations. It is possible to provide both a generic and a specific correction for the particular aircraft. The optics provides a 25degree Total Field of View and a 20o by 13.5o Instantaneous Field of View which was the maximum that could be achieved within the limitations of the 6.7-inch exit lens design and the large distance between the pilot and the HUD occasioned by the reclined high ‘G’ seat.  The exit lens is truncated, and the size is limited by the ability of the glass to withstand thermal shock. The field of view is about the maximum that can be achieved with a conventional refractive optics.

The Cathode Ray Tube is circular but with a blank area at the bottom; the beam is deflected into this area so that deflection calibration tests can be carried out without illuminating the phosphor. As usual the delection is magnetic and the focus electro-static. The deflection coils and the matching card are now all constructed by Rank Electronic Tubes and the item is delivered as a Tube Unit Assembly.The venerable P1 phosphor is still used but the first Anode voltage is now a nominal 18kV and the tube operates with a Focus voltage of 2.96kV to 4.76kV.

The Camera was left forward of the Combiner to retain commonality with the LANTIRN design. In a refractive optic design, the outside world and symbology can be captured from aft of the Combiner but with the reflective design this is not possible, and the symbology is added to the outside world view by video mixing after scan conversion in the Electronics Unit.

The Head Up Display castings were all made by Kent Alloys who worked for Medway Investment Castings.

 

The HUD Electronics Unit (EU)

The F-16 C/D Electronics Unit contains twenty circuit boards. The Processor/Symbol Generator uses the MIL-STD 1553B (Standardised Electronic Data Highway) databus architecture, the MIL-STD-1750 (Standardised Computer architecture) processor and the MIL-STD-1589A (Standardised Jovial J73 Computer language) software. This was the first time that all three Standards had been used together and the Company was way ahead of its US rivals in this respect. The foundations for the implementation of these Standards was laid down by FARL from 1978 and led to a highly successful LSI chipset for the 1553 Databus. The HUD EU has comprehensive video mixing and scan conversion and self-contained weapon aiming capability.

 

GEC-Marconi Avionics began development of diffractive (holographic) optical elements in the late 70’s building on the work of the Marconi Research Centre at Great Baddow under Dr Firth. A clean room was opened at Rochester in 1987 to carry out research and to manufacture holographic elements. It has an optical bench going down to bedrock to minimise the vibrations from the nearby motorway! 

The Company developed a diffractive optical system using three combiner elements which gave a large Head Motion Box. The F-16 Multinational Staged Improvement Program MSIP was the planned upgrade of the F-16 beyond the F-16A/B configuration. The F-16C (single seat) and F-16D (two seat) are improved versions of the 'A' and 'B' and would have the latest cockpit control and display technology. The initial version of MSIP included provisions for a wide-angle raster (WAR) HUD in its Stage 1. It would display a FLIR-generated image to the pilot to support manual low-level flight at night This WAR HUD became known as the LANTIRN HUD as the Air Force plans for a FLIR system coalesced into the LANTIRN program. In 1979 a development contract was published by the WPAFB for a holographic HUD for the F-16 and A-10 which were to be fitted with the LANTIRN Pod. LANTIRN is a podded sensor system for low-altitude day/night navigation and attack, and the HUD is used to superimpose infrared images on the pilot's view of the outside world. The following year the US Air Force awarded a development contract to Marconi Avionics for a wide-angle HUD to operate with the LANTIRN Pod on F-16s and A-l0s.

 The LANTIRN HUD is a holographic design, more correctly called a Diffractive HUD or DHUD; it uses the Combiner to collimate the light, eliminating the lens. The Combiner is a diffraction grating rather than a partially silvered screen. A diffraction grating has thousands of parallel lined etched on, and acts as a lens. The surface reflects light of a certain frequency, but all other frequencies are allowed through to give the pilot a clear view outside. The result is a field of view of 18° vertically and 30° horizontally compared with about 9° by 13° for a conventional HUD. By early 1981 design problems had emerged with the LANTIRN HUD and in 1984 an interim design was authorised with a wider-angle view than the HUD used in the F-l6A/B but a narrower angle view than the LANTIRN HUD; this called the  Wide Angle Conventional HUD (WACHUD) or simply the F-16C/D HUD.

The design and installation issues were resolved and the revised LANTIRN HUD was delivered in November 1983 and testing recommenced.

In 1988 full scale production of the LANTIRN or D-HUD began. Before the LANTIRN design went into production a radical change was made to the support structure for the Combiner Glass. The original version had a tie bar each side which was designed to support the Combiner assembly under the extreme stress caused by canopy loss or bird strike. However, it was found possible to produce a design without the tie bars which was equally effective and indeed looked much better.

Eventually 932 D-HUD’s were manufactured for the USAF.

The HUD PDU has both a raster and a cursive capability with the first application of ‘cursive in flyback’ in which the same amount of symbology as in the daytime high brightness mode can be drawn on the CRT using the raster flyback period of the Night mode. A good grey scale was provided for sensor video and the system could operate in 525, 625, or 875-line standards. The system accuracy was enhanced by the ability to apply corrections for the windshield. The F-16 windshield in particular acts as a lens which modifies the focus of the system and this is compensated for in the optical module design but in addition there are linear distortions away from the centre of the field of view caused by the curvature of the one-piece canopy and manufacturing variations. It is possible to provide both a generic and a specific correction for the particular aircraft. The optics provides a field of view of 18° vertically and 30° horizontally.

The Cathode Ray Tube is truncated top and bottom and has an area for deflection calibration tests. As usual the delection is magnetic and the focus electro-static: a P43 phosphor is used to give the narrow spectral emission required by the diffractive optic design. The deflection coils and the matching card were all constructed by Rank Electronic Tubes and the item is delivered as a Tube Unit Assembly.

The Camera is forward of the Combiner because in a refractive optic design, the outside world and symbology can be captured from aft of the Combiner but with the reflective design this is not possible, and the symbology is added to the outside world view by video mixing after scan conversion in the

 

The HUD Electronics Unit (EU) The LANTIRN Electronics Unit contains twenty circuit boards. The Processor/Symbol Generator uses the MIL-STD 1553B (Standardised Electronic Data Highway) databus architecture, the MIL-STD-1750 (Standardised Computer architecture) processor and the MIL-STD-1589A (Standardised Jovial J73 Computer language) software. This was the first time that all three Standards had been used together and the Company was way ahead of its US rivals in this respect . The foundations for the implementation of these Standards was laid down by FARL from 1978 and led to a highly successful LSI chipset for the 1553 Databus. The HUD EU has comprehensive video mixing and scan conversion and self-contained weapon aiming capability.

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