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Viper-like HMD for H-1 Helicopter Programme

Technical Information

Catalogue No: C0507
Category: Head-Mounted Equipment [HMD/NVG/Glasses]
Object Type: Module/Sub-Assembly/Component
Object Name: Viper-like HMD for H-1 Helicopter Programme
Part No: None
Serial No: None
Manufacturer: Marconi Electronic Systems
Division: Airborne Display [ADD]
Platform(s):
Year of Manufacture: circa 1998
Dimensions:
Width (mm):
280 
Height (mm):
275 
Depth (mm):
325 
Weight (g):
740 
Location: Main Object Store
Inscription(s):

[outer shell]
156610/5
[struck-through 156149/3]
────────────────
[optic]
502B901
sn: 1006

Notes:

This is the main and inner shells with part of the optical mounting frame and part of single relay optics.

This Helmet Mounted Display (HMD) was developed for the US Marine Corps’ H-1 programme (for both AH-1Z and UH-1Y) in the late 1990s to early 2000s. The solution adapted the Viper (visor projected) optics into a new shell and used the inner helmet developed for the Germany Army’s Tiger helicopter.

The objective was to display night-vision imagery from separately developed miniature digital night-vision cameras (from Ball Aerospace). A Litton Mission Computer had the key role of processing video from these helmet-mounted cameras and sending them to the HMD.

The display at that time was still CRT-based, in fact it was probably the highest resolution CRT display built at Rochester, something like 1100-line, 60Hz raster with fast cursive symbology. The CRT’s ran very hot (probably their deflection coils) but the image quality was good.

The project died when the performance of Night Vision Goggles jumped beyond that of the then-available camera-based technology and its associated digital video processing.

The photographs show the inner shell with the main optical shell removed revealing the mounting pins for the main shell. The main shell is attached to the inner shell by three latches (marked "LOCK" on the main shell). The archive only has one of the two relay optics but it can be mounted in the left and right positions. A composite photo shows how a pair of relay optics would mount on the frame.

The two scales (one for each relay optics) marked "60 65 70 75" allow the interpupillary distance to be set to suit the helmet's wearer.

In 1992 the Viper™ family of HMD’s was commenced comprising a range of visor projected systems from the Monocular Viper™ I, the Binocular Viper™ II, the NVG Viper™ 3 (Also called ‘Night Viper) and the monocular Viper™ IV. The family of helmet systems has now been renamed Striker®.

Viper™ I: This was a lightweight monocular visor projected Helmet Mounted Sight. The spherical visor is a standard aircrew visor but  has a dichroic patch on the right-hand side which combines and reflects dynamic flight data symbology to the pilot. The source is a high efficiency miniature “1 inch” CRT displays which projects via an optical relay assembly to the visor. The optical system gives a 20degree field of view. The helmet shell was a one piece unit and was fitted with a magnetic head tracker system.

 

Viper™ II: This was a lightweight binocular visor projected Helmet Mounted Display. The visor combines and reflects dynamic flight data symbology and raster information to the pilot, projected from two high efficiency miniature “1 inch” CRT displays via two optical relay assemblies. The highly efficient optical design allows the use of a standard spherically curved aircrew visor, with a 70% transmission neutral density partially reflecting combiner coating. The visor coating ensures high display brightness, while maintaining high real world transmission with no colouration. Use of a spherical visor shape means display accuracy is insensitive to visor rotation, thus enabling partial raising of the visor and still maintaining an accurate display. It provided 40° FOV with full overlap, a 15-mm exit pupil, and a 70-mm eye relief. Excluding the oxygen mask, it weighed 4.2 lbs (1.9 kg). The Viper™ II display module can be fitted to all sizes of USAF and USN fixed wing helmets and uses existing liner systems. The optical relay system for each eye channel can be adjusted for individual inter-pupillary settings with no changes or modifications to the visor. When coupled to a suitable Head Tracking System, such as the GEC-Marconi Avionics DC Magnetic System, the Viper™ II system can provide full space stabilised symbology and video pictures.   

 

Viper™ 3: (Note that the Roman III was not used for this HMD which was also known as ‘Night Viper’) This HMD was designed in collaboration with Delft in the Netherlands and was a visor-projected NVG replacement. The Viper 3 exploits the visor projection scheme common to HMDs and employs multiple-folded optical paths to carry the imagery from a pair of 18-mm Image Intensifier tubes to the pilot's spherical visor. This provides the pilot with an unobstructed binocular 40° FOV NVG capability on his see through visor. The Image Intensifier tubes are mounted on the sides of the helmet, to provide the best possible balance for low fatigue and safe ejection. The helmet is considered suitable for loads of up to 5-6Gs. An important feature of the optical design of the Viper 3 is that the addition of a dichroic beamsplitter to one of the mirrors in the optical path between the image intensification tubes and the visor allows the addition of a CRT to the Viper 3 design so that the system can become a combined projection HMD and NVG package, with the addition of a CRT and head tracking sensors. The addition of a CRT adds some weight but improves the centre-of-mass of the overall system. The Viper 3 design solves the principal problems associated with conventional clip-on ANVIS. The HMD had a two part shell with the inner form fitted for the pilot and the outer holding the optical system. The HMD was first flight tested in a Dutch Air Force F-16.

 

Viper™ IV: This HMD  has a monocular visor projected display giving a 40degree field of view. The HMD was used in extensive trials on the United States Air Force Research Laboratory's NF-16D Variable-stability In-flight Simulator Test Aircraft (VISTA). The Viper™ IV Helmet-Mounted Optics Module was integrated with a modified Helmet Integrated Systems Limited (HISL) HGU-86/P helmet, the Honeywell Advanced Metal Tolerant tracker, and a Marconi Avionics Programmable Display Generator. Other flight tests have been on the EPAF MLU F-16, AV-8B and Tornado.

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