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E3 Inertial Platform (training model)

Technical Information

Catalogue No: C1114
Category: Navigation/Inertial
Object Type: Model
Object Name: E3 Inertial Platform (training model)
Part No: None
Serial No: None
Manufacturer: Unknown
Division: Unknown
Year of Manufacture: circa 1960
Width (mm):
Height (mm):
Depth (mm):
Weight (g):
Location: Rack RAA09 [Main Store]

[written on masking tape]
...71 A1 to TP3 greater than...
...1 A1 to TP4 greater than...
... A1 to TP5 greater tha...
...h 3.6.2. (F.T.R)


This was possibly the unit shown on the Elliott stand at SBAC show in 1960. Just before Farnborough, Elliott Brothers had for the first time exhibited a wooden model of an inertial platform and it had been known for some time that they provided the inertial navigator for the ‘Blue Steel' air-to-surface missile. The ‘Blue Steel’ IN platform alone was large and heavy weighing over 180lbs and was nearly 2ft in diameter so was not suitable for many other applications.
In an attempt to make use of the experience from that design the Company embarked on a ‘Private Venture’ project for the development of a general-purpose instrument for aircraft navigation, and an experimental stable platform, E5 was built. This project was not completed, as it was realised that the platform was still likely to be too bulky for many applications, and improvements in technique appeared to offer scope for a reduction in size. This was eventually realised in the highly successful E3 stable platform.
The company research laboratory FARL designed the E3 platform in 1961 with the latest transistor circuits and the design was productionised by the Inertial Navigation Division. The weight was reduced to under 30lbs. The first flight of the E3 platform was in a Gloster Javelin at Cranfield with the unit mounted under the canopy between the pilot and the observer. The E3 Platform also had a trial fit in a Comet in 1964 which was managed by John Keeble. IND manufactured the system for the Nimrod MR1 with over 100 platforms being made between 1964 and 11970. The work led to the even more successful E3R for the Jaguar NAVWASS.

In an attempt to make use of the experience gained in the 1960’s designing the inertial navigator for the ‘Blue Steel' air-to-surface missile the Company embarked on the development of a general-purpose instru­ment for aircraft navigation, and an experimental stable platform, E5 was built. This project was not completed, as it was realised that the platform was likely to be too bulky for many applications, and improvements in technique appeared to offer scope for a reduction in size. A project to develop a new platform was commenced in the Company Research Laboratory, FARL, where fortuitously the majority of the small team of engineers had been in the Inertial Navigation Division including the Chief Engineer 'Dick' Collinson and the Chief Designer 'Staff' Ellis. FARL produced the E3 stable platform, using a novel gimbal system which permitted a very compact construction.  A trial of this platform was madse in early 1963 at Cranfield with the E3 Platform mounted under the canopy of a Gloster Javaelin. This design entered production for the Hawker Siddeley Aviation HS801 'Nimrod' maritime strike and reconnaissance aircraft and between 1964 and 1970 over 100 platforms were delivered.

However  a further development of the E-3 platform, the E-3R which permitted a wider range of manoeuvre, was specified for the BAC/Breguet  'Jaguar' fighter, and entered service in 1970 rapidly becoming an industry standard. The E3-R had a fourth gimbal and incorporated continuous rotation of the two vertical gyros and horizontal accelerometers to achieve 'rotaional averaging' giving greatly increased accuracy.

The Jaguar Navigation and Weapon Aiming Sub-System NAVWASS  comprised the MCS920M central digital computer, E3R inertial platform, projected map display and horizontal situation indicator together with the necessary power supply, electronic, interface and control units.

The main unit of the inertial subsystem is the platform assembly which contains a stabilized inertial platform or stable element, the basic attitude reference for the system. The chief function of the platform is to provide a means of accurately locating the gyros and accelerometers and to maintain their orientation fixed to the local vertical and to true north regardless of anv aircraft motion. The electronic control amplifier contains the electronic amplifiers and special excitation sources required for alignment and operation of the inertial platform. These include the gimbal servo amplifiers and the gyro spin motor power supply.


In 1967 Elliotts had been awarded a major contract for the design, development and integration of a Navigation and Weapon Aiming Sub-System (NAVWASS) for the RAF's new Jaguar aircraft.

The Jaguar was designed as a close air support aircraft for supporting ground troops in daylight. The NAVWASS enabled the pilot to navigate and fly at low level and high speed to acquire and accurately attack targets. Trials of the prototype Jaguar system were carried out using a Varsity aircraft at West Malling airfield in Kent


The Jaguar NAV/WASS  sub-system comprises four principal groups of equipment. The sensors, which measure what the aircraft is doing and feed these measurements into the computer; the computer sub-system which processes this measured information into a form which can be used by the pilot; the cockpit controls which control the system's mode of operation and lastly, the cockpit displays which show to the pilot the computer's outputs of converted measurement information and also information, such as target or waypoint position, which is being input into the computer. The system included an E3R inertial platform, Digital Computer, a HUD, Projected Map Display, Horizontal Situation Indicator and various cockpit control panels.

The RAA contains a number of models of equipment and aircraft. The equipment models were used as a marketing aid and often to ensure that the production unit will fit in the space; this was particularly true for Head Up Displays. Such equipment models will have minimal or no functionality. Models might  just be used as weighted units or as cockpit lighting evaluation units. The HUD used on the YF-16 was of the correct weight and envelope but only mounted the Spin 'chute button (a feature only required for the early test flights). Many of these models were made by professional model makers from the original drawings and could be quite expensive; alternatively the real hardware would be used.

The aircraft models range from the simple small scale kits to quite large display items. The large model aircraft were often a marketing tool from places like Airbus or Boeing but may be found in Boardrooms or Reception areas wheras the small models may be given as a visitor handout. Those models made from kits have largely been brought in from home but are useful to illustrate the platform alongside the equipment. The large models will be hugely expensive.

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