« Previous Next »

E3P Stable Platform

Technical Information

Catalogue No: C0081
Category: Navigation/Inertial
Object Type: Sensor/Transducer
Object Name: E3P Stable Platform
Part No: 75D 19930
Serial No: 001
Manufacturer: Elliott Bros (London) Ltd
Division: Inertial Navigation [IND]
Platform(s): Canberra
Year of Manufacture: 1966
Dimensions: Width (mm): 417
Height (mm): 253
Depth (mm): 250
Weight (g): 12,760
Location: Rack RAA09 [Main Store]

E.3.P. Stable Platform
Type No. 75D 19930
Ref. No. X 17104
Ser. No. 001

Handle with extreme care


A further development of the E3R Platform was a simplified version to be fitted in the wingtip pod of a Canberra electronic intelligence gathering aircraft. Only one of these E3P systems was delivered for experimental purposes, as shown by the Reference Number X17104.

Note the external, jacketed heating wire, soldered or brazed to the case, which allows low temperature startup.

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.


Click to enlarge Click to enlarge Click to enlarge