Fuel Level Tank Sensor Unit

These Fuel Tank Gauges work on a capacitive system whereby the tank unit is the capacitor and the fuel is a variable dielectric. The electronic circuits are calibrated to transmit this as a tank quantity.

The ‘Pacitor’ system seems to have been made by a number of companies such as Simmonds Aerocessories of London who advertised the product in 1952 and in that year they acquired Firth Cleveland Instruments and as that became the overall company name from 1953 onwards they are found under the  Firth Cleveland Instruments name. Elliott Bros purchased Firth Cleveland Instruments in 1961 and continued the brand from the Treforest works where they also made Flowmeters and Test sets for these. The former were used with the Beverley, Belvedere, Argosy 660 and long-range Britannia, while the latter were for fuel-flow systems in the refuelling portion of the Valiant tanker and in the Javelin, Buccaneer, Scimitar, Sea Vixen and Sea Venom

In addition Elliotts seem to be making Tank Units under a licence from Honeywell which may be because the an improved design was covered by a US Patent.

The Fuel flow business was important to Elliotts and it was in 1964 that the new Fuel Flow laboratory was opened at Rochester. It offered a unique service in Europe. It was designed to test fuel flow equipment for the new generation of supersonic aircraft where fuel temperature of 150°C or higher would be encountered, and units would be required to operate at rigid standards of accuracy under extreme conditions of temperature (up to 200°C ambient) and in areas of extreme vibration.

The Laboratory can achieve gravimetric calibration accuracy within an error band of ±0.1% of flow rate under the following conditions:

1. Flow rates from 50 to 120,000 lb/hr.

2. Fuel temperatures from -55°C to +180°C.

3. Ambient temperatures from -60°C to +200°C.

There is also a Vibrator capable of producing a maximum thrust of 500 pounds with frequencies of up to 3,000 c.p.s. for resonance searches.