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Sidewinder Recharging Unit

Product Specification Table
Gas Nitrogen 99.999% Pure
Pressure 0 – 42000 psi / 0 – 290 bar
Flow Rate Gaseous HP 23 scfm / 650 Litres/Min
Flow Rate Gaseous LP 50 scfm / 1400 Litres/Min
Hoses 2 x 50ft / 15 metre
Tank Coding DOT 4–L
Tank Capacity 75 Gallons / 300 Litres
Length 124 ins / 315 cms
Width 60 ins / 152 cms
Height 54 ins / 137 cms
Weight 3750 lbs / 1700 Kg
Temperature of Gas Within 7°C of Ambient
Purity Specification
Contaminants suspended in the gas are no greater than the following levels:
Moisture 2 ppm
Carbon Dioxide 2 ppm
Methane 6 ppm
Acetylene 1 ppm
Hydrocarbons 3 ppm

Liguid Nitrogen Guage

Sidewinder Recharging Unit (SRU)

McNaughton Dynamics Limited has developed a new universal “Sidewinder Recharging Unit” to supply all Nitrogen requirements for the Sidewinder Missile in addition to both high and low pressure gaseous Nitrogen for aircraft systems.

This innovative design provides large amounts of Nitrogen gas from a liquid Nitrogen tank, for charging aircraft and missile Nitrogen systems of all capacities. It is based on the successful Zwick range of Cryogenic Servicing Units, in service with air forces worldwide for the last twenty–five years.

Designed to be very simple to operate, the self-pressurising Sidewinder Recharging Unit (SRU) fills LAU–7 cylinders, 3860 and 4044 Test Sets and aircraft systems safely and quickly from one source of liquid. The cylinders can be charged on the flight line, giving a rapid turn round of the aircraft and minimising the transportation and handling of these vulnerable cylinders.

The machine is filled with 300 Litres of Liquid Nitrogen which is stored in a 400 psi / 27 bar cryogenic tank. Some of the liquid is boiled off and used to pressurise the tank so as to provide a continuous supply of pressure. A patented internal pump provides high pressure Nitrogen upon demand. After the tank and pump, the liquid is vaporised into gas by aluminium heat exchangers, warmed to ambient temperature and delivered to the control panel for distribution to the aircraft through two hoses and control valves.

Many air forces of the world have requirements for high–pressure pure Nitrogen (for charging LAU–7 cylinders used on the Sidewinder missile) and both high and low pressure Nitrogen (for filling tyres, struts and accumulators). It therefore made sense for us to develop an “all in one’ Sidewinder Recharging Unit. With an internal pump that is always available for use, the SRU can also deliver large quantities of high pressure gaseous Nitrogen for LAU 7 cylinder charging as well as other aircraft systems, again both on and off the aircraft. It can also be used for charging aircraft cylinder trolleys and supplying the 3860 and 4044 missile test sets. The SRU is fitted with an additional purifying system consisting of replaceable molecular sieve cartridge purifiers. In addition, it can be fitted with an optional Cryostat purity monitoring system.

Features and Benefits


The SRU saves time, both by filling the LAU 7 cylinders quickly on the flight line and also by charging the aircraft systems quicker. The unit is filled either once a week or up to once every three weeks depending on usage. This is done by a Liquid Nitrogen delivery vehicle and takes about 15 minutes. There is no pressure raising time as the Nitrogen is always available. High and low pressure hoses can be operated simultaneously as well as simultaneous charging of LAU 7 cylinders.


The SRU takes up much less space than the 20 cylinders it replaces and can be stored outside in all weather. It occupies 52 square feet or 4.8 sq metres only and can easily be moved manually or with a towing vehicle. The LAU 7 cylinders are charged in armoured tubes mounted on top of the unit.


The cost of gas generated from liquid is less than cylinder gas. There are no costs associated with storing, transporting or changing heavy(80 Kg) gas cylinders and no empty cylinders have to be returned.


The SRU is designed with high reliability components. The machine is based on a tried and tested military unit of which over a thousand were produced for service all over the globe. The hose end components are more robust for flight line service.


The SRU is designed to handle and dispense both high and low pressure gaseous Nitrogen safely. The tank is designed to DOT 4–L standards and can be operated for life without the need for annual testing.