The Army has approached the Indian industry to indigenously develop an auxiliary power unit (APU) for its fleet of Russian-made T-72 and T-90 battle tanks, that help not only conserve the life of the main engine but also reduce thermal and acoustic signatures when deployed in specific situations.

The Army’s requirement is for 3,257 APUs, which include 1,657 units for the T-90 and 1,600 units for the older T-72, which are the mainstay of the mechanised forces, according to an expression of interest issued today. Only Indian entities are eligible for the project under the ‘Make in India’ scheme.

  • An APU is a small engine or powered device that provides energy for functions other than propulsion
  • The APU increases tank’s stealth capabilities since the noise and heat emissions are much lower
  • Army’s requires 3,257 auxiliary power unit, including 1,657 units for T-90 and 1,600 units for the older T-72

According to Army sources, the “Acceptance of Necessity” for having APUs fitted on tanks was accorded by the Ministry of Defence in October 2019 after undertaking feasibility studies and Rs 1,325.92 crore have been earmarked for the purpose.

An APU is a small engine or powered device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft and naval ships as well as some large land vehicles. Though not commonly found, the concept of APUs on tanks dates back to World War II when these were mounted on American Sherman tanks.

According to the Army’s requirements, the APU should be able to concurrently operate the gunner, commander and driver sights, fire control system, radio sets, internal communication systems, navigation aids and charge batteries when the main engine is switched-off.

The APU should be able to function for a stretch of six hours at a time in temperatures ranging from minus 50 °Celsius to 45 °Celsius and at altitudes ranging up to 16,000 feet.

Since the APU would be mounted on the exterior, it would also be required to be waterproof up to a depth of five metres to enable deep-fording by the tank.

The APU would cater to power requirements when deployed in the surveillance mode during a lull in battle and during breaks or layovers in training.

At present, the main engine has to be kept running to operate the systems even if the tank is stationary. Besides reducing war and tear of the main engine, the APU would increase the tank’s stealth capabilities since the noise and heat emission would be much lower. The Army is also looking at developing solar powered APUs for armoured vehicles.