The US Air Force’s venerable Boeing B-52H Stratofortress strategic bomber is receiving important enhancements to its self-protection systems.
L3Harris was awarded a ten-year $947 million contract in 2021 to implement a host of improvements to enhance the B-52H’s AN/ALQ-172(2) self-protection suite. This contract forms part of the Stratofortress’ MARS (Maintainability and Reliability System) upgrade programme. According to reports, the AN/ALQ-172 has been in service onboard the B-52 series since the early 1980s. The original version was the AN/ALQ-172(V)1 fitted to now-retired B-52G bombers with the AN/ALQ-172(V)2 equipping the B-52H.
Capabilities and improvements
Open sources state that the AN/ALQ-172(2) can protect the aircraft against radar-guided air-to-air and surface-to-air threats. The system detects and jams low band (100 megahertz to two gigahertz/GHz), mid-band (two gigahertz to six gigahertz) and high-band (six gigahertz to 18GHz) threats. These threats can include simultaneous monopulse, multiple pulse, pulse Doppler and continuous wave radars.
According to L3Harris’ literature, the MARS upgrade extends the AN/ALQ-172(V)2’s frequency coverage. This may mean coverage has been extended upwards to circa 40GHz. Extending the system in this fashion would allow the AN/ALQ-172(V)2 to detect and jam K-band (24.05GHz to 24.25GHz) and Ka-band (33.4GHz to 36GHz) threats. K-band and Ka-band radars are often employed as seekers for active radar homing air-to-air and surface-to-air missiles. Field-programmable gate array technology has been added to the AN/ALQ-172(V)2 making the system easier to reconfigure in situ. The upgrade also added digital receivers while reducing overall weight and power consumption.
Stratofortress path
“There isn’t a single MARS contract,” says Jimmy Mercado, L3 Harris’ programme director for bomber electronic warfare. “The MARS campaign started as a series of form, fit, function (and) interface LRU (Line Replacement Unit) redesigns triggered by sustainment demand.” Mr. Mercado says that the first LRU to be redesigned was the system’s LRU-10 with work commencing in 2014. The AN/ALQ-172(V)2’s LRU-14 has also been redesigned via the MARS programme. As Mr. Mercado states both LRU-10 and LRU-12 are “in production and are fieldable”. He adds that “(a)ll but two LRU redesign contracts have been completed. The remaining two will complete in 2025. Production for MARS LRU-4 is expected to begin this year.”
Writ large, MARS heralds improvements “inherent from transitioning from analogue to digital technology, the use of digital receivers and high-speed signal processing, and increased accuracy and precision measurements,” Mr. Mercado continues. An open, modular approach has been taken to ease future upgrades. During a recent test flight five of the nine LRUs being upgraded were successfully evaluated. MARS shows there is growth potential for the EW systems protecting a bomber which may remain in service until 2050.
by Dr. Thomas Withington
