Sikorsky's first CH-53K King Stallion has achieved speeds of 120kt (222km/h) as the heavy-lift helicopter development project presses forward with flight envelope expansion and adds a second test aircraft to the effort.

The Lockheed Martin-owned rotorcraft manufacturer says its second three-engined prototype achieved flight on 22 January, and the two developmental aircraft have logged 35h since CH-53K flights began on 27 October 2015.

Operating from Sikorsky’s flight-test centre in West Palm Beach, Florida, the first engineering development model (EDM) recently achieved 120kt, just 21kt shy of its advertised speed of 141kt.


First CH-53K test aircraft achieves 120kts in West Palm Beach, Florida


The programme, which entered development in October 2005, will deliver 200 "super-heavy-lift" helicopters to the US Marine Corps as a replacement for the CH-53E Super Stallion, which the service plans to phase out by 2027.

Powered by three General Electric Aviation T408-400 turboshaft engines, the King Stallion will introduce fly-by-wire controls, “fourth-generation rotor blades” with anhedral tips, and increase the payload capacity threefold. It will carry 12.2t (27,000lb) over 110nm (204km) – 1.4t less than the original target set in 2005, but still significantly more than the Sikorsky CH-53E.

Sikorsky says its first two flight-test vehicles will examine structural flight loads and continue expanding the flight envelope while the third and fourth prototypes will concentrate on validating the CH-53K’s general performance, propulsion system and avionics once they begin flying later this year.

“Adding a second aircraft into flight status signifies another milestone for the CH-53K programme,” says Mike Torok, Sikorsky vice-president of CH-53K programmes. “With both aircraft in flight test, our flight envelope expansion efforts will accelerate as we continue to make good progress toward our initial operational test assessment and full aircraft system qualification.”


EDM-2 achieves first flight on January 22


The company confirms that 10 CH-53K aircraft are in various stages of construction ahead of the first of 194 production orders that will be placed, beginning in 2017 with two units. That includes four EDM aircraft and six “system demonstration and test articles”.

According to the US Navy’s budget submission for fiscal year 2017, $1.2 billion in research and development money is needed through 2021 to complete development activities.

The initial operational capability estimate has shifted right by about six months from July 2019 to the “first quarter of 2020” because of technical delays in 2015 that delayed first flight.

The marines want to stand up eight active-duty CH-53K squadrons, plus one training unit and one reserve squadron, says Sikorsky.

Production will move into high gear by 2020, but Sikorsky still has not officially decided which of its facilities will perform final assembly and checkout.