Sikorsky’s little Raider

David C Isby reviews the latest news from Sikorsky’s S-97 Raider programme and looks forward to the maiden flight of the company’s SB-1

The second S-97 prototype during flight-testing over Florida in June 2018.
Sikorsky

THE SIKORSKY S-97 Raider is now back in the air. Development of the S-97, originally designated the Light Tactical Helicopter, started in 2010 as a possible competitor for the US Army’s Armed Aerial Scout helicopter programme before it was cancelled. The S-97 is a Sikorsky-funded follow-on to the company’s X2 compound helicopter technology demonstrator that flew between 2005 and 2010 and set a number of speed records for helicopters in the 250kts (460km/h) range. The S-97, designed from the outset to be capable of unmanned flight, has attracted interest as the possible basis of a possible Future Attack Reconnaissance Aircraft Competitive Prototype (FARA CP) helicopter.

The S-97’s flight-testing was cut short on August 2, 2017. The first prototype (N971SK) was damaged in a hard landing caused by flight control software problems. By that time, it had already logged 20 flight test hours. The second prototype (N972SK), which had been carrying out ground testing since April 25, 2017, made its first flight on June 19 at Sikorsky’s Fflight Development Centre at West Palm Beach Florida. Its initial 90-minute flight was reportedly successful. On June 28, Sikorsky pilots Bill Fell and John Groth flew another 90-minute flight, demonstrating progress in the test programme.

To date, the S-97 has already demonstrated a capability to achieve 150kts (275km/h), and this is expected to increase to 200kts (370km/h) by September. The eventual top speed is designed to be over 250kts. Currently powered by the General Electric YT706-GE- 700R engine, the S-97 is designed so that the engine eventually selected to retrofit the US Army’s legacy UH-60 and AH-64 helicopters under the Improved Turbine Engine Program can be easily installed.

The 11,000lb (5,000kg) S-97 is based on scaled-up technology previously demonstrated on the 6,000lb (2,700kg) X2 design: fly-by-wire flight controls, allcomposite rigid rotor blades, hub drag reduction, active vibration control (addressing a major issue associated with the rotor configuration) and a pusher propeller driven by the main gearbox. Sikorsky sees the S-97 as a likely FARA CP helicopter, especially as the Army wants the FARA CP developed rapidly; the X2 technology would not have to be scaled up.

The most obvious innovation is the Advancing Blade Concept (ABC) rotor system comprising rigid, contra-rotating coaxial rotors, which enables high speeds and improved manoeuvrability. The ABC rotor system reportedly offers improved performance in hot temperature and high-altitude operations, exceeding current US Army specifications to be able to hover at 6,000ft at 95°F (35°C). One of the issues to be demonstrated in Sikorsky’s flight test programme is the ability of the flight control system to cope with vibration at high speeds.

The S-97 was designed as a risk-reduction project for the larger 32,000lb (14,500kg) SB-1 Joint Multi-Role-Technology Demonstrator aircraft. Sikorsky’s SB-1 is designed to meet the US Army’s Future Vertical Lift (FVL) Capability Set 3 requirements of 30,000lb (13,600kg) weight, the ability to carry 12 troops and a top speed of 230kts (425km/h). The rotorcraft eventually selected for the FVL Capability Set 3 is intended to replace the UH-60 Black Hawk. Sikorsky’s SB-1 design also has the potential to be developed into an attack helicopter version with a tandem cockpit, stub wings with hard points, and a chin weapon/ sensor turret that could replace the AH-64E.

Sikorsky expects to fly the SB-1 for the first time later this year, powered by Lycoming- Honeywell T55 engines, the same type of engine as used by the CH-47F Chinook. The Lycoming/ Honeywell T55 might be replaced by a new engine selected from contenders being developed under the Future Affordable Turbine Engine programme. Sikorsky has experienced delays with the development of its SB-1, mainly resulting from issues with the complex transmission design.

Sikorsky’s transmission requires the components to sustain highspeed flight turning two rotor heads in opposite directions, with two different drive masts. Reportedly, as a result of ground testing, transmission components were redesigned to incorporate high-technology alloys.

To take advantage of the design’s high-speed flight capabilities, the transmission also has to allow both engines to transmit up to 80% of their power output to the pusher airscrew while in level flight.

Canadian helicopters join Minusma mission

CH-147F Chinook 147307 on the flight line at Gao, Mali.
Royal Canadian Air Force

Under Operation Presence, Canada has deployed three CH-147F Chinook transport helicopters, ive CH-146 Grifon utility helicopters and around 250 personnel to Mali as part of the United Nations’ Minusma mission there.

The ffirst Canadian Chinooks and Grifons arrived by CC-177 Globemaster III on 15 July, 2018 for their year-long stay in Gao, although operational missions began on August 1, a day after a deadly attack on a convoy carrying election materials.

The Chinooks of Canada’s Air Task Force are being used for transport and logistics while the Grifons (with pintle-mounted machine guns) are being used for armed escort and medical evacuation. One of each helicopter will be kept as a spare. They take over from German Tigers and Belgian NH90 Caiman Tactical Transport Helicopters. Canada is also deploying a CC-130 Hercules aircraft to the United Nations Regional Support Centre in Entebbe, Uganda. Guy Martin

Two H145Ms for Luxembourg Defence

The Government of the Grand- Duchy of Luxembourg has ordered two Airbus Helicopters H145Ms, the European helicopter manufacturer announced on July 27, 2018.

The helicopters will be delivered before the end of 2019 and will enter service in early 2020, fulilling defence and security roles for Luxembourg Defence.

The H145Ms are being acquired via the NATO Support Procurement Agency (NSPA) in close cooperation with the Defence Directorate and Police Lëtzebuerg.

The helicopters will be operated and maintained at Luxembourg Findel Airport and the NSPA will negotiate a service contract to support the initial phase of operations, as well as standing up an air component within the Luxembourg Army and the constitution of a dual use government air hub at Findel.

Nigel Pittaway

Inaugural fflights of Indian AH-64E

Indian Air Force AH-64E Apache N4801A (msn 154801) at Mesa, Arizona.
Boeing Defense

Boeing has performed the inaugural flights of both the AH-64E Apache and CH-47F(I) Chinook helicopters for the Indian Air Force, the company announced on July 27, 2018.

Both helicopters are in an overall flight grey colour scheme, with the Apache (msn 154801) wearing the US civil registration N4801A and the Chinook (msn M2401) N279RN.

The IAF has 22 Apaches and 15 Chinooks on order and deliveries of both types will begin in 2019.

David Koopersmith, vice president and general manager of Boeing Vertical Lift, said: “We look forward to delivering this phenomenal capability to India. From coastal operations to high altitude mountainous missions, these aircraft will play vital roles in the Indian Armed Forces.”

Nigel Pittaway

Philippines Navy to receive two AW159s

The Philippine News Agency reported on July 24, 2018, that the Philippine Navy will receive two Leonardo AW159 Wildcat helicopters in March 2019.

Quoting Philippine Navy Vice Admiral Robert Empedrad, lag oicer in command, the news agency reported that the PHP 5.4 billion contract also includes weapons, mission equipment and logistics support.

The anti-submarine warfare helicopters will be deployed aboard the Philippine Navy’s two new guided missile frigates currently being constructed by Hyundai Heavy Industries in South Korea. Nigel Pittaway

British helicopters deploy to Mali

The Royal Air Force has deployed three Chinook HC5 helicopters from RAF Odiham to Mali, where they are Supporting French counterterrorism operations under Operation Barkhane.

The three helicopters had arrived in Gao by July 18, 2018, along with 90 British troops. The Chinooks are there to provide logistical support and to improve safety by moving troops by air, rather than ground where they are more vulnerable to attack, the Royal Air Force said.

The Royal Air Force added that British military personnel will not be involved in combat operations. In addition to the helicopters, British support to Operation Barkhane includes transport flights by the Royal Air Force. Although deployed mainly in support of the French-led counterterrorism and security mission in the Sahel region, the Chinooks are also working closely with the United Nations’ Minusma mission in Mali. Guy Martin