June 2023: Boeing Model 360
Experimental Advanced Technology Demonstrator first flight: June 10, 1987
The Boeing 360 was designed as a replacement for the US Marine Corps/Boeing Vertol CH-46 Sea Knight as a medium-lift, troop assault/cargo utility helicopter that lifts 24 combat troops. A single prototype was built with company funding with configuration definition work completed by 1980. Slightly larger overall than the Boeing CH-46 Sea Knight, it used the engines and drive system from the larger Boeing CH-47 Chinook helicopter.
Innovative features included an all-composite, low-drag airframe structure, composite drive system components and rotor hubs, high-speed transonic airfoils on the rotor blades and modularized sub-system components. Low-cost composite tooling and manufacturing techniques were also utilized. A six-axis cockpit isolation system for reduced vibration at high speed was also demonstrated.
A modified CH-47C/Model 234 Commercial Chinook drive system was used with power provided by two Textron Lycoming AL5512 (T55-L-11D) turboshafts each max rated at 4,200 shp (3,132 kW).
The normal design structural gross weight was 30,500 lb (13,800 kg) with 10,000 lb (4500 kg) of internal cargo. The maximum design alternate gross weight was 48,000 lb (21,700 kg).
A hydraulically powered, rear-loading ramp and the triple cargo hook system (based on the CH-47D) were included. The integral cargo handling system included roller rails in the cargo floor. The landing gear was a fully retractable, tricycle arrangement that also utilized composite components.
During flight testing, the Boeing 360 demonstrated a level-flight airspeed of 214 knots (396 km/h).
Advanced technologies and composite materials research and manufacturing methods that were developed and tested on the Boeing 360 were successfully migrated to other rotorcraft platforms, including the Boeing-Sikorsky RAH-66 Comanche.
The eventual US Marine Corps medium-lift replacement was the JVX/Bell Boeing V-22 Osprey tiltrotor program, when the MV-22 reached initial operational capability (IOC) in 2007.
Last flown in August 1992, the Boeing 360 was donated in 1999 to the American Helicopter Museum in West Chester, Pennsylvania, where it currently is on display.
Prepared by Ken Bartie
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