CH-46D Sea Knight

Naval aviation's first tandem-rotor helicopter, the Piasecki HRP, appeared during World War II. Fabric covered with a top speed of 104 M.P.H., its ungainly appearance earned it the nickname “Flying Banana.” Nevertheless, it was on the shoulders of this primitive helicopter that the Marine Corps first experimented with the concept of heliborne assault. In 1962, the service ordered another tandem-rotor design, the HRB (later designated CH-46) Sea Knight, featuring a rear cargo-loading ramp, a top speed of 166 M.P.H., and the ability to carry 4,000 lb. of cargo or 22 combat-equipped troops.

The first Sea Knights were delivered in June 1964, and as U.S. operations intensified in South Vietnam, there was a concerted effort to deploy them in-country to augment and ultimately replace the UH-34s in Marine Medium Helicopter Squadrons (HMM). The first squadron of CH-46s arrived in theater in March 1966, and during the first 35 days of operations, HMM-164 flew almost 2,700 combat sorties in the Sea Knight’s baptism of fire.

While the fuselages of squadron helicopters received holes from enemy fire during these combat hops, the operating environment proved equally worrisome. The dust and sand of South Vietnam, when sucked into the helicopter’s engine compressor, caused the engine to lose power. The particles also infiltrated the fuel systems and caused abrasions on the rotor blades. Modifications to the type, which included the installation of air filters and rotors with nickel-plated leading edges, helped remedy the problems. Deadly structural failures for a time grounded the aircraft, but over time and with the introduction of the more capable CH-46D version of the Sea Knight, the helicopter affectionately known as the “Phrog” became a mainstay of the Vietnam War. Over the course of the first true helicopter war, 106 leatherneck Sea Knights fell to enemy fire in missions ranging from supplying remote base camps to battlefield insertion and extraction to medical evacuation (MEDEVAC). The final flight for a Marine Corps CH-46 in South Vietnam occurred on April 30, 1975, when a “Phrog” extracted the last leathernecks of the Marine security detail from the rooftop of the American embassy during the evacuation of Saigon.

The CH-46 continued to serve the Marine Corps for the ensuing four decades with Marine Expeditionary Units (MEU) typically including Sea Knights on board amphibious assault ships to transport leathernecks ashore. The last version of the helicopter, the CH-46E, saw heavy combat service in the Global War on Terror in the sands of Iraq and the rugged terrain of Afghanistan. In the former theater of operations, “Phrogs” were a vital cog in the evacuation of casualties. “These guys flew in horrible conditions, facing everything from Iraqi aggressors to bad weather, to get as close to an injured Marine as possible,” one flight surgeon said of the abilities of the CH-46 pilots and aircrews. “During the heavier fighting, they would fly low and slow to make their way through dust storms and low visibility just to pick up a patient.”

While the Marine Corps, which retired its last CH-46Es in 2015, was the primary user of the Sea Knight, those in Navy markings performed a valuable function supporting deployments around the world. Equipping Helicopter Combat Support Squadrons (HC), CH-46s operating in detachments on board combat support ships carried everything from spare parts to food to ordnance to combatants as part of vertical replenishment (VERTREP) operations. Called “the 46 dance,” CH-46s spent hours flying between ships with pallets of cargo suspended beneath their fuselages. As one pilot remembered, the helicopter was always ready, “whether it was a medevac (medical evacuation) or getting a Coke to a sailor.” Some Sea Knights were designated HH-46s and operated as search and rescue platforms. The Navy also employed a limited number of RH-46s as minesweeping platforms. The last Navy CH-46s were retired from service in 2004.

The museum's CH-46D (Bureau Number 151952) spent much of its operational service in Helicopter Combat Support Squadron (HC) 6, It was flight delivered to the museum in 2003, by the squadron's commanding officer.

Specifications

Manufacturer: Vertol Division of the Boeing Company
Dimensions: Length: 44 ft., 10 in.; Rotor Diameter: 51 ft.; Height: 16 ft., 8 ½ in.
Weights: Empty: 13,065 lb.; Gross Weight: 23,000 lb.
Power Plant: Two 1,400 horsepower General electric T58-GE-10 shaft turbines
Performance: Maximum Speed: 166 M.P.H. at sea level; Service Ceiling: 14,000 ft.; Range: 230 miles
Crew: Two pilots, one crew chief and up to 22 assault troops