Sikorsky CH-124 Sea King - Design and Development

Design and Development

The advent of nuclear-powered attack submarines in the late 1950s prompted RCN leaders to assess the new threat they posed. Although these craft were noisier than older submarines and could therefore be detected at longer ranges, they were also capable of 30 knots (56 km/h) while submerged, which was faster than the top speed of the RCN's new St. Laurent class destroyers at 28.5 knots (52.8 km/h). Some RCN leaders harbored serious doubts that the destroyers could effectively pursue and destroy such fast vessels, even when operating in pairs. During a 25 February 1959 meeting of the Naval Board, it was decided that the Navy would counter the new threat by outfitting destroyers for helicopter operation.

The RCN had examined the feasibility of operating ASW helicopters from small escorts when it modified the Prestonian-class frigate HMCS Buckingham (FFE 314) in mid-1956 with a temporary helicopter landing platform. Successful trials were held in October 1956 using a Sikorsky HO4S-3 and a larger temporary landing platform was soon installed on the new destroyer escort HMCS Ottawa (DDE 229). Operational trials were conducted using an RCAF Sikorsky S-58, a substantially larger and heavier aircraft than the HO4S, and the success of these tests led to approval of the concept.

To achieve the goal, the RCN needed a helicopter capable of all-weather day-and-night operations with a heavy weapons load- capabilities the HO4S, the RCN's current utility helicopter, did not possess. Initial 1959 studies identified two helicopters that would meet the upcoming requirements- the Sikorsky S-61 (HSS-2) and the Kaman K-20 (HU2K)- but neither aircraft had flown at the time, so no choice was made. After further studies concluded that the smaller Kaman would better satisfy RCN requirements, the Treasury Board approved an initial procurement of 12 HU2K helicopters for $14.5 million in December 1960.

Despite this apparent setback for Sikorsky, several factors would derail the Kaman proposal. When the Naval Board held a follow-up meeting on 27 January 1961 to discuss the program, it was revealed that the asking price for the initial 12 units had nearly doubled to $23 million, a mere 6 weeks after the Treasury Board had approved the purchase. The Naval Board continued to endorse the HU2K, but some RCN leaders had serious misgivings due to the drastic price increase and staff reports that Kaman's performance projections might be overly optimistic. The Naval Board decided to await upcoming USN sea trials of the HU2K before rendering a final decision. The USN trials confirmed the calculations of RCN staff members; the HU2K was substantially heavier than promised, hampering its flight performance and rendering it incapable of meeting RCN requirements, even if Kaman were to install a proposed upgraded engine. The Sea King was ultimately chosen for production on 20 December 1961.

The first of 41 helicopters would be delivered in 1963 carrying the designation CHSS-2 Sea King. The airframe components were made by Sikorsky in Connecticut but most CHSS-2s were assembled in Longueuil, Quebec (Montreal) by United Aircraft of Canada (now Pratt & Whitney Canada), a subsidiary of Sikorsky's parent company. On 27 November 1963, the new landing platform aboard HMCS Assiniboine (DDH 234) was used for the first operational destroyer landing of a production CHSS-2. Upon the unification of Canada’s military in 1968, the CHSS-2 was re-designated CH-124.

The RCN developed a technique for landing the huge helicopters on small ship decks, using a 'hauldown' winch (called a 'Beartrap'), earning aircrews the nickname of 'Crazy Canucks'. The 'Beartrap' allows recovery of the Sea King in virtually any sea state. In 1968, the RCN, Royal Canadian Air Force (RCAF) and Canadian Army unified to form the Canadian Forces; air units were dispersed throughout the new force structure until Air Command (AIRCOM) was created in 1975.