In doing some reading on the early RCN helicopter programs, I came across some references to a number of early Sikorsky turbine helicopters numbered in the S-60 sequence, including a couple of contradictory descriptions of the S-63.
My main source here is
Wings of the Fleet: 50 Years of the Canadian Sea King, which compiles several articles on early RCN helicopter experiments and procurement. The two main articles of interest are:
Chapter 2: “'We Came To Mow Your Lawn' How and Why Canada Acquired the Sikorsky Sea King Helicopter" by John L. Orr
and
Chapter 3: "Seasprite to Sea King: The Royal Canadian Navy’s Ship-borne Antisubmarine Helicopter Capability" by Jason Delaney
Mr Orr refers to the S-63-2 as the main alternative to the Seasprite, but says it was heavier and more expensive. In a footnote, he describes it thus:
Chapter 2 said:
The S-63-2 was a twin-engine derivative of the single-engine S-62 Sea Guard acquired by the US Coast Guard and one of two “paper” helicopters proposed by Sikorsky to meet the RCN’s requirement. The other was the S-65, apparently a considerably smaller helicopter. Source: RCN NSS 7801-102 (STAFF) 18 June 1959. “Comparison Study Kaman HU2K and Sikorsky S-63-2.” See Annex A for helicopter specifications.
And he gives S-63-2 specs as follows.
Chapter 2 said:
Sikorsky S-63-2 (Proposal)
Description | Antisubmarine helicopter |
Engine | Two T-58 turbo-shaft engines. (T-58-6 or T-58-8) |
Provenance | Described in the reference as a “cut-down HSS-2 for RCN role.” |
Armament | Homing torpedoes or depth-bombs |
Source: 105. RCN NSS 7801-102 (Staff) 18 June 1959. Comparison Study Kaman HU2K and Sikorsky S-63-2. RCN NS 7820-102 (Staff) 18 January 1961, “ASW Helicopter Procurement.”
However, Mr. Delaney describes it somewhat differently.
Chapter 3 said:
"The S-63 was based on the prototype HSS-2 Sea King ASW helicopter with rotor control and transmission components of the HSS-1N (S-58) as well as three powerful engines."
Source: Jane’s All the World’s Aircraft, 1959/60 (Toronto: McGraw-Hill, 1960), 382–83.
But then there is also that mention of an S-65, smaller than the S-62 and thus much smaller than the S-61 Sea King. Orr gives it only a passing mention but does provide specs:
Chapter 2 said:
Sikorsky S-65 (Proposal)
Description | Antisubmarine helicopter |
Engine | One or possibly two T-58 turbo-shaft engines |
Provenance | Likely comparable to S-62 with flying-boat hull but probably with four-bladed main rotor derived from S-58. Possibly similar to four-bladed S-62 (Model S-62B) developed for the Indian Air Force. Smaller and approximately 2,500 pounds (lb) [1,134 kilograms (kg)] lighter than the S-63-2. |
Armament | Homing torpedoes or depth-bombs |
Source: Kenneth H. Sullivan and Larry Milberry, Power: The Pratt and Whitney Canada Story (Toronto: CANAV Books, 1989), 234; and RCN NS 7820-102 (Staff), 18 January 1961, “ASW Helicopter Procurement.”
Don't know if this is useful at all, but it sure seems as though the RCN was being given access to some early Sikorsky turbine concepts (c.1958-59) for a series of related flying boat hulled designs:
S-61: became SH-3 Sea King
S-62: became HH-52 Seaguard
S-62B: 4-bladed S-62 for Indian Air Force
S-63: sized between S-61 and S-62
S-65: Similar in size to S-62 but with 4-bladed S-58 rotors, possibly similar to S-62B
Obviously, these S-63 and S-65 designs never went forward, but it's interesting to see what looks like a series of very similar types, graduated in size to suit various customers and applications.
Edit: I missed that this thread is in Aerospace. Would it make sense for this post to be relocated to the Postwar projects subforum, since it deals with unbuilt designs?