Before the adoption of the Tri-Service system in 1962, the US Navy had its
own system of aircraft designations, completely different from that used by
the USAAF and USAF.  This consisted of up to five parts:

(1) One or two letters to indicate the function.  These included:

    A  = Attack
    BF = Fighter-bomber
    F  = Fighter
    HC = Transport helicopter
    HO = Observation helicopter
    HU = Utility helicopter
    J  = Utility
    N  = Trainer
    O  = Observation
    P  = Patrol
    PB = Patrol bomber
    R  = Transport
    SB = Scout bomber
    T  = Trainer
    TB = Torpedo bomber
    W  = Early warning

(2) A sequence number, to distinguish between aircraft of the same function
built by the same manufacturer.  The number was left out if it was 1.

(3) A letter to indicate the manufacturer.  Because the US Navy used
aircraft from considerably more than 26 different manufacturers, most of
the letters of the alphabet were shared between several companies; the same
company frequently used more than one letter at various times.  If the same
aircraft was built by more than one firm, the designation was changed to
reflect the individual manufacturers (for example, the Chance-Vought F4U
Corsair was also built by Goodyear, whose Corsairs were designated FG).
Some of the most important manufacturers were:

    A = Brewster, Noorduyn
    B = Beech, Boeing, Vertol
    C = Cessna, Curtiss, De Havilland Canada
    D = Douglas, McDonnell
    E = Cessna, Piper
    F = Fairchild, Grumman
    G = Goodyear
    H = McDonnell
    J = North American
    K = Fairchild, Kaman
    L = Bell
    M = Bell, Martin
    O = Lockheed, Piper
    P = Piasecki
    Q = Fairchild
    S = Sikorsky, Stearman
    T = Northrop
    U = Chance-Vought
    V = Lockheed, Vultee
    W = Wright
    Y = Consolidated, Convair

(4) After a dash, a number to indicate a subtype.

(5) Optionally, a letter to indicate a minor variation on a subtype.

For example, the F4U was the fourth fighter designed by Chance-Vought for
the US Navy.  The F4U-1A was a modified version of the first subtype of the
F4U.  The F4U was commonly known as the Corsair, but, as with Air Force
types, the name was not part of the formal designation (Vince Norris, who
has quite a few hours in USN aircraft, reports that they were always
referred to by their designations, not the proper names; using names
instead of numbers was the mark of a civilian).

When the Tri-Service system was adopted in 1962, aircraft then in USN
service (as well as some under development or recently retired) were
redesignated under the new system.  Some were simply given the designation
already used by the USAF for the same aircraft; others were given new
designations.  They included:

    Beech SNB Expediter           = C-45 *
    Bell HTL/HUL Sioux            = H-13 *
    Convair F2Y Sea Dart          = F-7
    Convair P4Y Privateer         = P-4
    Convair R4Y Samaritan         = C-131 *
    De Havilland Canada UC Otter  = U-1 *
    Douglas AD Skyraider          = A-1
    Douglas A3D Skywarrior        = A-3
    Douglas A4D Skyhawk           = A-4
    Douglas F3D Skyknight         = F-10
    Douglas F4D Skyray            = F-6
    Douglas JD Invader            = B-26 *
    Douglas R4D Skytrain          = C-47/117 *
    Douglas R5D Skymaster         = C-54 *
    Douglas R6D Liftmaster        = C-118 *
    Fairchild R4Q Boxcar          = C-119 *
    Grumman A2F Intruder          = A-6
    Grumman F9F Panther/Cougar    = F-9
    Grumman F11F Tiger            = F-11
    Grumman S2F Tracker           = S-2
    Grumman TF Trader             = C-1
    Grumman UF Albatross          = U-16 *
    Grumman WF Tracer             = E-1
    Grumman W2F Hawkeye           = E-2
    Kaman HOK/HTK/HUK Huskie      = H-43 *
    Kaman HU2K Seasprite          = H-2
    Lockheed GV/R8V Hercules      = C-130 *
    Lockheed P2V Neptune          = P-2
    Lockheed P3V Orion            = P-3
    Lockheed R7V/WV Constellation = C-121 *
    Lockheed TV Shooting Star     = T-33 *
    Lockheed T2V Seastar          = T-1
    Lockheed UV Jetstar           = C-140 *
    Martin P5M Marlin             = P-5
    Martin RM                     = C-3
    McDonnell F2D/F2H Banshee     = F-2
    McDonnell F3H Demon           = F-3
    McDonnell F4H Phantom II      = F-4
    North American AJ Savage      = A-2
    North American A3J Vigilante  = A-5
    North American FJ Fury        = F-1
    North American T2J Buckeye    = T-2
    North American T3J Sabreliner = T-39 *
    Piasecki HUP Retriever        = H-25 *
    Piper UO Aztec                = U-11
    Sikorsky HO4S/HRS Chickasaw   = H-19 *
    Sikorsky HR2S Mojave          = H-37 *
    Sikorsky HSS Sea King         = H-3 *
    Sikorsky HUS Seabat/Seahorse  = H-34 *
    Sikorsky HU2S Seaguard        = H-52
    Vertol HRB Sea Knight         = H-46
    Vought F8U Crusader           = F-8

(* Designation already used by USAF)