Since 1942 the US Navy had been considering a follow on aircraft for the very successful Grumman Avenger torpedo bomber. In response Grumman Aircraft Corporation came up with a design proposal Model G-55 the XBTF-1. With a 74 foot wing span and a 45,000 Lb. gross weight it would have been a very large aircraft for the day and eventually fell from consideration because the Navy felt it was too large for the aircraft carriers then in service.

       Also considered for an Avenger replacement was a variant of the Grumman F7F Tigercat. Grumman Model G-66 the XTSF-1 was a re-structured Tigercat airframe to make room for radar and an internal bomb bay. Despite impressive conceptual performance the design also fell from consideration because of its size and the fact that the Tigercat was experiencing problems in operating from aircraft carriers.

       Both of these designs did not progress beyond the mock-up stage.

       Model G-70 was a private venture initiative by Grumman to come up with a replacement for the very successful Avenger. The G-70 design was larger had a greater payload and in its original hybrid twin engine (piston and jet) configuration would have been 100 MPH faster than the Avenger.

       On October 9, 1944 the Navy accepted the Model G-70 (XTB3F-1 in Navy parlance) and an order was placed for 3 prototypes. The XTB3F-1 had a Pratt and Whitney-2800 radial piston engine in the nose and a Westinghouse J-30 jet engine in the tail. Between the cavernous weapons bay, capable of internally carrying two torpedoes, fuel storage and the ducting required to feed air from the wing root intakes to the rear mounted jet there was no room for crew in the fuselage so the radar bombardier was seated in the cockpit slightly below and to the pilot’s right.

      Only one of the three prototypes was actually completed with the jet engine. Ground testing of this one prototype caused the ducting to fail and the XTB3F-1 was never flown with in the hybrid configuration. The first flight of the new single engine design took place on 19 December 1946. Even with the design change there was still a need to replace the ageing TBF Avengers that were in a large part serving as carrier borne ASW (Anti-Submarine Warfare) platforms. With the removal of the ducting and the jet engine there was a lot of space in the design’s rather large fuselage that could be used for electronic equipment and the crew that was needed to operate it. However, even with the available space both the Navy and Grumman felt that it would be better to use two aircraft to accomplish the ASW mission, thus was born the Hunter–Killer concept.

      The change in roles caused a designation change; one of the prototypes became the XTB3F-1S and was modified as the Hunter prototype. The bomb bay of the XTB3F-1S was deleted and a large radome to house the APS-20 Radar was fitted in its place as well as room for two crew positions in the fuselage. The two new fuselage crew positions consisting of a radar operator and an Electronic Countermeasures operator. The pilot was now alone in the rather large cockpit.

      The third prototype became the XTB3F-2S and was modified as the Killer version which was fitted with an underwing radar and searchlight as well as the capability of carrying underwing stores of six 5 inch HVAR rockets, four 500 Lb. bombs or four Mk. 54 Depth Bombs. An ASW homing torpedo could be carried in the bomb bay.

      In the interim the Navy had changed its tactics and was combining VB (bombing) and VT (Torpedo) squadrons into the new VA (Attack) Squadron. So the XTB3F-1 (X for Experimental, T for Torpedo, B for Bomber, 3rd TB design from F – Grumman’s Manufacturer Designator) became XAF (1st Experimental Attack Design from Grumman). After several designation changes in July of 1949 the XTB3F-1S Hunter version would become the Grumman AF-2W Guardian and the XTB3F-2S Killer version would become the Grumman AF-2S Guardian.

      The first production Guardian, an AF-2W, flew on November 17, 1949. The first AF-2S took to the air on December 14, 1949. The last Guardian was delivered to the Navy in March of 1953. Grumman delivered 193 of the AF-2S type, 153 of the AF-2W type and 40 AF-3S versions which were similar to the AF-2S with the addition of MAD (Magnetic Anomaly Detector) boom.

      The Guardian served in the ASW/ maritime patrol role thru the Korean War but was not a very successful design being underpowered and sluggish on the controls. The Guardian was the largest single engined, piston powered aircraft to serve onboard aircraft carriers and suffered from a high accident rate. Shortly after the Korean War, the Guardian started to be replaced by the Grumman S2F Tracker a twin engined aircraft that combined the Hunter/Killer roles in one airframe. The AF Guardian was retired from active fleet service in August of 1955, but served with Naval Air Reserve units until 1957. Many Guardians saw service in the civilian forest firefighting role until 1978.

      As an avid modeler whose favorite subject is U.S. Navy aircraft I was very glad to receive the Special Hobby 1/48 Scale AF-2S Guardian “Submarine Killer” as a Christmas present. Knowing that there was a “Submarine Hunter” version out there I had to make a trek to my local hobby store and purchase it.

      When it came time to build these kits I ran into a bit of a glitch. The box art showed the “Killer” version SH 48135 but the instruction booklet in the box was for the “Hunter” version SH 48158. Must have been some kind of mistake at the factory. Thankfully, both kits have the same parts, so I went back the hobby store and exchanged the box cover and instruction booklet with an on the shelf kit and I was all set to go.

       Construction begins with the cockpit where you are given a choice between using photo etched or injection molded foot petals. This is one of several places in the assembly process were I feel the instruction could be clearer. No matter where I seemed to place the pedals they did not fit when I tried to glue the instrument panel to the cockpit base. The folded photo etched parts from step 8 & 9 do not fit where they are shown.

       I was impressed with the detail of the engine and thought it was one of the better features of the kit. Special Hobby has also taken time to have the engine at its correct 3° offset.

       The major pieces of the kits fit together well and very little puttying or sanding was required.

       The underwing stores do not come with any locating pins or holes and I added some so that there was a stronger bond to the underwing.

       Where these aircraft worked in teams I was kind of surprised that Special Hobby did not offer markings from the same unit with the two kits. Thankfully Carcal decals offers sheet CD48078 that has decals for two sets of teams. I chose the rooster tail marking from VS-37 on board the USS Princeton in 1955.

       Despite some minor difficulties I am glad to have these two models in my collection.

Bibliography:

       Naval Fighters Number Twenty - Grumman AF Guardian by Steve Ginter ISBN 0-942612-20-5

       Wikipedia Article on the Grumman AF Guardian

       National Museum Of Naval Aviation's Grumman Guardian

       Military Factory Website - Grumman AF Guardian

       Military Factory Website - List of Grumman Aircraft

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