Grumman XTSF The Grumman XTSF was a proposed twin - engine torpedo scout aircraft , designed by Grumman for the United States Navy towards the end of World War II . Based on the design of the F7F Tigercat fighter , enlarged and with the addition of a bomb bay , the XTSF was deemed too large for carrier operations , and the project was cancelled before any aircraft were built . Instead , the Navy chose to order the single - engine XTB3F , which became the successful AF Guardian . Design and development . In 1944 , it was determined that the Grumman XTB2F , then under development for the Navy , would be too large to practically and safely operate from aircraft carriers . Even the new s , known as " battle carriers " ( CVB ) and the largest aircraft carriers built by any nation to that point , would have difficulty operating the massive aircraft , which was the size of a U . S . Army Air Force medium bomber . As a result , in late June 1944 , Grumman submitted its G - 66 design to the Bureau of Aeronautics ( BuAer ) . After a review of the design by BuAer during the following month , a revised design was submitted , and on August 17 the existing contract for the XTB2F was modified to instead order two XTSF - 1 aircraft , to be based on Grumman ' s F7F - 2 Tigercat two - seat , twin - engined fighter - bomber , the first prototype intended to be a conversion of a F7F airframe . A mid - wing , all - metal , cantilever monoplane with two Pratt & Whitney Double Wasp radial engines mounted in streamlined nacelles under the wing , the XTSF - 1 was intended to carry two crew members in tandem seats , and featured an internal bomb bay and a SCR - 720 radar set , the radar later being replaced in the design by an AN / APS - 3 or AN / APS - 4 set . A second seat was added for the radar operator . The outer wing of the XTSF was lengthened by compared to that of the F7F - 2 , while the size of the horizontal stabilizer was increased by ) . The vertical stabilizer was also enlarged , while the aircraft ' s weight increased by almost two thousand pounds ( 900 kg ) over that of the Tigercat . The wings folded upwards for stowage aboard aircraft carriers , while the undercarriage and arrestor hook were hydraulically operated . Gun armament was planned to be four . 50 caliber ( 12 . 7 mm ) Browning M2 machine guns , or , alternatively , two 20 mm Hispano cannon , while a bomb bay based on that of the TBF Avenger was installed in a fuselage stretched by . Cancellation . A mockup of the cockpit , center fuselage and wing center section was built and was inspected by the BuAer in the fall 1944 . However , the contract for the prototype XTSF - 1s was terminated in January 1945 . This was due to a variety of factors , including the Navy ' s belief that the Grumman engineers and factory were already at capacity producing the F6F Hellcat , the F7F , and the F8F Bearcat , that the XTSF - 1 would be too large for practical operations from escort carrier s , and because it was believed the Grumman G - 70 , to be built as the XTB3F , was a better prospect . In addition , the F7F was proving difficult to certify for operations from aircraft carriers , further prejudicing the Navy against the design . Some sources erroneously state that the XTSF - 1 became the XTB2F , however this is not the case . The XTSF - 1 was the only aircraft ever designated by the U . S . Navy in the ' TS for Torpedo Scout ' category , the designation being superseded and incorporated , along with ' BT for Bomber - Torpedo ' , ' SB for Scout - Bomber ' and ' TB for Torpedo - Bomber ' , into the new ' A for Attack ' series .