Grumman XTB3F-1S

The Grumman XTB3F‑1S was a single‑engine torpedo‑bomber prototype developed for the United States Navy in the late 1930s. Ordered under the Navy’s experimental XTB (experimental torpedo bomber) series, the aircraft first flew in early 1939 and represented Grumman’s attempt to replace the aging TBD‑1 Devastator. Constructed with an all‑metal stressed‑skin monocoque fuselage, the XTB3F‑1S featured a low‑mounted mid‑wing, folding wings for carrier stowage, and a retractable tailwheel undercarriage – advanced attributes for its era. Powered by a Wright R‑1820 Cyclone radial engine delivering roughly 1,200 hp, it drove a three‑bladed variable‑pitch propeller and offered a top speed near 300 mph. Armament provisions included provisions for a single Mark 13 torpedo or up to 1,000 lb of bombs, plus forward‑firing .30‑caliber machine guns and a rear defensive gun station. Though flight tests demonstrated respectable handling and payload capability, the Navy ultimately selected the more powerful TBF Avenger, ending the XTB3F‑1S program after only two prototypes. Its design experiments – especially the use of retractable gear and modular wing folding – informed Grumman’s subsequent carrier‑based aircraft and cemented the firm’s reputation as a leader in naval aviation innovation.