The Martin AM Mauler was designed to a US Navy requirement during the critical middle years of World War 2. It appeared in competition with three other designs presented by Curtiss, Douglas and Kaiser-Fleetwings. By this time, the US Navy required a carrier-based single-seat, single-engine monoplane to undertake a dual-role position in its inventory, accepting and surpassing the capabilities of single-role dive bombers and torpedo bombers of the day. The aircraft would be powered by a Pratt & Whitney R-4360 Wasp Major radial piston engine. The US Navy commissioned two prototypes from the Glenn L. Martin Company on May 31st, 1944 under the developmental designation of "XBTM-1".
On August 26th, 1944, the prototype XBTM-1 completed its first flight. A second prototype was authorized and completed for additional flight testing thereafter. This was followed by some sixteen preproduction examples for formal evaluation and ironing out any recognized deficiencies in design. However, the war in Europe ended in May of 1945 with the Soviet capture of Berlin and the capitulation of Japan followed in August after the dropping of two atomic bombs, bringing about the formal end of World War 2. With the end of the war, the large procurement order that once numbered as many as 785 aircraft was decidedly trimmed down to a more manageable 132 production examples. This was followed in 1946 by a redesignation of the BTM-1 to AM-1 (generically as the "Martin AM Mauler"). The AM-1 proved fortunate, however, as many American aircraft projects were outright cancelled with the end of the conflict.
While initial deliveries to USN flight units began in July of 1947, technical issues with the tail hook design persisted which delayed the type's formal introduction until March of 1948. Once ironed out, the Mauler made a respectable - though limited - legacy for itself, proving a solid performer and handy hauler. It was noted that landing a fully-laden airframe required some skill even under experienced hands, particularly on the deck of a moving carrier. This was the cost of capability, however, for the Mauler was well-known for its ordnance-hauling capabilities cleared for up to a 4,500lb standard load out of externally-held ordnance though it was suggested that these airframes could field beyond double that if pressed as such.
Outwardly, the Mauler exhibited a typically designed propeller-driven aircraft frame with a front-mounted engine compartment, forward-set cockpit (under a clear view bubble canopy) and curved tail rudder atop the tapered empennage. The main wing assemblies were straight, low-mounted and set ahead of amidships with slight dihedral apparent. Horizontal planes were set low on the vertical tail fin to clear the airflow of the main wing elements. The radial piston engine powered a large, four-bladed propeller assembly, a deviation from the wide-accepted three-bladed types en vogue during the war. Perforated dive brakes were affixed to the trailing wing edges for the dive bombing/torpedo bombing roles. The undercarriage was wholly retractable and of the "tail-dragger" configuration with two main landing gear legs (single-wheeled) and a retractable tail wheel at rear. The tail hook intended to snag along one of the presented cables aboard American carrier decks was set under the tail in the conventional way and lowered when the aircraft was inbound and ready for landing. The main landing gear legs rotated and retracted flat against the wing undersides inboard of the wing's midway point. As a carrier-minded aircraft, the Mauler was purposely given a strong undercarriage and folding main wing units, the wings folding at their midway section, just outboard of the cannon housings.
Standard armament of Maulers consisted of 4 x 20mm M2 cannons with 200 rounds per gun afforded, two cannons to each wing. Experience with machine gun-only armament in World War 2 showcased growing limitations especially against larger bomber-type aircraft, even when an aggressor was outfitted with six or eight such weapons. Cannon armament proved the future prior to the missile age and the Americans finally accepted this evolution (though the jet-era upcoming North American F-86 Sabre of the Korean War still fielded all-machine-gun armament). The cannons were set at the midway point of each wing with barrel muzzles protruding slightly ahead of the leading wing edges. External ordnance was primarily carried under the wings across multiple hardpoints. The Mauler was cleared to carry torpedoes and conventional drop bombs - one test flight featured 3 x torpedoes affixed as follows: one under the fuselage and two along the inboard section of each wings, just under the cannon housings. Drop bombs were then arranged six to a wing underside along a row of small hardpoints. It was this sort of formidable display that allowed the Mauler to accomplish both the dive bombing and torpedo bombing roles that proved so prevalent in the heavy fighting in the Pacific Theater of War against the Empire of Japan during World War 2.
Power for the Mauler was served through a Pratt & Whitney R-4360-4 Wasp Major radial piston engine outputting at 2,975 horsepower. This provided the airframe with a top speed of 367 miles per hour with a cruise speed closer to 188 mile per hour. Operational range was in the vicinity of 1,400 miles with a service ceiling measuring 27,000 feet. Rate-of-climb was listed at 2,780 feet per second. All specifications were roughly comparable to the competing Douglas A-1 Skyraider.
Hampered by the conclusion of war and its inherently beneficial wartime industry, the Mauler soldiered on as best it could. Douglas had begun development of the similar - though dimensionally smaller - carrier-based attack warplane all its own by the end of the war, first flight recorded on March 18th, 1945. This aircraft was already introduced in 1946 as the A-1 Skyraider and posed a direct threat to the future of the Mauler. Some 3,180 Skyraiders would eventually be purchased by the United States Navy compared to the far fewer Maulers.
With such a threats against its expansion, the Mauler led a rather limited service life ultimately overtaken by the Skyraider itself. Initially, Maulers served with US Atlantic-based fleets before being relegated to land-based service. From there, final Mauler units were in active in frontline service up until 1950 before being retired for good in 1953 to the tune of 151 examples completed. Seventeen new-build units were commissioned as two-seat radar countermeasures (Electronic CounterMeasures - ECM) platforms under the alternative designation of "AM-1Q". Martin proposed a Carrier Onboard Delivery (COD) version to the United States Navy as the JR2M-1 "Mercury" to no avail - these would have been specialized transport aircraft charged with resupplying at-sea carriers with fresh supplies - a role since handled by dedicated navalized aircraft and helicopters.
All told, the Martin AM Mauler was fielded through US Navy squadrons VA-44, VA-45, VA84, VA-85, VA-174 and VC-4. The aircraft was later used by reserve units during the vehicle's waning years. The Mauler was never used in anger, even through the Korean War (1950-1953), the stage set for the A-1 Skyraider's entrance into battle.
The original competing aircraft to the US Navy requirement - the Curtiss XBTC, Douglas XBT2D-1 and the Kaiser-Fleetwings XBTK-1 - all measured differently in their respective service lives. The XBTC was produced in just two prototype examples before being scrapped, the XBT2D-1 went on to become the legendary A-1 Skyraider of Vietnam War fame and the XBTK-1 fizzled after five prototypes. By this measure, the Martin Mauler was something of a limited success behind the A-1 Skyraider.
(OPERATORS list includes past, present, and future operators when applicable)
✓Close-Air Support (CAS)
Developed to operate in close proximity to active ground elements by way of a broad array of air-to-ground ordnance and munitions options.
✓Maritime / Navy
Land-based or shipborne capability for operating over-water in various maritime-related roles while supported by allied naval surface elements.
41.2 ft (12.55 m)
50.0 ft (15.24 m)
16.8 ft (5.13 m)
15,432 lb (7,000 kg)
25,794 lb (11,700 kg)
+10,362 lb (+4,700 kg)
(Showcased structural values pertain to the base Martin AM Mauler production variant)
1 x Pratt & Whitney R-4360-4 Wasp Major air-cooled radial piston engine developing 2,975 horsepower and driving a four-bladed propeller unit at the nose.
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