Throughout much of the Second World War, US Navy carrier-based squadrons were equipped with two classes of bombers--the two seat scout bombers which equipped VS and VB squadrons and the three-seat torpedo bombers which equipped VT squadrons. When the war in the Pacific began, the Douglas SBD Dauntless and the Douglas TBD Devastator were the primary aircraft which filled these roles. The TBD was not very successful, but the SBD Dauntless gave an outstanding performance at the Battle of Midway and is generally rated as one of the best dive bombers of the war.
As the war progressed, the SBD Dauntless and the TBD Devastator were gradually supplanted in Navy service by the Curtiss SB2C Helldiver and the Grumman/General Aviation TBF/TBM Avenger. Douglas was faced with a situation in which its products were being displaced from Navy carrier decks by other manufacturer's aircraft.
Douglas attempted to get back in the game by introducing two new types, the XSB2D-1 Destroyer two seat scout bomber and the three-seat XTB2D-1 Skypirate torpedo bomber. Prototypes of both were ordered during 1943.
The XSB2D-1 was intended as the successor to the SBD Dauntless and was powered by a 2300 Hp Wright R-3350-14 engine. It had an inverted gull wing. The XSB2D-1 was equipped with a tricycle undercarriage, rather unusual at the time for a carrier-based aircraft. It was equipped with a heavy defensive armament consisting of two remotely-controlled turrets, one in the dorsal position just ahead of the vertical tail and the other in the ventral position.
The XTB2D was designed as a replacement for the TBM Avenger. Like the SB2D, it had a tricycle undercarriage, but it was a much larger aircraft and was powered by a 28-cylinder Pratt & Whitney R-4360 radial engine driving contrarotating propellers. Proposed defensive armament included a power-operated dorsal turret containing two 0.50-inch machine guns and a single 0.50-8nch flexible gun in the ventral position.
However, by this time in the war the US Navy had established almost complete air superiority over most of its areas of operation in the Pacific, and it was thought that defensive armament on its bombers was no longer needed. The Navy soon began to have second thoughts about multi-seat bombers and began to consider the development of a single-seat aircraft which could fulfill both dive-bombing and torpedo bombing roles. To meet this need, the Navy introduced a new category of aircraft, termed BT, where BT stood for Bombing, Torpedo.
To meet this new need, Douglas adapted its XSB2D-1 into a single seat aircraft designated XBTD-1. The two remotely controlled turrets were removed and the gunner's seat was eliminated. Two wing-mounted 20-mm cannon were added, the internal bomb bay was enlarged, and fuel capacity was increased. Several other manufacturers also submitted prototypes--the Curtiss XBTC-1, the Kaiser-Fleetwings XBTK-1, and the Martin XBTM-1.
Although 623 BTD-1s were ordered in early 1944, the Navy changed its mind in July of 1944 and decided to discontinue the BTD-1 program and substitute batches of BTCs, BTK's and BTMs in its place. Of these, only the Martin BTM was destined to enter service, and was produced in only relatively small numbers as the AM-1 Mauler.
Undeterred by the cancellation of its BTD program, Douglas went to work on a completely new aircraft to meet the Bomber-Torpedo requirement. The Douglas team was lead by Chief Engineer Ed Heinemann, Chief Designer Leo Devlin, and Chief Aerodynamicist Gene Root. The design that emerged owed little to the earlier BTD. It had low-mounted, straight-tapered wings which folded directly upward for stowage. Large dive brakes were installed on each side of the fuselage behind the wing trailing edge and underneath the rear fuselage. The main undercarriage members retracted backwards and rotated through 90 degrees into wells in the lower wing. The rear of the fuselage had a retractable tailwheel and arrester hook. The engine was to be a 2500 hp Wright R-3350-24 eighteen-cylinder radial. The single pilot was seated underneath a bubble canopy which slid to the rear. The offensive weapons load was to be carried on racks underneath the fuselage and under the wings, no internal weapons bay being provided. There was no provision for any defensive armament.
The Navy was sufficiently interested in the project that they diverted funds originally slated to the BTD-1 to purchase 15 examples under the designation XBT2D-1. This order was increased to 25 on July 21, 1944.
In order to get the first two XBT2D-1s into the air as quickly as possible, they were both fitted with the main undercarriage struts and wheels of the Vought F4U-1. In addition, due to the late availability of the R-3350-24W, the first four XBT2D-1s had the less-powerful 2300 hp R-3350-8. The aircraft was tentatively given the name Dauntless II.
The first XBT2D-1 (Bu No 09085) made its maiden flight from Mines Field, CA on March 18, 1945, with Douglas test pilot LaVerne Brown at the control. The plane was delivered to the Navy Proving Ground at Patuxent River, Maryland. Flight tests were satisfactory, and the performance was excellent, with no signicant flaws being found.
On May 5, 1945, a Letter of Intent for 548 production BT2D-1s was signed. Following V-J Day, the order was reduced to 377 and then further to 277.
The second aircraft flew on May 8, 1945. It was used for flight vibration tests of the propeller. In June, it was sent to the NACA wind tunnel at NAS Moffett Field, CA for full-scale wind tunnel tests. Aircraft number 3 (BuNo 09087) was returned to the factory in July of 1945 for the incorporation of full strength catapulting and arresting provisions. It did not fly until Aug 17, 1945.
Aircraft number 4 (BuNo 09088) flew for the first time on October 6, 1945.
25 XBT2D-1s were built. the first four were powered by the 2300 hp Wright R-3350-8, with one being tested with a large propeller spinner. All other aircraft were powered by the 2500 hp R-3350-24W that had originally been specified. The aircraft were armed with two wing-mounted 20-mm cannon. There were three large pylons for externally-carried offensive armament, one underneath the fuselage centerline, and one underneath each inboard wing panel. In addition, there were twelve small racks under the outer wings.
In late 1945, two XBT2D-1s (BuNos 09098 and 09099) were converted by the manufacturer as prototypes for a three-seat night attack version. Positions were installed within the fuselage aft of the cockpit for a pair of radar operators, with an exit door on each side of the aircraft. A radar pod was mounted underneath the port wing and a searchlight pod underneath the starboard wing. There were no dive brakes fitted to the fuselage sides.
XBT2D-1 BuNo 09096 was converted as a prototype for a single-seat photographic reconnaissance version as XBT2D-1P.
XBT2D-1 BuNo 09109 was converted to a radar countermeasures aircraft as XBT2D-1Q.
The last XBT2D-1 (BuNo. 09109) was converted into a two-seat electronic countermeasures aircraft and redesignated XBT2D-1Q. The ECM operator's station was installed inside the fuselage. The radar pod was installed underneath the port wing, and a chaff dispenser pod was installed underneath the starboard wing.
In February of 1946, the BT2D-1 was renamed Skyraider. In April of 1946, the Navy eliminated the BT designation category, replacing it by A for Attack. The BT2D-1 was redesignated AD-1.
In the spring of 1946, a few XBT2D-1s were delivered to the Pacific Fleet Air Headquarters at NAS Alameda for
service trials. These tests uncovered some serious problems with main undercarriage and wing skin failures, most
of which took place when when the landing weights and landing sinking speeds were high. The aircraft's structural
strength was obviously too weak to stand up to the rigors of hard carrier landings.
09085/09109 Douglas XBT2D-1 c/n 1913/1937 BuNos reassigned from cancelled SB2D-1 batch. 09098 and 09099 converted to XBT2D-1N 09096 converted to XBT2D-1P 09102 at NAS Oceana, Virginia 09109 converted to XBT2D-1Q 09107 converted to XBT2D-1W, then to XAD-1W. 09108 converted to XAD-2.
Engine: One Wright R-3350-24W Duplex Cyclone 18-cylinder air-cooled radial engine, rated at 2500 hp for takeooff, 2200 hp at 11,000 feet. Performance: Maxiumum speed 375 mph at 13,600 feet, 357 mph at sea level clean cruising speed 164 mph. Initial climb ratge 3680 feet/minute. Service ceiling 33,200 feet, Initial climb rate 3680 feet/min. Range 1430 miles carrying 1 torpedo. Weights: 10,500 pounds empty, 15,000 pounds normal loaded, 17,500 pounds maximum. Dimensions: Wingspan 50 feet 0 1/4 inches, length 39 feet 5 inches, height 9 feet, wing area 400.33 square feet. Armament: Two 20-mm cannon in the wing, 400 rpg. 3 external hard points for up to two tons of bombs, torpedoes, rockets, drop tanks, or an APS-4 radar pod.