Douglas SBD Dauntless (A-24 Banshee)

		Douglas SBD Dauntless (A-24 Banshee)

The Dauntless first entered service in mid-1939 and distinguished itself in the Battle of Midway against Japanese carriers Akagi, Kaga, Soryu and Hiryu. Its capacity to absorb battle damage made it a rugged adversary and is one of aviation history's classic warplanes.

Designed as a light bomber and reconnaissance aircraft, by designer Ed Heinemann who worked for Jack Northrop, the Dauntless SBD (Scout Bomber Douglas) was one of the 35 US aircraft types that engaged in the major battles of WW II. Despite being slow and low-tech, it would change the course of the Naval Pacific war. It served during WWII with the US Navy, US Marines and US Army air squadrons. During the war, the Royal New Zealand Air Force received the Dauntless and were flown by No. 25 Squadron in the South Pacific. It also flew for the Free French as trainers and close-support aircraft in 1944. The French Navy Dauntlesses were the last ones to see combat and were used against the Viet Minh, in French Indochina flying from the French carrier Arromanches (ex-HMS Colossus).

The airplane originated with the design of the Northrop BT-1, powered by a 700 hp Pratt & Whittney R-1535-64 Twin Wasp Junior engine, when the Northrop Corporation was a subsidiary of The Douglas Aircraft Corporation. Northrop was dissolved on September 8, 1937 and Northrop designs continued production under Douglas.¹ On November 28, 1937, numerous major modifications were ordered on the BT-1, one of which was the landing gear being changed from retracting backwards into large fairing trousers beneath the wings, to folding laterally into recessed wheel wells.² The new model XBT-2, became the forerunner of the now well known Dauntless.

The configuration of the Dauntless was a three spar, low-wing, cantilever monoplane of all-metal construction, except for the fabric covered flight controls. It had a two-man tandem cockpit with emergency flight controls for the rear gunner. The rear cockpit control stick could be unclipped from the left cockpit sidewall and inserted into a socket in the floor. The gunner did not have control over the landing gear or tail hook, but he had just enough control that he could return to the carrier and ditch nearby.

The hydraulically actuated perforated split-flaps and dive-brakes were the most distinctive feature of the Dauntless. This detail was developed on the BT-1 after serious tail buffeting was experienced while diving. 318 slightly ovalized three-inch holes were drilled into the flaps upon the suggestion of the National Advisory Committee for Aeronautics. When the buffeting complaint first surfaced during testing with the flaps fully open, Ed Heinemann took a ride in the backseat to see for himself. The horizontal stabilizers flapped through a two-foot arc which he admitted, "scared the hell out of me." After running out of solutions to correct the problem, Heinemann contacted the NACA for assistance. After wind-tunnel tests were performed, it was suggested that the single wave generated by the flaps be broken up into smaller eddies by perforating the flaps. After the modification was completed, test pilot Vance Breese reported that the NACA recommendation was entirely successful. Despite anticipation that the hole-pattern would affect total-lift, this was found not to be the case. Furthermore, it was found that the aircraft could be slowed even greater using both the dive-brakes and flaps together without re-inducing tail buffeting.

The Douglas Dauntless was a direct development of the Northrop BT-1. Early on, severe tail buffeting was encountered, which was eliminated by perforated flaps. Also shown are the trouser fairings that housed the landing gear when retracted.

When the redesigned XBT-2 was delivered to Anacosta on August 24, 1938 for flight testing with a larger 1,000 hp Wright R-1920-G133 engine, the performance was greater than expected with a top speed of 265 mph (429 km/h). The aircraft was then delivered to Langley Memorial Aeronautical Institute in February 1939 for wind tunnel tests and numerous design changes were recommended. Modifications were made to the flight controls, leading-edge slots, a dorsal fin was added, and 21 different tail combinations were tested. The NACA recommended that the perforated flaps developed on the BT-1 be eliminated, but this decision was reversed despite a slight loss in airspeed.

The initial order was for 36 aircraft, but was increased to 144 which included both SBD-1s and SBD-2s. Modifications included a center auxiliary fuel tank for a total capacity of 210 gallons. The production engine was a 1,000 hp Wright R-1820-32. Armament consisted of two forward firing 0.50 caliber in machine guns in the engine nose cowling and one flexible rearward firing, drum-fed 0.30 caliber machine gun. A swinging bomb cradle carried a 1,000 lb bomb below the fuselage and a 100 lb bomb was mounted under each wing. The bomb cradle was designed so that the bomb would swing clear of the prop during dive-bombing maneuvers.

The SBD-2 fuel capacity was increased to 310 gallons with the elimination of the center auxiliary tank and replaced with 65 gallon tanks in the outer wing panels. SDB-2s were later retrofitted with self-sealing tanks, which reduced total fuel capacity to 260 gallons. Armament was reduced by the removal of one forward firing 0.50 machine gun in the engine nose cowling.

The SBD-3 (A-24-DE) was the first fully combat ready version with a total production of 585 airplanes.³ Flotation gear was removed, alclad replaced dural for construction, armor protection and a bullet-proof windscreen was installed. The engine was upgraded to a 1,000 hp Wright R-1820-52. Forward firing armament was changed to two 0.50 machine guns, (same as the SBD-1) and rear armament was increased to twin, belt-fed 0.30 machine guns.

The SBD-4 retained the same engine as the -3, but a new Hamilton Standard hydromatic constant-speed propeller was installed. The electrical system was upgraded to 24 volts and an electric fuel pump replaced a hand-operated fuel boost pump. The USAAF A-24-DE Dauntless was basically the same airplane as the SBD-3 except for Army instrumentation and a pneumatic tailwheel tire installed instead of the Navy solid rubber tire. The arrestor gear was eliminated on the A-24.⁴

The Douglas Dauntless retained the perforated flaps developed on the Northrop BT-1, but the landing gear retracted laterally into recessed wheel wells. Also visible in this photo are the leading-edge wing slots.

The SBD-5 (A-24B-DT) was the main production model built with a larger 1,200 hp Wright R-1820-60 engine. The engine air intake was removed from the upper cowling which was the main distinguishing mark of all earlier models. The bomb load was increased to 2,250 lb with a 1,600 lb bomb under the fuselage and a 325 lb bomb under each wing. The twin rearward-firing guns were no longer add-ons and were factory installed.

The SBD-6 was fitted with a 1,350 hp Wright R-1820-66 engine and was equipped with ASV (Air to Surface Vessel) radar. The all-metal fuel tanks were replaced by self-sealing bladder fuel tanks with a total capacity of 284 gallons. The initial order was for 1440 SBD-6s, but this was scaled back to 450 which were delivered between March and July of 1944. This reduction came about because the Dauntless was now being replaced by the Curtiss SB2C Helldiver.

One feature of the Dauntless that was unusual at the time was that it lacked folding wings, which was considered essential for parking on carriers. Designer, Ed Heinemann, wanted the wings to be as strong as possible to withstand the 5G+ pullouts that would be required. To accommodate parking, an innovative solution was to extend troughs out from the carrier deck for the tailwheel, so the main gear could be positioned just at the deck's edge.

Image illustrates trough extending out from the carrier deck to accommodate Dauntless parking.

The first squadrons to receive the Dauntless were USMC VMB-2 in late 1940 and VMB-1 in early 1941. The first Navy squadrons were equipped with SBD-2s and at the end of 1941 were assigned to VB-6 on the USS Enterprise squadron and VB-2 on the USS Lexington.⁵ Other Navy squadrons equipped with the SBD Dauntless were VB-3, VB-5, VS-2, VS-3, VS-5 and VS-6. Other USMC squadrons were equipped with the plane as well.⁶ Nine examples were sent to the Royal Navy Fleet Air Arm and were designated the Mk.I but were not used operationally. A small quantity was supplied to Mexico.

The Dauntless first saw action on December 7, 1941 when SBD-2s were transitioning from the USS Enterprise to Pearl Harbor and ran right into the Japanese attack, while US Marine Corp BT-1s were destroyed on the ground at Ewa. At the time of the attack at Pearl Harbor, the Dauntless was the standard dive bomber⁷ and was the first US Navy plane to sink an enemy ship (Japanese sub I-70) in WWII, just three days after Pearl Harbor.⁸ The first real test came on May 7, 1942, when US aircraft carriers, USS Lexington and USS Yorktown, faced three Japanese carriers in the Battle of the Coral Sea. The two-day battle was the first naval battle in which victory was decided by aircraft alone. Dauntless dive-bombers fought well alongside other US aircraft and were credited with forty of the ninety-one enemy aircraft downed.⁹ During the battle, the US lost the carrier USS Lexington and the Japanese lost the light carrier Shoho, which was sunk by Dauntless and Devastator bombers.¹⁰ The Shokaku received serious bomb damage and Zuikaku's air group was badly depleted, eliminating these carriers from the upcoming Midway operation. While the battle was a technical victory for Japan, the US had prevented Japanese ships from supporting an invasion of Port Moresby, New Guinea, and a proposed air assault on Australia.

A Dauntless SBD warms up on the Yorktown during the battle of Midway. Shown is the engine air intake on the upper cowling which was the main distinguishing mark of all earlier models.

In the great Battle of Midway in June US naval aircraft, spearheaded by Dauntless dive-bombers, sank the Japanese carriers, Akagi, Kaga, and Soryu. Only the Hiryu remained operational which would launch a retaliatory strike against the USS Yorktown later in the day. However, before the day ended, US carrier planes found and bombed Hiryu, putting her out of action. A Japanese cruiser and 250 aircraft were also destroyed, for the loss of only one US carrier, a destroyer and 150 aircraft. The Battle of Midway turned the tide of war against the Japanese in the Pacific.

In the summer of 1941, 168 SBD-3s were delivered to the USAAF, designated as the A-24 Banshee. The Army had been looking for an airplane to compete with the Junkers Ju-87 Stuka dive bomber, but operated no similar aircraft of this type. The A-24 faired rather badly in combat and the USAAF was not as successful with the Dauntless as was the Navy. On 29 Jul 1942, seven A-24s were sent on a bombing mission to Buna, without top cover, and were intercepted by A6M Zeros—only one A-24 urvived and it was decided to be withdrawn from first-line service.¹¹ Despite of the apparent lack of success with the A-24, the USAAF continued procurement with 170, A-24As (SBD-4) and 615, A-24Bs (SBD-5).

The lack of success for the Banshee has been attributed to an Army Air Force bias against dive-bombing. Although they were aware of the Junkers Ju-87 Stuka's success against ground targets, the US Army had few tanks at the beginning of the war and little experience countering them. Unlike the US Navy and German Luftwaffe, which had perfected dive-bombing, the AAF utilized it as a glide bomber with little success. Army pilots were trained to dive at a 30-degree steep glide and were limited to a maximum of 45-degrees.¹² The Navy preferred a 70-degree "Hell Dive" thus avoiding Zeros and were exposed to anti-aircraft fire for a shorter period. With the dive-brakes extended, the Banshee could not maintain level flight, so the pilot had to retract the dive brakes just before pull-out. Unlike the Stuka, which had a completely automated bombing system, the Stuka could recover from a 60-90 degree dive even if the pilot blacked-out during the bombing maneuver.

As the war went on, the Dauntless equipped no less than twenty Marine squadrons and were retained until late 1944. It was the main type US navy dive-bomber and was not only used in the Pacific, but also during the Allied landing in North Africa and in the Battle of the Atlantic.

A small batch of SBD-5s were handed over to the Royal New Zealand Air Force in 1944 to equip the No. 25 Squadron on Piva, Bougainville Island in the Solomon Chain. The unit flew its first strike against the Japanese on 24 March. The squadron made nineteen sorties, four for artillery spotting, and the rest bombing attacks on enemy gun positions along with No. 30 Squadron. On the 25th, No. 25 Squadron made fourteen sorties and No. 30 Squadron twelve. Targets were enemy troops and gun positions around their perimeter. Their position was so close to the enemy , they could fly a round circuit, land, rearm, and attack the target repeatedly. Ground crews had a perfect view of the bombing and were able to witness bombs falling on the enemy. For the next fortnight, both squadrons bombed and strafed the enemy by day and carried out perimeter patrols by night. After a successful tour, the squadron was disbanded and the remaining seventeen aircraft were returned to the USMC.

The Dauntless had the lowest attrition rate of any US carrier aircraft, because of its ability to absorb battle damage. Dauntless aircraft accounted for many Japanese aircraft shot down in air-to-air combat, and finished their wartime career as antisubmarine bombers and as attack aircraft, carrying depth charges and rocket projectiles respectively. The total production of the Dauntless was 5,938 aircraft built. The first SBD-1 was completed in April 1940 and flown on May 1, 1940 with production continuing until to the end of 1944. First-line capacity tailed off for the US Navy and USMC by late 1944, and the Douglas Dauntless was superseded by the unpopular Curtiss SB2C Helldiver.

Specifications:
Douglas SBD (A-24) Dauntless

XBT-2 SBD-2 SBD-5 SBD-6

Dimensions:
Wing span: 41 ft 6 in (12.65 m) 41 ft 6-3/8 in (12.66 m) 41 ft 6-3/8 in (12.66 m) 41 ft 6-3/8 in (12.66 m)

Length: 31 ft 9 in (9.68 m) 32 ft 1-1/4 in (9.79 m) 33 ft 1-1/4 in (10.09 m) 33 ft 1-1/4 in (10.09 m)

Height: 12 ft 10 in (3.91 m) 13 ft 7 in (4.14 m) 13 ft 7 in (4.14 m) 13 ft 7 in (4.14 m)

Weights:
Empty: 5,037 lb (2,285 kg) 5,652 lb (2,564 kg) 6,404 lb (2,905 kg) 6,554 lb (2,973 kg)

Loaded: 7,018 lb (3,183 kg) 8,643 lb (3,920 kg) 9,359 lb (4,245 kg) 9,465 lb (4,293 kg)

Performance:
Maximum Speed: 265 mph (427 km/h)
@ 16,000 ft (4,875 m) 256 mph (412 km/h)
@ 16,000 ft (4,875 m) 255 mph (410 km/h)
@ 14,000 ft (4,265 m) 262 mph (422 km/h)
@ 18,500 ft (5,640 m)

Service Ceiling: 31,000 ft. (9,175 m) 27,260 ft. (8,310 m) 25,530 ft. (7,780 m) 28,600 ft. (8,715 m)

Normal Range: 604 miles (972 km) 1,225 miles (1,970 km) 1,115 miles (1,795 km) 1,230 miles (1,980 km)

Max Range: 1,458 miles (2,345km) 1,370 miles (2,205 km) 1,565 miles (2,520 km) 1,700 miles (2,735 km)

Powerplant XBT-2: Powerplant SBD-2: Powerplant SBD-5:

Wright R-1820-G133, 1,000 hp,
(750 kw), Radial 9 cylinder, Air-cooled. Wright R-1820-32, 1,000 hp,
(750 kw), Radial 9 cylinder, Air-cooled. Wright R-1820-60, 1,200 hp,
(895 kw), Radial 9 cylinder, Air-cooled.

Armament SBD-1: Armament SBD-2: Armament SBD-5:

Two forward-firing 0.50 mg.
One rearward-firing 0.30 mg.
One 1,000 lb fuselage bomb.
Two 100 lb wing bombs. One forward-firing 0.50 mg.
One rearward-firing 0.30 mg.
One 1,000 lb fuselage bomb.
Two 100 lb wing bombs. Two forward-firing 0.50 mg.
Twin rearward-firing 0.30 mg.
One 1,600 lb fuselage bomb.
Two 325 lb wing bombs.

Specifications:
Douglas SBD (A-24) Dauntless
	XBT-2	SBD-2	SBD-5	SBD-6
Dimensions:
Wing span:	41 ft 6 in (12.65 m)	41 ft 6-3/8 in (12.66 m)	41 ft 6-3/8 in (12.66 m)	41 ft 6-3/8 in (12.66 m)
Length:	31 ft 9 in (9.68 m)	32 ft 1-1/4 in (9.79 m)	33 ft 1-1/4 in (10.09 m)	33 ft 1-1/4 in (10.09 m)
Height:	12 ft 10 in (3.91 m)	13 ft 7 in (4.14 m)	13 ft 7 in (4.14 m)	13 ft 7 in (4.14 m)
Weights:
Empty:	5,037 lb (2,285 kg)	5,652 lb (2,564 kg)	6,404 lb (2,905 kg)	6,554 lb (2,973 kg)
Loaded:	7,018 lb (3,183 kg)	8,643 lb (3,920 kg)	9,359 lb (4,245 kg)	9,465 lb (4,293 kg)
Performance:
Maximum Speed:	265 mph (427 km/h) @ 16,000 ft (4,875 m)	256 mph (412 km/h) @ 16,000 ft (4,875 m)	255 mph (410 km/h) @ 14,000 ft (4,265 m)	262 mph (422 km/h) @ 18,500 ft (5,640 m)
Service Ceiling:	31,000 ft. (9,175 m)	27,260 ft. (8,310 m)	25,530 ft. (7,780 m)	28,600 ft. (8,715 m)
Normal Range:	604 miles (972 km)	1,225 miles (1,970 km)	1,115 miles (1,795 km)	1,230 miles (1,980 km)
Max Range:	1,458 miles (2,345km)	1,370 miles (2,205 km)	1,565 miles (2,520 km)	1,700 miles (2,735 km)

Powerplant XBT-2:	Powerplant SBD-2:	Powerplant SBD-5:
Wright R-1820-G133, 1,000 hp, (750 kw), Radial 9 cylinder, Air-cooled.	Wright R-1820-32, 1,000 hp, (750 kw), Radial 9 cylinder, Air-cooled.	Wright R-1820-60, 1,200 hp, (895 kw), Radial 9 cylinder, Air-cooled.
Armament SBD-1:	Armament SBD-2:	Armament SBD-5:
Two forward-firing 0.50 mg. One rearward-firing 0.30 mg. One 1,000 lb fuselage bomb. Two 100 lb wing bombs.	One forward-firing 0.50 mg. One rearward-firing 0.30 mg. One 1,000 lb fuselage bomb. Two 100 lb wing bombs.	Two forward-firing 0.50 mg. Twin rearward-firing 0.30 mg. One 1,600 lb fuselage bomb. Two 325 lb wing bombs.

Endnotes:

1. Rene J. Francillon. McDonnell Douglas Since 1920, Volume I. Annapolis, Maryland: Naval Institute Press, 1990. 23.
2. Ibid. 254.
3. Ibid. 257.
4. Kenneth Munson. Bombers 1939-45, Patrol and Transport Aircraft. London: Blanford Press, 1969. 105.
5. Rene J. Francillon. 260.
6. David Mondey. The Concise Guide to American Aircraft of World War II. New York: Smithmark Publishers, 1996. 124.
7. Howard Mingos, ed. The Aircraft Year Book for 1943. New York: Aeronautical Chamber of Commerce of America, Inc., 1943. 240.
8. Bill Yenne. McDonnell Douglas, A Tale of Two Giants. New York: Crescent Books, 1985. 45.
9. Kenneth Munson. 105
10. Bill Yenne. 42.
11. Rob Stern and Don Greer. SBD Dauntless in Action. Carrollton, Texas: Squadron Signal Publications, 1984. 17.
12. Stephan Wilkinson. May 2021, Dauntless Forever. Aviation History. Volume 31, No. 5. 33.

Other Sources:
Douglas J. Ingells. The McDonnell Douglas Story. Fallbrook, Ca: Aero Publishers, Inc., 1979. 62.
Robert D. Loomis. Great American Fighter Pilots of World War II. New York: Random House, 1961. 29-42.
Michael O'Leary. July 1998. SBD, Slow But Deadly. Warbirds International. Volume 17, No. 5. 30-36.
Bill Marsano. April/May 1998. The Battle of Midway, Round Two. Air & Space. Volume 13, No. 1. 67.
Graham White. Allied Aircraft Piston Engines of World War II. Warrendale Pennsylvania: Society of Automotive Engineers, Inc., 1995. 203.

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