Blog 49: 8/26/23: Historical Deep-dive: The Douglas Slow-But-Deadly, SBD Dauntless Dive-bomber
Douglas SBD Scout Bomber from Chino, California, Air Museum. Fully restored in 2010.
Hi and welcome back to Brooke In The Air! I'm still recovering from surgery so you get a great blog this week! This week we take an historical deep dive at the plane that did so much to win the second World War. The Douglas Aircraft Corporation’s SBD-Dauntless dive bomber!
Douglas SBD-2 currently on display at the National Museum of the US Air Force, Wright-Patterson Air Force Base, Dayton, Ohio.
Without any doubt, no aircraft did so much to win the Pacific War for the Americans than the famed Douglas SBD Dauntless. Even when the Dauntless was to be replaced by the arguably more advanced Curtiss SB2C Helldiver, pilots refused to give up their beloved SBD Dauntless Dive Bombers. By the war’s end, Helldivers only made up a total of 23% of the US Navy’s scout bombing force. Dauntless dive bombers are probably best remembered as the aircraft that delivered the death blow to the Kido Butai, the primary carrier striking force, at the Battle of Midway in 1942.
Technically a scout plane, the SBD ("Scout Bomber Douglas") was the United States Navy's main carrier-based scout and dive bomber from mid-1940 through mid-1944. The SBD was also flown by the United States Marine Corps, both from land air bases and aircraft carriers. The SBD is best remembered as the bomber that delivered the fatal blows to the Japanese carriers at the Battle of Midway in June 1942. The type earned its nickname "Slow But Deadly" (from its SBD initials) during this period. As without attached ordnance, it could dogfight fighters quite well. Not the best, but it could fill in as a stop gap measure.
During its combat service, the SBD especially proved to be an excellent naval scout plane and dive bomber. It possessed long range, good handling characteristics, maneuverability, potent bomb load, great diving characteristics from the perforated dive brakes, good defensive armament, and ruggedness (it was especially hard to kill). One land-based variant of the SBD – omitting the arrestor hook — was purpose-built for the U.S. Army Air Forces, as the A-24 Banshee.
DESIGN ORIGIN
Northrup (under Douglas) XBT-1 (top) and XBT-2 (bottom) prototypes designed into the SBD
Early Vindicator Scout bomber in flight - Succeeded by the Dauntless
Design work on the Northrop BT-1 began in 1935. It was really nothing more than a poor prototype, At the time, Northrop was a subsidiary of the Douglas Aircraft Company. While unsuccessful in its own right, the BT prototype was subsequently redesigned into the Douglas SBD Dauntless, which would form the backbone of the Navy's dive bomber force. In 1937, the Northrop Corporation was taken over by Douglas, and the active Northrop projects continued under Douglas Aircraft Corporation. The Northrop BT-2 was developed from the BT-1 by modifications ordered in November 1937, and provided the basis of the SBD, which first entered service in mid-1939. Chief engineer Ed Heinemann led a team of designers who considered a development with a 750 kW Wright Cyclone engine. The plane was developed at the Douglas El Segundo, California, plant, and that facility, along with the company's Oklahoma City plant, built almost all the SBDs produced. One year earlier, both the U.S. Navy and Marine Corps had placed orders for the new dive bomber, designated the SBD-1 and SBD-2 (the latter had increased fuel capacity and different armament). The SBD-1 went to the Marine Corps in late 1940, and the SBD-2 to the Navy in early 1941, replacing the SBU Corsair and Curtiss SBC Helldiver squadrons on US carriers. Distinctive perforated split flaps or "dive-brakes" had been incorporated into the BT-1 to eliminate tail buffeting during diving maneuvers. Unusual for carrier aircraft, folding wings were not chosen for the design, opting instead for structural strength.
DESIGN VERSIONS - NEW AND IMPROVED
The next version was the SBD-3, redesigned from the SBD-2, which began manufacture in early 1941 just before the attack on pearl harbor. This version had increased armor, self-sealing fuel tanks, and four machine guns.
The SBD-4 provided a 12-volt (up from 6-volt) electrical system, and a few were converted into SBD-4P reconnaissance aircraft. A few of these survived the end of the war.
The next (and most produced) version by far, the SBD-5, was produced mostly in the Douglas plant in Tulsa, Oklahoma.
Douglas SBD-4 Over Midway, 1942, from USS Enterprise
This version was equipped with a 890 kW engine and an increased ammunition supply. Over 2,400 of these were built. A few of them were shipped to the Royal Navy for evaluation. In addition to American service, the SBD saw combat against the Japanese Army and Navy with No. 25 Squadron of the Royal New Zealand Air Force—but the RNZAF soon replaced them with the larger, faster, heavier and land-based Vought F4U Corsairs.
Some SBD-5s were also flown by the Free French Air Force against the German Heer and Luftwaffe. Several SBD squadrons were also sold to Mexico for self-protection.
The U.S. Army Air Force had its own version of the SBD, called the A-24 Banshee. It lacked the tail hook used for carrier landings, and a pneumatic tire replaced the solid tail wheel. First assigned to the 27th Bombardment Group (Light) at Hunter Field, Georgia, A-24s flew in the Louisiana maneuvers of September 1941.
There were three versions of the Banshee (A-24, A-24A and A-24B) flown by the army to a very minor degree in the early stages of the war.
COMBAT OPERATIONS (COMBAT OPS)
-Chronological-
U.S. Navy and Marine Corps SBDs saw their first action at Pearl Harbor, when most of the Marine Corps SBDs of Marine Scout Bombing Squadron 232 (VMSB-232) were destroyed on the ground at Ewa Mooring Mast Field. Most U.S. Navy SBDs flew from their aircraft carriers, which did not operate in close cooperation with the rest of the fleet. Most Navy SBDs at Pearl Harbor, like their Marine Corps counterparts, were destroyed on the ground.
The first major use of the SBD in combat was at the Battle of the Coral Sea where SBDs and TBD Devastators sank the Japanese light aircraft carrier (CVL) Shōhō and damaged the Japanese fleet carrier Shōkaku. SBDs were also used for anti-torpedo combat air patrols (CAP) and these scored several victories against Japanese aircraft trying to attack the carriers USS Lexington and USS Yorktown.
The Dauntless’s relatively heavy gun armament with two forward-firing 12.7 mm M2 Browning machine guns and either one or two rear flexible-mount 7.62 mm AN/M2 machine guns was effective against the lightly-built Japanese fighters, and many pilots and gunners took aggressive attitudes to the fighters that attacked them. A notable example was SBD pilot Lieutenant Stanley "Swede" Vejtasa who was attacked by three A6M2 Zero fighters; he shot down two of them and cut off the wing of the third in a head-on pass with his wingtip.
The SBD's most important contribution to the American war effort came during the Battle of Midway in early June 1942.
Four squadrons of Navy SBD dive bombers attacked and sank or fatally damaged all four Japanese fleet carriers present, disabling three of them in the span of just six minutes (Akagi, Kaga, Sōryū) and, later in the day, Hiryū. They also caught two straggling heavy cruisers of the Midway bombardment group of four, heavily damaging them, with the cruiser Mikuma eventually sinking.
Douglas SBD-3 in Combat over the Kido Butai taskforce, likely the carrier Kaga. Note the unique dive breaks deployed here on the wings as it gets ready to pull out of the dive, having released its bomb.
At the Battle of Midway, Marine Corps SBDs were not as effective. One squadron, VMSB-241, flying from Midway Atoll, was not trained in the techniques of dive-bombing with their new Dauntlesses (having just partially converted from the SB2U Vindicator, the predecessor to the Dauntless). Its pilots resorted to the slower but easier glide bombing technique. This led to many of the SBDs being shot down during their glide, although one survivor from these attacks is now on display at the National Naval Aviation Museum and is the last surviving aircraft to fly in the battle. The carrier-borne squadrons were effective, especially when they were escorted by Grumman F4F Wildcats. The success of dive bombing resulted from one important circumstance as noted here:
Unlike American squadrons that attacked shortly before one at a time, allowing defending Japanese Zero fighters to concentrate on each squadron to shoot them down or drive them away from the carriers, three squadrons totaling 47 SBDs (VS-6, VB-6, and VB-3), one squadron of 12 TBD torpedo aircraft (VT-3), and six F4F fighters (from VF-3) all arrived simultaneously, with two of the SBD squadrons (VS-6 and VB-6) arriving from a different direction from the other squadrons. Without central fighter direction, the approximately 40 Zeros concentrated on the TBDs, with some fighting the F4Fs covering the TBDs, leaving the SBDs unhindered by fighter opposition in their approach and attack (although most of the TBDs were shot down).
SBDs played a major role in the Guadalcanal campaign, operating off both American carriers and from Henderson Field on Guadalcanal. SBDs proved lethal to Japanese shipping that failed to clear New Georgia Sound (The Slot) by daylight. Losses inflicted included the carrier Ryūjō, sunk near the Solomon Islands on 24 August. Three other Japanese carriers were damaged during the six-month campaign. SBDs sank a cruiser and nine transports during the Naval Battle of Guadalcanal.
The SBD's strengths and weaknesses became evident. While the American strength was dive bombing, the Japanese stressed their Nakajima B5N2 "Kate" torpedo bombers, which had caused the bulk of the damage during the Japanese attack on Pearl Harbor.
In the Atlantic Ocean the SBD saw action during Operation Torch, the Allied landings in North Africa in November 1942. The SBDs flew from USS Ranger and two escort carriers. Eleven months later, during Operation Leader, the SBDs saw their European debut when aircraft from Ranger attacked Nazi German shipping around Bodø, Norway.
By 1944 the U.S. Navy began replacing the SBD with the more powerful SB2C Helldiver. During the Battle of the Philippine Sea in June 1944, a long range twilight strike was made against the retreating Japanese fleet, at (or beyond) the limit of the combat radius of the aircraft. The force had about twenty minutes of daylight over their targets before attempting the long return in the dark.
Of the 215 aircraft in the strike, only 115 made it back to the carriers; Twenty were lost to enemy action in the attack, and 80 were lost as one by one they expended their fuel and had to ditch into the sea. In the attack were 26 SBDs, all of which made it back to the carriers.
The Battle of the Philippine Sea was the last major engagement of the carrier-borne SBDs. Marine squadrons continued to fly SBDs until the end of the war. Although the Curtiss Helldiver had a more powerful engine, a higher maximum speed and could carry nearly a thousand pounds more in bomb load, many of the dive bomber pilots preferred the SBD, which was lighter and had better low-speed handling characteristics, critical for carrier landings. I.e. it was more survivable.
The Dauntless was one of the most important aircraft in the Pacific War, sinking more enemy shipping in the Pacific than any other Allied bomber. Barrett Tillman, in his book on the Dauntless, claims that it has a "plus" score against enemy aircraft, meaning it was credited with more victories over enemy planes than losses from enemy action. This is considered to be a rare event for a nominal "bomber," and especially a scout bomber. A total of 5,936 SBDs were produced during the war. The last SBD rolled off the assembly lines at the Douglas Aircraft plant in El Segundo, California, on 21 July 1944. The Navy placed emphasis on the heavier, faster and longer-ranged SB2C. From Pearl Harbor through April of 1944, SBDs had flown 1,189,473 operational hours, with 25% of all operational hours flown off aircraft carriers.
Forward-firing 5-inch Rockets mounted to the underside of the wing of an SBD-6 Dauntless Dive Bomber, rigged for close-air support, 1944.
Its battle record shows that in addition to six Japanese carriers, 14 enemy cruisers had been sunk, along with six destroyers, 15 transports or cargo ships and scores of various lesser craft.
DEPLOYMENT TO THE US ARMY AIR FORCE
The USAAF sent 52 A-24 Banshees (the Army version of the SBD) in crates to the Philippines in the fall of 1941 to equip the 27th Bombardment Group, whose personnel were sent separately. However, after the Japanese attack on Pearl Harbor, these bombers were diverted to Australia and the 27th BG fought on the Bataan Peninsula as infantry. While in Australia the aircraft were reassembled for flight to the Philippines, but their missing parts, including solenoids, trigger motors and gun mounts delayed their shipment. Plagued with mechanical problems, the A-24s were diverted to the 91st Bombardment Squadron and designated for assignment to Java instead.
Referring to themselves as "Blue Rock Clay Pigeons" (after a brand of trap shooting targets popular in the southern United States), the 91st BS based at Malang attacked the enemy-held harbor and airbase at Bali in Indonesia, and damaged or sank numerous ships around Java during the Dutch East Indies campaign. After the Japanese downed two A-24s and damaged three so badly that they could no longer fly, the 91st received orders to evacuate Java in early March of 1942.
The A-24B (equivalent to the U.S. Navy SBD-5, with the omission of the arrestor hook) arrived in 1943 with the more powerful 1,200-hp Wright R-1820-60 Cyclone engine, a more powerful engine than either the A-24 or A-24A.
As a result of this improved engine, the A-24B could fly slightly faster and higher than the earlier models. The A-24B lacked the small air intake on the top of the engine cowling present on the earlier models and that is an easy way to distinguish the B model. The 407th Bomb Group, assigned to the 11th Air Force, flew A-24Bs against the Japanese held island of Kiska, Alaska, during July and August 1943.
A handful of A-24s survived in the inventory of the USAAF long enough to be taken over by the Air Force (USAF) when that service became independent of the Army in September 1947. The USAF established a new designation system for its aircraft, eliminating the "A-" (for attack) category (through 1962); all of the single-engined "A-" aircraft were given "F-" (for fighter) nomenclature (or were determined to be obsolete and scrapped); thus the few remaining A-24 Banshees became known as F-24 Banshees, soldiering on in a reserve role until 1950 when they were scrapped.
OPERATING VARIANTS
XBT-2
prototype, airframe was a production Northrop BT-1 heavily modified and redesignated as the XBT-2. Further modified by Douglas as the XSBD-1.
SBD-1
Marine Corps version without self-sealing fuel tanks; 57 built.
SBD-1P
reconnaissance aircraft, converted from SBD-1s.
SBD-2
Navy version with increased fuel capacity and different armament but without self-sealing fuel tanks, starting in early 1941; 87 built.
SBD-2P
reconnaissance aircraft, converted from SBD-2s.
SBD-3
began to be manufactured in early 1941. This provided increased protection, self-sealing fuel tanks, and four machine guns; 584 were built.
SBD-4
provided a 24-volt (up from 12 volt) electrical system; In addition, a new propeller and fuel pumps rounded out the improvements over the SBD-3. 780 built.
SBD-4P
Reconnaissance aircraft, converted from SBD-4s. The P stood for photo.
SBD-5
The most produced version, primarily produced at the Douglas Aircraft plant in Tulsa, Oklahoma. Equipped with a 1,200-hp engine and an increased ammunition supply. A total of 2,965 were built, and a few were shipped to the Royal Navy for evaluation. In addition to American service, these saw combat against the Japanese with No. 25 Squadron of the Royal New Zealand Air Force which soon replaced them with F4Us, and against the Luftwaffe with the Free French Air Force. A few were also sent to Mexico.
SBD-5A
As the A-24B, for USAAF but delivered to USMC; 60 built.
SBD-6
The final version, providing more improvements, including a 1,350 hp (1,010 kW) engine, but production ended in the summer of 1944; 450 built.
A-24 Banshee (SBD-3A)
USAAF equivalent of the SBD-3 without arrestor hook; 168 built.
A-24A Banshee (SBD-4A)
USAAF equivalent of the SBD-4; 170 built.
A-24B Banshee (SBD-5A)
USAAF equivalent of the SBD-5; 615 built.
ON DISPLAY
You can see the SBD in the US at the following museums
Airworthy Models
A-24A
42-60817 – based at the Erickson Aircraft Collection in Madras, Oregon as an SBD-3.
A-24B
42-54682 – based at the Lone Star Flight Museum in Houston, Texas as an SBD-5.
SBD-4
10694 – based at the National Museum of World War II Aviation in Colorado Springs, Colorado.
SBD-5
28536 – based at the Planes of Fame in Chino, California.
54532 – based at the Commemorative Air Force – Airbase Georgia in Peachtree City, Georgia
On display Only
A-24B
42-54582 – National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio.
42-54654 – Pima Air & Space Museum, adjacent to Davis-Monthan Air Force Base, Tucson, Arizona.
SBD-2
02106 – National Naval Aviation Museum at Naval Air Station Pensacola, Florida. Veteran of the Pearl Harbor attack and the Battle of Midway.
02173 – Pearl Harbor Aviation Museum at Ford Island, Hawaii.
