Douglas SBD Dauntless Scout / Dive Bomber

Posted on September 24, 2015
By Ray Panko | [email protected] | Pearl Harbor Aviation Museum

Key Points

• Half the aircraft on U.S. carriers were Dauntlesses in the first year of the war
• On scouting missions, 18 SBDs flew in pairs, searching a 90-degree pie slice of the ocean. If they found the enemy, they would radio a report and, if feasible, attack with 500-lb. bombs.
• On bombing missions, a squadron of Dauntlesses conducted high-precision/high-risk dive-bombing attacks, plunging almost vertically and releasing bombs at low levels. In the critical first year of the war, SBDs sank or helped sink six carriers, one battleship, three cruisers, one submarine, and 14 transports. This was nearly 30 percent of the total tonnage of the Imperial Japanese Navy’s prewar fleet.
• In air combat, SBDs had a kill ratio of 3.2 to 1. During the Battle of the Coral Sea in May 1942, pilot Lt. John Leppla got four kills and his gunner, John Liska, three. The next day, Stanley “Swede” Vejtasa shot down three Zeroes, adding to an earlier kill. Moved to fighters, Vejtasa shot down seven aircraft at the Battle of Santa Cruz during the Solomon Islands Campaign. This probably saved the heavily damaged USS Enterprise.
• Officially, SBD meant “scout/bomber from Douglas.” Air crews, however, often called it “Slow but Deadly.”
• The museum’s current SBD-5 is a loaner. Our own SBD is undergoing restoration. During the first, critical year of the war, the Navy flew SBD-2s and SBD-3s. The SBD-2 had just two forward-firing .30-caliber machine guns and a single rear-facing machine gun. Neither the SBD-2 nor the SBD-3 had a reflector bombsight. Instead, they had telescopic sights that tended to fog up in the Pacific. Finally, SBDs during the first year of the war were painted blue/gray on their upper surfaces over light gray on the lower surfaces, not deep navy blue.

In terms of both numbers and impact, the Douglas SBD Dauntless was America’s most important naval aircraft during the first critical year of the war. At the start of the war, half of a carrier’s aircraft were SBDs.[1] Although its pilots called it “Slow but Deadly” after Midway, SBD[2] officially stood for Scout/Bomber from Douglas.[3] As scouts, SBDs located enemy ships and patrolled for submarines. As dive bombers, they conducted high-payoff, high-risk attacks on Japanese shipping and land targets. In the four critical carrier battles during the first year of the war, Dauntless did most or all of the damage to the Japanese fleets. SBDs were also surprisingly good at fighting other aircraft. It is one of the few bombers in history to have more air combat victories than losses.

Dive bombing has a simple rationale: If you want to shoot someone, fire from close range. Of course, the closer you get to the enemy, the more likely he is to shoot you. Diving nearly vertically on a ship and releasing your bomb at low altitude is highly accurate. The quickness of your dive also reduces your risk somewhat.[4] However, dive bombing was ultimately a high-payoff, high-loss activity.

The Attack Sequence

Figure 1 shows a typical dive-bombing attack. Weather permitting, SBD bomber flights of 18 aircraft cruised at 18,000 feet.[5] They flew in stacked Vs of three for mutual protection. If the air was clear, pilots could see 30 to 40 miles.[6] Early Japanese ships lacked radar, so dive bombers frequently attacked with the element of surprise.[7] When the Dauntless group found its target, the dive bombers attempted to approach out of the sun for surprise. They first dropped down to about 8,000 feet, accelerating as they descended. This increased their chances of surprise and placed them at a good starting altitude.

Figure 1: Dive Bombing Attack

During an attack, SBDs dove on the target sequentially, about five seconds apart. Each SBD pulled up its nose, went into a stall, opened its dive flaps, and peeled off toward the target.[8] (Witnesses say that a succession of SBDs diving on a target looked like a silver waterfall.[9]) The SBDs dove nearly vertically, at an angle of 70 degrees.[10] To enhance accuracy, the SBD’s big perforated dive flaps slowed the aircraft’s descent speed to only about 276 mph (240 knots).[11] This allowed the SBD to adjust its dive to compensate for the violent maneuvers the target would make. On the negative side, lower speed put them in range of anti-aircraft fire from the target and nearby ships for the entire 30 to 40 seconds of the dive.

Figure 2: Dive Brakes

U.S. Navy photograph.

The pilot tried to attack along the length of the ship because downrange error tended to be substantially larger than sideways error.[12] However, Japanese ships maneuvered violently, forcing many beam attacks. The SBDs in a squadron attempted to attack from slightly different directions in order to throw off the aim of anti-aircraft gunners and so that at least some of them might get favorable angles.[13]

Finally, at 1,500 to 2,000 feet,[14] the pilot released the bomb. The bomb swung on its crutch to clear the propeller[15], then fell toward its target. Ideally, SBDs would drop big 1,000-lb. general purpose or armor-piercing bombs.[16] Fuses were set with delays of 1/100 second for explosion at contact or 1/250 second to adjust penetration before the detonation. However, some SBDs on bombing missions carried smaller but still powerful 500-lb. bombs.[17] The SBD-3 had a practical range of 250 miles with a 1,000-lb. bomb or 325 miles with the 500-lb. bomb they carried on scouting flights to increase combat radius.[18] After the drop, the pilot executed a painful pullout at up to six Gs.[19] He then jinked hard to try to escape the gauntlet of anti-aircraft fire streaming from screening warships.

Exact doctrine for attacks varied throughout the war. Pacific Aviation Museum’s Bob Naylor did an Oral History with Admiral James D. “Jig Dog” Ramage (Navy Cross), who was the commanding officer of Bombing 10 off the USS Enterprise at the Battle of the Philippine Sea. He described the initial approach to the target at 12,000 feet as being from head on and directly opposite the target vessel’s direction of travel. He described pulling his nose up and rolling inverted as the aircraft began to stall. This resulted in an approach to the target from dead astern, giving the pilot perhaps a few extra seconds to aim as the vessel tried to maneuver. Doctrine called for bomb release at 2,000 feet. The SBD would only then begin recovery from the dive, going “wings level” at about 500 feet.

Midway and Richard Best

Shortly after Pearl Harbor, American carriers conducted hit-and-run raids on Japanese strongholds. Although most attacks did little damage, they allowed the Navy to learn what worked and what did not. The most successful raid took place against Lae and Salamua on Papua New Guinea. One hundred and four raiders flew over the central mountain range and attacked the ships of a Japanese landing force in the harbors. They sunk three transports and damaged several other ships, escaping with a single loss.[20] At the Battle of the Coral Sea on May 4-8, 1942, SBDs and TBD Devastator torpedo bombers destroyed light carrier Shoho, and SBDs damaged to fleet carrier Shokaku. After the battle, Shokaku and Zuikaku were either too damaged or had lost too many of their aircraft to participate in the Battle of Midway a month later. At Midway, SBDs from Enterprise and Yorktown mortally wounded fleet carriers Kaga, Akagi, and Soryu in a battle of only 10 minutes. They returned the next day and sunk the fourth Japanese carrier, Hiryu. Gone were four of the six carriers that had attacked Pearl Harbor just half a year earlier.

In this crushing defeat for the Japanese, the American victory owed a great deal to a single pilot — Lt. Richard Best, the commander of squadron VB-6 on Enterprise.[21] Both Enterprise squadrons arrived together. Due to a mix-up in communication, VB-6 and VS-6 both began to attack Kaga. This left nearby Akagi unattacked. Best tried to get VB-6 to switch to Akagi, but only his two wingmen followed him. Normally, three SBDs could not take out a major carrier, and Best’s wingmen only did minor damage. Best, however, put his bomb[22] in the middle of the flight deck. His bomb broke into the hangar deck, where the Japanese were loading aircraft. When the bomb exploded, it turned the hangar deck into an inferno of burning fuel and exploding bombs. Crewmen were literally blown over the side.[23] Within minutes, Akagi was a burning hulk. If Best had not taken out Akagi, the battle easily could have turned in favor of the Japanese because Japan would have two carriers left with which to retaliate. Best also fought in the subsequent attack that sunk Hiryu.

Figure 3: Richard H. Best

Source: U.S. Navy.

After returning to Enterprise, Best began coughing up blood and developed a fever. He was transferred to the hospital in Pearl Harbor, where X-rays showed cloudy spots on his lungs.

On his mission against Akagi, his oxygen canister was faulty, creating caustic soda. X-rays revealed that the caustic soda had activated latent tuberculosis. Best spent three years in a Navy hospital, and during the next 10 years, he spent four in the hospital. During his career after the Navy, he worked for Douglas Aircraft and the Rand Corporation.[24]

Guadalcanal

Although the Battle of Midway greatly weakened the Japanese fleet, the IJN remained potent. When U.S. Marines landed on Guadalcanal in August 1942, the Japanese sent surface ships to shell Henderson Field and to drop off Japanese troops on the island. Marine and Navy SBDs based on Guadalcanal blunted many of these thrusts. During the period from August to mid-November, aircraft from Guadalcanal sank 14 transports, three destroyers, and two cruisers.[25] They had a share in the sinking of battleship Hiei and damaged 14 other ships. On Nov. 14 alone, they sank seven Japanese ships. In addition, during the desperate attempt to hold Guadalcanal, the U.S. Navy engaged in two major carrier battles. In the Battle of the Eastern Solomons and the Battle of Santa Cruz, SBDs were the Navy’s big weapons.

Overall, from December 1941 through December 1942, SBDs sank six carriers, one battleship, three cruisers, one submarine, and 14 transports. Some of these kills were made in conjunction with surface ships, but the total is amazing even when it is qualified.[26] To put the damage that SBDs did in perspective, this damage was nearly 30 percent of the tonnage of the IJN prewar fleet.[27]

Scouting

Figure 4: Scouting

Source: Naval Aviation Museum

The “SB” in the Dauntless’ naval designation meant that it was both a scout and a bomber. Each aircraft carrier had two Dauntless squadrons; one was designated the scouting squadron. This squadron was designated as VS (heavier-than-air,[28] scouting), followed by a dash and its unit designation. VS-6 was the scouting squadron on the Enterprise at the beginning of the war. It was also called Scouting 6. Enterprise also had a bombing squadron, VB-6. In practice, the two squadrons handled the two roles interchangeably. For example, in the Battle of Midway, both Enterprise squadrons bombed the Japanese carriers.

On scouting missions, a squadron of 18 SBDs flew in pairs. Figure 4 shows that the pairs would take off in a fan. Adjacent pairs would fly about 10 degrees apart. This would allow a squadron to search a quarter of the sky. Each pair flew out about 200 miles, did a dogleg of 20 to 50 miles, and then flew back.[29] Scouting Dauntlesses typically flew at 1,000 to 1,500 feet to conserve fuel.[30] As they flew, their pilots constantly searched the horizon with 7×50 binoculars.[31]

Figure 5: Scouting

If a pair spotted enemy ships, a rear-seat gunner would radio information to the fleet in Morse code.[32] Using a hand-held cipher wheel, the gunner encrypted the transmission, if there was time. This type of encryption could be broken in a few hours, but by then there would be no need to maintain its secrecy.

Often, the pair would then shadow the fleet to mark its progress. However, each scouting SBD carried a 500-lb. bomb. If they had the element of surprise, they attacked one of the ships. In some cases, scouts from adjacent “pie slices” would divert to join the attack. At the beginning of the Battle of Santa Cruz during the Guadalcanal campaign, two scouting SBDs from Enterprise’s VS-10 squadron hit Zuiho, instantly knocking the carrier out of the battle.[33]

Dauntlesses also conducted anti-submarine patrols for the fleet. In fact, America’s first sinking of a Japanese submarine occurred on Dec. 10, 1941. On submarine patrol, Lt. Dickinson from Enterprise struck I-70 submarine, which sank in less than a minute. For Dickinson, the victory was sweet because his previous SBD had been shot down three days earlier during the Pearl Harbor attack.[34]

Air Combat

Although the SBD was designed for scouting and bombing, it was a nasty customer in a dogfight. Beginning with the SBD-3, the Dauntless had two forward-firing .50-caliber machine guns. These guns had heavy slugs and could outrange the Zero’s two 7.7 machine guns and 20mm cannon. Also, beginning with the SBD-3, the rear gunner had two .30-caliber machine guns. Although the SBD could hardly be called agile, it had light controls and was far from sluggish in turns.[35] Like its Japanese counterpart, the Val, the Dauntless could dogfight.

The SBD’s first air combat, however, was a disaster.[36]^,[37] On Dec. 7, 1941, Enterprise sent a flight of 18 Dauntlesses to scout in front of the carrier and then land at Ford Island. Most were SBD-2s with only twin .30-caliber machine guns in the front and a single .30-caliber machine gun in the rear. As they flew into Oahu, they found themselves in the middle of a war. A third of the aircraft were shot down — one by friendly fire. Eight of the 36 crew members died, as well.[38] Although in shock, the surviving SBD crews that reached Ford Island quickly rearmed and took off in search of the Japanese fleet.[39]

Rear Gunners

When SBDs flew, they stayed in close formation for mutual protection. On the day the Marines landed on Guadalcanal, Japan’s leading ace, Saburo Sakai,[40]^,[41] saw eight SBDs near Tulagi. Thinking they were Wildcats, he attacked them from the rear. He discovered his mistake too late. The rear gunners riddled his aircraft was with bullets. He lost an eye and was temporarily paralyzed over half his body. Although he made a legendary 500-mile flight home with the crippled aircraft, his war was essentially over.

One person who got a back-seat kill was not even a crew member, and he got it when the aircraft was sitting on a carrier’s deck during an attack. AMM Bruno Gaido jumped into the back seat of a waiting SBD and shot down an attacking Mitsubishi G4M bomber. He was subsequently transferred to air crew.[42]

Rear-seaters had to be careful not to shoot off their own tails. At the Battle of Midway, Cmdr. McClusky’s gunner almost shot off both sides of the tail accidentally.[43] Fortunately, the aircraft was damaged, but not disabled. One rear-seat gunner who visited Pacific Aviation Museum was asked if there was an interrupter gear to keep the rear gunner from shooting off his tail. He shook his head and said, “*&% no. You just didn’t shoot your tail off!”

Pilots

Most air combat maneuvering successes, however, were due to pilots. At Coral Sea, Lt. Cmdr. Bob Dixon was scouting the Japanese fleet. He trailed the fleet for an hour after contacting it by hiding in the rain and clouds. Although Zeros attacked him during this vigil, he turned to meet them head on whenever they approached. His long-ranging .50-caliber heavy machine guns forced the Zeros to keep their distance.[44]

The day after the Battle of the Coral Sea brought another opportunity for SBDs to confront Japanese fighters. Stanley “Swede” Vejtasa and his flight were on antisubmarine patrol when they were jumped by a dozen Zeros. With no Wildcat cover, Vejtasa turned into the attack, firing his two .50-calibers into the oncoming Japanese. In the swirling flight that followed, he downed three of the Zeros. For this action, Swede received the Navy Cross. It was his second. His earlier medal had been awarded for helping to sink three Japanese ships and, incidentally, for shooting down his first Zero. Not surprisingly, Vejtasa was transferred to fighters.[45] The move was a good one. At the Battle of Santa Cruz during the Guadalcanal campaign, Swede got seven more kills on a single mission, probably saving the already heavily damaged Enterprise. Hel also got another Navy Cross.

Of course, being able to fire from both front and rear made the SBD even deadlier.[46] At the Battle of the Coral Sea, Lt. John Leppla got four kills, and rear gunner John Liska got three. At Santa Cruz in October, Liska got his fourth rear-seat kill. Unfortunately, Leppla, who had been transferred to fighters, was killed in this battle.

Figure 6: Left to Right: Lieutenant Commander James Flatley with Lieutenants Stanley Vejtasa and Leppla

3.2:1 Kill Ratio

Overall, 43 SBDs were known or thought to have been brought down by enemy aircraft. However, SBDs had a remarkable 138 official air-combat victories.[47] This was a kill ratio of 3.2:1 — better than some fighters.

Development

Figure 7: Douglas Plant in El Segundo

Source: Naval Aviation Museum

Before World War II, the Navy had long focused on dive bombing.[48] They learned that aircraft had to be developed specifically for dive bombing to survive in that role.[49] In particular, dive bombers needed extremely strong wings for the high-G pull out at the end of the dive. The SBD’s wing was based on the box structure of the DC-2 wing.[50]

The Dauntless began at the Northrop Aircraft Company as the XBT-1 project, which eventually became the BT-1. The BT-1 prototype’s split dive flap caused severe tail buffet until the National Advisory Committee on Aviation (NACA) solved the problem by suggesting that the wing be pierced by holes. Although a few BT-1s were built, the aircraft had significant problems that the new and small Northrop company could not afford to solve.[51] Northrop sold its production plant to Douglas. The design crew also moved to Douglas, including Ed Heinemann — “Mister Attack.” Heinemann had a hand in most American attack aircraft for several years during and after the war.[52]

There were six versions of the SBD. The first two were limited aircraft built in small numbers. The SBD-1 had no armor or even self-sealing fuel tanks. Its forward-firing guns were small .30-caliber machine guns, and the rear-seat gunner had only a single .30-caliber machine gun. In addition, its range was very limited. It was so bad that the Navy gave it to the Marines.[53] Only 57 Dash-1s were built.

The SBD-2 was improved by adding two 65-gallon wing tanks to increase range.[54] In addition, the SBD-2 was able to carry additional 100-lb. bombs under each wing. The Navy took possession of 87 SBD-2s.[55] This was the main version of the Dauntless through the Battle of the Coral Sea.[56]

After Coral Sea, the SBD-3 was dominant. The Navy ordered the SBD-3 in June 1940 after the Stuka had proven the dive bomber concept in Europe.[57] After Pearl Harbor, the Navy increased its order by 500.[58] The “Speedy 3” had a more powerful engine and slightly higher speed, but its main improvements came in armor, armament, and self-sealing fuel tanks.[59]^,[60] The pilot’s guns were increased from .30-caliber to .50-caliber, which had much better range and hitting power. The rear gunner received a second .30-caliber machine gun. The Navy bought 584 SBD-3s, and the Army bought 168 of the equivalent A-24s.

Late in 1942, Douglas introduced the slightly improved SBD-4, which had extra radio equipment, radar, a Hamilton Standard constant-speed propeller, and a 24-volt electrical system. The Navy bought 780 SBD-4s, and the Army bought 170 A-24s.

The main production version of the Dauntless was the much-improved SBD-5, which Douglas introduced in May 1943. The Navy bought 2,965, and the Army bought 675 A-24s. The SBD-5 got a 200-hp increase in engine power and a larger fuel tank. More important, while earlier models of the SBD had a three-power telescope for bomb aiming, the SBD-5 finally got a reflector sight for the pilot (and one for the gunner.) In the hot and humid Pacific, the telescope sight tended to fog up, forcing the pilot to eyeball the target without the scope. Although the SBD-5 was an excellent aircraft, it was not available in the decisive first year of the war.

The final version of the Dauntless was SBD-6, which got an additional 150 hp. Only 450 SBD-6s were built because the war ended.

Although the SBD had a long production run, it was almost a footnote in airplane production. Before World War II started, the SBD was considered obsolete, and January 1942 was scheduled to see its final delivery. Its successor was to be the Curtis SB2C Helldiver, which was planned to have twice the bomb load, fly 60 mph faster, and fly much farther. However, the SB2C was a developmental nightmare, and in the first critical year of the war, SBDs did all of the dive bombing. Although the SBD was eventually replaced at sea by the SB2C, its replacement proved to be only a modest improvement operationally while being much more difficult to service.

The Marines continued to use the SBD from land bases throughout the war, making the SBD one of the few planes that spanned the conflict. All told, Douglas built 5,963 SBDs for the Navy and nearly identical A-24s for the Army.[61]

Figure 8: Marine SBDs operating from land

Source: Naval Aviation Museum Captain Lawrence Waite Photograph Collection

All SBDs used versions of the Wright R-1820 Cyclone 9. The “R” indicates that it was a radial (air-cooled) engine. It had a single row of nine cylinders (hence, the final 9). The “1820” was its displacement in cubic inches.

Figure 9: Wright R-1820 Cyclone 9 Engine

The R-1820 Cyclone was a popular engine during the war, and even afterward. Most famously, it powered the B-17. It also powered the Grumman J2F Ducks based in Hangar 37 during the attack, and the North American T-28B and T-28C trainers. It also powered early Vietnam helicopters, including the Army’s H-21 Piasecki “flying banana” and the Sikorsky H-34 Seahorse used by the Marines. A two-row version of the engine, the R-2600, powered the B-25.

The Dauntless was already considered to be obsolete before the war began and was scheduled to end production. Pearl Harbor changed those plans, and the SBD was in use almost to the end of the war. Its scheduled replacement was the Curtis SB2C Helldiver (scout/bomber, second from Curtis). The Helldiver would carry a bigger bomb load, farther, at substantially higher speeds. Unfortunately, the SB2C specifications called for two of the aircraft to fit on a carrier’s elevator at the same time. This seemingly innocuous specification caused horrendous problems with design. The Helldiver that finally emerged was very late and only a modest improvement over the SBD in performance. Pilots hated the difficult and temperamental SB2Cs almost as much as did the maintenance personnel who had to keep it flying. Nevertheless, the SB2C had many ship kills later in the war.

Figure 10: Curtis SB2C Helldiver Dive Bomber

Source: National Archives and Records Administration: 80-G-348290.

Toward the end of the war, it became clear that the days of dedicated dive bombers were over. Powerful F4U Corsairs proved to be excellent dive bombers without sacrificing speed and agility in combat. In addition, five-inch rockets gave Corsairs and other fighters attack precision without dangerously close bomb release. By the time the Korean War began, the enemy had radar-controlled anti-aircraft weapons that made close bombing completely suicidal.

Some visitors, seeing the Dauntless, think it is the kind of aircraft that future president George H.W. Bush flew. However, Bush flew a torpedo bomber, the TBM Avenger. Figure 8 shows 1/72-scale models of the two aircraft. The Avenger is obviously much bigger. Also, while the Dauntless had two crew members, the Avenger had three.

Figure 11: The Dauntless and the Avenger

The Dauntless currently on the floor of Hangar 37 is a loaner. The museum has raised its own SBD from the cold waters of Lake Michigan. It is now under restoration.

Figure 12: The Museum’s SBD

Characteristics

Source: Naval Aviation Museum

Source: Tillman [1976] for the aircraft, White [1995] for the engine, Stille [2007] for the combat radius.

Special thanks goes to the docents and members of the museum staff who reviewed a draft of this post. Exceptionally valuable were the comments and suggestions of Jerry Cerney, Bob Naylor, Keith Omata, and Dave Verret.

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http://articles.latimes.com/2001/nov/03/local/me-65245. Last viewed September 2015.

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