America's “Dauntless” Dive-Bomber Was a World War II Classic
October 15, 2019 Topic: Security Region: Americas Blog Brand: The Buzz Tags: Dauntless BomberWorld War IIU.S. NavyU.S. Air ForceDouglas SBD

America's “Dauntless” Dive-Bomber Was a World War II Classic

An excellent plane.

Key point: These bombers were vital when it came to defeating Imperial Japan.

World War II gave us many stories of aerial warfare, men and their machines fighting their way to victory and glory in the name of humanity. However romantic such a notion may be, World War II was the first in which airpower actually won battles, decided the outcome of campaigns, and ultimately the course of the conflict itself. That victory came about as a result of Allied airmen dropping ordnance onto the most important things the Axis countries owned, turning them into rubble or wreckage. It’s a simple formula actually: precisely drop enough lead or high explosive onto something, and it will be destroyed.

“Fighter Pilots Make Movies. Bomber Pilots Make History!”

But not everyone saw the worth of that idea in the 1930s and 1940s. Most airpower enthusiasts of the day saw bombing in terms of large formations of huge multi-engined planes, fighting their way past hostile defenses to carpet an objective with bombs, the target being embroiled in the mess.

The early days of World War II, however, did not see America’s few victories won by huge formations of heavy bombers. Those battles were won by one small, tubby, and not terribly fast airplane, flown by men whose courage and tenacity are still a source of envy and wonder to historians of the period. There was a saying going around at the time: “Fighter pilots make movies. Bomber pilots make history!” The men who made that history were the aviators of the Navy and Marine scout and bombing squadrons, and their war horse was the Douglas SDB Dauntless dive-bomber.

It is sometimes difficult to remember that before laser-, infrared-, and satellite-guided bombs came into being, delivering ordinance from aircraft was hardly a precision process. Huge sums of money were spent developing specialized bombsights for level bombers, to help lay their loads onto targets with some modicum of accuracy. However, without some sort of terminal guidance for the bombs themselves, even the famed Norden bombsight of World War II would do no better than to lay a string of bombs across an area the size of several football fields. There were, however, simpler and more intuitive ways of putting a bomb close to an aim-point from the air.

Concept Of Dive-Bombing Created

Nobody knows who first came up with the idea of aiming bombs at a target from a diving airplane, but sometime in World War I this became an intuitive way of getting bombs closer to the desired target. The result was a specialized kind of weapons delivery known as dive-bombing. Technical dive-bombing was a uniquely American creation, the product of a small cadre of U.S. Marine Corps (USMC) aviators who wanted to provide close bombing support to riflemen on the ground. It was Lieutenant L.H.M. Sanderson who, in 1919 as a member of Marine Observation Squadron Nine, noted that a diving aircraft pointed at a target made more accurate deliveries, causing the tactical adoption of glide- and dive-bombing by the USMC. Further experimentation showed that the reduced horizontal velocity component of the diving aircraft (compared to that of a level bomber) combined with the superior view of the target by the pilot made for truly precise weapons deliveries by skilled pilots.

Navy Begins Procuring Dive-Bombing Aircraft

By the mid-1930s, the Navy and Marines had both seen the virtues of dive-bombing. The USMC was using it to support troops on the ground as flying artillery, while their sea-service brethren developed the tactics as a precision antishipping tactic. To this end, the Navy’s Bureau of Aeronautics (BuAer) began to procure purpose-built dive-bombing aircraft, with the specialized equipment and structures necessary to make them a truly deadly form of warfare. These included aerodynamic “dive brakes” (to slow and steady the aircraft during the dive), extra structure (to withstand the stresses of pulling out after the dive), “trapeze” bomb-release systems (to help the bomb clear the propeller), and telescopic bombsights (to assist the pilot in putting the weapon precisely onto the target).

Seeking The Next Generation Of Bombers

Curtiss, long a supplier of Navy and Marine aircraft, produced most of the early dive-bombers. In fact, it was a demonstration by Marine Curtiss F8C Helldivers that led German Air Minister Ernst Udet to procure several for the emerging Luftwaffe as the inspiration for the famous Ju-87 Stuka. The 1930s were a time of amazing technological advancement in the aviation industry, and several new companies began to produce dive-bombers for the Navy and Marines. One of these was the Vought SB2U Vindicator, the first all-metal, low-wing monoplane procured for use by the sea services. Brought into service in 1938, the Vindicator provided a great deal of experience in operations of such aircraft, and led the BuAer to look for a more advanced model for the Navy and Marines. That search led to an emerging aircraft manufacturer in southern California: the Douglas Aircraft Company (DAC).

Founded by Donald Douglas, DAC already had an impressive standing in the aviation world by the late 1930s. Manufacturer of the incomparable DC-3 (which became the military C-47/R4D Skytrain/Dakota), DAC already had built a solid reputation with the Navy with the TBD Devastator torpedo bomber. Despite the unfortunate reputation it would acquire at the Battle of Midway in 1942 (where 39 out of 43 would be shot down), the TBD was the finest carrier-based torpedo bomber in the world when it was delivered in 1937. Like the SB2U, the TBD was a rugged, all-metal, low-wing monoplane that clearly represented the future of carrier aircraft. With the clouds of war beginning to grow, the DAC was going to be a major player in that effort.

Initially, the contract for the Vindicator replacement went to the El Segundo division of Northrop, which was producing a fairly conventional scout bomber design known as the BT-1. But, Northrop sold this division to DAC, and with it came one of the greatest aircraft designers of all time: the legendary Ed Heinemann. Heinemann had already produced a number of successful designs and almost immediately saw the possibilities for an improved model of the BT-1. At the same time, Heinemann began to be influenced by DAC’s founder on how he might design better aircraft for the sea services.

“They Have To Take Punishment And Still Work”

He would later write in his book, Aircraft Design: “One day when I was a young man just beginning to design airplanes, the great person who founded the company that bore his name, Donald Douglas, took me by the shoulder and taught me a lesson that was simple, though vital to success. At the time, we were trying to generate business from the U.S. Navy. ‘Navy planes take a beating,’ he said. ‘They slam down on the carriers when they land and get roughed up by the unforgiving elements of the high seas. If we want the Navy to buy our airplanes, we must build them rugged. They have to take punishment and still work.’”

Applying this and other ideas to the basic BT-1 design, he refined it into the XBT-2, what became known as the Scout-Bomber-Douglas Aircraft Company, or SBD.

SBD Rolled Out With Several Changes

The SBD was a surprising little airplane, as much for what it did not have in the way of features as for what it did have. For example, the SBD broke with the trend for folding wings to save deck and hangar space. By using a compact wing and platform, Heinemann was able to design the SBD to be small enough to fit up to three dozen onto U.S. carriers along with their other squadrons of fighters and torpedo bombers. The lack of a folding wing also saved weight and removed a weak point that made for a more rugged design. Another SBD innovation was the inclusion of perforated split dive brakes, which also functioned as flaps on takeoff and landing.

When fully extended, the split flaps allowed a pilot to dive the SBD at an angle of up to 80° with a terminal velocity (the point where aerodynamic resistance balances engine power and gravity) of around 250 knots. This limited the stresses on the aircraft during pullout and provided a more stable platform during the dive. Nevertheless, the Dauntless (the name the Navy gave the SBD) was stressed to withstand up to 9 “gees” during maneuvering, and even was able to handle so-called “zero lift” (nearly vertical) dives. To help the pilot see the target and assist in aiming, a padded 3X sighting scope was mounted over the control panel. All of this was designed to help the two-man crew (a pilot and radio operator/gunner) to put a bomb onto the deck of a moving ship or a ground target with accuracy.

Along with the aforementioned features, Heinemann designed the SBD to take full advantage of the new advances in lightweight materials and structures to improve weight and durability. Although relatively new for its day, the Dauntless had a hydraulic system to power extend and retract the landing gear and dive brakes/flaps, replacing earlier hand-cranked systems. To protect against enemy fighters, two forward-firing .50-caliber M2 machine guns were mounted in the cowling, while a pair of twin .30-caliber Brownings was carried in a rear-firing flexible mount.