[Llarry]

Periods of war spur more innovation in engineering aircraft and their powerplants. Exhibit A is World War II, when there were a large number of new design aircraft and when powerplant technology shifted into overdrive.

At the beginning of the war, Douglas aircraft was supplying both torpedo bombers (the TBD Devastator) and dive bombers (the SBD Dauntless) to the Navy.

The TBD was recognized as obsolescent and did not fare well in the early carrier battles, but Grumman filled the breach with the superior TBF Avenger, later produced by Eastern as the TBM.

The SBD, on the other hand, was produced in large numbers for Navy and Marine Corps squadrons (and even in some numbers as the Army Air Forces A-24) and served until the end of the war. By 1943-44 it was replaced on the carriers with the Curtiss SB2C Helldiver, which served into the postwar years as well.

But the Navy was constantly looking for improved bombing and torpedo aircraft. Reliable Douglas Aircraft, suppliers of Navy aircraft since the 1920s was given contracts for several types during the war.

The first of these was the SB2D (SB = scout/bomber, 2 = 2nd model, D = Douglas), which flew in 1943. The SB2D sported much more power than its SBD predecessor, courtesy of a Wright R-3350 radial of 2,300 hp. It also had an internal bomb bay and remote-controlled rear-facing machine guns in dorsal and ventral positions. All this made the SB2D very heavy and only two were built. Then Douglas tried again by reworking the aircraft to eliminate the gunner and the heavy defensive armament -- the result was the BTD-1 which incorporated torpedo attack capability and flew in 1944. The Navy bought a number, but they never saw squadron service; they were still too complex and heavy.

Engineer Ed Heinemann was Douglas' chief designer and in 1944 hit upon the winning formula: The design must be as simple and lightweight as possible. He went to Washington D.C. to present the Navy with a clean-sheet design that would stress those qualities. The airplane would be a single-place model with the capability to dive bomb or conduct torpedo attacks. There would be rigorous weight control in the design process; the weight saved would be available for payload of fuel and weapons. He sketched the proposal out to the Navy Bureau of Aeronautics and committed to a rapid detail design stage with an aggressive schedule for a first flight. He also requested the cancellation of existing contracts for the overly complex aircraft. The Navy bit and Heinemann returned to California to get to work.

The Navy ordered 25 production-equivalent examples as the XBT2D-1 and the aircraft, soon to be dubbed the Skyraider, first flew in March 1945. A month later, the Navy ordered 548 examples as the AD-1. The A (for Attack) category would replace scout bombers (SB), bombers (B) and torpedo bombers (TB) in the future. The AD Skyraider would go on to serve for thirty years and proved amendable to modifications such as night attack, electronic warfare, airborne early warning, etc. The Navy would buy 3,180 ADs from 1945 to 1957 -- redesignated A-1 in 1962.

To return to the torpedo bomber story, Douglas also designed and built an XTB2D-1 torpedo bomber seeking to replace the Avenger. The TB2D was a monster using a Pratt & Whitney R-4360 engine of 3,000 hp and having a wingspan of 70 feet -- a real disadvantage on Navy carriers. It also featured remote-controlled rear-firing machine guns like the SB2D. Again, overly complex and overweight; only two were built. In addition, it appeared that the days of the torpedo bomber were numbered and indeed the last torpedo attack on enemy ships by the U.S. Navy was in 1945.

If something good came out of these overweight and complex aircraft that the Navy did not buy, it was the Ed Heinemann/Douglas aircraft engineering philosophy of simplicity and light weight. That served Douglas well in later years in the design of the Navy heavy attack nuclear bomber -- the A3D (later A-3) Skywarrior and the A4D (later A-4) Skyhawk light attack nuclear bomber, both of which were built in large numbers and served many years.