In the history of American aviation, the contrast between Curtiss-Wright and Douglas Aircraft in the early 1930s illustrates a fundamental truth about organizational design: that focused, lean companies with strong engineering leadership consistently outperform sprawling corporate empires whose size has become a substitute for vision. Nowhere is this contrast more elegantly illustrated than in the story of the Douglas XO-35 and XB-7 — a pair of aircraft that represent Douglas at a critical transitional moment, poised between the biplane age it was leaving behind and the monoplane future it would help define.
Curtiss-Wright at this time was the corporate iceberg that aviation historian Peter Bowers wrote about so perceptively. Its Wright element built two different engine families — the Whirlwind radial and various Curtiss liquid-cooled designs — serving different customers, different philosophies, and often competing internal factions. The empire was vast, the overhead crushing, the creative agility increasingly limited. Donald Douglas, by contrast, had built Douglas Aircraft Company around himself and the engineers he had personally recruited — men who shared his standards, his ambitions, and his insistence on technical excellence. The result was an organization that could take risks, iterate quickly, and produce designs that actually advanced the state of the art.
Douglas in Transition: Biplane to Monoplane
By 1930, Douglas had established its reputation with a series of capable military designs, primarily biplanes serving the Air Corps and the Navy. The transition to monoplane design was underway across the industry, driven by the aerodynamic advantages that a cantilever or semi-cantilever monoplane offered over the wire-braced biplane — reduced drag, higher speeds, better structural efficiency for carrying loads. Douglas engaged this transition thoughtfully rather than recklessly, producing designs that combined proven technologies with carefully chosen innovations.
The XO-35 began design development in 1930, and it reflected exactly this philosophy. The Army Air Corps wanted an observation aircraft — a two-seater that could range widely over enemy territory, report troop dispositions, and return safely. Douglas proposed a design that was, for its time, genuinely advanced: a low-wing monoplane with a distinctive gull wing configuration, two-place tandem seating with the observer in front and the pilot in the rear, and — most remarkably for an observation aircraft of 1930 — retractable landing gear.
The Design: Revolutionary Details
The retractable undercarriage was the XO-35's most technically significant feature. In 1930, retractable gear was an exotic innovation seen primarily in racing aircraft. Its application to a military utility aircraft represented exactly the kind of forward-thinking engineering that separated Douglas from more conservative competitors. The drag reduction from eliminating fixed undercarriage was substantial — the difference between looking like a 1928 design and looking like something from 1934 or 1935.
Power came from the Curtiss V-1570 Conqueror engine, the same 675-horsepower liquid-cooled unit used in the XP-31 Swift discussed elsewhere in this series. The Conqueror was a capable engine for its time — powerful, relatively reliable, and producing the smooth-running characteristics of a liquid-cooled design. It gave the XO-35 a performance envelope that was genuinely competitive with contemporary fighters in terms of speed.
The gull wing configuration was chosen partly for structural reasons — it allowed a shorter, simpler undercarriage geometry — and partly for ground clearance with the large propeller that the Conqueror required. The result was an aircraft with an unusually elegant appearance, the graceful downward sweep of the inner wing panel giving the XO-35 a distinctive visual character that set it apart from the angular utility of most military aircraft of the period.
| Role | Observation / Light bomber experiment |
|---|---|
| Engine | Curtiss V-1570 Conqueror, 675 hp |
| Crew | 2 (observer forward, pilot aft) |
| Wingspan | 65 ft |
| Length | 45 ft |
| Maximum speed | 182 mph |
| Service ceiling | 20,400 ft |
| Wing configuration | Low-wing gull wing monoplane |
| Landing gear | Retractable |
| Number built | 2 |
The XB-7: A Bomber in Disguise
The second aircraft in the program was designated XB-7, reflecting the Air Corps' interest in exploring whether the XO-35 airframe could serve as a light bomber. The distinction between observation and light bombing in the early 1930s was often somewhat artificial — both missions required a fast, rangy, two-place aircraft with reasonable payload capacity, and the same fundamental design could serve both purposes with relatively minor modifications.
The XB-7 experiment confirmed what the Air Corps suspected: the airframe had genuine potential as a light bomber, and its speed would have made it difficult to intercept by contemporary fighters. But "potential" and "production contract" are different things, and only two aircraft were ever completed. The program was cancelled in favor of more conventional designs that the Army found less technically challenging to operate and maintain.
The Corporate Lesson
The XO-35/XB-7 program ended without production orders, and in that sense it can be called a failure. But the failure was one of circumstance and timing rather than concept. The aircraft was technically sound and aerodynamically advanced for its era. Its innovations — retractable gear, gull wing monoplane configuration, tandem crew arrangement — were all features that would become standard on subsequent designs. Douglas learned from it and moved forward; the company's trajectory through the 1930s and 1940s, culminating in the DC-3 and the SBD Dauntless and the A-20 Havoc, demonstrates what a focused organization can accomplish when it applies lessons intelligently.
Curtiss-Wright, facing the same technological transition at the same time, moved more slowly and less confidently. The contrast is instructive: controlled growth, strong leadership, and a culture of engineering excellence allowed Douglas to innovate in ways that a corporation bloated by merger could not match. The XO-35 and XB-7 are, in their quiet way, evidence of how good companies think — even when the programs themselves don't result in production aircraft.