Today's photo is another from a collection of vintage Douglas photos that we've been featuring for the last several weeks. Last week's photo showed a DC-2 being looked at by a couple of gentlemen...and if you look closely, you'll recognize the same two in today's photo, walking off into the background. These images were taken on the grounds of Santa Monica's Clover Field, probably sometime in early or mid July, 1934 (TWA took delivery of the DC-2 from last week on July 20, 1934, so these would likely have been taken just shortly before).
The Douglas O-2 biplane observation aircraft had been a relative success with the USAAC, and Douglas wanted to follow up with a more modern monoplane design, the O-31. The USAAC signed a contract with Douglas in January 1930 for two prototype aircraft, which were to be designated XO-31. Powered by a Curtiss V-1570 Conquerer V-12 water-cooled engine, the two-place design utilized a wire-reinforced, fabric-covered gull-wing with an all-aluminum fuselage, the aft portion of which was corrugated for strength.
After the first of the pair flew in December 1930, it was back to the drawing board, as the aircraft was found to have lateral stability issues. Several different vertical stabilizer designs were tried. Instead of delivering the second aircraft as an XO-31, it was redesignated the YO-31, and sported a larger tail and longer cowling. This second aircraft is the one seen in today's photo. Subsequently a number of additional YO-31A and O-31 aircraft were produced (13 in all), before Douglas switched to the O-43 design, which was ordered in 1934, the same year as this photo was taken. It uncertain how long the YO-31 survived, or what became of it, but it clearly was still at Clover field three years after being built.
(A special shout-out this week to Josh Nyhus of APSoCal for his invaluable help in identifying this plane...when I got the photo, I had a Dickens of a time figuring it out. Tip o' the hat to Ian Hall for trying to solve the mystery, as well. Thanks, guys!)