Doyle O-2 Oriole: The parasol-winged Doyle O-2 Oriole monoplane was flown by the NACA at Langley starting in 1929. The O-2 designation was not a military type number, but rather a company designation. The Oriole was later traded as partial payment for a Fairchild 22. The O-2 was outfitted with a fore-and-aft sliding weight in the cockpit for longitudinal stability tests.
