The Waco 10/GXE/Waco O series was a range of three-seat open-cockpit biplanes built by the Advance Aircraft Company, later the Waco Aircraft Company.

The Waco 10 was a larger span development of the Waco 9, both single-engine three-seat single-bay biplanes constructed around steel-tube frames. The wing covering was fabric, and both upper and lower planes carried ailerons, which were strut linked. The two passengers sat side by side in a cockpit under the upper wing and ahead of the pilot, who had a separate cockpit. It had a split-axle fixed undercarriage and a tailwheel. The main undercarriage was fitted with hydraulic shock absorbers, unusual at the time on a light aircraft. The fin could be trimmed on the ground to offset engine torque, and the tailplane could be trimmed in flight. Initially it was powered by a Curtiss OX-5 water-cooled 90° V-8 engine producing 90 hp (67 kW).

Its first flight was in 1927. It was numerically the most important type to be built by Waco, with at least 1,623 built over a period of 7 years from 1927 to 1933 and was fitted with a very large variety of engines of radial and V configuration.

In 1928, after the Waco 10 had entered production, Waco changed its designation system so that the basic model 10, powered by a 90 hp (67 kW) Curtiss OX-5 engine became the GXE. Later aircraft used three-letter designations, the first denoting the engine, the second denoting the wing installed, S or T meaning Straight or “Tapered” wing, and the final O indicating it was a derivative of the 10. 

(Sources: US Civil Aircraft by Joseph Juptner and Wikipedia)