The Emsco Corporation took its name from the initials of its founder E.M Smith. In early 1929, Emsco bought out the Albatross Corporation and their aircraft, designed by Charles Rocheville. One of these was the American Albatross B-1 of 1928, a
high-wing, braced monoplane with a single engine producing and with accommodation for six passengers. The Emsco Challenger was a development of it and was quite similar apart from having three engines totalling . It was intended as the first of a range of similar Emsco aircraft, differing in having one or two engines. The Challenger's wing was built in two parts, both rectangular in plan out to semi-elliptical tips, which met on top of the
fuselage and were mounted with a 1.5°
dihedral. They had wooden structures built around two
box spars and were
fabric-covered. Parallel struts from beyond midspan braced the spars to the lower fuselage
longerons and the rear struts were also braced near their midpoints to the upper longerons; all struts were enclosed in wide,
airfoil-section fairings. Its inset ailerons were long and narrow. The fuselage of the Challenger was built around a rectangular cross-section, chrome-molybdenum steel frame and given an oval cross-section by
bulkheads. The cabin region was
plywood skinned; aft, formers, and stringers were fabric-covered. One of the three , six-cylinder
Curtiss Challenger radial engines was in the nose under a wide-
chord fairing. The other two were mounted uncowled on the wing bracing struts, assisted by more struts between engine and upper fuselage and others between the struts. The pilots occupied an enclosed
cockpit, placed high and just ahead of the wing
leading edge, with
side-by-side seating and dual control. A passageway connected the cockpit and the windowed, well-furnished passenger cabin. Cabin and cockpit were accessed by a door on the port side, equipped with a built-in ladder, via a compartment containing a curtained-off lavatory and a luggage space. The
empennage, like the fuselage, was steel-framed and fabric-covered. Both
fin and
tailplane, the latter mounted at midfuselage height, had straight, swept leading edges and carried balanced control surfaces with straight, unswept rear edges and round tips. The
rudder was deep, extending to the keel, and worked within an
elevator cut-out. The Challenger had a fixed tailwheel
undercarriage. Its mainwheels were on faired, cranked axles hinged from the central fuselage underside, braced by drag struts hinged further aft; these members were enclosed in
balsa and fabric airfoil fairings. Short, vertical
oleo legs were attached to the bottom of the outer engine mountings. The wheels had independent
Bendix brakes and were almost entirely enclosed in large
dural-tube, fabric-covered fairings. A small tailwheel was mounted on a rubber-sprung pylon. ==Development==