The Avia A.23 was a single bay biplane with its wings mounted without stagger. Both wings were almost rectangular, though the tips were slightly angled; both carried light dihedral. The upper wing was a little larger in both span and chord and was in three parts, with a short centre-section held over the fuselage on a low cabane. The lower wing was in two parts and mounted on the lower fuselage, braced to the upper wing with a pair of outward-leaning, parallel interplane struts made of profiled steel tubes. Only the upper wings carried ailerons. The wings were two-spar wooden structures and were fabric covered. Its single engine was an uncowled, Walter-built Jupiter IV on a steel tube mounting and with a pair of long, airfoil-section fuel tanks placed on the upper wing near the ends of the centre-section. Behind its firewall the fuselage, built from steel tubes, was rectangular in section and housed a passenger cabin long fitted with six permanent and two folding seats. Each passenger in the fixed places had a window in the plywoodwalls. There was engine access via a hatch in the front of the cabin and a toilet at the back. Doors over the wings gave access to the cabin. The A.23 was flown from an open, side-by-side cockpit in the upper fuselage aft of the cabin, with the captain on the left and second pilot/radio operator at his right. A door below the right-hand seat gave access to the engine hatch via the cabin. The cockpit was normally accessed through a low, tetragonal, port-side door. Behind them was a baggage hold. The A.23's straight-edged tailplane, mounted on the upper fuselage and strut-braced from below, was adjustable in flight and carried separate rounded, balanced elevators. Its fin was small, with a large, rounded, balanced rudder which extended down to the keel and worked in a gap between the elevators. All components were steel-framed and fabric-covered. Its fixed, conventional undercarriage originally had mainwheels on a single axle, mounted on V-struts from the lower fuselage with wire cross-bracing. The rear components of the V-struts had rubber disc shock absorbers. By May 1928 the axle had gone and the landing gear made more robust with a transverse X-strut. A castoring steel tailskid had its own rubber shock absorber.
Operational history
The first A.23 flew in 1926. From 1928, seven A.23s flew ČSA's Prague-Marienbad and Prague-Uzhhorod; some remained in service until 1936.
