02/08/2026. Remarks by Johan Visschedijk: "The installation of engines with different outputs in the Letov Š 16 bomber/reconnaissance series resulted in at least eight other versions, designated as Š 116 to Š 816. They were produced in small numbers, most often for the purposes of engine testing or for air races; with them, the number of aircraft derived from the original Š16 type and produced for the Czechoslovakian AF climbed to 115.

Two Š 816 light bomber prototypes were created (c/n Š 816.1 and Š 816.2), both fitted with a 550 hp Praga ESV twelve-cylinder liquid-cooled V-engine.

The first prototype was created by converting the sole Š 516 (c/n Š 516.1) racer with an ungeared ESV engine, covered with a streamlined cowling, and with a radiator under the fuselage, just in front of the landing gear.

The second prototype (pictured on top of the page) was created by converting the fifteenth production ŠB 16 (c/n ŠB 16.2) day bomber with a geared ESV engine with a rectangle cowling, and with a radiator on the front of the nose.

The former aircraft was first flown on 17 March, 1931, the latter appeared in the spring of 1933, both were transferred to the 6th Air Regiment in Prague. However, these engines did not stand out for their reliability, therefore, the type was not put into production."