|Sikorsky S-26 Type D-1 & D-2|
|Designer||Igor I. Sikorsky|
|First flight||late 1915|
|Number built||2 |
|Developed from||Sikorsky S-22|
Two redesigned, smaller bombers powered by four Sunbeam engines were produced in the Sikorsky S-26 Type D1 and D2 Il'ya Muromets. The D-1 model was scrapped in 1916 but the D-2 was accepted and sent to the front in 1916, but the type was dropped in favor of concentrating on the Type Gs.
The D bombers used only three crew and used a top-to-bottom glassed-in fuselage reminiscent of many WWII bombers. 
For more information, see Wikipedia:Sikorsky Ilya Muromets.
- Durkota, p.324.