instruments were 'home made,' designed for the 'Grand.' They were particularly necessary because of the enclosed cabin." Operational history After the Russky Vityaz's first test flights between 10 and 27 May 1913 O.S., it was established that a passenger could even walk around the cabins without causing any problems to stability. The aircraft left the ground after a takeoff run. After the first test flight with his co-pilot and mechanic on board, Sikorsky noted, "in order to keep the engines close to the center line, they were mounted in two tandem groups on both sides of the fuselage. This was done chiefly to protect the plane from the danger of unsymmetrical thrust if one of the outer engines should stop." However, this configuration resulted in poor take-off and climb performance, due to propeller inefficiency. In June 1913, the airplane was altered so that the two rear engines were remounted outboard on the leading edges, "...transforming the installation into a four-in-line. The change resulted in a substantially improved take-off and a slightly better climb The rudders were still effective enough to hold the plane against two engines stopped on one side." On 2 August Sikorsky flew the "Grand" for one hour and fifty-four minutes with eight persons on board. Sikorsky made a total of fifty-three flights with the "Grand" before it was damaged by falling debris from a different aircraft. Sikorsky's aspirations for the Russky Vityaz proved to be short-lived. While parked on the runway on 23 June 1913, the aircraft was crushed by an engine that fell off a single-seat Morane-Saulnier aircraft during a landing. Sikorsky decided not to repair the seriously damaged Russky Vityaz and began working on his next brainchild — the Ilya Muromets. Specifications (Russky Vityaz) References External links Detailed description with plan drawings. Basically a translation of the German article "Der Doppeldecker von Sykorsky" below. World’s first four-engine airplane Russky Vityaz: the Era of Sykorsky Vladimir Bykov, Авиалайнеры мира ("Airliners of the World") – Сикорский С-21 Русский Витязь (Sikorsky S-21 Russky Vityaz) (in Russian) 1910s Russian experimental aircraft Aircraft first flown in 1913 Biplanes Four-engined piston aircraft Four-engined tractor aircraft RBVZ aircraft Russky Vityaz