Rotorcraft Update: It's a gas
In certain oil-rich regions of Russia and its federated republics, natural gas is so abundant that it is treated as a waste product of the crude-oil extraction process. Anxious to cash in on whatever technological opportunities that beckoned, engineers from the Mil design bureau developed a variant of the Mi-8 helicopter that used natural gas as a fuel. The prototype rotorcraft was a one-off proof-of-concept helicopter, one that proved surprisingly successful in burning this relatively inexpensive, very clean fuel. Now work has begin on a follow-up helicopter, again to be based on the Mi-8 airframe and dubbed, in Russian, the “gazolet” (for “gascraft”).
The program will be a cooperation between Mil and Interavigaz, a natural gas company based in Zelinograd, Russia. The new helicopter would be capable of consuming a variety of fuels, including liquefied natural gas, jet-A and a mixture of both in any ratio. Economical ways to contain and transport natural gas–which has a far higher volume per given unit of energy than fuels that remain liquid at sea-level pressure–aboard the helicopter have to be worked out. On the previous prototype the gas was contained in large externally mounted tanks. No deadline for first flight has yet been set.