 At this point in time, Russian rocket engines were built with typical aviation piston-engine manufacturing technology, weighing , it could be broken down into discrete forged-steel sections – a conical head with 60 centrifugal injectors, the cylindrical chamber, and the nozzle – joined with bolts and copper gaskets.It was ignited with a nichrome glow plug, later replaced with silicon-carbide and was cooled regeneratively by both propellants, the chamber walls by a spiral flow of incoming fuel (kerosene) and the nozzle section by the flow of oxidizer (Nitric Acid).On 21 June Isaev proposed a new design using compressed air instead of a pump to force propellant to the engine.