At the rim, 96 miniature jets would exhaust the burning propellants (LOX and kerosene) around the rim of the base of the vehicle, which gained the vehicle extra thrust at high altitude – acting as a zero-length truncated aerospike nozzle. A similar system with non-rotating engines was studied for the N1 rocket. That application had a much smaller base area, and did not create the suction effect a larger peripheral engine induces. The Roton engine had a projected vacuum ISP (specific impulse) of ~, which is very high for a LOX/kerosene engine –and a thrust to weight ratio of 150, which is extremely light.