Methods comparison of returning the first stage of the reusable rocket
The article considers in detail the basic types of the first stages returning, such as returning along the ballistic trajectory to the launching site or another prepared site through the reusable engines, operating on the onboard fuel reserves (vertical landing); landing, employing parachute-jet systems; the first stage returning employing the aerodynamic quality, lifting wings and a turbojet engine. The main disadvantages of each method of the first stages returning were considered in detail. Comparison of the method of the first stage returning employing the aerodynamic quality, lifting wings and a turbojet engine with the method of returning along the ballistic trajectory through the reusable engines operating on the onboard fuel reserves was performed. Both stages had equal remaining mass of m<sub>r</sub> = 0.38; specific thrust parameters of r<sub>sp</sub> = 300 s for the turbojet engine; flight range of L = 300 km; and initial return speed of u<sub>s1</sub> = 2000 m/s. The first stage returning method employing the aerodynamic quality, lifting wings and a turbojet engine requires lower relative mass of the means of returning α<sub>r</sub> = 0.27, compared to the method of returning by the vertical landing, where α<sub>r</sub> = 0.51. In addition, usage of the first stage, returned to the launching site over the ballistic trajectory, reduces the payload mass m<sub>p.l.</sub> by 23% compared to the single-shot rocket because a part of the fuel remains for returning to the prepared site. In consequence of this, the rocket carrier does not carry all payload. With employing the method of the first stage returning employing the aerodynamic quality, lifting wings and a turbojet engine the payload reduced only by 7% compared to the single-shot rocket.