The article is devoted to the achievements of the famous scientist Friedrich Zander who graduated from the Riga Polytechnical Institute and worked in the field of aviation and rocket building. Zander’s ideas in relation to spacecraft gravity-assisted manoeuvring, the way of moving in space under the effect of solar radiation pressure forces, elliptic trajectory, where the start planet and target tangents are situated on the same plane, etc., trigger modern professionals’ interest. The methodologies for calculating liquid-propellant rocket engines developed by Zander marked a starting point in their further development and subsequent formation of the theory of engines. The ideas contained in Zander's spaceship-aeroplane project are also very important. Among the most important ideas are the proposal to use multistage rockets for flying in space; the idea of an aircraft shaped (i.e. vehicles using the aerodynamic characteristic) spacecraft with "aircraft" take-off and landing. Zander proposed to use the most efficient types of engines for each specific segment of flight: in the lower layers of the Earth's atmosphere – engines designed to fly in the air; in the upper layers – liquid-propellant rocket engines; in open space – solar radiation pressure forces. His practical works on jet and rocket engines as well as on the first Soviet rocket GIRD-Х, which used only liquid propellants, are no less important and significant.