The wind tunnel tests of the SLON, the future successor of the Antonov An-124 in the VKS (Russian Aerospace Forces) began on a scale model at TsAGI (Central Aerohydrodynamic Institute), which directs the development of the aircraft under a contract with the Russian Ministry of Industry and Trade. According to the TsAGI, the SLON model, probably made in a 1/50th scale, is made of aluminum and steel, weighs 120 kg and has a length of 1.64 m and a wingspan of 1.75 m. The tests began three months late, which the institute explained by the complexity of the three-dimensional realization of the very sophisticated wing of the aircraft, which is supposed to ensure high aerodynamic qualities at cruising speeds. TsAGI plans to complete the first tests in the T-106 wind tunnel by the end of the year and to evaluate the aerodynamic performance at take-off and landing of the aircraft in the T-106 and T-102 wind tunnels in 2020.

TsAGI also commented the SLON will be able to take off from 3,000 meter runways. Even though the SLON is expected to supersede the Antonov An-124, its maximum payload (180 tonnes vs. 120) is almost equivalent to that of the An-225 Mriya, of which only one unit was built in 1985. The aircraft will be powered by four Aviadvigatel PD-35 two-shaft turbofan engines, together producing 140 tonnes of take-off thrust. Again, the total thrust provided is quite close to that of the An-225.

However, the shorter length and smaller in size of the SLON in comparison with the An-225 make the aircraft lighter, with 8 tonnes less than the Mriya thanks to the use of modern materials.