Engine running on new fuel for Soyuz-2 tested
Instead of kerosene, naphthyl fuel was used for the first time in November 2017 - at the start of Soyuz-2 from Vostochny, then they launched the third stage of the rocket. Launches with the use of naphthyl in the first and second steps of the "Union" have not been carried out before.
Replacing kerosene with naphthyl is part of the Soyuz-2 modernization program for launches from Vostochny. According to the agency, the first and second stages of all Soyuz launch vehicles have been equipped with RD-107 / RD-108 engines for 60 years. All this time, the engines run on kerosene with oxygen as an oxidizing agent.
Naphthyl is an environmentally friendly type of hydrocarbon fuel using polymer additives. Its use will increase the payload of three-stage medium-class launch vehicles launched into orbits of all types.
It was previously reported that naphthyl "is not a mixture of" hydrogen, oxygen and kerosene, "but hydrocarbon fuel with the smell of well-refined kerosene. Naphthyl (RG-1) has been manufactured and used as fuel for launches of Zenit type rockets since 1985." So wrote the deputy head of Roscosmos, Alexander Lopatin, in a reply to RIA Novosti in 2013. Lopatin also noted that the T-1 naphthyl from kerosene T-1, currently used in the Soyuz type LV, is distinguished by a relatively lower content of aromatic compounds and a large content of naphthenes. Physicochemical and toxic properties of kerosene T-1 and naphthyl (RG-1) are approximately the same.
Then the reason for the correspondence was the dissatisfaction of the residents of the Amur Region with the construction of the Vostochny cosmodrome and the likely use of highly toxic heptyl on launch vehicles launched from it.