The United Launch Alliance has formally announced its new “Vulcan” rocket design, after learning two important lessons. The first is not to rely on foreign rocket engine technology, after Russian space officials refused to allow the RD-180 rocket engine to be used on military flights and then the US Congress weighed in also banning its use; the second, that its rockets simply had to be cheaper to compete with upstart SpaceX’s Falcon 9 series, with its, reusable first stage.
The “Vulcan”, named in a recent competition (after the Roman God of fire and the “Star Trek” planet/race), will use new methane burning engine technologies. It harks back to a reusable engine concept once considered for the Apollo era Saturn V.
The Vulcan rocket will use two stages. The first stage will use two reusable 550,000lb ( 2,400 kN) Sea Level thrust LOx (liquid Oxygen)/Liquid Methane-burning BE-4 rocket engines currently being developed by Blue Origin led by Amazon billionaire Jeff Bezos. However, unlike the reusable first stage concept being developed by Blue Origin or its competitor Space X (the pair are at loggerheads over a patent for the technique), ULA has reasoned that reusing just the first stage engines in a pod would be more cost effective and mass efficient than trying to recover the entire stage. To this will be added a cryogenic upper stage and up to six solid rocket boosters for each launch depending on payload mass.
Although initially the venerable LOx/Liquid Hydrogen powered Centaur stage will be used as the Vulcan’s second stage, a new multi-use in-orbit advanced LOx/Hydrogen upper stage, dubbed Advanced Cryogenic Evolved Stage (ACES), is being developed using a new internal combustion driven pressurisation, thruster and power generation system.
Most revolutionary, however, is the first stage engine recovery process. It is a complicated one that relies on hypersonic inflatable thermal protection, parachutes/parafoils and aircraft/helicopter snagging. However, if successful, the process could cut 65% of the launch costs of the launch vehicle. Such a system was once proposed for later versions of the Saturn V rocket – albeit using a somewhat suspect water splashdown parachute/airbag recovery technique (mixing hot engines and salt water would have been damaging). A similar technique was envisaged for salvaging engines from a Space Shuttle-derived heavy lift launch vehicle.
Post Script: In one way, ULA chose wisely to include Vulcan as a late entrant into the naming competition, compared with some of its other duff competitors. However, Vulcan has been used before in aerospace, not only for Avro’s excellent delta-winged Cold War bomber, but also in its Vulkan spelling for a Soviet rocket. It was to be a super-powerful derivative of the Energia heavy-lift rocket – the Soviet Union’s most powerful. In the end the money ran out before it could be built. So that is not a problem except that that billionaire, Paul Allen, also owns a firm called Vulcan Aerospace, which is intent on launching rockets from the Stratolaunch aircraft called, you guessed it: Vulcan. They own the legal title to the name apparently. That leaves Zeus – the runner up name in the ULA competition – or just possibly a new entrant for the Star Trek buffs: Romulan. We wonder if the new ULA rocket will have a “cloaking device”?