After a decade of testing, propylene rocket fuel may be ready for prime time
Vector has received a patent for its liquid oxygen-propylene rocket engine.
In May, Vector launched a full-scale prototype of the Vector-R rocket.
For a long time Rocket Propellant-1, or RP-1, reigned supreme as the fuel of choice for the first stage of rockets. This highly refined form of kerosene, which was derived from jet fuel, powered the Saturn, Delta, Atlas, Soyuz rockets throughout the 20th century. It even served as fuel for modern rockets like the Falcon 9.
RP-1 has the benefit of being dense, which means a lot of fuel can be packed into a relatively small tank. However, RP-1 isn't the most efficient fuel, a measurement known as specific impulse. Liquid hydrogen, by contrast, has a really high specific impulse. But because it is not at all dense, it can't efficiently be used as a first stage fuel.
This is one reason why a number of major new rocket engines developed during the last decade, including SpaceX's Raptor and Blue Origin's BE-4 engines, have been designed to use methane as a fuel. It represents a compromise between RP-1 and hydrogen—not quite as dense as the former, and with not quite as high a specific impulse as the latter. Methane is also useful if you want to go to Mars, because it is relatively abundant in the red planet's thin atmosphere and could be used to refuel an ascent vehicle.
However a long-time rocket scientist named John Garvey believes there is another viable fuel for rockets, propylene, and he has been working with it for more than a decade. After Garvey co-founded Vector in late 2015 along with Jim Cantrell and Eric Besnard, he got a chance to put his propylene fuel into action for a real orbital rocket.
And now, he says, propylene has proven itself. Vector has
received a patent for its liquid oxygen-propylene rocket engine and is nearing the first flight of its orbital Vector-R rocket, which is powered by three of these engines.
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