Stratolaunch Systems Corporation, a space transportation company founded by Microsoft co-founder Paul G. Allen, has released the latest update about its PGA liquid rocket engine. The engine, named after the billionaire business magnate and philanthropist, is being developed with the help of additive manufacturing and could offer an innovative solution for launching vehicles into space.
Founded in 2011, Stratolaunch Systems is something of an interesting player within the aerospace field. For instance, its mandate is not strictly to develop rockets for commercial launches like many other developers in the industry. Rather, Stratolaunch’s express goal is to enable “convenient, affordable, routine, airline-style access to space” for the purpose of empowering researchers and “problem solvers” to find inspiration and solutions to the Earth’s problems in space.
As the company succinctly states: “Stratolaunch Systems Corporation believes in safeguarding Planet Earth for future generations.”
Much of this effort starts with the company’s PGA Engine, a high performing liquid rocket engine that uses liquid oxygen and liquid hydrogen as propellants. The aim with the rocket is to offer a more affordable price-to-orbit and to enable a “more rapid cadence” than existing rocket launch technology.
Stratolaunch’s propulsion team, which has fully designed the PGA Engine in-house, is currently manufacturing and testing prototype sub scale and full scale hardware for the rocket engine. At this stage, the team says it has completed ignitor development and is undergoing injector testing. Once these tests are completed, the team will prepare to do a full scale preburner test at NASA’s Stennis Space Center. If all goes according to plan, this test will be carried out before the end of the year.
What is particularly exciting to us about the rocket engine is that 85% of its current iteration is made up of 3D printed parts. Like other rocket launch companies, Stratolaunch is leveraging additive manufacturing to not only speed up the design and prototyping phase but also to integrate complex geometries into the engine’s structure which would be impossible with more traditional manufacturing process.
In terms of the engine’s capacity, Stratolaunch says the PGA Engine will be able to produce 200,000 lbf of thrust and will have the highest specific impulse of any rocket engine propellent. This impressive force is largely owed to the fact that the PGA is a hydrogen/oxygen engine. This also means that the only by-product of the engine’s combustion will be water.
The one-of-a-kind rocket engine will reportedly be ideal for both air-launch and in-space propulsion and will be cheaper and more easily reusable than existing non-hydrogen/oxygen powered engines.
When the rocket engine is complete and has successfully undergone an array of tests, Stratolaunch says the air-launch system will use the “world’s largest aircraft as a mobile launch platform” to deploy launch vehicles equipped with satellites.
Among the aircraft the company is exploring for its PGA Engine is the Pegasus rocket manufactured by Northrop Grumman (flight proven); the Medium Launch Vehicle (MLV), an in-development medium-class air-launch vehicle (expected to have its first flight in 2022); the Medium Launch Vehicle Heavy, a variant on the MLV with the capacity to deploy heavier payloads (in early development); and the Space Plane, a reusable aircraft designed for in-orbit applications and cargo return (still in its design study stage).