Firing rockets straight up into the air is an incredibly inefficient way of getting payloads into space, largely due to gravity and the drag caused by the rocket moving through the atmosphere—not to mention the disposable nature of rocket flight.
Imagine flying from New York to San Francisco, and throwing the aircraft away at the end of journey. That’s pretty much how most rocket launches work—except for SpaceX, which is landing its first stage rockets for reuse. That’s why rockets are so expensive.
There are a few solutions to this problem. You can land the rocket and reuse it (like SpaceX), you can float your rocket up on a balloon and launch it (as is the plan of startup Zero2Infinity), or you can fly the rocket up on an aircraft and launch it from altitude.
The latter method is preferred by companies such as operator Stratolaunch Systems Corporation (founded by Microsoft Cofounder Paul Allen) and manufacturer Scaled Composites (founded by mutton-chopped aviation legend Burt Rutan), which have recently been performing engine tests on their humongous Stratolaunch airplane.
The Stratolaunch plane is not only the largest all-composite aircraft in the world, but is also the largest aircraft by wingspan, with wings that measure 385 feet from tip to tip. That’s longer than a football field, just to give you some perspective.
The Stratolaunch plane itself consists of six Pratt & Whitney PW4056 turbofans, each one kicking out 56,750 pounds of force. It will be capable of carrying over half a million pounds of payload, and will be able to fire it’s Orbital ATK-provided rockets into a variety of orbits, including low-Earth orbit, sun synchronous orbit and more.
So, with that kind of force acting on the airframe and wings, you’d expect Scaled Composites to be relying quite heavily on computer-aided engineering programs, right? Right!
Scaled Composites’ software of choice for this task is HyperSizer from Collier Research. HyperSizer is derived from software developed at NASA Langley Research Center, and is designed for the structural analysis of air and space vehicles (it has been used extensively on Orion too).
The software automatically performs design, stress analysis and sizing optimization based on user requirements, and couples with finite element analysis (FEA) software, such Nastran, Abaqus, ANSYS, and OptiStruct, to reduce the weight of structures by 20 percent to 40 percent.
For the Stratolaunch project, engineers at Scaled Composites have been using the results of their HyperSizer analyses to inform the design of their laminates for use in the aircraft’s fuselage and wings, providing stiff and lightweight structures.
“To ensure the most efficient use of materials in an all-composite structure of any size requires effective employment of design and manufacturing optimization tools from the very earliest stages,” said Collier Research President Craig Collier. “HyperSizer software can provide insight into how producible a structure is and whether there might be any manufacturing issues. It can incorporate laminate fabrication preferences in early-stage design thought; ease-of-manufacturing is becoming a major influence with strength design of laminate structures.”
Stratolaunch is scheduled to make its first launch in 2019. But, then, I think we have heard similar claims from Scaled Composites before (*cough* Virgin Galactic *cough*).
So, maybe we should take that delivery date with a tiny grain of salt.
In any case, good luck to them. Cheaper access to space benefits everyone, and the more options we have for getting people and cargo into space, the better!