Rocket Crafters notes safety of hybrid rockets after SpaceX disaster
SpaceFlight Insider spoke with former NASA astronaut and current Rocket Crafters CEO and Chairman Sid Gutierrez about the potential of hybrid rockets in the wake of the Sept. 1, 2016, explosion that consumed a SpaceX Falcon 9, its Amos-6 satellite, and damaged the launch site at Cape Canaveral’s SLC-40.
According to Gutierrez, the propellants used couldn’t be safer. Nitrous oxide (N2O – more commonly known as laughing gas) and acrylonitrile butadiene styrene (ABS) – the same material that Lego bricks are made from. He noted that ABS is transportable on commercial aircraft, a far cry from cryogenic fuels.
SpaceX’s Falcon 9 rocket is fueled by a mixture of RP-1 (highly refined rocket-grade kerosene) and liquid oxygen. The volatile nature of this mixture was made apparent with this month’s accident at SLC-40.
Gutierrez rode fire to orbit twice: first as the pilot of STS-40 on the Space Shuttle Columbia in 1991 and then as the commander of Space Shuttle Endeavour on STS-59 in 1994.
The veteran astronaut noted that safety is one of the foremost rationales behind his company’s use of hybrid rocket engines.
“I wish I could have flown on a hybrid [fueled rocket] instead,” Gutierrez said. “I think that’s the reason that Virgin Galactic selected a hybrid rocket motor for their spaceship.”
For simplicity, Gutierrez broke the main types of rocket motors into three groups – liquid, solid, and hybrid. With liquid-fueled engines, two liquid propellants are combined under high pressure. The fuel and oxidizer within solid-fueled motors are mixed and combined well before the actual launch date. As noted, Rocket Crafters’ Intrepid rocket uses ABS and nitrous oxide.
“Nitrous oxide is much safer and easier to work with than liquid oxygen, and it is much more forgiving in terms of, you know, the temperatures you keep it at and how it operates,” Gutierrez told SpaceFlight Insider.
Gutierrez went on to note that since the fuel was in a solid form whereas the oxidizer is in a liquid form, this makes it more difficult for the two to mix and, therefore, means that an accident is less likely.
“You can, literally, pour the nitrous oxide down the center of the fuel grain and, unless you ignite it, unless you have some source of heat? Nothing will happen,” Gutierrez told SpaceFlight Insider. “The nitrous oxide would pool out the other side and you’d be left with, essentially, a wet Lego brick sitting there.”
According to Gutierrez, in the interest of having their launch vehicle operate as precisely as possible and being able to maintain a high degree of control, the Titusville, Florida-based company uses helium as its header gas on their nitrous oxide system as it is a self-pressurizing gas. Using helium should ensure that the pressure from this system is constant.
Some 30 tests of this design have already been completed (these were carried out in Utah). Since moving to Florida, Rocket Crafters has partnered with the Florida Institute of Technology on the construction of a test stand. This stand will be used to test the 400 lbf (1,880 N) version of the engine that Rocket Crafters is currently working on. If everything goes according to how the company plans, these tests should begin within the next few weeks. There are plans underway to develop a 5,000 lbf (22.2 kN) capable engine.
Although Rocket Crafters has plans to build larger motors, the company has its eyes fixed on the burgeoning CubeSat market. With the first launches of Intrepid currently scheduled to begin in the 2018–2019 time frame.
While there are a number of launch sites at Cape Canaveral that are available, the possibility remains that recently dubbed Launch Complex 39C (a portion of Kennedy Space Center’s historic Launch Complex 39B) might be used to launch Intrepid from.
“We are considering 39C, we walked around there at the pad and noted that there’s this giant hydrogen tank. So, we think that there’s too much around there,” Gutierrez said. “Launches from that site would be driven by the activity of other launch vehicles – and we’re looking at other launch sites due to that.”
“These smallsat operators want to launch on their schedule on the orbits that they want to go to,” Gutierrez told SpaceFlight Insider. “They want to be able to accomplish this at a reasonable price – and you can’t do that with a large launch vehicle like a Falcon 9.”
Rocket Crafters is looking at placing roughly 550 lbs (250 kg) to a 466 mile (750 km) orbit. While this is a far cry from the Falcon 9’s listed capabilities of some 50,265 lbs (22,800 kg) to low-Earth orbit, Rocket Crafters has stated that it is looking into bigger rockets and scaling their technology up.
Video Courtesy of Rocket Crafters, Inc.
Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology, Space.com, The Mars Society and Universe Today.