United Kingdom-based launch company Orbex says it has raised an additional $24 million in venture capital funding as it continues development of its small satellite launcher. This booster is planned to be similar in size and performance to Rocket Lab’s Electron vehicle.
Orbex CEO Chris Larmour said this brings the total amount of money raised by the company to $69 million. It presently has 55 employees, but Larmour said the plan is to expand to around 90 by the middle of 2021 with this new round of funding. This staffing level, he said, should be enough employees to reach orbit with.
“We’re very focused on being capital efficient, which is another word for cheap,” Larmour said in an interview. “We’re raising money as we need it, and not too much, and not too aggressively. This is quite adequate for what we need to do.”
Founded in 2016, Orbex is developing its “Prime” rocket to lift as much as 200kg to low-Earth orbit, and it intends to launch this booster from the as-yet undeveloped Sutherland launch site in northern Scotland. The rocket’s name was chosen to put the emphasis on the rocket’s customers—small satellite operators seeking a dedicated launch into space.
“We were trying to communicate to our customers, who are these CubeSat customers, that they were the prime customer, not the secondary payload,” Larmour said. “That’s the reason it’s called Prime.” The company has signed launch contracts with six customers.
Propane as rocket fuel
Larmour said one of the fundamental design problems for a small rocket is that surface-to-area ratios become really punishing, making it difficult to design an efficient and economically viable booster. This drove the company’s choice of propellant: biologically derived propane, which remains a liquid even when chilled down to the same temperature as liquid oxygen.
The company’s engineers realized they could reduce the mass of tanks and other structures by embedding the propane fuel tank inside the liquid oxygen tank. They’ve ended up with a co-axial tank design, and Larmour said this decision has shaved 30 percent off the total structural mass of the vehicle. “That’s a pretty big advantage when you’re launching 150 kilos,” he said.
Larmour also said Orbex has a plan to reuse the rocket’s first stage, without using parachutes or helicopters like Rocket Lab has done with its Electron vehicle. For now, however, he does not want to talk about this publicly.
The Prime rocket will have six engines on its first stage and one on its second. The first stage engines have a thrust of nearly 8,000 pounds of force, or about 30 percent more than the Rutherford engines that power Electron. Larmour said the company has been testing its engine technology since 2017 and performed hundreds of tests. However, he declined to say when the complete engine might be ready to perform a full-duration test firing.
The company is targeting 2022 for its first launch, but Larmour admitted there may be some wiggle room in that date. “There will always be something that comes along that delays it, so the launch will probably drift from that, but that’s the target at the moment,” he said.
Orbex is among several private companies racing to develop small launch vehicles in Europe. Asked about this competition, Larmour said he’s most closely tracking German companies such as Isar Aerospace, Rocket Factory Augsburg, and HyImpulse; Spanish startup PLD Space; and another British company, Skyrora.