Rocket Lab’s Rutherford engine qualified for flight

Rae Botsford End

On Monday, March 21, aerospace startup Rocket Lab announced that its Rutherford engine, named for the New Zealand-born British physicist, has finally been qualified for flight.

After more than two years of rigorous testing, more than 200 engine hot fires as part of the qualification program, and many more engine test fires before the program began, the 5,000 lbf (22.24 kN) Rutherford engine is now qualified for flight on the company’s currently-in-progress Electron launch vehicle.

It’s the first oxygen/hydrocarbon engine to have all of its major components made using additive manufacturing – that is, 3-D printing – “including the regeneratively cooled thrust chamber, injector, pumps, and main propellant valves,” according to the website.

The engine also has an unusual turbopump, which uses brushless DC motors and high-performance lithium polymer batteries instead of the gas turbines typically used in turbopumps. The design is, therefore, simpler thermodynamically, and it can be modified with software as needed.

Furthermore, like the rest of the Electron, the whole engine was designed in-house.

“Rutherford started as a clean sheet of paper. Without the burden of heritage engines, we were able to make the most of today’s most advanced technologies in ways not attempted before,” said Lachlan Matchett, Rocket Lab’s propulsion lead, in the press release.

Nine Rutherford engines are used to power the Electron’s first stage, and the second stage of the rocket bears a Rutherford variant that is made for the vacuum of space.

The engine was designed specifically for the Electron, a vehicle tailored for taking small satellites to low-Earth orbit (LEO) as inexpensively as possible. The rocket is capable of delivering a 150 kg payload to a 500 km Sun-synchronous orbit, precisely what is needed by the constellation-satellite market.

“We are seeing the vehicle come together, and are looking to move to manufacturing at quantity for both our test and commercial flights,” said Peter Beck, CEO of Rocket Lab.

“At quantity” is a subtle reference to the sheer frequency of launches Beck hopes to achieve with the Electron. The company’s goal is high-frequency, low-cost launches, making it easier for companies to put satellites in the sky. It’s an appealing notion for many commercial ventures – by last spring, Rocket Lab had already secured commitments for the first 30 launches of the Electron. Between the company’s suborbital flight experience and the Rutherford test fires that had already been done, the lack of an actual Electron test flight evidently became less important. Recent customers include NASA and Moon Express, as well as Spire, who signed on last month for 12 launches, according to TechCrunch.

In the past year, however, the target date for the first launch has been significantly pushed back. In May 2015, Beck had expected the first Electron launch would occur by December of last year. Now, the target is mid-2016.

Part of the challenge for Rocket Lab is that the company did not decide to build just a rocket, but also its own launch range in New Zealand. Surrounded by ocean and unburdened by the kind of air traffic common in the U.S., Beck’s home country is thought to be a more viable option for the desired launch frequency. Above all, the goal is to make space accessible.

Beck formed Rocket Lab in 2007, and the company is now a U.S. company with a New Zealand subsidiary.

Video courtesy of Rocket Lab