Rockets of Today

PRIME — Britain

Britain, though notorious for being the only government to achieve orbit and then cancel its space program, is not without a substantial aerospace industry, and it’s starting to produce its share of New Space startup companies. One of them is called Orbex, and their promised rocket is rather interesting in that it burns a fuel that nobody else uses: cryogenic propane. (Since they announced this, Isar has also selected propane.) And one thing they like to emphasize is that they source it from people who produce it as a biofuel, so the whole rocket is almost carbon-neutral. Propane doesn’t burn as clean as methane, but it’s pretty close. One advantage of propane is that it can be stored as a liquid at room temperature without having to use a lot of pressure, yet it can also be chilled to the temperature of liquid oxygen without freezing. In the latter state it gains density. Their stages actually put the propane tank inside the lox tank. Maybe the intent is to make sure that if something boils off, it will be the oxygen. The tanks are carbon composite.

The engine is 3D-printed, as is becoming commonplace nowadays. They claimed it’s the largest 3D-printed engine in the world, though that record probably won’t last for very long, if it’s even still true now. They’ll use the same engine on the first and second stages, with a large bell on the upper one. The lower stage will have six engines. They have not clarified what power cycle the engine uses, though they have stated that it’s not pressure-fed — it does have a turbopump of some kind. The engines are being developed in Denmark, while the rest of the rocket is made in Scotland.

They also claim that the first stage will be reusable. No details have been given about how it will land or be recovered, or when they plan to try to get that process to work. I do think there’s a bright future ahead for whoever can be the first to regularly land and reuse a small orbital booster, so it’s nice to see a few people saying they’re going to make the effort at it. A couple of others going for it are the Miura from Spain’s PLD Space, and the New Line 1 from China’s LinkSpace. Rocket Labs is also planning to attempt it with the Electron, though the rocket was not originally designed for reuse. It sure would be nice to see a couple of them succeed, and start making solid fuel rockets obsolete. That could do a lot to reduce the environmental impact of satellite launches, along with the cost.

One place they might launch is from a complex in the Azores, similar to the one in the Canaries that the Spanish companies are planning to use. But they are also working on constructing a small launch complex on the north coast of Scotland, at a place called A’Mhòine. It looks like that would be used for polar or sun-synchronous orbits only... but the plan could be in trouble because the location is environmentally sensitive. If built, the Scottish site would probably also be used by any other British companies that produce a small launcher, such as Skyrora. (Well, they’re partly British, being divided between Scotland and Ukraine.) That company does not yet have its own entry. They were apparently nostalgic for Britain’s Black Arrow program and aimed to revive its technology, including the use of peroxide instead of lox, though this approach is rather primitive. But they are using modern techniques such as 3D printing, and their engine’s power cycle is a unique hybrid between archaic and modern — they power turbines by decomposing peroxide, like a Soyuz, but it then drains into the main chamber as in a staged-combustion design. They have yet to fly anything above ten kilometers.

The other interesting thing Skyrora has done is that they are trying out a kerosene substitute made from waste plastic, which they call “ecosene”. They have started testing the fuel in a small upper-stage engine.

Orbex, meanwhile, has only shown the public nonworking prototypes. Before 2022 they only had a second stage to show, but now they have a full stack put together... supposedly. This apparently put them in the lead relative to other European startups such as RFA, but then their CEO Chris Larmour resigned in April 2023 with no named replacement, with statements indicating that the company might be changing strategies. This left many industry watchers wondeing if Orbex had ever been anywhere near ready to put anything into service. Skyrora is now widely being taken more seriously than Orbex is, with terms like “smoke and mirrors” sometimes being heard in discussions of Orbex. But this didn’t stop Orbex from breaking ground on constructing their launch pad at the Scottish spaceport, which is confusingly called Sutherland despite being about as far north as you can go in Great Britain.

Prime: mass 18 t, diam 1.3 m, thrust unknown, imp unknown, type unknown (propane), payload 0.15t (0.8% — unknown if reusable mode), cost unknown.