SKYRORA — Britain

I disregarded Skyrora for a long time, feeling that they weren’t a very serious contender, and that their Scottish neighbors Orbex looked more legitimate. But the consensus is tilting a lot more toward Skyrora now, as Orbex shows little evidence of any concrete progress toward an orbital launch. Skyrora has at least gotten suborbital launches off the ground.

One reason why I disregarded them at first was because the founder, Volodimir Levykin, seemed to be just another techbro who wanted a space hobby, and the hobbyhorse he chose to ride was the idea of (a) reviving Britain’s old Black Arrow launcher that the government cancelled in 1971 after it launched a single satellite named Prospero, and (b) the retrieval of that satellite so it could be put on display. Both ideas seemed unhelpful, as the Black Arrow technology would not be competitive today. (Levykin did succeed in getting the wreck of the Black Arrow booster returned to Britain from its crash site in the Outback, which is harmless enough.) In its early days Skyrora used to have its operations divided between Scotland and Levykin’s birth country, Ukraine, but of course operating there is no longer feasible.

The reason why I don’t see value in reviving the technology of the Black Arrow is that it burned its kerosene fuel with hydrogen peroxide instead of liquid oxygen. This lowers the engine performance significantly, as it takes about 25% greater propellant mass to produce the same energy, and the only benefit is to make building the rocket easier and cheaper for those whose capabilities are less advanced. Since advanced capabilities are everywhere nowadays, with even relatively small companies developing staged-combustion engines more advanced than any of Black Arrow’s competitors — so much so that in those days even NASA regarded such technology as an impossible dream — I figured that a company using it today would seem to have earned a place at the kids’ table next to wannabes like ARCA.

But the difference in performance is smaller than you might think, as the peroxide exhaust contains more hydrogen, which increases its average velocity, so the difference in specific impulse is only about a 13% advantage for lox. This makes the kerosene-peroxide fuel combination competitive with storable hypergolic propellants such as unsymmetric dymethylhydrazine, while also being nontoxic. So it’s entirely usable for orbital launches, though whether the cost savings can pay off in today’s market remains an open question.

Skyrora built a two-stage sounding rocket called the Skylark L, with a simple pressure-fed engine. They sent it up in 2022 and it quickly failed, reaching an altitude of only 300 meters. They have not tried it again, which is concerning. They appear to be concentrating on the engine for their orbital rocket, which they call the Skyrora XL. That “Skyforce-2” engine will, they say, use “advanced turbopump techniques”, and I have no idea which techniques they might be counting as advanced. Like many modern engine builders, they are using 3D printing to construct it. The booster will use nine engines, as is now commonplace, the second stage will use a single one, and the third stage will have a smaller re-ignitable engine which sounds like it’s probably pressure-fed. They call that the “LEO engine”. They are also talking up the idea of turning the third stage into a “space tug”, though that name is probably overbold, since it sounds like it’s just a basic satellite platform with some ability to maneuver between orbits.

For fuel they aren’t going to use conventional RP-1 kerosene, but instead a special formula they’ve come up with which they call “Ecosene”, which is a renewable fuel made from recycled plastic. This helps get them favorable government support, and fulfills another of Levykin’s personal goals, which is to make spaceflight more carbon-neutral.

They intend to launch from SaxaVord spaceport on the Scottish island of Unst — a site which has also attracted competitors such as Rocket Factory Augsburg, ABL before they gave up, HyImpulse *, and Orbex — the latter having backed off from the plan to build their own spaceport on the A’ Mhòine peninsula. Other spaceports are also being considered, such as one that might be built in Nova Scotia.

(* HyImpulse is a German company that wants to reach orbit using hybrid rocket engines. This is a technology that’s usually primitive enough to make peroxide look good, which they claim they can push to a level of performance matching a kerosene-and-lox rocket. I have doubts.)

The Skyrora factory is in Cumbernauld, where Craig Ferguson grew up.

XL: mass unknown, diam unknown, thrust 630 kN, imp unknown, type unknown (kerosene and peroxide), payload ~0.5 t, cost unknown.