Rockets of Today

RFA — Germany

OHB is a company based in Bremen, Germany, which is up north near the Netherlands. They began back in the fifties as marine outfitters, then switched to aerospace in the eighties. They have 3000 employees, and subsidiaries all over Europe. One of them is called MT Aerospace. It’s in Augsburg, down south near Austria. They started working on a rocket, and the parent company split that effort into a new subsidiary: Rocket Factory Augsburg. It may be one of the better staffed and funded attempts at a commercial smallsat launcher.

So what are they coming up with? A small 3D-printed kerosene engine, a booster using nine of them, and a second stage with a large bell version of it — a very familiar pattern by now. But there are a couple of differences. One is that they are going for a staged combustion engine right from the start, without practicing on a gas generator first. Another is that, like SpaceX’s gigantic Starship, they are making their cryogenic tanks out of stainless steel, with common bulkheads. I’m told they went with steel before SpaceX did, but can’t confirm that yet. They’re also using carbon fiber, but only for secondary structural parts like the interstage.

They claim their engine is now ready to run at full power and duration, without having actually tried it. This is not reassuring. But you gotta respect that they’ve built the first European staged-combustion engine, and gotten it to run for more than a few seconds.

They also have a kick stage, which is not optional. I guess it’s the only payload platform they offer. It supposedly uses “green” propellant, but details are not clear.

They keep talking about how their manufacturing techniques are like those used to make automobile parts. Their goal is to mass produce rockets like cars. Like Astra, their business plan looks like it will depend on volume to make a profit. Wherher the market will provide such volume to them, or anyone, is not clear. They will launch from Norway, which means polar orbits only, or geostationary transfer with a bit of inefficiency.

They say they’re going to go for reuse of the first stage, but there is no visible sign of this in what they’ve shown so far, nor have they offered any details. It looks like they’re going to get it working expendably first, then try for reuse later, which is sensible.

In early 2022, about a year before planned launch, they asked the public to name their engine.  I would vote for calling it “Stage Mother”, but they went with “Helix”.

Honestly, their local rivals Isar may be closer to getting off the ground, but I wrote RFA up first just for being more innovative and interesting. Isar and RFA may soon end up having to share the same launch facility at the Norwegian island of Andøya. Isar’s Spectrum rocket is jsut about the same size and shape as RFA’s, with the usual nine engines on the bottom which, as far as I can guess from their promotional guff, are conventional gas generators. (Why don’t we see rockets with seven engines instead of nine? That would probably be a better balance between lower and upper stage thrust needs. The only seven engine design upcoming is the New Glenn, which does not use the same engine, or even the same fuel, on the second stage.) The one interesting thing Isar has done is to choose propane as their fuel, on the grounds that it offers the highest “density specific impulse”, which I guess means exhaust momentum per unit volume, or something like that.

RFA 1: mass unknown, diam 2.00 m, thrust unknown, imp unknown, type ZOk, payload 1.6 t, cost unknown.