In 1975, a German aerospace engineer named Lutz Kayser founded Orbital Transport und Raketen AG (OTRAG) with a heresy: rockets did not need to be exquisite. They needed to be cheap, identical, and mass-produced. His plan was to build orbital launch vehicles the way Henry Ford built Model Ts — by bolting together hundreds of identical low-pressure pipes.

The core unit, called a Common Rocket Propulsion Unit (CRPU), was a 27-inch diameter, 40-foot-long commercial steel tube. Inside: kerosene and nitric acid — storable, cheap, requiring no cryogenic infrastructure. The engine was a pressure-fed ablative nozzle costing under $1,000 to manufacture. No turbopumps. No exotic alloys. A single CRPU produced about 6,000 pounds of thrust. To build a heavy-lift booster, you simply bolted hundreds of CRPUs together in a bundle and lit them simultaneously.

Kayser projected launch costs of $500/kg to LEO in 1978 dollars — roughly $2,300/kg today. For context, the Space Shuttle came in at $54,000/kg. SpaceX's Falcon 9 hit $2,700/kg forty-five years later.

OTRAG needed a launch site near the equator. West Germany refused. Kayser cut a deal with Mobutu Sese Seko of Zaire, leasing a Belgium-sized chunk of Shaba Province. Between 1977 and 1979, OTRAG conducted four successful test flights from Zaire — the first private company in history to launch its own rocket from its own spaceport. The fourth flight reached 20 km altitude and demonstrated multi-CRPU thrust vectoring by differential throttling — the same technique SpaceX would later use on Falcon Heavy.

Then the diplomatic knives came out. The Soviet Union accused OTRAG of building an IRBM in Africa. France lobbied against it to protect Ariane. The United States quietly pressured Bonn over MTCR concerns. In 1979, Mobutu — under Franco-Soviet pressure — expelled OTRAG. Kayser moved to Libya in 1980, where Gaddafi funded further tests until 1987, when West Germany invoked export control law and forced the program shut. The hardware was dismantled. Kayser's patents lapsed. He died in 2017 having watched SpaceX independently reinvent his throttle-controlled cluster architecture.

Why it works now:

• Additive manufacturing can produce pressure-fed ablative engines at $200/unit — Kayser assumed $1,000.
• Modern avionics solve the "hundreds of engines firing in sync" problem that doomed the Soviet N-1. Falcon Heavy runs 27 Merlins; Starship Super Heavy runs 33 Raptors. OTRAG's math was right — the electronics just didn't exist.
• Storable propellants (green hypergolics like LMP-103S) eliminate the toxicity objections against nitric acid.
• Equatorial launch politics have relaxed: Alcântara (Brazil), Kourou, and Andøya all court commercial customers.
• The economic case Kayser made in 1975 — that the cost driver is manufacturing complexity, not payload sophistication — is now industry orthodoxy. Rocket Lab's Rutherford engine, Firefly's Reaver, and Stoke Space's approach are all downstream of it.

A modern OTRAG-architecture booster — call it a bundle of 200 3D-printed methane-oxygen pressure-fed CRPUs — could realistically hit sub-$1,000/kg for medium-lift payloads with a development budget under $300 million. That's the price of a mid-range biotech Series B.