In 1969 Dietrich Koelle proposed his BETA III design. This was to deliver 20 tonnes to orbit with a launch mass of 600 tonnes. In 1996 and 1998 he updated the design for use as an ISS resupply vehicle in place of the shuttle, and as a space tourism vehicle for 100 passengers.

The BETA III / STV-100 launch vehicle with a 100 passenger cabin had a launch mass of about 780 tonnes. 685 tonnes propellants were required for ascent, leaving a net mass of 75 tonnes, including 12.5 tonnes propellants for manoeuvring, reserves and landing. The total cabin mass was estimated to be 11.6 tonnes, plus 8.4 tonnes for the passengers and crew. The cargo capability of the unmanned version would be 17 tonnes.

The cabin design featured a 6.5 m diameter pressure vessel with three levels, each one equipped with 34 seats in a circular arrangement, providing an optimum viewing opportunity for each passenger. In the centre was a relatively large cylindrical zero-g exercise volume. Ample space for galleys, toilets, storage boxes and equipment was provided. On top of the passenger cabin was a cockpit with seats for the Commander and the Tourist Guide. Although the mission would be performed completely automatically a chief pilot was felt to be required for psychological reasons. In addition, three attendants would take care of the passengers. The seats would be inclined almost horizontally for the launch and landing phases. The cabin diameter is about 6.5 m.

The BETA STV-100 Mass Summary was as follows:

• Launch Mass ( GLOW) 780 tonnes
• Propellant Mass (ascent) 685 tonnes
• Passenger Cabin (equipped) 11.6 tonnes
• 100 Passengers + 5 Crew 8.4 tonnes
• Vehicle Dry Mass 62.2 tonnes, consisting of:
  • Structure 17.0 tonnes
  • Tanks and Insulation 12.6 tonnes
  • TPS (Thermal protecion) 5.8 tonnes
  • Main engine system 16.8 tonnes
  • OMS/RCS 1.6 tonnes
  • LGS (Landing Gear System) 2.4 tonnes
  • Equipment & Margin 6.0 tonnes
• On-board propellants 12.8 tonnes
• OMS/RCS propellants 1.5 tonnes
• Residuals, reserve 2.8 tonnes
• Landing propellants 8.5 tonnes
• Vehicle NET MASS 75.0 tonnes
• Net Mass Fraction (NMF) 10.9 %

The total thrust level at take-off was 10700 kN, providing a launch acceleration of 1.4 g. which Koelle had found to be optimum for SSTO vehicles. 12 to 24 engines would be arranged around plug nozzle with a centre engine to minimize base drag at launch and to perform orbital manoeuvres (injection, retro impulses). The average specific impulse including the plug nozzle effect at ascent was assumed to be 428 sec, with 350 sec at launch and 455 s in vacuum.

During ascent the thrust level was reduced by throttling and/or cutting off selected engines in order to achieve the maximum performance and limit the thrust acceleration to some 3.5 g. Use of an optimum throttling programme indicated a remarkable reduction of velocity losses and the total required velocity.

In fact the design greatly resembled the first stage of Russia's N1 moon rocket.

Manufacturer: MBB. LEO Payload: 17,000 kg (37,000 lb). to: 90 km Orbit. at: 6.00 degrees. Liftoff Thrust: 1,070.000 kN (240,540 lbf). Total Mass: 780,000 kg (1,710,000 lb). Development Cost $: 2,000.000 million. in: 1969 average dollars. Launch Price $: 2.000 million. in: 1969 price dollars. Cost comments: Specific cost believed to be below $100/kg.