The Air Force on Feb. 29 awarded the final other transaction agreements (OTA) to Aerojet Rocketdyne [AJRD] and United Launch Alliance (ULA) for shared public-private investments in rocket propulsion system (RPS) prototypes, according to a service statement.

The award to Aerojet Rocketdyne is for development of the AR1 rocket propulsion system. The initial government investment is $115 million. The other award, to ULA, is for the development of the Vulcan/BE-4 and ACES rocket propulsion systems. The initial government investment for ULA is $47 million with $46 million for the Vulcan/BE-4 effort and $800,000 for the ACES effort.

Two OTAs were previously awarded to Space Exploration Technologies Corp. (SpaceX) and Orbital ATK [OA] on Jan. 13. Blue Origin is privately funding the BE-4 engine with ULA investment. ULA said Feb. 29 BE-4 development is on schedule to achieve qualification for flight in 2017 to support the first Vulcan flight in 2019.

Aerojet Rocketdyne is also adding Dynetics as a key team member for AR1 engine development. Under a teaming agreement, Dynetics will supply elements of the AR1 engine’s main propulsion system, the ignition system and ground support equipment as well as provide analysis support to critical engine decisions, according to an Aerojet Rocketdyne statement.

The OTA awards are part of an Air Force plan to transition off the Russian-supplied RD-180 propulsion system used on the Atlas V rocket by entering into innovative partnerships with industry with the ultimate goal to competitively procure launch services in a domestic launch market.

These RPS investments, which will initially occur over the course of 12-18 months, will build the foundation for future investments in industry launch system solutions and launch service commitments from invested companies. Concurrently, the Air Force will continue to award launch services contracts to certified providers who demonstrate the capability to design, produce, qualify and deliver launch systems and provide the mission assurance support required to deliver national security space satellites to orbit.

The Air Force has awarded a portfolio of investments in industry’s RPS solutions, which vary depending on what industry proposed. The solicitation allowed companies to submit proposals for the development of a RPS prototype, which ranged from full development of a new RPS, modifications to an existing RPS to meet NSS requirements, smaller projects to address high risk items for an RPS or subcomponents or activities required to test or qualify a new or existing RPS to meet national security launch requirements.

Therefore, the value of each agreement varies depending on what was proposed. At least one third of the total cost of the RPS prototype project will be paid out of funds provided by parties to the transactions other than the federal government.

ULA is a joint venture of Lockheed Martin [LMT] and Boeing [BA].