It is possible that in following years Orbital ATK will present new medium rocket as a competition for SpaceX and ULA. Orbital ATK is targeting to take some part from NROL missions market.
On 14 January 2016 Orbital ATK announced about their plans for new EELV rocket; it should not be surprising after US Air Force awarder Orbital ATK with contracts for new solid rocket boosters (Graphite Epoxy Motor-GEM-63XL-You can read more here) and part of upper stage with modified engine (an extendable nozzle for Blue Origin’s BE-3U). Contracts were part of new program which is oriented for supporting American companies developing new rocket propulsion technologies. Thanks due these grants Orbital ATK was able to consider starting new project which will be based partially on technologies developed under US Air Force contracts - on new solid fueled rocket booster and modified upper stage.
New Orbital ATK rocket is basing on assumption that solid rocket engine will be comparable with powerful liquid fueled RD-180. According to Mark Pieczynski from Orbital ATK, solid fueled propulsion which is part of Common Booster Segment should be strong enough and in case heavy payloads, boosters could be equipped in more than one core. Second stage will be powered by Blue Origin BE-3U/EN liquid fueled engine (liquid oxygen/liquid hydrogen) with thrust at 690 kN in vacuum (technical specification of this version of BE-3 was not officially confirmed by Blue Origin, basic version of BE-3 gives around 490 kN of thrust).
Orbital ATK plans are targeted on first’s tests of Common Booster Core on 2017, first static tests of the rocket on 2018 and first operational activity on 2019. GEM-63XL solid booster for new Vulcan rocket by ULA is going strong and is keeping schedule. In case of positive results after tests it will also be considered as replacement for AJ-60A boosters utilized with present ULA rocket, Atlas V. Boosters are also planned as support for new Orbital ATK rocket; this fact combined with basing new rocket on technologies developed for GEM-63XL shows how crucial for Orbital ATK were contracts for developing new rocket propulsion technologies. It also shows that at least two new rockets (Vulcan and new Orbital rocket) will have few common elements - boosters and propulsion of upper stage. Orbital ATK is going to base on this fact their new rocket. They would like to participate in NROL contracts which previously were won by ULA; to win, Orbital is going to offer better price per launch. It should be possible with solid fueled rocket (less expensive maintenance and start costs) basing on solutions sponsored by future customer (which is US Air Force). In this way they will be able to compete with ULA. Their rocket should be less expensive if it will actually be solid fueled rocket with possibility of combining booster cores depending on payload. If it will become liquid fueled its fate could be similar to new Ariane 6, which was also at the beginning solid fuel rocket and after changes its main attribute-low cost became impossible to keep it.