Stratolaunch Systems, company established by one of the founders of Microsoft, Paul Allen, is reaching next milestone in their project of HTHL launch vehicle.

In huge hangar on Mojave Desert in California potential competitor for WhiteKnightTwo (created by Virgin Galactic owned by Richard Branson) is almost finished. Few days ago on press conference inside Stratolaunch Systems hangar, press representatives were able to see gigantic plane called Stratolauncher finished in 76%. It is only necessary to install engines, landing gear and one tail and Stratolaunch should be ready until the end of 2016, as it was announced in November 2015.

Stratolauncher is part of launch vehicle which is developed by Vulcan Aerospace and its subsidiary Stratolaunch Systems since 2011. Based on large carrier airplane with rocket attached between two fuselages, Stratolaunch system will be able to deliver payload to space with lower cost comparing to conventional rockets and will be more independent from weather conditions; it will be also independent from expensive rocket launch sites due the fact that it will operate from ordinary runways. It will start from airfield, reach designated altitude, deploy rocket with payload, return and land on the airfield. Plan assumes creating launch system similar to Pegasus rocket which is successfully operated by Orbital ATK, Virgin Galactic WhiteKnight and few other projects which are still, in spite of Pegasus, in various phases of development.

Recent year was time of various changes in Stratolaunch Systems. Company became part of other company belonging to Paul Allen, Vulcan Inc. and its subsidiary Vulcan Aerospace. Orbital ATK, which was chosen as main contractor for developing rocket vehicle, was changed due the decision of management of Vulcan Inc. Orbital ATK which offered Pegasus II rocket with solid fueled engines was not able to meet economical demands of Vulcan Inc. and Aerojet Rocketdyne became new contractor to develop rocket propulsion. On November 17, 2015, Chuck Beames (president of Vulcan Aerospace) announced that company still has not clear vision of rocket, but carrier plane should be ready in 2016.

Stratolaunch carrier plane was designed by Burt Rutan and Scaled Composites (subsidiary of Northrop). It was based on White Knight carrying SpaceShipOne space plane, also designed by Burt Rutan and Scaled Composites. To reduce costs, Paul Allen decided to buy two Boeing 747-400 to utilize engines, avionics, landing gear and minor parts for building prototype of Stratolauncher. Plane was designed from the beginning as extremely large, equipped with twin fuselage and wingspan at 117 m (largest wingspan plane ever produced) and able to lift up to 250 t (rocket with payload). Place with latches for second stage rocket were designed between fuselages. Propulsion of the plane will be six engines from Boeing 747-400, which will be also source of avionics, landing gear and other minor systems. Engines will be installed under the wings on the left and right side of the twin fuselage. Pilots and operators will take place in right fuselage; both fuselages are different in shape than Boeing 747-400-they are quite similar to shape of the fuselage in flying boat. Each fuselage will have separate horizontal and vertical stabilizers.