LOS ANGELES – Suborbital space vehicle developer XCOR Aerospace has begun final assembly of the prototype two-seat Lynx Mk. 1 spaceplane at its Mojave, California, facility.

The company will use the liquid-rocket powered Mk. 1 to demonstrate its reusable capability for flights to around 200,000 ft. from Mojave’s runway. The vehicle, which will also be used for crew training, will pave the way for a later, more capable Lynx Mk. 2 production version capable of flying to altitudes of 100 km-plus, up to four times per day. XCOR also plans to develop a Mk. 3 variant that will be used to carry payloads in an external dorsal pod or launch micro satellites using a top-mounted upper stage.

Final assembly follows the delivery of several key components to XCOR, the major one being the pressurized cockpit section that was developed by AdamWorks, a Colorado-based high-strength composites manufacturer that also produced the main components of the internal pressure vessel for Sierra Nevada’s DreamChaser space vehicle. The company adds that "with the fuselage, pressure cabin and strakes delivered, XCOR is bonding these structures together and integrating sub-assemblies, such as the landing gear, at its hangar in Mojave."

XCOR also notes that development testing of the Lynx’s pump-fed XR-5K18 liquid oxygen/kerosene rockets, including cold flow and hot-fire runs, continues at Mojave using a "first generation fuselage." The Lynx Mk. 1 and 2 will be powered by a tail-mounted cluster of four of these 2,900-lb. rockets. The production version of the Lynx, which is designed to achieve a much greater apogee of around 328,000 ft., will have a lower dry weight with a lighter, integral liquid oxygen tank built into the aeroshell. The Mk. 3 version will have an upgraded propulsion system as well as beefed-up landing gear, aerodynamic changes and structural enhancements to handle the additional weight of the payload pod.

The company said earlier this year it hoped to begin long-awaited test flights by the end of December. But with much assembly work and testing remaining, it appears a target date in 2015 now seems more realistic. Operational flights of the Lynx Mk. 2 are expected to follow a year to 18 months later. As part of longer-term plans to support a higher operational tempo, XCOR is meanwhile developing a research and development center in Midland, Texas. It is also establishing an operational and manufacturing site at Kennedy Space Center in Florida with the assistance of Space Florida.