LOS ANGELES — Virgin Galactic will attempt the first rocket-powered atmospheric flight tests of SpaceShipTwo (SS2) “toward the end of the year” following the granting of an experimental launch permit by FAA.

The permit was approved for powered flight tests by Scaled Composites, developer of the SS2 and its WhiteKnightTwo carrier aircraft, from the company’s Mojave, Calif., facility. Virgin Galactic says that “with 80 test flights completed, WhiteKnightTwo is substantially through its test plan, while the more recently constructed SpaceShipTwo has safely completed 16 free flights, including three that tested the vehicle’s unique ‘feathering’ re-entry system.

Additionally, 10 test firings of the full-scale SpaceShipTwo rocket motor, including full-duration burns, have been safely and successfully completed.”

The upcoming tests will verify the aerodynamic performance of the SS2 with the full weight of the Sierra Nevada-developed RM2 rocket motor system on board.

“Integration of key rocket motor components, already begun during a now-concluding period of downtime for routine maintenance, will continue into the autumn,” Virgin Galactic adds. The company says that although experimental launch permits have been granted to other rockets, FAA’s clearance of SS2 is the first for a “rocket-powered vehicle that carries humans.”

FAA clearance comes as Scaled continues to refine the aerodynamic control surfaces of the SS2 following initial glide tests. The latest modification includes the addition of inward-facing, broad chord strakes to the twin tails. Dubbed “mega-strakes,” the devices are believed to have been added for additional pitch stability.