(SpaceX) has achieved the highest “hop” of its Grasshopper vertical takeoff and landing test vehicle (VTVL), reaching almost 263 ft. on March 9 at the company’s test site in McGregor, Texas.
The VTVL, combining a modified Falcon 9 first stage, landing legs and a Merlin 1D engine, first flew last September. The testbed is a key element of SpaceX’s longer-term ambition to develop a reusable booster to lower launch costs. Following separation from the second stage, the concept involves flying the first stage of the rocket back to the launch site for an autonomous vertical landing.
SpaceX says the latest flight included a 34-sec. hover and ended with the most accurate landing so far in the center of the launch pad. “At touchdown, the thrust-to-weight ratio of the vehicle was greater than one, proving a key landing algorithm for Falcon 9,” the company adds. The hover and landing phase was conducted using the Grasshopper’s specially developed, closed-loop thrust vector and throttle control system.
The March 9 flight was Grasshopper’s fourth. Following the first hop in September, which reached 8.2 ft., the vehicle reached almost 18 ft. in November and 131 ft. in December. SpaceX says Grasshopper will be tested on flights up to 1,000 ft., when it will demonstrate its ability to hover. According to earlier information in a draft environmental assessment document published by thein September 2011, the following series of test flights could see the vehicle climb as high as 11,500 ft. on hops lasting up to 160 sec.