SpaceX's Grasshopper VTVL takes a 40 meter hop
By Brian Dodson
December 26, 2012
The SpaceX Grasshopper vertical takeoff vertical landing (VTVL) testbed has successfully flown to a height of 40 meters (131 ft), hovered for a bit and subsequently landed in a picture perfect test on December 17, 2012. The Grasshopper had previously taken two hops to less than 6 m (20 ft) in height, but the latest test was the first that saw it reach an altitude taller than the rocket itself, which is a modified Falcon 9 orbital launch vehicle. The flight lasted 29 seconds from launch to landing, and carried a 1.8 m (6 ft) cowboy dummy to give an indication of scale.
Despite their seeming inefficiency, vertical takeoff vertical landing (VTVL) rockets have long been a fixture in the world of space flight. The first manned VTVL spacecraft was the Apollo Lunar Lander, which landed on and took off from the Moon vertically, a task made far easier by the Moon's one-sixth gravity. This was followed in the 1990s by the McDonald-Douglass Delta Clipper, a one-third scale test model of a proposed single-stage-to-orbit launch rocket.
Since that time a handful of VTVL spacecraft have emerged from plans on paper to successful hardware. Most have been small, and the largest burst of activity was associated with the Northrop Grumman / NASA Lunar Lander Challenge in the latter half of the previous decade.
Several VTVL suborbital and orbital launchers are currently in various stages of (mostly early) development. The latest and largest of these is SpaceX's Grasshopper, which is built of the first stage tanks of a Falcon 9 launch rocket, a single Merlin-1D engine (the Falcon 9 uses nine such engines), and a supporting structure for four hydraulically damped steel landing legs. The Grasshopper stands 32.3 meters (106 ft) tall and is 3.66 meters (12.0 ft) in diameter, making it the largest VTVL craft ever flown.
Grasshopper is also distinguished from most other VTVL craft in that it is the testbed of a project to convert an active commercial orbital medium-lift (10,000 kg to low earth orbit) launch vehicle into a recoverable launch system. Prior VTVL craft (aside from the Lunar Lander) were intended to be research vehicles or one-off demonstrators.
Looking to the future, testing is expected to take up to three years, during which subsonic tests will be carried out at SpaceX's McGregor, Texas facility. An initial FAA permit for up to 70 suborbital launches per year will allow flights at altitudes up to 3,500 m (11,500 ft) with durations of up to nearly three minutes. SpaceX has already requested FAA approval to increase the altitude of some of the initial test flights. Supersonic flight tests are expected in due course, but no firm details have been announced.
CEO Elon Musk, speaking about the Grasshopper program, said in November 2012: "Over the next few months, we’ll gradually increase the altitude and speed ... I do think there probably will be some craters along the way; we’ll be very lucky if there are no craters. Vertical landing is an extremely important breakthrough – extreme, rapid reusability."
The successful December 17, 2012, test fight can be seen in the video below.
Source: Elon Musk via Twitter
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