Falcon 9 preparing to stretch her legs via Grasshopper trials

by Chris Bergin

The prospect of a Falcon 9 v1.1 first stage returning to terra firma following launch is continuing to advance along a path towards reality, as the SpaceX team push forward with testing on the system’s landing legs at their Texas test facility. Photos of the Grasshopper 2 (GH2) test vehicle have surfaced, showing the leg structures that are likely to be similar to those that will fly on a real mission this year.

Showing some leg:

SpaceX have a busy 2014 schedule, mainly revolving around their Falcon 9 v1.1 manifest, along with the debut of their Falcon Heavy launch vehicle and continued test efforts relating to the company’s plans to create a fully reusable launch system.

Z6There is a large amount of synergy between the company’s goals, with the Falcon Heavy powered by three F9 v1.1 core stages, while the F9 v1.1’s other name is the F9-R, thanks to its design allowing for an incremental approach to testing the technologies required for allowing the stages to return to Earth for re-use.

The debut of the Falcon 9 v1.1 – carrying the CASSIOPE satellite – involved the first “boost back” test of the first stage, while sources note there was also a boost back test during the SES-8 mission, or at least the restart of the first stage post staging.

It has not yet confirmed how much testing was involved on the most recent F9 v1.1 mission, which successfully lofted the Thaicom-6 satellite.

Z3A1It has been rumored that the upcoming CRS-3/SpX-3 mission – currently tracking a NET (No Earlier Than) March 1 launch date – may involve the first Falcon 9 v1.1 to sport landing legs. However, this is currently classed as doubtful, with no confirmation from SpaceX.

However, photos published last year by SpaceX – showing the birth of the core stages at their Californian nursery – did confirm preparations were already taking place for the addition of landing legs on the flight hardware.

Ultimately, as portrayed in SpaceX videos, the Falcon 9 First Stage, Second Stage and Dragon spacecraft will all eventually sport the capability to return to land for re-use, during crewed Dragon missions.

Grasshopper testTesting towards that goal – specific to the first stage – has been ongoing via the Grasshopper system at SpaceX’s McGregor facility, ahead of a new phase of testing is scheduled to take place in New Mexico, utilizing the Grasshopper 2 (GH2) system.

Testing the technology via the Grasshopper has already resulted in a number of stunning successes.

The main role of the Grasshopper is to test hardware elements such as propulsive targeted landing and its own preliminary landing legs structure.

Numerous tests have involved the Grasshopper showing its ability to carry out incremental objectives, opening with a short hop of just six feet during Test 1, through to a massive 1,066 foot leap during Test 6.

The seventh test proved to be the most stunning, as the Grasshopper did much more than rise upwards before returning to its concrete pad.

Grasshopper Divert TestThat leap completed a divert test, flying to a 250m altitude with a 100m lateral maneuver before returning to the center of the pad.

Ultimately, the test demonstrated the vehicle’s ability to perform more aggressive steering maneuvers than have been attempted in previous flights.

The test sequence for this Grasshopper is understood to be complete, as SpaceX move towards a test schedule with the larger, upgraded version, known as Grasshopper 2 (GH2).

Z9The GH2 is also at the Texas test site, an impressive looking vehicle, that appears to be a mirror of a Falcon 9 v1.1 first stage dimensions.

Photos taken by several local people from a public road in the vicinity of the test site – some of which were provided to L2 (along with newly added video), while other photos were posted openly on the internet – provide a glimpse of the landing leg structures that appear to be closely based on the hardware that SpaceX is expected to employ when they actually fly with legs on a Falcon 9 mission to space.

It is understood the vehicle is currently suspended slightly above the ground, on hold downs points, with the legs deployed.

Z3Soot can be seen on the base of the vehicle and the legs themselves, likely via static test firings.

Questions sent to SpaceX last month, relating to the landing legs and test schedule, were accepted by the company, but are yet to be answered.

What is already understood is the vehicle may fly at McGregor via validation testing, before heading to Spaceport America in New Mexico.

Notably, limitations at the Texas site result in an AGL (Altitude above Ground Level) ceiling for Grasshopper of 2,500 feet.

Once GH2 arrives in New Mexico, it will be able to fly to much greater altitudes.

Z5The specifics behind the design of the legs is open to speculation, although they are clearly based on the prototype leg system, photos of which were recently published by SpaceX, from its position on the factory floor at Hawthorne.

These legs will be stowed on the aft of the first stage during the ride uphill, prior to deploying via pneumatic cylinders driven by compressed helium once the stage is on the final part of its powered descent.

SpaceX Chief Designer and CEO Elon Musk had already noted the design is a nested, telescoping piston using high pressure helium, given the requirement the system needs to be ultra light.

Should SpaceX provide additional details on the leg system and test plan, another article will follow.

(Images: SpaceX, L2, Jim Howard, NSF Member TomNTex)

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