Grasshopper (rocket)

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Grasshopper v1.0 in September 2012

Grasshopper and the Falcon 9 Reusable Development Vehicles (F9R Dev) are experimental technology-demonstrator, suborbital reusable rockets that make vertical takeoffs and vertical landings.[1] Two prototypes have been built to date, and both are ground-launched test vehicles for the broader SpaceX reusable launch system development program.[2] A third prototype test vehicle was being built as of April 2014.[3][dated info]

Grasshopper was announced in 2011[4] and began low-altitude, low-velocity hover/landing testing in 2012. The initial Grasshopper test vehicle was 106 ft (32 m) tall and made eight successful test flights in 2012 and 2013 before being retired. A second Grasshopper-class prototype test vehicle design—the larger and more capable Falcon 9 Reusable Development Vehicle (F9R Dev) based on the larger Falcon 9 v1.1 launch vehicle form factor—will result in two additional VTVL test vehicles which will be used for testing at higher altitudes and supersonic speeds as well as additional low-altitude testing with the larger vehicle. The F9R Dev1 vehicle was built in 2013–2014 and made its first low-altitude flight test on 17 April 2014; it was lost during a three-engine test at the McGregor test site.[5] A second F9R Development Vehicle—F9R Dev2—is currently being built.

The Grasshopper and F9R Dev vehicles are being developed and tested by Space Exploration Technologies (SpaceX) in order to assist development of the reusable Falcon 9 and reusable Falcon Heavy rockets, which will require vertical landings of the near-empty Falcon 9 and Falcon Heavy first-stage booster tanks and engine assemblies. The project is privately funded by SpaceX, with no funds provided by the government.

Grasshopper and F9R Dev are only two elements of the multi-element, incremental SpaceX reusable launch system development program test program, a program that includes Grasshopper and F9R Dev1 testing in low-altitude, low-velocity environments at the SpaceX Texas test site; high-altitude, mid-velocity testing of the F9R Dev2 test vehicle at Spaceport America in New Mexico; and high-altitude, high-speed controlled-descent tests of post-mission (spent) Falcon 9 booster stages on Falcon 9 missions that began in September 2013 and have continued into 2014.

History[edit]

The Grasshopper technology demonstrator first became known publicly in the third quarter of 2011, when space journalists first wrote about it after analyzing US government space launch regulatory documents.[1]

Shortly thereafter, SpaceX confirmed the existence of the test vehicle development program, and projected it would begin the Grasshopper flight test program in 2012.[4][6] Grasshopper began flight testing in September 2012 with a brief, three-second hop at the company's Texas test site,[7] followed by a second hop in November 2012 with an 8-second flight that took the testbed approximately 5.4 m (18 ft) off the ground, and a third flight in December 2012 of 29 seconds duration, with extended hover under rocket engine power, in which it ascended to an altitude of 40 m (130 ft) before descending under rocket power to come to a successful vertical landing.[8]

From the announcement in 2011, SpaceX has achieved each of the schedule milestones that they publicly announced. SpaceX said in February 2012 that they were planning several vertical-takeoff, vertical-landing (VTVL) test flights during 2012,[2] and confirmed in June 2012 that they continued to plan to make the first test flight within the next couple of months.[6] Updated photos of the rocket on the test pad appeared in a news article on 11 Sep 2012,[9] They achieved first flight on September 21, 2012.[7]

Beginning in October 2012, SpaceX discussed development of a second generation Grasshopper test VTVL vehicle, one that would have lighter-weight landing legs that fold up on the side of the rocket, would have a different engine bay and would be nearly 50% longer than the first Grasshopper vehicle.[10] In May 2013, they announced that the higher-altitude, higher-velocity part of the Grasshopper flight test program would be done at Spaceport America—and not at the Federal Government's adjacent White Sands Missile Range facility as previously planned[11] —near Las Cruces, New Mexico, and signed a three-year lease for land and facilities at the recently operational spaceport.[12] SpaceX indicated in May 2013 that they do not yet know how many jobs will move from McGregor, Texas to New Mexico.[13]

SpaceX retired the Grasshopper test vehicle after making a total of eight successful test flights between September 2012 and October 2013.[14] SpaceX began flight tests of the F9R Dev vehicle—F9R Dev1—in April 2014.[15]

As of May 2014, the FAA permit to fly the Falcon 9 Reusable Development Vehicle in Texas is open until February 2015.[16]

Description[edit]

Two versions of the prototype reusable test vehicles have been built, the 106-foot tall Grasshopper (formerly referred to as Grasshopper v1.0) and the 160-foot tall Falcon 9 Reusable Development Vehicle-also known as F9R Dev— which was formerly known as Grasshopper v1.1.[3]

Grasshopper[edit]

When Grasshopper was first disclosed in September 2011, the rocket was described to consist of "a Falcon 9 first-stage tank, a single Merlin-1D engine, four steel landing legs and a support structure, plus other pressurization tanks attached to the support structure" with a height of 32 m (106 ft).[1] Photos released in September 2012 revealed the test article landing gear to be considerably more sophisticated, with the tank and rocket engine as previously described.

Grasshopper can land on Earth with the accuracy of a helicopter.[17] and made seven test flights through August 2013. On August 13, 2013, the Grasshopper vehicle successfully completed a "divert test", flying to 250 meters altitude while completing a 100 meter lateral maneuver, and then returning to land on the pad.

Grasshopper made its eighth, and final, test flight on October 7, 2013, flying to an altitude of 744 m (2,441 ft) (0.46 miles) before making its eighth successful landing.[18] The Grasshopper test vehicle is now retired,[14] but the second and third test rockets have just begun their flight test program in April 2014.

Falcon 9 Reusable Development Vehicle (F9R Dev)[edit]

The Falcon 9 Reusable Development Vehicle, or F9R Dev, was initially announced in October 2012, when SpaceX indicated that a second Grasshopper vehicle with fold-up landing legs would be built on the longer Falcon 9 v1.1 platform.[10] F9R Dev was formerly referred to, late 2012–early 2014, as Grasshopper v1.1.[3][18]

In March 2013, it was announced that the second Grasshopper-class suborbital flight vehicle would be constructed out of the Falcon 9 v1.1 first-stage tank that had been used for qualification testing in Texas at the SpaceX Rocket Development and Test Facility prior to March. It was to be rebuilt as the next Grasshopper-class prototype test vehicle with landing legs similar to those to be used in actual launches.[19] In May 2013, the design for the retractable landing leg was shown to be a telescoping piston on an A-frame. The total span of the four legs is approximately 18 m (60 ft), and the landing gear weighs less than 2,100 kg (4,600 lb); the deployment system uses high-pressure Helium.[20]

Test plans call for the F9R Dev2 to be high-altitude flight tested only at Spaceport America, New Mexico,[12][21] at altitudes up to approximately 300,000 ft (91,000 m).[19] SpaceX began constructing a 30 m × 30 m (98 ft × 98 ft) pad at Spaceport America in May 2013, 7 km (4.3 mi) southwest of the spaceport's main campus, and will lease the pad for US$6,600 per month plus US$25,000 per test flight. As of May 2013, the spaceport administrator expected SpaceX to be operational at the Spaceport sometime between October 2013 and February 2014, and that is the time that the lease payments were expected to begin.[22]

In August 2013, SpaceX announced that an F9R Dev test vehicle would fly in New Mexico with all nine engines of the fully loaded Falcon 9-R, whereas Grasshopper had flown exclusively with only a single Merlin 1D engine in place, the center engine which is planned to be used to complete the last phase of the deceleration and landing.[23] Later reports indicated that the F9R Dev vehicle in Texas, F9R Dev1, will take off and accelerate to with only three engines—as the prototype test rocket will never need approach the full takeoff weight of a fully loaded Falcon 9 with an orbital payload—while completing the descent and landing with only one engine.[24] The testing is expected to start in New Mexico only after low-altitude initial flight tests of F9R Dev1 are accomplished in Texas at the SpaceX Rocket Development and Test Facility.[18]

SpaceX performed a short-duration ground test (static test) of F9R Dev1 on March 28, 2014 at their McGregor, Texas test site,[25] and made their maiden test flight of the new vehicle, to an altitude of 250 meters (820 ft), on April 17, 2014.[15][24] The F9R Dev1 vehicle's final flight was on 22 August 2014. Flight anomaly during the ascend stage triggered flight termination system leading to the mid-flight explosion of a rocket. No injuries or near-injuries were reported and FAA representative was present during the test. Video from the accident was released by CBS and multiple images from the accident were posted on a social media.[5][26]

Development funding[edit]

SpaceX is funding all of the development and testing of the Grasshopper and F9R-Dev test vehicles, with no contribution by the government.[21]

Flight test program[edit]

Flight tests will include subsonic and supersonic testing.

Releases of public information in 2011 indicated that the subsonic tests would occur at SpaceX McGregor, Texas facility in three phases, at maximum flight altitudes of 670 to 11,500 ft (200 to 3,510 m), for durations of 45 to 160 s (0.75 to 2.67 min). At the time, testing was expected to take up to three years and the initial FAA permit allows up to 70 suborbital launches per year.[1][27] A half-acre concrete launch facility was constructed to support the test flight program.[6] In September 2012, SpaceX announced that they have requested FAA approval to increase the altitude of some of the initial test flights.[28]

The first flight test, called a "brief hop" by journalist Clark Lindsey, occurred on 21 Sep 2012.[29] The flight of the near-empty rocket stage was to a height of 6 ft (1.8 m) and lasted 3 seconds.[7]

Looking forward to the next year, CEO Musk 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."[30] Then in March 2013 Musk said that SpaceX hoped to reach hypersonic speed before the end of 2013.[31] In May 2013, SpaceX moved the location of the higher-altitude, higher-velocity flight testing to Spaceport America, from the previous plan to do that testing at White Sands Missile Range.[2][7][12]

On the 29 Sep 2013 webcast for Falcon 9 Flight 6, SpaceX indicated that there were additional flights of the Grasshopper planned at the Texas test site, in addition to flights for a couple of follow-on prototype vehicles, both based on the larger Falcon 9 v1.1 booster stage. F9R Dev1 would fly low-altitude tests in Texas, while a series of higher-altitude tests were planned for the F9R Dev2 test vehicle at the New Mexico Spaceport America test site.

The first flight test of the F9R Dev test vehicles occurred in April 2014,[24] and have continued with the fifth test flight in August 2014.

Flight tests[edit]

Grasshopper[edit]

The first VTVL flight test vehicle—Grasshopper, built on a Falcon 9 v1.0 first-stage tank—made a total of eight test flights in 2012–2013. All flights were from the McGregor, Texas test facility.

Flight tests at the Texas facility were limited to a maximum altitude of 2,500 ft (760 m) by an FAA regulatory permit.[32] which was later increased to 10,000 ft (3,000 m) for the F9R Dev testing.[15]

Test # Date (year-month-day) Highest altitude Duration Remarks
1 2012-09-21[7] 1.8 m (6 ft)[7] 3 seconds[7]
2 2012-11-01[33] 5.4 m (17.7 ft)[33] 8 seconds[33]
3 2012-12-17[34] 40 m (131 ft)[34] 29 seconds[34] First flight to include the cowboy mannequin
4 2013-03-07[35] 80 m (262 ft)[36] 34 seconds[36] Touchdown thrust-to-weight ratio greater than one[37]
5 2013-04-17[38] 250 m (820 ft)[38] 61 seconds[citation needed] Demonstrated ability to maintain stability in wind[39]
6 2013-06-14[40] 325 m (1,066 ft)[40] 68 seconds[41] New navigation sensor suite tested; needed on the F9-R for precision landing[42]
7 2013-08-13[43] 250 m (820 ft)[43] 60 seconds Also performed 100 m (330 ft) lateral maneuver before returning to the pad.[43]
8 2013-10-07[44] 744 m (2,441 ft)[45] 79 seconds[46] Final flight of Grasshopper. Vehicle retired after the flight.[14]

Falcon 9 Reusable Development Vehicle testing[edit]

The second VTVL flight test vehicle—F9R Dev1, built on the much longer Falcon 9 v1.1 first-stage tank, and with retractable landing legs—made its first test flight on April 17, 2014.[24] Five low-altitude test flights have been flown in the McGregor, Texas area using F9R Dev1.[3][15][47]

A third flight test vehicle—F9R Dev2—is currently being built and will be flown at the high-altitude test range available at Spaceport America in New Mexico. It will be flown at altitudes up to approximately 91,000 meters (300,000 ft).[3][15]

Test # Date (year-month-day) Test vehicle Location Highest altitude Duration Remarks
1 2014-04-17[3] F9R Dev1 McGregor 250 m (820 ft)[3] Hovered, moved sideways, landed successfully.[24]
2 2014-05-01[48] F9R Dev1 McGregor 1,000 m (3,300 ft)[49] Hovered, moved sideways, landed.[48]
3 2014-06-17 F9R Dev1 McGregor 1,000 m (3,300 ft)[50] First test flight with steerable grid fins.[50]
4 2014-08-01[51] F9R Dev1 McGregor
5 2014-08-22[51] F9R Dev1 McGregor Vehicle was self-destroyed following a flight anomaly that began to take F9R Dev1 off of its planned flight path. No injuries. Flight data will be analyzed to determine the cause.[47][52][full citation needed]

Related over-water flight testing[edit]

In March 2013, SpaceX announced that, beginning with the first flight of the stretch version of the Falcon 9 launch vehicle—the sixth flight overall of Falcon 9 (then anticipated for summer 2013), every first stage would be instrumented and equipped as a controlled descent test vehicle. SpaceX intends to test propulsive-return over-water until a return to the launch site and a powered landing is accomplished successfully. They cautioned the public to expect several failures before a successful landing is achieved.[53] For the first flight of the v1.1 Falcon 9 in 2013, after stage separation, the first-stage booster would do a deceleration burn to slow it down and then a second burn just before it reached the water. When all of the over-water testing is complete, they intend to fly back to the launch site and land propulsively, perhaps as early as mid-2014.[53] The over-water tests will occur in both the Pacific and Atlantic oceans, south of Vandenberg Air Force Base and east of Cape Canaveral Air Force Station.

When announced in early 2013, SpaceX did not expect a successful booster recovery in the first several powered-descent tests,[54] but does hope to make the first land landing and dry stage recovery sometime in 2014.[55]

The first flight test of the booster controlled descent was on 29 September 2013. The test was successful—with substantial test milestones achieved and a great deal of engineering test data—but the booster was not successfully recovered from the ocean. SpaceX tested a large amount of new technology on the flight, and that—coupled with the technology advancements made on the Grasshopper technology demonstrator—they now believe they have "all the pieces of the puzzle, ... [they] were able to successfully transition from vacuum through hypersonic, through supersonic, through transonic, and light the engines all the way and control the stage all the way through—we have all the pieces necessary to achieve a full recovery of the boost stage."[56] Musk said "the next attempt to recover the Falcon 9 first stage will be on the fourth flight of the upgraded rocket. This would be third commercial Dragon cargo flight to ISS", scheduled for 2014.[57]

See also[edit]


References[edit]

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External links[edit]