Grasshopper (rocket)

Grasshopper v1.0 in September 2012

Grasshopper and the Falcon 9 Reusable Development Vehicles (F9R Dev) were experimental technology-demonstrator reusable rockets that performed vertical takeoffs and landings.[1] The project was privately funded by SpaceX, with no funds provided by the government.[2] Two prototypes were built, and both were launched from the ground.[3]

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 was the larger and more capable Falcon 9 Reusable Development Vehicle (F9R Dev, also known as F9R Dev1) based on the Falcon 9 v1.1 launch vehicle. It was tested at higher altitudes and supersonic speeds as well as providing additional low-altitude tests. 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 on 22 August 2014.[5]

The Grasshopper and F9R Dev tests were fundamental to the development of the reusable Falcon 9 and reusable Falcon Heavy rockets, which are planned to require vertical landings of the near-empty Falcon 9 and Falcon Heavy first-stage booster tanks and engine assemblies. The Grasshopper and the F9R Dev tests led into a series of high-altitude, high-speed controlled-descent tests of post-mission (spent) Falcon 9 booster stages that accompanied the commercial Falcon 9 missions since September 2013. The latter eventually resulted in the first successful booster landing on 21 December 2015.

History

Grasshopper rocket performing a 325-meter flight followed by a soft propulsive landing in an attempt to develop technologies for a reusable launch vehicle.

The Grasshopper technology demonstrator first became known publicly in the third quarter of 2011, when space journalists first wrote about it after analyzing space launch regulations of the Federal Aviation Administration.[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]

Releases of public information in 2011 indicated that the subsonic tests would occur in McGregor, Texas 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][7] 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.[8] 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."[9]

Grasshopper flight tests

The first VTVL flight test vehicle—Grasshopper, built on a Falcon 9 v1.0 first-stage tank—made a total of eight test flights between September 2012 and October 2013.[10] All eight flights were from the McGregor, Texas test facility.

Grasshopper began flight testing in September 2012 with a brief, three-second hop, 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.[11] 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 vertical landing.[12] The Grasshopper test vehicle is now retired.[10]

Flight tests at the Texas facility were limited to a maximum altitude of 2,500 ft (760 m) by the initial FAA regulatory permit.[13]

Test # Date (year-month-day) Highest altitude Duration Remarks
1 2012-09-21[14] 1.8 m (6 ft)[14] 3 seconds[14] A "brief hop"[15] with a near-empty tank.
2 2012-11-01[16] 5.4 m (17.7 ft)[16] 8 seconds[16]
3 2012-12-17[17] 40 m (131 ft)[17] 29 seconds[17] First flight to include the cowboy mannequin
4 2013-03-07[18] 80 m (262 ft)[19] 34 seconds[19] Touchdown thrust-to-weight ratio greater than one[20]
5 2013-04-17[21] 250 m (820 ft)[21] 61 seconds Demonstrated ability to maintain stability in wind[22]
6 2013-06-14[23] 325 m (1,070 ft)[23] 68 seconds[24] New navigation sensor suite tested; needed on the F9-R for precision landing[25]
7 2013-08-13[26] 250 m (820 ft)[26] 60 seconds successfully completed a "divert test" performing 100 m (330 ft) lateral maneuver before returning to the pad.[26]
8 2013-10-07[27] 744 m (2,440 ft)[28] 79 seconds[29] Final flight of Grasshopper. Vehicle retired after the flight.[10]

As Elon Musk stated, Grasshopper could land on Earth with the accuracy of a helicopter.[30]

From the announcement in 2011 until 2014, 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,[3] and confirmed in June 2012 that they continued to plan to make the first test flight within the next couple of months.[6]

F9R Dev1 flight tests

The Falcon 9 Reusable Development Vehicle, or F9R Dev, was announced in October 2012. F9R Dev1 was initially named, since late 2012 until early 2014, as Grasshopper v1.1.[31][12] In March 2013 Musk said that SpaceX hoped to reach hypersonic speed before the end of 2013.[32] 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.[33]

In 2014 the FAA permit was increased to 10,000 ft (3,000 m) for the F9R Dev testing at McGregor,[34] when the first Grasshopper was limited to an altitude of 2,500 ft (760 m).

The F9R Dev1 was built on the much longer Falcon 9 v1.1 first-stage tank, and with retractable landing legs.

SpaceX performed a short-duration ground test (static test) of F9R Dev1 on March 28, 2014 at their McGregor, Texas test site,[35] and made their maiden test flight of the new vehicle, to an altitude of 250 meters (820 ft), on April 17, 2014.[34][36] The F9R Dev1 vehicle's fifth flight on 22 August 2014 was also its final one.[31][37] Anomalous sensor data from the vehicle during its ascent triggered the flight termination system, leading to the destruction of F9R-Dev1. No injuries or near-injuries were reported and an FAA representative was present during the test. Video from the accident was released by CBS and multiple images from the accident were posted on social media.[5][38]

Test # Date (year-month-day) Test vehicle Location Highest altitude Duration Remarks
1 2014-04-17[31] F9R Dev1 McGregor 250 m (820 ft)[31] Hovered, moved sideways, landed successfully.[36]
2 2014-05-01[39] F9R Dev1 McGregor 1,000 m (3,280 ft)[40] Hovered, moved sideways, landed.[39]
3 2014-06-17 F9R Dev1 McGregor 1,000 m (3,280 ft)[41] First test flight with steerable grid fins.[41]
4 2014-08-01[42] F9R Dev1 McGregor
5 2014-08-22[42] F9R Dev1 McGregor Vehicle exploded following a flight anomaly that began to take F9R Dev1 off of its planned flight path. No injuries.[37][43] A blocked sensor was the cause of the flight anomaly. The sensor had no backup in the prototype F9R Dev vehicle but would have had a redundant backup in the flight-version Falcon 9.[44]

Discontinued F9R Dev2

In May 2013, they announced that the higher-altitude, higher-velocity part of the Grasshopper flight test program would be done at Spaceport America near Las Cruces, New Mexico—and not at the Federal Government's adjacent White Sands Missile Range facility as previously planned[3][14][45][46]—and signed a three-year lease for land and facilities at the recently operational spaceport.[45] SpaceX indicated in May 2013 that they do not yet know how many jobs will move from Texas to New Mexico.[47]

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, planning to lease the pad for US$6,600 per month plus US$25,000 per test flight.[48]

A third flight test vehicle—F9R Dev2—was initially planned to be flown only at the high-altitude test range at Spaceport America[45][2] and at altitudes of up to 91,000 meters (300,000 ft).[31][34][33] In September 2014, following the destruction of the F9R Dev1, SpaceX changed the plans, so the F9R Dev2 vehicle would fly first in McGregor for low-altitude testing. The initial FAA permit to fly the Falcon 9 Reusable Development Vehicle at McGregor in Texas was open until February 2015.[49]

In May 2015, a specialized press article stated that due to the technical success of the landing attempts on the sea and on the ASDS, SpaceX was planning on using the New Mexico site for testing the returned stages.[50][51]

On 19 February 2015 SpaceX announced that the F9R Dev2 would be discontinued.[52]

During April 2015, SpaceX performed tanking tests on the In-Flight Abort rocket on the Vandenberg Air Force Base SLC-4E. Since this rocket only had three Merlin 1D engines, and the New Mexico site will be used for testing the returned first stages, it was speculated that the discontinued F9R Dev2 was re-purposed as the launch vehicle in the In-Flight Abort Test.[53]

Construction description

Grasshopper design

Grasshopper consisted of "a Falcon 9 [v1.0] first-stage tank, a single Merlin-1D engine" with a height of 32 m (106 ft).[1] The landing gear was fixed.

F9R Dev1 design

F9R Dev1 was constructed out of the used first-stage tank of the Falcon 9 v1.1,[33] so it was 160-foot tall,[31] nearly 50% longer than the first Grasshopper.[54] The landing leg was retractable by design; a telescoping piston on an A-frame. The total span of the four legs was approximately 18 m (60 ft) and the weight less than 2,100 kg (4,600 lb); the deployment system used high-pressure helium.[55] The legs had less weight than on the first Grasshopper. The F9R Dev1 had a different engine bay than the first Grasshopper vehicle.[54]

The F9R Dev1 vehicle in Texas was intended to take off and accelerate with three engines—as the test flight never needs the full thrust to take off a fully loaded Falcon 9 with an orbital payload—while completing the descent and landing with only one engine.[36] The original 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 vertical landing.

Falcon 9 post-mission landing tests

Falcon 9 first stage attempts landing on ASDS after second stage with CRS-6 continued onto orbit. Landing legs are in the midst of deploying.

In 2013, SpaceX moved to using their mainstream Falcon 9 vehicles for VTVL testing, in addition to their existing tests with flying test vehicles. 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.[56] SpaceX attempted numerous over-water landings. both over the sea, resulting in soft landings into the water, and onto specialized Autonomous Spaceport Drone Ships: barges modified to be landing platforms. None were completely successful.

SpaceX finally succeeded in landing a production vertical-landing rocket on land in late 2015. The first attempt to land the first stage of the Falcon 9 on land, near its launch site, occurred on Falcon 9 Flight 20, on 21 December 2015. The landing was successful, and the first stage of the Falcon 9 full thrust vehicle was recovered.[57][58][59] By May 27, 2016, SpaceX had successfully completed three first-stage landings on a drone ship at sea.[60]

See also

Falcon 9 Flight 20 immediately before landing on Landing Zone 1

References

  1. 1 2 3 4 Mohney, Doug (2011-09-26). "SpaceX Plans to Test Reusable Suborbital VTVL Rocket in Texas". Satellite Spotlight. Retrieved 2012-12-30.
  2. 1 2 Shotwell, Gwynne (June 4, 2014). Discussion with Gwynne Shotwell, President and COO, SpaceX. Atlantic Council. Event occurs at 22:35–26:20. Retrieved June 9, 2014. This technology element [reusable launch vehicle technology] all this innovation is being done by SpaceX alone, no one is paying us to do it. The government is very interested in the data we are collecting on this test series. ... This is the kind of thing that entrepreneurial investment and new entrants/innovators can do for an industry: fund their own improvements, both in the quality of their programs and the quality of their hardware, and the speed and cadence of their operations.
  3. 1 2 3 Simberg, Rand (2012-02-08). "Elon Musk on SpaceX’s Reusable Rocket Plans". Popular Mechanics. Retrieved 2012-02-07.
  4. 1 2 Lindsey, Clark (2011-10-12). "Grasshopper news". RLV and Space Transport News. Retrieved 2011-11-23.
  5. 1 2 Elon Musk (August 22, 2014). "Three engine F9R Dev1 vehicle auto-terminated during test flight". Twitter.
  6. 1 2 3 "Reusable rocket prototype almost ready for first liftoff". Spaceflight Now. 2012-07-09. Retrieved 2012-07-13. SpaceX has constructed a half-acre concrete launch facility in McGregor, and the Grasshopper rocket is already standing on the pad, outfitted with four insect-like silver landing legs.
  7. ↑ "Draft Environmental Assessment for Issuing an Experimental Permit to SpaceX for Operation of the Grasshopper Vehicle at the McGregor Test Site, Texas" (PDF). Federal Aviation Administration. 2011. Retrieved 2011-11-24.
  8. ↑ Lindsey, Clark (2012-09-17). "SpaceX Grasshopper tests aim to quickly move up in altitude". NewSpace Watch. Retrieved 2012-09-17. (Subscription required (help)).
  9. ↑ Coppinger, Rod (2012-11-23). "Huge Mars Colony Eyed by SpaceX Founder Elon Musk". Space.com. Retrieved 2012-11-25. '
  10. 1 2 3 Klotz, Irene (2013-10-17). "SpaceX Retires Grasshopper, New Test Rig To Fly in December". Space News. Retrieved 2013-10-21.
  11. ↑ Boyle, Alan (2012-12-24). "SpaceX launches its Grasshopper rocket on 12-story-high hop in Texas". MSNBC Cosmic Log. Retrieved 2012-12-30.
  12. 1 2 "Grasshopper flies to its highest height to date". Social media information release. SpaceX. 12 October 2013. Retrieved 14 October 2013. WATCH: Grasshopper flies to its highest height to date - 744 m (2441 ft) into the Texas sky. http://youtu.be/9ZDkItO-0a4 This was the last scheduled test for the Grasshopper rig; next up will be low altitude tests of the Falcon 9 Reusable (F9R) development vehicle in Texas followed by high altitude testing in New Mexico.
  13. ↑ Abbott, Joseph (2013-05-08). "SpaceX’s Grasshopper leaping to NM spaceport". Waco Tribune. Retrieved 2013-10-25.
  14. 1 2 3 4 Clark, Stephen (2012-09-24). "SpaceX's reusable rocket testbed takes first hop". Spaceflightnow. Retrieved 2012-09-25.
  15. ↑ Lindsey, Clark (2012-09-22). "SpaceX Grasshopper vertical takeoff/vertical landing rocket first test". NewSpace Watch. Retrieved 2012-09-23. (Subscription required (help)).
  16. 1 2 3 "Grasshopper Two-Story Hop 11/1/12". SpaceX. 5 November 2012. Retrieved 6 November 2012.
  17. 1 2 3 "Grasshopper hops ever higher". NewSpace Journal. 24 December 2012. Retrieved 25 December 2012.
  18. ↑ "FAA Permitted Launches". Federal Aviation Administration. 8 March 2013. Retrieved 9 March 2013.
  19. 1 2 "More on Grasshopper’s "Johnny Cash hover slam" test". NewSpace Journal. 9 March 2013. Retrieved 9 March 2013.
  20. ↑ "GRASSHOPPER COMPLETES HIGHEST LEAP TO DATE". 10 March 2013.
  21. 1 2 Lindsey, Clark (2013-04-13). "SpaceX Grasshopper reaches 250 meters". NewSpace Watch. Retrieved 2013-04-23. (Subscription required (help)).
  22. ↑ "Elon Musk's twitter". 22 April 2013.
  23. 1 2 Bergin, Chris (14 June 2013). "Testing times for SpaceX’s new Falcon 9 v.1.1". NASASpaceFlight (not affiliated with NASA). Retrieved 15 June 2013.
  24. ↑ Bergin, Chris (20 June 2013). "Reducing risk via ground testing is a recipe for SpaceX success". NASASpaceFlight (not affiliated with NASA). Retrieved 21 June 2013.
  25. ↑ SpaceNews Launch Report, accessed 15 July 2013.
  26. 1 2 3 Boyle, Alan (2013-08-14). "SpaceX's Grasshopper test rocket flies sideways successfully". NBC News. Retrieved 2013-08-15.
  27. ↑ "SpaceX's Grasshopper flight on 10/07".
  28. ↑ "Grasshopper 744m Test – Single Camera (Hexacopter)". SpaceX Youtube channel. 2013-10-12.
  29. ↑ Grasshopper Completes Half-Mile Flight in Last Test
  30. ↑ "Musk’s Space Talk Wows Crowd at South by Southwest". Moon and Back. 2013-03-11. Retrieved 2013-03-11.
  31. 1 2 3 4 5 6 Bergin, Chris (2014-04-22). "Rockets that return home – SpaceX pushing the boundaries". NASAspaceflight.com. Retrieved 2014-04-23.
  32. ↑ Lindsey, Clark (2013-03-09). "Elon Musk debuted video of latest Grasshopper flight at SXSW". NewSpace Watch. Retrieved 2013-03-14. (Subscription required (help)).
  33. 1 2 3 "Spacex May try to land or recover the first stage of it next Falcon 9 v1.1 launch this summer". Next Big Future. 2013-03-23. Retrieved 2013-04-06.
  34. 1 2 3 Norris, Guy (2014-04-28). "SpaceX Plans For Multiple Reusable Booster Tests: Controlled water landing marks a major stride toward SpaceX’s Falcon rapid-reusability goal". Aviation Week. Retrieved 2014-04-26. The April 17 F9R Dev 1 flight, which lasted under 1 min., was the first vertical landing test of a production-representative recoverable Falcon 9 v1.1 first stage, while the April 18 cargo flight to the ISS was the first opportunity for SpaceX to evaluate the design of foldable landing legs and upgraded thrusters that control the stage during its initial descent.
  35. ↑ Malik, Tariq (2014-04-14). "SpaceX to Attempt Daring Reusable Rocket Test During Dragon Launch Today". SpaceNews. Retrieved 2014-04-15.
  36. 1 2 3 Abbott, Joseph (2014-04-17). "Grasshopper's successor flies at SpaceX's McGregor site". Waco Tribune. Retrieved 2014-04-18.
  37. 1 2 Foust, Jeff (2014-08-23). "Falcon 9 test vehicle destroyed in accident". NewSpace Journal. Retrieved 2014-08-23.
  38. ↑ Stephen Clark (2014-08-22). "SpaceX rocket prototype explodes in test flight". Spaceflight Now. Retrieved 2014-08-23.
  39. 1 2 Abbott, Joseph (2014-05-01). "SpaceX's Grasshopper successor flies again". Waco Tribune. Retrieved 2014-05-02.
  40. ↑ SpaceX (May 2, 2014). "F9R Flight Test - 1,000m". YouTube.
  41. 1 2 1000m Fin Flight | Rocket Cam and Wide Shot
  42. 1 2 "Commercial Space Data - Launches". Federal Aviation Administration. Dates of Grasshopper launches
  43. ↑ Harwood, William (August 22, 2014). "SpaceX rocket explodes during test flight in Texas". CBS News.
  44. ↑ Dean, James (2014-08-03). "SpaceX targeting Saturday launch from Cape". Florida Today. Retrieved 2014-08-03.
  45. 1 2 3 Lindsey, Clark (2013-05-07). "SpaceX to test Grasshopper reusable booster at Spaceport America in NM". NewSpace Watch. Retrieved 2013-05-07. (Subscription required (help)).
  46. ↑ "Reusable rocket prototype almost ready for first liftoff". spaceflightnow.com. 2012. Retrieved 2012-05-12.
  47. ↑ Abbot, Joseph (2013-05-07). "SpaceX moving Grasshopper testing to New Mexico". Waco Tribune. Retrieved 2013-05-08.
  48. ↑ Leone, Dan (2013-05-13). "SpaceX Leases Pad in New Mexico for Next Grasshopper Tests". SpaceNews. Retrieved 2013-08-03.
  49. ↑ "Commercial Space Data / Active Permits". FAA Data & Research. U.S. Federal Aviation Administration. Retrieved 2014-04-23. Permit no. EP 14-010, Company: Space Exploration Technologies Corporation, Vehicle: Falcon 9-R, Location: Texas, Expiration: Feb 26, 2015
  50. ↑ Bergin, Chris (2015-03-19). "Spaceport America set for SpaceX reusability testing". nasaspaceflight.com. Retrieved 2015-05-12.
  51. ↑ Abbott, Joseph (2014-09-12). "SpaceX updates: Launch moved to Sept. 20; new test rocket may arrive in 2 months". Waco Tribune. Retrieved 2014-09-13.
  52. ↑ Klotz, Irene (2015-02-19). "SpaceX bypassing replacement for lost Falcon 9R landing test vehicle". Portal To The Universe. Retrieved 2015-12-24.
  53. ↑ Bergin, Chris (2015-04-10). "SpaceX conducts tanking test on In-Flight Abort Falcon 9". nasaspaceflight.com. Retrieved 2015-05-10.
  54. 1 2 "A 2nd-gen Grasshopper + A new video of first hop". NewSpace Watch. 2012-10-02. Retrieved 2012-11-04. (Subscription required (help)).
  55. ↑ Lindsey, Clark (2013-05-02). "SpaceX shows a leg for the "F-niner"". Retrieved 2013-05-02. (Subscription required (help)). F9R (pronounced F-niner) shows a little leg. Design is a nested, telescoping piston w A frame... High pressure helium. Needs to be ultra light.
  56. ↑ Lindsey, Clark (2013-03-28). "SpaceX moving quickly towards fly-back first stage". NewSpace Watch. Retrieved 2013-03-29. (Subscription required (help)).
  57. ↑ SpaceX on Twitter: "The Falcon 9 first stage landing is confirmed. Second stage continuing nominally. https://t.co/RX2QKSl0z7"
  58. ↑ Wow! SpaceX Lands Orbital Rocket Successfully in Historic First
  59. ↑ de Selding, Peter B. (2015-10-16). "SpaceX Changes its Falcon 9 Return-to-flight Plans". SpaceNews. Retrieved 8 November 2015.
  60. ↑ Kramer, Miriam (27 May 2016). "SpaceX does it again: Company lands third rocket on drone ship in the ocean". Mashable. Retrieved 10 June 2016.
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