On April 27, 2013, Elon Musk tweeted a photograph showing the base of the first Falcon 9 v1.1 first stage on the big stand at McGregor, though only through a misty cloud of smoke during an ignitor test. The photo confirmed the long-suspected octagonal arrangement of Merlin 1D engines.
Merlin 1D, Falcon Heavy, and Falcon 9 v1.1
By the end of 2010, SpaceX had completed development and two flight tests of its Merlin 1C-powered Falcon 9. For several years the company had discussed a more powerful Falcon 9 version that would be powered by a higher-thrust Merlin engine, but an official effort was not announced until April 5, 2011.
On that date SpaceX announced that it would develop a new rocket. Press attention focused on the triple-body Falcon Heavy rocket shown in press release materials, but the real story was about the new upgraded Merlin 1D engine that would power the rocket, and about a new two-stage core version that would become known as Falcon 9 v1.1.
Each of the Falcon Heavy’s 27 Merlin 1D engines would produce 63.5 tonnes thrust at sea level, nearly 1.5 times more than the Merlin 1C engines that powered the first two Falcon 9 rockets.
Using the new engines, combined with propellant crossfeeding from the twin boosters to the central core, Falcon Heavy would be able to lift a surprising 53 tonnes to LEO, 19 tonnes to GTO, or 13.6 tonnes toward Mars. Plans called for the first Falcon Heavy to fly a demonstration mission in 2013 from Vandenberg AFB Space Launch Complex 4 East, the former Titan 4 pad.
Falcon Heavy as Originally Presented by SpaceX, April 2011
Falcon 9 v1.1 was divulged with much less fanfare. It would be a two-stage rocket powered by nine Merlin 1D engines off the pad. This Falcon 9, substantially more capable than either Falcon 9 or the originally planned Falcon 9 Block 2 version, would, according to a briefly released information sheet that was swiftly withdrawn, would be able to lift 16 tonnes to LEO or 5 tonnes to GTO, would stand 69.2 meters, and would weigh 480 tonnes at liftoff. The company continued to show Falcon 9 Block 2 as the baseline in its Payload Users Guide, but Falcon 9 v1.1 clearly was more than a “block” upgrade.
Weighing 50% more, standing one-third taller, powered by brand new engines, using new tank and thrust structures, and using new launch equipment, Falcon 9 v1.1 was for all practical purposes a brand new rocket.
On April 25, 2011, Elon Musk, in a Space News interview, confirmed that Falcon Heavy would use a “stretched” Falcon 9 stage augmented by two additional “first stages”.
He stated that Merlin 1D would fly in mid-2012 on a Falcon 9 mission, most likely on the seventh flight of the rocket. (This, of course, turned out to be over-optimistic.) Mr. Musk described how the Merlin 1D combustion chamber was being explosively formed, streamlining the production process. He noted that a fully integrated Merlin 1D was already being test-fired.
Design details of Falcon Heavy, and of Merlin 1D performance, were not provided at the time. In order to achieve the payload capability claimed by SpaceX, the new rocket engine would have to provide improved specific impulse and the stages would have to provide very high, almost unrealistic and certainly unprecedented, propellant mass ratios. SpaceX claimed that the two “first stage” strap-on units would achieve a 30 to 1 gross mass to dry mass ratio, implying an unprecedented propellant mass fraction of better than 0.966.
Falcon 9 v1.1
Falcon 9 Block 1 and Falcon 9 v1.1 Comparison
Falcon 9 v1.1 itself was not named in public until May 14, 2012, when NASA announced that it had modified its Launch Services (NLS) II contract with Space Exploration Technologies (SpaceX) by adding a new “Falcon 9 v1.1” variant to the program. The modification allowed SpaceX to offer “Falcon 9 v1.1” in competition for future launch contracts.
An image of “Falcon 9 v1.1” was provided during a presentation made on March 9, 2012 by Jeffrey White, an Iridium Director. The image showed a stretched Falcon 9, with both stages stretched.
It also showed, compared to Falcon 9 Block 1, shortened interstage and propulsion sections. The bigger rocket appeared to be outfitted with Merlin 1D engines, possibly in a rearranged configuration. An octagonal arrangement, with a ninth, center engine, was suspected by outside observers.
“Falcon 9 v1.1” represented an improvement over the long-expected “Falcon 9 Block 2” that, originally, was to be powered by improved Merlin 1C engines. The SpaceX user’s guide continued to show outmoded “Block 2” performance data as of May 14, 2012, but the SpaceX web site was updated with v1.1 performance numbers on June 6 or 7, 2011.
Payload to was shown to be 13.15 tonnes to a 185 km x 28.5 deg low earth orbit, 4.85 tonnes to a 185 x 35,788 km x 28.5 deg geosynchronous transfer orbit, or 2.9 tonnes to escape velocity.
The Merlin 1D powered “Falcon 9 v1.1” was apparently set to be the building block for the company’s announced Falcon Heavy, but “v1.1” clearly would be a substantial performer in its own right, pushing deep into EELV payload territory.
Drawing of Falcon Erector at Vandenberg AFB SLC 4E was Presented During February 2013 Press Tour of Launch Site
Falcon 9 v1.1 was expected to premier at Vandenberg AFB Space Launch Complex 4 East during 2013. During a May 18, 2012 interview, Elon Musk said that all Falcon 9 rockets after the first five would be 1.1 versions. He also referred to the original Falcon 9 as “v1.0”.
A massive construction effort neared completion at SLC 4E during early 2013. The rebuilt flat pad had a massive fixed launch vehicle erector similar to the type used by Delta IV. It also had a big horizontal hanger connected to the pad by a curved roadway, consistent with use of a wheeled transporter.
An extension of the Cape Canaveral SLC 40 Hanger was noted during May, 2012 to accomodate the longer rocket. Construction of a new transporter/erector system at SLC 40 was being performed during the early months of 2013.
Also read: SpaceX Falcon 9 v1.1 Full Thrust
Merlin 1D
Merlin 1D Development Testing During 2012
Merlin 1D development was well underway by the time of the April 2011 announcement. Its explosively formed chamber dispensed with the tube-wall chamber construction of the Merlin 1C. The engine as originally announced would produce 63.5 tonnes thrust at sea level and 70.31 tonnes thrust in vacuum. Its vacuum specific impulse was target to be 310 seconds.
The engine had an expansion ratio of 16, a chamber pressure of 1,410 psi, and an ability to throttle down to 70%. It also would have an unprecedented 150:1 vacuum thrust to weight ratio.
During the August 2011 Joint Propulsion Conference, SpaceX VP of Propulsion Tom Mueller said that the Merlin 1D test engine had demonstrated a vacuum thrust to weight ratio greater than 150:1 and a vacuum specific impulse greater than 309 seconds.
He also said that the engine had performed a 185 second long burn at up to 66.68 tonnes thrust. Engine data was subsequently updated to show 66.68 tonnes sea level thrust, 73.03 tonnes vacuum thrust, a sea level specific impulse of 282 seconds, and a vacuum specific impulse of 311 seconds. This was believed to be the highest specific impulse ever achieved by a gas-generator cycle first stage kerosene rocket engine.
On March 20, 2013 SpaceX announced that the Merlin 1D engine had completed flight qualification testing. During the 28-test program, Merlin 1D completed 1,970 seconds of total test time, the equivalent of more than 10 full duration missions. The program included four tests at or above the 66.68 tonnes sea-level thrust and 185 second duration needed for a Falcon 9 v1.1 flight. The testing took place at SpaceX’s McGregor, Texas facility.
Merlin 1D Vacuum
Merlin 1D Vacuum Testing at McGregor
A single Merlin 1D Vacuum version would power the Falcon 9 v1.1 second stage. In September, 2012, SpaceX provided an image of a Merlin 1D Vacuum engine being tested. The engine will be fitted with an extended nozzle, not shown in its ground test image, to improve specific impulse. The specific impulse has not been announced, but it will likely exceed the 311 seconds listed for the first stage engine.
Grasshopper
Fifth Grasshopper Flight Reached 250 Meter Altitude
In late 2012, SpaceX began test program that at the time seemed to be an expensive research-oriented side show. It later turned out to be a key part of Falcon 9 v1.1 development effort. The effort was called “Grasshopper”.
Grasshopper was a vertical takeoff vertical landing test vehicle. It was composed of a Falcon 9 first stage fitted with a single Merlin 1D engine and, at its base, a massive landing leg structure. Four fixed landing legs supported the stage both prior to takeoff and upon landing.
Grasshopper took off and landed on a concrete apron at McGregor, using no hold-down arms or other similar launcher equipment. The vehicle flew 2.5 meters off the ground in September, 2012. It rose 5.4 meters in November and 40 meters in December. In March, 2013, it flew to an 80.1 meter height where it hovered briefly before returning to land. In April, 2013, Grasshopper rose to 250 meters. SpaceX provided a dramatic helicoper-based aerial view of that flight.
On March 28, 2013, Elon Musk announced that Falcon 9 v1.1 would perform similar “fly-back” tests during early missions. After separation, the stage would fire its center engine to scrub horizontal velocity, vastly reducing reentry heating. It would then attempt to restart its engine just before it hit the ocean to demonstrate a final vertical velocity reduction.
It became clear that the company planned to eventually develop a “fly back” version of its Falcon 9 v1.1 first stage. Such a stage would actually return to its launch site for a propulsively controlled vertical landing using deployable landing legs that would be much lighter than those fitted to Grasshopper. Musk noted that testing of such a system would take awhile and that a successful reentry was not necessarily expected during the initial tests. A fly-back test would not occur for many months at the earliest.
First Flight Preparations
Falcon 9 v1.1 Payload Fairing Testing Preparations at Plum Brook Station near Sandusky, Ohio in March, 2013.
The big test stand at McGregor was modified to accept the larger, more powerful v1.1 first stage during late 2012. An entirely new ground-level test stand was also under construction during this time. The new stand, which appeared to use a water deluge system to dampen accoustic energy, was likely being constructed for Falcon Heavy testing.
Structural Falcon 9 v1.1 first and second stage structural test articles were seen at McGregor during late 2012 and early 2013. The structural test stands previously built for Falcon 9 v1.0 had to be stretched to handle the longer stages.
On satellite launch missions, Falcon 9 v1.1 would use a large, never-flown payload fairing. During late 2012 and early 2013, SpaceX installed a test version of its new 5.2 meter diameter fairing in NASA’s massive Plum Brook Station vacuum test chamber in Sandusky, Ohio. The fairing, with a 13.9 meter usable length, was to perform separation testing with the chamber pumped down to near-vacuum conditions.
The first Falcon 9 v1.1 flight first stage was shipped from Hawthorne to McGregor during March 2013, where it was erected onto the big test stand. An initial 10 second test was planned to take place in early May. Assuming all goes well, a full three-minute test would follow several days later.
The first flight of the Falcon 9 with Merlin 1D engines was expected to launch Canada’s Cassiope, a 360 kg weather research and communications satellite into an elliptical low earth orbit from Vandenberg SLC 4E. A second flight would lift 3.6 tonne SES-8 to geosynchronous transfer orbit from Cape Canaveral SLC 40.
Vehicle Configurations
| LEO Payload (metric tons) 185 km x (1) 28.5 deg (CC) (2) 98 deg (VA) (3) 9.1 deg (KW) (4) 51.6 deg (CC) | Geosynchronous Transfer Orbit Payload (metric tons) 185×35,788 km x 28.5 deg ~1,800 m/s from GEO | Escape Velocty Payload C3=0 km2/s2 | Configuration | Liftoff Height (meters) | Liftoff Mass (metric tons) | Price (2005) $Millions | |
| Falcon 9 Block 1 (Merlin 1C) 2010 | 9.0 t (1) 8.5 t (4) | 3.4 t | 2 t | 2 Stage Falcon 9 (Merlin 1C) + 3.6 m or 5.2 m PLF | 53 m | 318 t | $35-55 m (2007) |
| Falcon 9 v1.1 (Merlin 1D) >2013? | 13.15 t (1) | 4.85 t | 2.9 t (est) | 2 Stage Falcon 9 v1.1 (Merlin 1D) + 3.6 m or 5.2 m PLF | 69.2 m | 480 t | $54-59.5 m (2013) |
| Falcon Heavy >2013? | 53 t | 19 t | 13.6 t | 3 Falcon 9xMerlin 1D cores + 1xMerlinVac Upper Stage + PLF | 69.2 m | 1,450 t | $80-124 m (2013) |
Vehicle Components
| Falcon 9 Stage 1 – Block 1 Merlin 1C Version Estimated | Falcon 9 Stage 2 – Block 1 Merlin 1C Version Estimated | Falcon 9 Stage 1 – “v1.1” Merlin 1D Version Estimated | Falcon 9 Stage 2 – “v1.1” Merlin 1D Version Estimated | |
| Diameter (m) | 3.66 m | 3.66 m | 3.66 m | 3.66 m |
| Length (m) | ~29 m (est) not incl I/S | ~10.1 m incl I/S | ~42.6 m (est) not incl I/S | ~12.6 m incl I/S |
| Empty Mass (tonnes) | ~19.24 t? burnout | ~3.1 t? burnout | ~28 t? burnout | ~4.7 t? burnout |
| Propellant Mass (tonnes) | ~239.3 t? used | ~48.9 t? used | ~411 t? used | ~73.4 t? used |
| Total Mass (tonnes) | ~258.5 t? | ~52 t? | ~439 t? | ~78.1 t? |
| Engine | Merlin 1C | Merlin Vac | Merlin 1D | Merlin 1D Vac |
| Engine Mfgr | SpaceX | SpaceX | SpaceX | SpaceX |
| Fuel | RP1 | RP1 | RP1 | RP1 |
| Oxidizer | LOX | LOX | LOX | LOX |
| Thrust (SL tons) | 387.825 t | 598.75 t | – | |
| Thrust (Vac tons) | 442.938 t | 42.18 t | – | ~45 t? |
| ISP (SL sec) | 266 s | – | 282 s | – |
| ISP (Vac sec) | 304 s | 336 s | 311 s | ~340s? |
| Burn Time (sec) | 180 s | 346 s | – | – |
| No. Engines | 9 | 1 | 9 | – |
| Comments | – | – | – | – |
| Falcon 9 Payload Fairing | ||||
| Diameter (m) | 5.2 m | |||
| Length (m) | 13.9 m | |||
| Empty Mass (tonnes) | ~ 2.0 t? |
