SpaceX Falcon Heavy

Falcon Heavy Launch from KSC LC 39A as Illustrated in Early 2015

Falcon Heavy is a planned modular growth version of the existing two-stage SpaceX Falcon 9 that may become the world’s heaviest lifting rocket when it enters service.  With two strap-on liquid boosters augmenting a two-stage core, the 68.4 meter tall rocket will weigh 1,462.8 tonnes at liftoff and will rise on the combined 1,800 tonnes of sea level thrust produced by 27 Merlin 1D engines, according to the SpaceX web site. 

In a fully expendable configuration, SpaceX says that Falcon Heavy will be able to lift more than 45 tonnes to a 28.5 deg low earth orbit (LEO), or about 18 tonnes to a  27 deg inclination geosynchronous transfer orbit (GTO) from Florida.  If propellant crossfeed from the boosters to the central core was implemented, LEO payload would exceed 53 tonnes and  GTO payload would reach 21.2 tonnes. 

Since these capabilities exceed by far any known prospective government or commercial payloads, it seems likely that SpaceX will surrender much of this performance to recover the booster and core stages.  Company images have shown landing legs and grid fins on the big stages. 

An $85 million price has been advertised to lift only 6.4 tonnes to GTO, far below the 21.2 tonne expendable crossfeed possibility.  Plans have been announced to build landing pads at the former site of Cape Canaveral’s Launch Complex 13, one of the original “ICBM Row” Atlas launch sites, to recover Falcon Heavy boosters.  Such landings would require full boost-back burns that would use more propellant than any recovery attempts performed to date by Falcon 9 v1.1 first stages.

As of February 2015, even as its launch pads and initial hardware are being built, many Falcon Heavy details remain mysterious outside SpaceX.    

Falcon Heavy History

Since September 2005, when it originally announced plans to develop Falcon 9, SpaceX had projected future heavy-lift variants of its kerosene/LOX rocket.   Early plans would have added two Falcon 5 first stages as strap-on boosters to a central Falcon 9 first stage to create a “Falcon 9S5”.  A “Falcon 9S9” would have used three parallel Falcon 9 stages.  “9S5” would have lifted more than 16 tonnes to low Earth orbit (LEO).  “9S9” would have boosted more than 24 tonnes to the same orbit. 

In 2006, SpaceX announced that it would develop a new regeneratively cooled Merlin 1C, replacing the ablatively-cooled Merlin 1B originally planned to power the Falcon family.  A new Falcon 9 Heavy, projected to be able to launch more than 29 tonnes to LEO or 15 tonnes to geosynchronous transfer orbit (GTO), resulted.  Although the Heavy did not officially enter development during this time, since the basic Falcon 9 effort was then-underway, the larger launch vehicle was always listed as part of future plans 

In April 2008, SpaceX described plans for an even more-powerful Merlin 1C that would power a “Block 2” version of Falcon 9.  The upgraded Merlin 1C would produce 56.69 tonnes of sea-level thrust and 63.45 tonnes of thrust in vacuum, a substantial increase from the 43 tonnes of sea-level thrust produced by the “Block 1” Merlin 1C.   A “Block 2” version of Falcon 9 Heavy was not announced, leading some to believe that SpaceX had shelved plans for the bigger rocket.  It was apparent, however, that a “Block 2” version, if it were developed, would be able to lift more than 30 tonnes to LEO. 

Falcon Heavy as Announced in 2011

In 2010, the first two “Block 1” Merlin 1C-powered Falcon 9 rockets flew successfully.  The second launch orbited the COTS 1 demonstration Dragon spacecraft, which was successfully recovered after reentery.  Then, on April 5, 2011, SpaceX announced that it would develop the long-suspected “Block 2”, which would essentially be a new rocket.  Press attention focused on the triple-body Falcon Heavy rocket shown in press release materials the same day, but the real story was about the new upgraded Merlin 1D engine that would power both rockets.  The new two-stage core version would become known as Falcon 9 v1.1.    

As originally announced, 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.  Performance announced at the time included 53 tonnes to LEO, 19 tonnes to GTO, or 13.6 tonnes toward Mars using crossfeed.  Plans called for the first Falcon Heavy to fly a demonstration mission in 2013 from Vandenberg AFB Space Launch Complex 4 East, where the former Titan 4 pad was to be rebuilt. 

With its planned Vandenberg AFB launch site, the Falcon Heavy demonstration mission seemed designed to show the Pentagon that Falcon 9 could handle EELV-type defense missions.  Only Vandenberg could support launches to near-polar orbits typically used for reconnaissance missions.  At the same time, Elon Musk announced plans to launch Falcon Heavy from Florida, either from a reconfigured SLC 40 at Cape Canaveral or from a mothballed Shuttle pad at Kennedy Space Center.

Vandenberg Launch Site

On July 13, 2011, SpaceX broke ground on the SLC 4 East reconstruction project.  The big Titan 4 fixed and mobile towers were replaced by a “flat” pad and a new Horizontal Integration Facility (HIF).  A giant wheeled transporter-erector was built to move assembled rockets from the HIF to the pad.  The erector also served as an umbilical tower.  When it reached the pad, powerful hydraulic cylinders would erect it and the rocket. 

SLC 4E Under Construction with Transporter-Erector at Pad, HIF in Background

In the end, the SLC 4E inaugural launch was performed by the first Falcon 9 v1.1, the sixth Falcon 9.  After a five week campaign, the rocket lifted off on September 29, 2013 at 16:00 UTC with Canada’s 500 kg Cassiope and with five small cubesats that together weighed about 100 kg, bound toward a planned 300 x 1,500 km x 80 deg orbit. 

The flight was the first for Falcon 9 with a payload fairing, the first powered by Merlin 1D engines, the first use of the new “Octaweb” thrust section, and featured the first attempt to slow the first stage for a reentry and water landing. 

The attempt was performed by re-igniting three of the first stage engines after staging, about 7 minutes 45 seconds after liftoff.  This hypersonic reentry burn slowed the stage to reduce reentry heating.  A second re-ignition of only the center engine also occurred shortly before impact with the Pacific Ocean, but roll rates on the stage quickly exceeded the control ability of the reaction control system.  The roll rate pushed propellant toward the tank edges, causing the engine to shut down.  The stage fell, impacted the ocean, and broke into pieces.  

KSC Launch Complex 39A

After the final Space Shuttle launch in 2011, which took place from Kennedy Space Center LC 39A, NASA sought parties who might be interested in using the historic launch site.  The ocean-side pad had hosted the first Saturn V launch, the first manned lunar orbital and landing missions, and the first space shuttle launch, among other accomplishments.  

United Launch Alliance, SpaceX, and Blue Origin, among others, expressed interest.   In the end, NASA awarded SpaceX a 20-year lease of the site during April 2014.   The company revealed that it intended to debut Falcon Heavy on a “Demosat” mission from LC 39A. 

On May 20, 2014, NASA removed MLP 2 from LC 39A, marking the final run of a Saturn V era crawler transporter to the launch pad.  SpaceX soon took over the complex and began constructing a new HIF right on top of the crawlerway just outside the LC 39A fence line.

  It also began modifying the launch pad itself, while keeping the existing service tower and rotating service structure.  Kerosene infrastructure began to be returned to the pad for the first time since the days of Saturn V.  Plans called for a transporter erector to carry Falcon Heavy from the HIF up the incline to the pad using two new railroad tracks, rather than on a wheeled transporter as at SLC 4E.  Rocket exhaust would be diverted through a rebuilt flame trench toward the north by a modified flame diverter.

SpaceX hoped to have the site ready for testing during 2015.

Falcon Heavy Description

View of Octaweb Merlin 1D Engine Configuration at SpaceX Hawthorne Factory

Falcon Heavy was expected to be based on existing Falcon 9 v1.1 hardware.  The first stage and boosters would use the Octaweb design with nine Merlin 1D engines in a circle of eight surrounding one configuration.  The stages would also be equipped with four extendable landing legs and four grid fins for recovery attempts.

Illustrations sometimes showed boosters that were longer than the core stage.  On other occasions the stages were shown to be identical.  Some illustrations showed the same second stage used by Falcon 9 v1.1.  Other drawings showed a stretched second stage.  Some reports suggested that propellant densification by cooling would be used to increase propellant loading.  As with Falcon 9 v1.1, the actual configuration would likely only become known when the rocket was erected on the launch pad for the first time.   

The actual thrust of the Merlin 1D engines became another unknown during 2015, when SES announced that its pending Falcon 9 v1.1 launch would be the first to use higher-thrust Merlin 1D engines.  Thrust was said to be increasing by 20%.  Would Falcon Heavy use these higher-thrust engines? 

The stages were expected to be 3.66 meters in diameter and to use lightweight Aluminum Lithium tanks assembled using friction stir welding machines at the Hawthorne, California factory.   The interstage, 5.2 meter diameter payload fairing, and booster nose cones, among other components, would use carbon composites.

  The Merlin Vacuum second stage engine would produce 81.65 tonnes of thrust and would burn for up to 375 seconds.  The core stage would throttle back to allow the boosters to burn out and separate well before the core stage completed its burn. 

Booster and core stage recovery will apparently reduce GTO performance by about 50% from its expendable version maximum.  If only the boosters are recovered and the core first stage is expended, GTO performance will likely be reduced by about 30% from its expendable maximum. 

Propellant crossfeed was not expected to be implemented at first, if ever, but was shown as an ultimate performance option.  Only time will tell which modes of operation SpaceX will end up using.  Both the viability of recovery itself and the cost effectiveness of recovery and reuse remained unproven as of February 2015.

Also read: X Falcon 9 v1.1 – Space Launch Report

Planned Flights

On May 29, 2012, Intelsat announced that it had selected Falcon Heavy to launch one of its satellites to GTO, becoming the first commercial customer for the rocket.  During December of the same year, Falcon Heavy won the $165 million U.S. Air Force Space Test Program 2 mission, which would fly from Florida. 

This was Falcon Heavy’s first government launch contract.  During July, 2014, Inmarsat announced that it had signed contracts for up to three Falcon Heavy launches to GTO, with the first satellite expected to weigh 5.9 tonnes and to fly in 2016.   In early January, 2015, ViaSat Inc. announced that it had also decided on Falcon Heavy to launch 6.4 tonne ViaSat-2 to GTO in mid-2016.   

The inaugural Falcon Heavy mission was expected to be a demonstration mission without a paying satellite customer from KSC LC 39A, possibly before the end of 2015 but just as likely in 2016.  Before the inaugural launch can occur, SpaceX will need to build and test Falcon Heavy. 

By February 2015, the company had built structural test articles that it planned to test at its McGregor, Texas site.   A big new static test stand at McGregor, with a deep below-grade exhaust trench, would host what would likely be a long series of static tests with three clustered stages firing together for the first time.  The launch site would need to be completed and tested, a process that would culminate in the static firing of a Falcon Heavy on the launch pad. 

Vehicle Configurations

Vehicle Components

Falcon Heavy Flight Log

Date    Vehicle        No.   Payload               Mass   Site    Orbit (kmxkmxdeg)
————————————————————————————-
–/–/15 Falcon Heavy  FH-1  Demo Flight 1                KC 39A                 ???
–/–/16 Falcon Heavy  FH-2  STP-2 (GPIM)                 KC 39A                 ???
–/–/16 Falcon Heavy  FH-3  ViaSat 2              5.9 t  KC 39A                 GTO
–/–/17 Falcon Heavy  FH-3  Intelsat              6.4 t  KC 39A                 GTO
————————————————————————————-

KC = Kennedy Space Center, Florida
VA = Vandenberg AFB, California