SpaceX successfully debuts Falcon Heavy in demonstration launch from KSC

by Chris Gebhardt

The long-awaited and much anticipated heavy lift rocket from SpaceX has become the most powerful and capable rocket presently in service around the world after its debut launch from LC-39A at the Kennedy Space Center on Tuesday, 6 February. The historic launch set sail near the end of its available window at 15:45 pm Eastern.

Falcon Heavy:

The highly-anticipated heavy lift rocket, the Falcon Heavy, has become the most powerful and capable rocket currently in service around the world.

Standing 229.6 ft (70 m) tall and 39.9 ft (12.2 m) wide and producing 5,548,500 pounds of thrust, max, in vacuum, the Falcon Heavy is capable of placing:

  • 140,660 lbs (63,800 kg) into Low Earth Orbit,
  • 58,860 lbs (26,700 kg) into Geosynchronous Transfer Orbit (GTO), and sending
  • 37,040 lbs (16,800 kg) to Mars.

The inaugural Falcon Heavy on LC-39A at the Kennedy Space Center. Credit: SpaceX

For context, the Mars Curiosity rover and needed equipment sent to Mars by an Atlas V rocket (in its 541 – four solid rocket motors – configuration) weighed 8,583 lbs (3,893 kg) – compared to FH’s ability to send 37,040 lbs to Mars.

For GTO missions, the Delta IV Heavy is the closest U.S. competitor to Falcon Heavy and can take 31,350 lbs (14,220 kg) to GTO (compared to FH’s 58,860 lbs GTO capability).

Even more impressively, Falcon Heavy is capable of sending 7,720 lbs (3,500 kg) of payload to Pluto – more than seven times the mass of NASA’s New Horizons spacecraft which was launched by the most powerful variant yet flown of the Atlas V, the 551 with five solid rocket motors.

These payload capabilities are extremely impressive and will provide a greater payload capacity to space at a much lower price than is currently available from other rocket providers, with a starting baseline price of just $90 million USD for a Falcon Heavy.

However, Falcon Heavy is not be the most powerful rocket to take flight from the Kennedy Space Center’s LC-39A.

Comparison between Low Earth Orbit (28 degree orbital inclination) payload lift capability of the Falcon Heavy and a select group of other rockets. Credit: SpaceX

That honor goes to the mighty Saturn V, which produced 7.891 million pounds of thrust and could take a whopping 310,000 lbs (140,000 kg) to LEO.  The Space Shuttle also produced more thrust at liftoff and could take a roughly 200,000 lb Orbiter and up to ~53,000 lbs of additional cargo in its payload bay into LEO.  However, by deployable payload to LEO, Falcon Heavy will greatly outperform the Shuttle.

Overall, Falcon Heavy’s development has been a well-documented learning curve for SpaceX, with the complexity of the vehicle and its 27 first stage engines at the heart of that.

With 27 engines powering the first stage, Falcon Heavy is the U.S. rocket with the most number of first stage engines, and in fact is only eclipsed historically worldwide by the Soviet N1 rocket, which had 31 first stage engines.

Due to this complexity and the teething issues worked through for its static fire last month, it was possible Falcon Heavy would have needed more time than just its opening launch day window to get off the ground.

This is true of all launch attempts for all rockets, and it is equally true that each launch attempt holds the possibility of a rocket lifting off on time without issue.

In fact, SpaceX’s static fires of all boosters before their opening launch attempts are specifically designed to ferret out issues with the rocket and the ground systems so that launch day campaigns run smoothly – as has been seen numerous times with the company’s Falcon 9.

Moreover, for historical context, the Saturn V launched on its very first attempt on 9 November 1967, and SpaceX’s own Falcon 9 launched on its very first launch attempt on 4 June 2010.

With static fire and Launch Readiness Review (which was held over the weekend) complete, SpaceX turned towards final launch preparations for Falcon Heavy and the start of its launch countdown.

Launch timeline/events:

The overall launch countdown followed the timing and sequence of that used by the Falcon 9, with RP-1 rocket-grade kerosene loaded into the three Falcon 9 cores that make up the first stage of the Falcon Heavy beginning at T-85 minutes… a moment also known as the start of the autosequence countdown.

A fueled Falcon Heavy sits on LC-39A. Credit: SpaceX

From this point on, every fueling and system activation/checkout was handled automatically by SpaceX’s ground computers and the Falcon Heavy’s onboard flight computers.

The start of RP-1 kerosene load into the second stage followed several minutes later – timed to allow RP-1 second stage fueling to conclude in the final minutes of the count.

At T-45 mins, densified Liquid Oxygen (LOX) loading into the three first stage cores commenced.  Like with RP-1 fueling, densified LOX fueling of the second stage began several minutes later to allow second stage LOX load to end around 3 minutes prior to liftoff.

In the final minute of the automated count, the Falcon Heavy entered “start up” – the final sequence of alignments of the rockets various systems that fly the vehicle off the pad.

Falcon Heavy launches from 39A

At T-30 seconds, with all fueling complete and propellant lines purged and ready for launch, the Launch Director confirmed that the entire launch team is still “go for launch”.

In the seconds prior to engine start, Pad 39A’s upgraded sound suppression water system began dumping and shooting water onto the base of the TEL (Transporter/Erector/Launcher) and the Falcon Heavy to dampen the sound energy produced by the power of the 27 Merlin 1D engines.

At T-3 seconds, the engine start command sequence began, with Falcon Heavy’s onboard computers triggering a staggered start sequence of the rocket’s 27 engines in the same approach used and tested during the Falcon Heavy’s first and only static fire on 24 January 2018.

Chamber ignition of the 27 Merlin 1D engines then occurred, with all engines reaching maximum sea-level thrust very quickly and undergoing immediate health checks.

Falcon Heavy’s engines ignite as the massive rocket prepares for its maiden launch. Credit: Nathan Koga for NSF/L2.

With all showing green with engine start, at T-0 the Falcon Heavy’s onboard computers commanded the T0 umbilicals in the six Tail Service Masts (TSMs) at the base of the TEL as well as the T0 umbilicals on the TEL itself for the second stage and payload fairing to separate from the rocket.

The TSMs feed propellant into the three first stage cores and provide all the electrical and data connections between Falcon Heavy’s cores and the ground.

At the same time, Falcon Heavy’s onboard computers triggered the release of the eight hold down clamps that kept the rocket firmly attached to the reaction frame of the TEL.

The moment the hold down clamps release, Falcon Heavy was producing 5.1 million pounds of thrust and lifted off from LC-39A at the Kennedy Space Center to begin her maiden flight.

Falcon Heavy lifts off from LC-39A on its maiden voyage. Credit: Nathan Koga for NSF/L2

Once liftoff occurred, Falcon Heavy rose vertical from 39A before slowly pitching over onto a course that resulted in a 29 degree inclination to Earth’s equator.

The massive vehicle then began its downrange journey from Kennedy, heading out over the Atlantic Ocean on an easterly trajectory from the pad.

As the vehicle climbed through MaxQ (moment of greatest mechanical stress on the vehicle) and passed out of the dense lower atmosphere, its total thrust increased from 5.1 million pounds to over 5.5 million pounds.

Just over 2 minutes after liftoff, Falcon Heavy’s onboard computers command shutdown of the two outboard, side boosters and the start of their separation sequence.

General overview of Falcon Heavy’s flight profile. Credit: Original Artwork Design by SpaceX for Falcon 9; Falcon Heavy Version by Jerome Strach

The two side cores separated at the same time.  As this happens, the portions of the attach struts bolted to the two side cores retracted into protective cradles on the side cores.  At the same time, the parts attached to the center core retracted into the center core.

In this way, the struts can be returned for examination and potential refurbishment and reuse.

Once the two side cores are in free flight, NASASpaceflight understood that two options are available for the side boosters’ return timelines to Cape Canaveral. These options were confirmed by Elon Musk via the retweeting of the above graphic.

One plan involved staggering the timing of post-separation events between the two side boosters by ~15 seconds.

Falcon Heavy’s two side boosters fly back in formation toward LZ-1 and LZ-2 at Cape Canaveral Air Force Station. Credit: Nathan Koga for NSF/L2

Under this plan, immediately after separation, side booster #1’s cold gas thrusters fires to reposition the core into the proper orientation for the Boostback Burn – which would begin immediately.

Side booster #2 would also use its cold gas thrusters to flip itself around, but its Boostback Burn would not begin right away.  Instead, it would maintain attitude control via its cold gas thrusters but would wait approximately 15 seconds before beginning its Boostback Burn.

As such, side booster #1’s Entry Burn would occur ~15 seconds before side booster #2’s, and booster #1 would land back at Cape Canaveral ~15 seconds before side booster #2 lands just 500 feet away.

The second option involves both side boosters performing their Boostback, Entry, and Landing burns together and touching down simultaneously 500 ft apart from one another on LZ-1 and LZ-2. This turned out to be the reality.

As the two side boosters began their journeys back to Cape Canaveral’s landing pads, the remaining part of Falcon Heavy – essentially a regular Falcon 9 at this point with a single core of 9 Merlin 1D engines, a second stage, and a payload – continued on to orbit.

The center core continued to fire its engines after side booster separation, accelerating the remaining stack for several more seconds before the center core was commanded to shutdown and separate.

The separation occurred at a higher velocity than is usually seen on single stick Falcon 9 flights given the extra power and performance from three boosters working together for over two minutes.

The now free-flying center core used its cold gas thrusters to flip itself around as it begins pinpoint targeting of the ASDS (Autonomous Spaceport Drone Ship) Of Course I Still Love You positioned, according to launch hazard documents, 212 miles (342 km) downrange from LC-39A. The center booster didn’t successfully make it back to the Drone Ship.

For the second stage, once the center core separated, the second stage’s single Merlin MVac engine – optimized for use in a vacuum – ignited to continue bringing the Falcon Heavy’s first payload to orbit.

The next major event was payload fairing separation.  

Once preliminary orbital insertion was achieved, the second stage engine shut down, and the entire second stage and payload was in an Earth parking orbit – a stable orbit around Earth for final checkouts and preparations for the next burn.

The SpaceX Roadster to Mars

After a coast phase, the second stage reignited for the Trans Mars Injection burn – a burn that accelerate the second stage and its Tesla Roadster payload into an Earth-escape velocity, sending the duo into a Mars-distance heliocentric orbit.

A Mars-distance heliocentric orbit is an orbit around the sun that reaches its farthest point (aphelion) at the same orbital distance as Mars – roughly 141 million miles, or ~1.5 AU from the Sun).

Very importantly, the second stage and Tesla Roadster are not going to Mars.  They are going to Mars orbital distance.

Overall, the maiden flight of Falcon Heavy is designed to validate the rocket’s overall performance while also providing flight data to support the various models already developed and run regarding the vehicle.

Falcon 9 v. Falcon Heavy capability and services comparison. Credit: SpaceX.

The flight will also be a test of the Falcon family’s second stage and its ability to inject a payload into an orbit beyond that of Earth’s.

SpaceX has two more Falcon Heavy flights planned for this year.  One of those is the USAF STP-2 mission for the DoD which will fully certify Falcon Heavy for EELV (Evolved Expendable Launch Vehicle) national security missions for the U.S. Air Force set for launch in June.

In this case, the “Expendable” part of the EELV rocket program does not mean Falcon Heavy has to fly in a fully expendable configuration for the Air Force.  The name EELV is a holdover from the beginning of the program when only fully expendable Atlas V and Delta IV rockets were certified for critical Department of Defense satellite launches.  

Falcon 9 is currently a certified EELV program rocket, but has flown two missions for the US government (NROL-76 for the National Reconnaissance Office and the OTV-5 mission with the X-37B spaceplane for the U.S. Air Force) that saw boosters return to Cape Canaveral for landing, recovery, and reuse.

The other Falcon Heavy flight on the docket for this year is Arabsat 6A for Saudi Arabia.

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