SpaceX’s first Block 5 Falcon Heavy days away from critical static fire test


The first commercial launch of SpaceX’s Falcon Heavy rocket – this time in a Block 5 configuration – is as few as ten days away from a targeted window beginning at 6:36 pm EST (22:36 UTC), April 7th. That target hinges on whether Falcon Heavy is ready and able to roll out to Pad 39A and successfully conduct its first integrated static fire, currently scheduled on April 1st.

The payload for this mission – communications satellite Arabsat 6A – had its original Lockheed Martin manufacturing and SpaceX launch contracts signed back in the first half of 2015, while the 6000 kg (13,200 lb) spacecraft was effectively completed once it was shipped from California to Florida at the start of 2019. After approximately 12 months of delays from an original launch target shortly after Falcon Heavy’s 2018 debut, Arabsat 6A’s four-year journey will hopefully reach completion in a geostationary transfer orbit. At the same time, the US Air Force says that it will be watching this launch – and the one meant to follow soon after – as a critical test along the path to fully certifying the powerful rocket for military launches.

As a pathfinder for an unproven rocket, SpaceX’s first Falcon Heavy launch suffered a number of likely minor to moderate anomalies as company engineers and technicians learned for the first time how the rocket actually behaves in the real world, under real-world conditions and operations. Case in point, the first integrated Falcon Heavy was taken through its first wet-dress rehearsal – in which the vehicle is filled with a flight load of fuel and oxidizer – on January 11th. An anomaly required additional work and took nearly two weeks to resolve, culminating in the rocket’s first (and successful) static fire on January 24th. An additional two weeks after that, SpaceX went ahead with the first attempted launch of Falcon Heavy with great success, pushing the T-0 back several hours due to weather but ultimately completed an almost flawless debut, aside from an anomaly that caused the center core to impact the ocean surface at high speeds.

Despite the invaluable experience gained by those orchestrating the launch and those who built the vehicle, Falcon Heavy’s second launch may result in similar teething pains, particularly due to the fact that the rocket’s complete upgrade to Block 5 hardware likely necessitated significant design changes across the board. In other words, the rocket SpaceX aims to launch in early April may be quite a bit different from the vehicle that launched 14 months prior, creating much of the same uncertainty inherent in the first launch(es) of any new rocket. Still, many of the complex boosters’ connection and separation mechanisms that were flight-tested for the first time that February were likely more or less unchanged in the move from Block 2/3 to Block 5 hardware.

Falcon Heavy prior to its first static fire test, January 2018. (SpaceX)

“Again, I don’t want to tempt fate. But this is a much stronger octaweb structure. It’s made of a much higher strength of bolted aluminum. A 7000 series instead of a 2000 series. So the strength of the octaweb is dramatically greater. It also has quite a bit of thermal protection in case there’s say, an engine fire, or something like that. Such that it does not melt the octaweb.” – SpaceX CEO Elon Musk, May 2018

“Biggest process change [for Block 5] was eliminating Tig welding of the thrust structure or “Octaweb” and the move to a bolted design but this made it much easier and faster to produce overall as well.” – SpaceX VP of Production Andy Lambert, April 2018

A step further, SpaceX CEO Elon Musk has indicated that one major section of Block 5 upgrades – moving from a welded to a bolted thrust structure (i.e. octaweb) – was expected to be a boon for Falcon Heavy, while also making octawebs far easier to manufacture, assemble, and even disassemble. According to Musk, new bolted octawebs are also “dramatically” stronger, a boon for Falcon Heavy boosters – particularly the center core – that need to survive forces multiple times stronger than those subjected upon Falcon 9 first stages.

Falcon 9’s engine section is an extremely strong structure known as an octaweb. (SpaceX)

Meanwhile, according to comments made by Air Force officials to Spaceflight Now, the USAF is looking at SpaceX’s Arabsat 6A and subsequent STP-2 Falcon Heavy launches as critical steps along the way to fully certifying the rocket for valuable military payloads. Currently, the only option available for military and NRO payloads past a certain weight or in need of exceptionally high-energy orbits is ULA’s Delta IV Heavy rocket, an extremely expensive ($300M+ per launch) rocket with a bad track record of schedule reliability.

An Air Force spokesperson this week confirmed the agreement to use previously-flown side boosters for the STP-2 mission. The center core will be new for the Arabsat 6A and STP-2 launches.

“This provides an early opportunity for the Air Force to understand the process for using previously-flown hardware with the goal to open future EELV missions to reusable launch vehicles,” the spokesperson said in response to an inquiry from Spaceflight Now.

Given that STP-2 will need to reuse both of the Arabsat 6A Falcon Heavy’s side boosters, the USAF official also specifically noted that the military branch would be examining SpaceX’s refurbishment processes and the performance of the flight-proven stages with the intention of ultimately allowing reused rockets to launch military satellites. As such, the successful launch, landing, refurbishment, and re-launch of both Falcon Heavy side boosters (B1052 & B1053) will be doubly critical for SpaceX.

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SpaceX’s first Block 5 Falcon Heavy days away from critical static fire test
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