On May 11 SpaceX successfully completed the maiden flight of its Falcon 9 Block 5—the first U.S. rocket that will take humans into space since the retirement of the space shuttle program.
Not only that, but Falcon 9 managed to deploy Bangladesh’s first telecom satellite and also successfully land the rocket’s first stage on the SpaceX drone ship.
Remember when we all saw the first videos of the Grasshopper technology demonstrator make its first vertical landing? That was only six years ago back in 2012. Now we see a rocket landing vertically, and it’s kinda meh. It’s pretty amazing how quickly revolutionary technologies become mundane, isn’t it?
But philosophical musings aside, the new Block 5 contains a whole bunch of recent upgrades that are designed to reduce costs; increase operational and manufacturing efficiency; and, above all, increase reliability and safety for the human crew.
Elon Musk spoke to reporters before the launch, and here are some highlights of the technological innovations that went into the Block 5.
Composite Overwrapped Pressure Vessel
Cast your mind back to September 9, 2016, when SpaceX lost one of its Falcon 9 rockets in a huge explosion during a test. That explosion was caused by a fault in one of the three composite overwrapped pressure vessels (COPVs) on board the rocket. The composite overwrapped pressure vessels contain high-pressure helium and nitrogen immersed in the fuel and oxygen tanks.
The failure was caused by oxygen accumulating between the COPV liner and overwrap in a gap in the liner, leading to ignition and the subsequent failure of the COPV and the loss of the vehicle and its payload. This time, Musk and company are taking no chances.
“The composite overwrapped pressure vessels—they're actually rated to twice. The burst pressure of the composite overwrapped pressure vessels must be more than twice what they're actually loaded to on the pads,” said Musk. “We have tested the daylights out of those things, 17 ways to Sunday. Because, obviously, we had that failure a few years ago and want to make sure that it's extremely robust.”
Musk is confident that the COPV problem has been resolved, and then some.
“This is by far the most advanced pressure vessel designed by humanity,” he said.
Increased Engine Thrust
The Merlin engines that power the lower and upper stages of the Falcon 9 already had the highest thrust-to-weight ratio of any rocket engine in the world. But SpaceX was not content with resting on its laurels.
“Engine thrust [of the lower stage] has been increased by approximately 8 percent to 190,000 pounds of thrust at sea level. We think there's probably a little more room there—maybe going up to 10 percent or so—as well as some small increases in specific impulse of a few seconds. So, both the efficiency of the engine and the thrust of the engine have increased, while not increasing—making any material change to the mass of the engine. The vacuum version of Merlin [second stage engines] increased in thrust by about 5 percent … to 220,000 pounds force.”
Increased Reusability
Reusability is the key to SpaceX reducing costs. The reason that spaceflight is so expensive is because traditional rockets are pretty much single use only. Imagine how much your vacation flight tickets would cost if you disposed of the aircraft as soon as it landed. That’s why spaceflight is expensive.
“The key to the Block 5 is that it’s designed to do 10 or more flights with no refurbishment between each flight,” said Musk. With refurbishment, the Block 5 is capable of being launched 100 times—that’s compared to the Block 4, which could be flown “upwards of 10 times, but with a fair amount of work between each flight,” said Musk. “Our goal—just to give you a sense of how reusable we think the design can be—we intend to demonstrate two orbital launches of the same Block 5 vehicle within 24 hours, no later than next year."
Human Rated
One of the biggest differences between a satellite launch vehicle and a human launch vehicle is in the margins of safety, which are related to the loads experienced by the spacecraft.
“A typical rule of thumb would be, for a launching a satellite, you need to design the rocket to 25 percent margins, like, essentially, if you take your worst-case flight load, worst possible scenario that the rocket would encounter, and then add 25 percent to that, the rocket has to be designed 25 percent above the worst-case expected load, for the case of a satellite launcher. For a human-rated launcher, it has to be designed to 40 percent above the worst-case load … that’s really difficult to do without making the rocket really heavy.”
Leg Latches
The landing legs help the returning first stage fix itself to the drone barge upon landing.
“The landing legs, you'll notice, if you look carefully that there are no sort of outward scallops on the perimeter of the landing leg, which were used to clamp down the leg during ascent. We have now brought those features inside the leg itself. So, you'll see sort of a cleaner outer contour. And it has an internal latch mechanism that can be opened and closed repeatedly, with ease.”
“So, essentially deploying the landing gear and stowing the landing gear is now a very easy thing to do, whereas previously it required several hours to restow the landing gear. [It] can now be done with an actuator very easily.”
Thermal Protection Material
Traveling through the thick soupy atmosphere at the hypersonic speeds that are required to reach orbit tends to get a little hot. Thermal protection is needed to protect the rocket and payload components. Previous Falcon 9 iterations relied on thermal paint for heat protection.
“If you look, aesthetically, there’s the black interstage. That is the structure that joins the upper and lower stage, as well as the raceways, the landing legs—they all use a new thermal protection material developed at SpaceX, which is highly reusable and does not require paint.”
Miscellaneous
In addition to all of the above, the Falcon 9 Block 5 has a better flight computer, engine controllers, and a new, more advanced inertial measurement system, all of which contribute to the new rocket’s enhanced reliability.
Musk says that this latest iteration will be the last block number to be developed, meaning that only incremental platform upgrades will occur in the future, as opposed to any major design changes that would justify a new block model. Instead, SpaceX will focus its major design work on developing the BFR Mars transport rocket.
BFR stands for “Big Falcon Rocket,” according to SpaceX president Gwynne Shotwell, but given that Musk has said the name was inspired by the BFG weapon in the Doom video games, the “F” could conceivably stand for something else.
As mentioned, the Block 5 will be the homegrown rocket that finally returns U.S. astronauts to space. So far, an unmanned test flight of the Crew Dragon spacecraft is scheduled to lift off to the International Space Station in August 2018. And, if all goes well, we could even see a crewed test flight by the end of the year.
Thanks to Mike Killian for his photos from the Block 5 launch. You can see more of his space and aviation pictures at MikeKillianPhotography.com.