Falcon 9 Block 5

Falcon 9 Block 5 is a partially reusable, human-rated, two-stage-to-orbit, medium-lift launch vehicle designed and manufactured in the United States by SpaceX. It is the fifth major version of the Falcon 9 family and the third version of the Falcon 9 Full Thrust. It is powered by Merlin 1D engines burning rocket-grade kerosene (RP-1) and liquid oxygen (LOX).

The main changes from Block 3 (the original Falcon 9 Full Thust) to Block 5 are higher-thrust engines and improvements to the landing legs along with numerous other small changes to streamline recovery and re-use of first-stage boosters and increase production rate. Each Block 5 booster is designed to fly 10 times with only minor maintenance and up to 100 times with major refurbishment.

In 2018, Block 5 succeeded the transitional Block 4 version. The maiden flight of the Block 5 launched the satellite Bangabandhu-1 on May 11, 2018. The CRS-15 mission on June 29, 2018 was the last Block 4 version to be launched, completing the transition to an all-Block 5 fleet.

Overview


The Block 5 design changes are principally driven by upgrades needed for NASA's Commercial Crew program and National Security Space Launch requirements. They include performance upgrades, manufacturing improvements, and "probably 100 or so changes" to increase the margin for demanding customers.

In April 2017, SpaceX CEO Elon Musk said that Block 5 will feature 7–8% more thrust by uprating the engines (from 176000 lbf to 190000 lbf per engine). Block 5 includes an improved flight control system for an optimized angle of attack on the descent, lowering landing fuel requirements.

For reusability endurance:
 * expected to be able to be launched at least 10 times; achieved in 2021
 * up to 100 uses with refurbishment;
 * a reusable heat shield protecting the engines and plumbing at the base of the rocket;
 * more temperature-resistant cast and machined titanium grid fins;
 * a thermal-protection coating on the first stage to limit reentry heating damage, including a black thermal protection layer on the landing legs, raceway, and interstage;
 * redesigned and requalified more robust and longer life valves;
 * redesigned composite overwrapped pressure vessels (COPV 2.0) for helium, to avoid oxygen freezing inside the structure of the tanks that lead to rupture.

For rapid reusability:
 * reduced refurbishment between flights;
 * a set of retractable landing legs for rapid recovery and shipping.
 * the Octaweb structure is bolted together instead of welded, reducing manufacturing time.

Improvements
Since the debut of Block 5, SpaceX has continued to iterate on its design, manufacturing processes, and operational procedures. Among other changes, the initial Block 5 boosters did not have the redesigned composite overwrapped pressure vessel (COPV2) tanks. The first booster with COPV2 tanks was booster B1047 on the Es'hail 2 mission on November 15, 2018, and the second booster using the COPV2 tanks was CRS-16/B1050, which had its first launch on December 5, 2018. Later Block 5 boosters are also easier to prepare for flight, so SpaceX "prefer to retire" older cores by assigning them to expendable missions when possible.

A pressure relief valve was added to the grid fins’ hydraulic system following a stall that resulted in a landing failure in 2018. Similarly, after a booster was damaged at sea in 2022, much of the fleet was upgraded with "self-leveling" landing legs. These legs help ensure the booster can be properly secured to the Octograbber, even in suboptimal sea states.

To improve the rocket's performance, SpaceX has tweaked throttle settings and separation timings.

Mission extension kits
SpaceX CRS-18 featured a Falcon mission-extension kit to the standard second stage, which equipped the second stage with a dark-painted band (for thermal control), extra COPVs for pressurization control, and additional TEA-TEB ignition fluid. The upgrades afforded the second stage with the endurance needed to inject the payloads directly into geosynchronous or high energy orbit where the second stage needs hours after launch. Based on mission requirements, they are Medium Coast & Long Coast kits, i.e., the number of helium bottles for pressurization and added batteries for power and other hardware to make sure that the fuel and stages systems operate as long as needed.

Merlin 1D Vacuum short nozzle version
Transporter-7 mission launch debuted a new Merlin 1D Vacuum nozzle extension design or variant aimed at increasing cadence and reducing costs. This new nozzle extension is shorter and, as a result, decreasing both performance and material usage; but with this nozzle, the engine produces 10% less thrust in space. This nozzle is only used on lower-performance missions, as it decreases the amount of material needed by 75%. This means that SpaceX can launch over three times as many missions with the same amount of rare niobium metal as with the longer design. As of June 2023, the characteristics of the small nozzle second stage are unknown.

Human rating
The NASA certification processes of the 2010s specified seven flights of any launch vehicle without major design changes before the vehicle would be NASA-certified for human spaceflight, and allowed to fly NASA astronauts.

The Block 5 design launched astronauts for the first time on May 30, 2020, on a NASA-contracted flight labelled Crew Dragon Demo-2. This was the first crewed orbital spaceflight launched from the United States since the final Space Shuttle mission in 2011, and the first ever operated by a commercial provider.