Falcon 9 Block 5 is a partially reusable two-stage-to-orbit medium-lift launch vehicle designed and manufactured in the United States by SpaceX. It is the fifth version of Falcon 9 Full Thrust,^[10][11] powered by SpaceX Merlin engines burning rocket-grade kerosene (RP-1) and liquid oxygen (LOX).

The main changes from Block 3 to Block 5 are higher-thrust engines and improvements to the landing legs. Numerous other small changes helped streamline recovery and re-usability of first-stage boosters, increase production rate, and optimize re-usability. Each Block 5 booster is designed to fly 10 times with only minor attention and up to 100 times with refurbishment.^[12]

In 2018, Falcon 9 Block 5 succeeded the transitional Block 4 version. The maiden flight launched the satellite Bangabandhu-1 on May 11, 2018. The CRS-15 mission on June 29, 2018 was the last Block 4 version of Falcon 9 to be launched. This was the transition to an all-Block 5 fleet.^[13][14]

The Block 5 design changes are principally^[16] 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.^[17]

In April 2017, SpaceX CEO Elon Musk said that Block 5 will feature 7–8% more thrust by uprating the engines (from 176,000 pounds-force (780,000 N) to 190,000 pounds-force (850,000 N) per engine).^[12] 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;^[18][19] achieved in 2021^[20]
• up to 100 uses with refurbishment;^[19][18][21]
• a reusable heat shield protecting the engines and plumbing at the base of the rocket;
• more temperature-resistant cast and machined titanium grid fins;^[22]
• 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;^[19]
• a set of retractable landing legs for rapid recovery and shipping.^[23]
• the Octaweb^[24] structure is bolted together instead of welded, reducing manufacturing time.^[25]

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.^[27][28]

The Block 5 design launched astronauts for the first time on May 30, 2020, on a NASA-contracted flight labelled Crew Dragon Demo-2.^[37] 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.^[38]

• Falcon 9 Full Thrust, has 1st and 2nd stage specifications
• Falcon Heavy, derivative launcher
• List of Falcon 9 and Falcon Heavy launches
• List of Falcon 9 Block 5 first-stage boosters
• Saturn IB, Apollo crewed LEO launcher (1966-1975)
• SpaceX Starship
• Falcon 9