# 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 Thrust) 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 the production rate. Each Block 5 booster is designed to fly ten times with only minor maintenance between launches and potentially up to 100 times with periodic 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 to be launched on a Block 4 rocket, 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 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 176,000 pounds-force (780,000 N) to 190,000 pounds-force (850,000 N) 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 fly ten times with only minor maintenance between launches achieved in 2021
* potentially fly up to 100 times with periodic 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.

### Short nozzle second stage

The Transporter-7 mission marked the debut of a second stage with a Merlin 1D Vacuum engine with a shorter nozzle extension designed to accelerate production and reduce costs. Unlike the first stage, the second stage on the Falcon 9 is not reused. This variant sacrifices 10% thrust in exchange for a 75% reduction in material usage, primarily the rare metal niobium. As a result, SpaceX can triple its launch frequency using the same amount of this critical resource. Due to its reduced performance, this nozzle is exclusively used on missions with lower performance requirements.

## 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, 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.

## Specifications

Specifications and characteristics are as follows:
| Characteristic | First stage | Second stage |
| Height | 42.6 m (140 ft) | 12.6 m (41 ft) |
| Diameter | 3.7 m (12 ft) | 3.7 m (12 ft) |
| Empty mass | 22,200 kg (48,900 lb) | 4,000 kg (8,800 lb) |
| Gross mass | 433,100 kg (954,800 lb) | 111,500 kg (245,800 lb) |
| Structure type | LOX tank: monocoque Fuel tank: skin and stringer | LOX tank: monocoque Fuel tank: skin and stringer |
| Structure material | Aluminum lithium skin; aluminum domes | Aluminum lithium skin; aluminum domes |
| Engines | 9 × Merlin 1D | 1 × Merlin 1D Vacuum |
| Engine type | Liquid, gas-generator | Liquid, gas-generator |
| Fuel | Kerosene (RP-1) | Kerosene (RP-1) |
| Oxidizer | Subcooled liquid oxygen (LOX) | Liquid oxygen (LOX) |
| LOX tank capacity | 287,400 kg (633,600 lb) | 75,200 kg (165,800 lb) |
| RP-1 tank capacity | 123,500 kg (272,300 lb) | 32,300 kg (71,200 lb) |
| Engine nozzle | Gimbaled, 16:1 expansion | Gimbaled, 165:1 expansion |
| Total thrust | 7,607 kN (1,710,000 lb$_f$) | 934 kN (210,000 lb$_f$) |
| Propellant feed system | Turbopump | Turbopump |
| Throttle capability | 845–482 kN (190,000–108,300 lbf) | 930–360 kN (210,000–81,000 lb$_f$) |
| Restart capability | Yes (only 3 engines for boostback/reentry/landing burns) | Yes, dual redundant TEA-TEB pyrophoric igniters |
| Tank pressurization | Heated helium | Heated helium |
| Ascent attitude control (pitch, yaw) | Gimbaled engines | Gimbaled engine and nitrogen gas thrusters |
| Ascent attitude control (roll) | Gimbaled engines | Nitrogen gas thrusters |
| Coast/descent attitude control | Nitrogen gas thrusters and grid fins | Nitrogen gas thrusters |
| Shutdown process | Commanded | Commanded |