Falcon 9 Full Thrust (also known as Falcon 9 v1.2) is a partially reusable, two-stage-to-orbit, medium-lift launch vehicle designed and manufactured in the United States by SpaceX. It is the third major version of the Falcon 9 family, designed starting in 2014, with its first launch operations in December 2015. It was later refined into the Block 4 and Block 5. As of , all variants of the Falcon 9 Full Thrust (including Block 4 and 5) had performed launches with only one failure: Starlink Group 9-3.
On 22 December 2015, the Full Thrust version of the Falcon 9 family was the first launch vehicle on an orbital trajectory to successfully vertically land a first stage. The landing followed a technology development program conducted from 2013 to 2015. Some of the required technology advances, such as landing legs, were pioneered on the Falcon 9 v1.1 version, but that version never landed intact. Starting in 2017, previously flown first-stage boosters were reused to launch new payloads into orbit. This quickly became routine, in 2018 and in 2019 more than half of all Falcon 9 flights reused a booster. In 2020 the fraction of reused boosters increased to 81%.
Falcon 9 Full Thrust is a substantial upgrade over the previous Falcon 9 v1.1 rocket, which flew its last mission in January 2016. With uprated first- and second-stage engines, a larger second-stage propellant tank, and propellant densification, the vehicle can carry substantial payloads to geostationary orbit and perform a propulsive landing for recovery.
Design
A principal objective of the new design was to facilitate booster re-usability for a larger range of missions, including delivery of large commsats to geosynchronous orbit.
Like earlier versions of the Falcon 9, and like the Saturn series from the Apollo program, the presence of multiple first-stage engines can allow for mission completion even if one of the first-stage engines fails mid-flight.
Modifications from Falcon 9 v1.1 The third version of the Falcon 9 was developed in 2014–2015 and made its maiden flight in December 2015. The Falcon 9 Full Thrust is a modified reusable variant of the Falcon 9 family with capabilities that exceed the Falcon 9 v1.1, including the ability to "land the first stage for geostationary transfer orbit (GTO) missions on the drone ship" The rocket was designed using systems and software technology that had been developed as part of the SpaceX reusable launch system development program, a private initiative by SpaceX to facilitate rapid reusability of both the first–and in the long term, second—stages of SpaceX launch vehicles. Various technologies were tested on the Grasshopper technology demonstrator, as well as several flights of the Falcon 9 v1.1 on which post-mission booster controlled-descent tests were being conducted.
In 2015, SpaceX made a number of modifications to the existing Falcon 9 v1.1. The new rocket was known internally as Falcon 9 Full Thrust, and is also known as Falcon 9 v1.2, Enhanced Falcon 9, Full-Performance Falcon 9, and Falcon 9 Upgrade.
A principal objective of the new design was to facilitate booster reusability for a larger range of missions, including delivery of large commsats to geosynchronous orbit.
Modifications in the upgraded version include: liquid oxygen subcooled to and RP-1 cooled to for density (allowing more fuel and oxidizer to be stored in a given tank volume, as well as increasing the propellant mass flow through the turbopumps increasing thrust) upgraded structure in the first stage longer second stage propellant tanks longer and stronger interstage, housing the second stage engine nozzle, grid fins, and attitude thrusters center pusher added for stage separation design evolution of the grid fins modified Octaweb upgraded landing legs Merlin 1D engine thrust increased to the full-thrust variant of the Merlin 1D, taking advantage of the denser propellants achieved by subcooling. Merlin 1D vacuum thrust increased by subcooling the propellants. several small mass-reduction efforts. The modified design gained an additional of height, stretching to exactly including payload fairing, while gaining an overall performance increase of 33 percent. The new first-stage engine has a much increased thrust-to-weight ratio.
The full-thrust first stage booster could reach low Earth orbit as a single-stage-to-orbit if it is not carrying the upper stage and a heavy satellite.
Versions launched in 2017 have included an experimental recovery system for the payload fairing halves. On 30 March 2017, SpaceX for the first time recovered a fairing from the SES-10 mission, thanks to thrusters and a steerable parachute helping it glide towards a gentle touchdown on water.
On 25 June 2017 flight (Iridium NEXT 11–20), aluminum grid fins were replaced by titanium versions, to improve control authority and better cope with heat during re-entry. Following post-flight inspections, Elon Musk announced the new grid fins likely will require no service between flights.
Autonomous flight termination system SpaceX has been developing for some time an alternative autonomous system to replace the traditional ground-based systems that had been in use for all US launches for over six decades. The autonomous system has been in use on some of SpaceX' VTVL suborbital test flights in Texas, and has flown in parallel on a number of orbital launches as part of a system test process to gain approval for use on operational flights.
In February 2017, SpaceX's CRS-10 launch was the first operational launch utilizing the new Autonomous Flight Safety System (AFSS) on "either of Air Force Space Command's Eastern or Western Ranges." The following SpaceX flight, EchoStar 23 in March, was the last SpaceX launch utilizing the historic system of ground radars, tracking computers, and personnel in launch bunkers that had been used for over sixty years for all launches from the Eastern Range. For all future SpaceX launches, AFSS has replaced "the ground-based mission flight control personnel and equipment with on-board Positioning, Navigation and Timing sources and decision logic. The benefits of AFSS include increased public safety, reduced reliance on range infrastructure, reduced range spacelift cost, increased schedule predictability and availability, operational flexibility, and launch slot flexibility."
Block 4 In 2017, SpaceX started flying incremental changes to the Falcon 9 Full Thrust version, calling them "Block 4". At first, only the second stage was modified to Block 4 standards, flying on top of a "Block 3" first stage for three missions: NROL-76 and Inmarsat-5 F4 in May 2017, and Intelsat 35e in July. Block 4 was described as a transition between the Full Thrust v1.2 "Block 3" and the following Falcon 9 Block 5. It includes incremental engine thrust upgrades leading to the final thrust for Block 5. The maiden flight of the full Block 4 design (first and second stages) was the NASA CRS-12 mission on 14 August 2017.
Block 5
SpaceX announced in 2017 that another series of incremental improvements were in development, a Falcon 9 Block 5 version, which has succeeded the transitional Block 4. The largest changes between Block 3 and Block 5 are higher thrust on all of the engines and improvements on landing legs. Additionally, numerous small changes will help streamline recovery and re-usability of first-stage boosters. Alterations are focused on increasing the speed of production and efficiency of re-usability. SpaceX aims to fly each Block 5 booster ten times with only inspections in between, and up to 100 times with refurbishment.
Block 5 second stages can be built with a mission extension kit to allow longer duration and/or more engine starts.
Rocket specifications
Falcon 9 Full Thrust specifications and characteristics are as follows:
Characteristic First stage Second stage Payload fairing Height Diameter Empty mass Gross mass Structure type LOX tank: monocoqueFuel tank: skin and stringer LOX tank: monocoqueFuel tank: skin and stringer Monocoque halves Structure material Aluminum lithium skin; aluminum domes Carbon fiber Engines 9 × Merlin 1D 1 × Merlin 1D Vacuum rowspan=14 Engine type Liquid, gas-generator Fuel Kerosene (RP-1) Oxidizer Subcooled liquid oxygen (LOX) Liquid oxygen (LOX) LOX tank capacity RP-1 tank capacity Engine nozzle Gimbaled, 16:1 expansion Gimbaled, 165:1 expansion Total thrust 845.2 kN x 9 () 934 kN x 1 () Propellant feed system Turbopump Throttle capability per engine per engine Restart capability Yes (only 3 engines for boostback/reentry/landing burns) Yes, dual redundant TEA-TEB pyrophoric igniters Tank pressurization 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 Nitrogen gas thrusters Shutdown process Commanded Stage separation system Pneumatic Pneumatic
The Falcon 9 Full Thrust uses a 4.5 meter long interstage which is longer and stronger than the Falcon 9 v1.1 interstage. It is a "composite structure consisting of an aluminum honeycomb core surrounded by a carbon fiber face sheet plies". The overall length of the vehicle at launch is 70 meters, and the total fueled mass is 549,000 kg. The aluminium-lithium alloy used is 2195-T8.
The Falcon 9 Full Thrust upgraded vehicle "includes first-stage recovery systems, to allow SpaceX to return the first stage to the launch site after completion of primary mission requirements. These systems include four deployable landing legs, which are locked against the first-stage tank during ascent. Excess propellant reserved for Falcon 9 first-stage recovery operations will be diverted for use on the primary mission objective, if required, ensuring sufficient performance margins for successful missions". The nominal payload capacity to a geostationary transfer orbit is with the first-stage recovery (the price per launch is US$62 million), versus with an expendable first-stage.
Development history
Development As early as March 2014, SpaceX pricing and payload specifications published for the expendable Falcon 9 v1.1 rocket actually included about 30 percent more performance than the published price list indicated. At that time, the additional performance was reserved for SpaceX to conduct reusability testing with the Falcon 9 v1.1 while still achieving the specified payloads for customers. Many engineering changes to support reusability and recovery of the first stage had been made on this earlier v1.1 version. SpaceX indicated they had room to increase the payload performance for the Falcon 9 Full Thrust, or decrease launch price, or both.
In 2015, SpaceX announced a number of modifications to the previous version Falcon 9 v1.1 launch vehicle. The new rocket was known internally for a while as Falcon 9 v1.1 Full Thrust, but was also known under a variety of names including Falcon 9 v1.2, Enhanced Falcon 9, Full-Performance Falcon 9, Upgraded Falcon 9, and Falcon 9 Upgrade. Since the first flight of the "full thrust upgrade", SpaceX has been referring to this version as just Falcon 9.
SpaceX President Gwynne Shotwell explained in March 2015 that the new design would result in streamlined production as well as improved performance:
So, we got the higher thrust engines, finished development on that, we're in [qualification testing]. What we're also doing is modifying the structure a little bit. I want to be building only two versions, or two cores in my factory, any more than that would not be great from a customer perspective. It's about a 30% increase in performance, maybe a little more. What it does is it allows us to land the first stage for GTO missions on the drone ship.