FALCON USER’S GUIDE Figure 2-2: The Falcon Heavy demonstration mission launched from KSC on February 6, 2018 The first stage is comprised of three cores: a center core and two side boosters (the first stage of Falcon 9 is used as a side booster); each core has nine Merlin 1D (M1D) engines. Each of the 27 first stage engines produces 190,000 lbf of thrust at sea level, for a total of 5,130,000 lbf of thrust at liftoff. The two side boosters are connected to the center core at the base engine mount and at the forward end of the LOX tank on the center core. With nine engines in each first-stage core, Falcon Heavy has propulsion redundancy – unlike any other heavy-lift launch system. The launch vehicle monitors each engine individually during ascent and can, if necessary, preemptively command off-nominal engines, provided the minimum injection success criteria are achievable with the remaining engines. This engine-out reliability provides propulsion redundancy throughout first-stage ascent – a feature unique to Falcon launch vehicles. STRUCTURE AND PROPULSION The first-stage propellant tank walls of the Falcon vehicles are made from an aluminum lithium alloy. Tanks are manufactured using friction stir welding—the highest strength and most reliable welding technique available. An insulated common dome separates the LOX and RP-1 tanks, and an insulated transfer tube carries LOX through the center of the RP-1 tank to the engine section. Four grid fins near the top of the first stage along with four deployable legs at the base are nominally flown to support recovery operations. Nine SpaceX Merlin engines power the Falcon 9 first stage with up to 854 kN (190,000 lbf) thrust per engine at sea level, for a total thrust of 7,686 kN (1.71 million lb ) at liftoff. The first-stage engines are configured in a circular pattern, with f eight engines surrounding a center engine. Twenty-seven SpaceX Merlin engines power the Falcon Heavy first stages for a total thrust of 5,130,000 lbf at liftoff. The figure below shows the nomenclature for the center core and side boosters (center, plus y-axis and minus y-axis.) © Space Exploration Technologies Corp. All rights reserved. 6