Falcon 1 Overview
The Falcon Launch Vehicle Family provides breakthrough advances in reliability, cost, flight environment and time to launch. In providing our launch and placement services, we recognize that nothing is more important than getting our customer’s satellite or other spacecraft safely to its intended destination.
Falcon 1 is a two stage, liquid oxygen and rocket grade kerosene (RP-1) powered launch vehicle. Designed in-house from the ground up by SpaceX, Falcon 1 was the first privately developed liquid fuel rocket to achieve Earth orbit. Read more about Falcon 1's history making flight.
| Falcon 1 | ||
| Length: | 21.3 m (70 ft) | |
| Width: | 1.7 m (5.5 ft) | |
| Mass: | 27,670 kg (61,000 lbs) | |
| Thrust on liftoff: | 347 kN (78,000 lbf) | |
Liftoff of the SpaceX Falcon 1 Flight 4 vehicle from Omelek Island in the Kwajalein Atoll, at 4:15 p.m. (PDT) / 23:15 (UTC). It achieved an elliptical orbit of 621x643 km, 9.3 degrees inclination, and carried into orbit a payload mass simulator of approximately 165 kg (364 lbs), designed and built by SpaceX specifically for this mission.
First Stage
The primary structure is made of a space grade aluminum alloy in a graduated monocoque, common bulkhead, flight pressure stabilized architecture developed by SpaceX. The design is a blend between a fully pressure stabilized design, such as Atlas II, and a heavier isogrid design, such as Delta II. As a result, Falcon 1 first stage is able to capture the mass efficiency of pressure stabilization, but avoid the ground handling difficulties of a structure unable to support its own weight.
A single SpaceX Merlin engine regeneratively cooled engine (described below) powers the Falcon 1 first stage. After ignition of the first stage engine, Falcon is held down and not relased for flight until all vehicle systems are verified to be functioning nominally before release for liftoff.
Helium tank pressurization is provided by composite over-wrapped inconel tanks from Arde Corporation, the same model used in Boeing’s Delta IV rocket.
Stage separation occurs via redundantly initiated separation bolts and a pneumatic pusher system.
The first stage returns by parachute to a water landing, where it is picked up by ship in a procedure similar to that of the Space Shuttle solid rocket boosters. The parachute recovery system is built for SpaceX by Irvin Aerospace, who also builds the Shuttle booster recovery system.
Second Stage
The tank structure is made of aluminum-lithium, an alloy possessing the highest strength to weight ratio of any aluminum and currently used by the Space Shuttle External Tank. Although we intend to continue researching alternatives in the long term, for this particular application it has the lowest total system mass for any material we have examined, including liquid oxygen compatible super-alloys and composites.
The tanks are precision machined from plate with integral flanges and ports, minimizing the number of welds necessary. The major circumferential welds are all done by an automated welding machine, reducing the potential for error and ensuring consistent quality.
A single SpaceX Kestrel engine powers the Falcon 1 upper stage. A highly reliable and proven TEA-TEB pyrophoric system is used to provide multiple restart capability on the upper stage.
Helium pressurization is again provided by composite over wrapped inconel tanks from Arde. However, in this case the helium is also used in cold gas thrusters for attitude control and propellant settling when a restart is needed.
Typical Falcon 1 flight profile for direct insertion from launch through deployment and recovery of 1st stage
SpaceX Merlin Engine
The main engine, called Merlin, was developed internally at SpaceX, drawing upon a long heritage of space proven engines. The pintle style injector at the heart of Merlin was first used in the Apollo Moon program for the Lunar Excursion Module (LEM) landing engine, one of the most critical phases of the mission.
Propellant is fed via a single shaft, dual impeller turbo-pump operating on a gas generator cycle. High pressure kerosene fuel flows through the walls of the combustion chamber and exhaust nozzle before being injected into the combustions chamber. This provides significant cooling, permitting the engine to operate at a higher level of performance. The turbo-pump also provides the high pressure kerosene for the hydraulic actuators, eliminating the need for a separate hydraulic power system. Additionally, actuating the turbine exhaust nozzle provides roll control during flight.
Combining these three functions into one device, and verifying its operation before the vehicle is allowed to lift off, provides significant improvement in system-level reliability.
| Sea Level Thrust : | 512 kN (115,000 lbf) |
| Vacuum Thrust: | 569 kN (128,000 lbf) |
| Sea Level Isp: | 275s |
| Vacuum Isp: | 304s |
With a vacuum specific impulse of 304s, Merlin is the highest performance gas generator cycle kerosene engine ever built, exceeding the Boeing Delta II main engine, the Lockheed Atlas II main engine and on par with the Saturn V F-1.
SpaceX Kestrel Engine
Kestrel, also built around the pintle architecture, is a high efficiency, low pressure vacuum engine. It does not have a turbo-pump and is fed only by tank pressure.
Kestrel is ablatively cooled in the chamber and throat and radiatively cooled in the nozzle, which is fabricated from a high strength alloy. The nozzle exhibits high strength at extreme temperatures and is highly resilient to impact. Thrust vector control is provided by electro-mechanical actuators on the engine dome for pitch and yaw. Roll control (and attitude control during coast phases) is provided by helium cold gas thrusters.
A highly reliable and proven TEA-TEB pyrophoric system is used to provide multiple restart capability on the upper stage. In a multi-manifested mission, this allows delivery of separate payloads to different altitudes and inclinations.
| Vacuum Thrust: | 6,245 lbf |
| Vacuum Isp: | 325s |
Designed for Maximum Reliability
The vast majority of launch vehicle failures in the past two decades can be attributed to three causes: engine, stage separation and, to a much lesser degree, avionics failures. An analysis of launch failure history between 1980 and 1999 by Aerospace Corporation showed that 91% of known failures can be attributed to those subsystems.
Engine Reliability
It was with this in mind that we designed Falcon 1 to have the minimum number of engines. As a result, there is only one engine per stage and only one stage separation event per flight.
Another notable point is the SpaceX hold-before-release system – a capability required by commercial airplanes, but not implemented on many launch vehicles. After first stage engine start, the Falcon is held down and not released for flight until all propulsion and vehicle systems are confirmed to be operating nominally. An automatic safe shut-down and unloading of propellant occurs if any off nominal conditions are detected.
Stage Separation Reliability
Here Falcon takes advantage of simplicity, by having two stages and therefore only one stage separation event – the minimum practical number. Moreover, the stage separation bolts are all redundantly initiated, fully space-qualified, with a zero failure track record in prior launch vehicles.
Falcon Design Features that Enhance Reliability:
- Two stage design for minimum number of separation events
- Redundant stage and fairing separation systems
- Dual redundant avionics system
- Propulsion redundancy and simplicity
- Simplest possible turbopump design — one shaft drives both LOX and RP-1
- Robust structure with high margins
- Hold before liftoff system
Limited number of independent subsystems:
- High pressure kerosene tapped from turbopump to drive thrust vector control hydraulic system
- Turbopump exhaust gas is used for roll control
Fairing Volume
Below are the standard fairing dimensions for Falcon 1 Launch Vehicles. Dimensions are in meters and in inches inside the brackets. Custom fairings in larger lengths and diameters are available at incremental cost.
Falcon 1 fairing
SpaceX Launch and Placement Services
Falcon 1 Payloads
Current plans are for payloads that would have previously flown on Falcon 1 to be served by flights on Falcon 9, utilizing excess capacity. This is a very cost-effective solution for small satellite launch needs. For more information on Falcon 9 capabilities, see the Falcon 9 overview.
For further information, contact us at sales@spacex.com.
