Falcon 1

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Falcon 1

Falcon 1 rocket in front of the FAA building in Washington DC.
Fact sheet
Function	Orbital launch vehicle
Manufacturer	SpaceX
Country of origin	USA
Size
Height	21.3 m (70 ft)
Diameter	1.7 m (5.5 ft)
Mass	38,555 kg (85,000 lb)
Stages	2
	Capacity
Payload to LEO	670 kg (1480 lb)
Payload to SSO	430 kg (990 lb)
Launch History
Status	Active
Launch Sites	Omelek Island SLC-3W Vandenberg AFB LC-36 Cape Canaveral
Total launches	2
Failures	1
Partial Failures	1
Maiden flight	March 24, 2006 22:30 GMT
First Stage
Engines	1 SpaceX Merlin
Thrust	454 kN (102,000 lbf)
Specific Impulse	255 s (sea level) (2.6 kN·s/kg)
Burn time	169 seconds
Fuel	RP-1/LOX
Second Stage
Engines	1 SpaceX Kestrel
Thrust	31 kN (7,000 lbf)
Specific Impulse	327 s (vacuum) (3.2 kN·s/kg))
Burn time	378 seconds
Fuel	RP-1/LOX

The Falcon 1 is a partially reusable launch system, designed and manufactured by SpaceX, a space-transportation startup company founded by entrepreneur and PayPal founder Elon Musk to provide commercial launch-to-space services. The two-stage-to-orbit rocket uses Lox/RP-1 for both stages, the first powered by a single Merlin engine and the second powered by a single Kestrel engine.

It is the world's first privately funded and developed liquid-fueled orbital launch vehicle, and is currently priced at US$6.7 million.^[1]

[edit] Design

The Falcon 1 is designed to minimize price per launch for low-Earth-orbit satellites. It is also intended to verify components and structural design concepts that will be reused in the Falcon 9. The first stage returns by parachute to a water landing and is recovered for reuse, while the second stage is not reusable.

[edit] First stage

First-stage view of the Merlin engine.

The first stage is made from friction-stir-welded aluminum alloy. It employs a common bulkhead between the LOX and RP-1 tanks, as well as flight pressure stabilization. It can be transported safely without pressurization (like the heavier Delta II isogrid design) but gains additional strength when pressurized for flight (like the Atlas II, which cannot be transported unpressurized). The resulting design has the highest mass fraction of any current first stage. The parachute system, built by Irvin Para­chute Corp­oration, uses a high-speed drogue chute and a main chute. Due to problems with LOX boil-off during the launch of the first vehicle, future vehicles are expected to have foam insulation applied to the exterior of the LOX tank.

Until SpaceX gains experience with reusing the first stage, the quoted price presupposes that no reuse of the first stage is taking place. If and when the recycling process is perfected, the launch price may be expected to drop.

[edit] Second stage

The second stage tanks are built with a cryogenic-compatible aluminum–lithium alloy. The helium pressurization system pumps propellant to the engine, supplies pressurized gas for the attitude control thrusters, and is used for zero-g propellant accumulation prior to engine restart. The pressure tanks are made by Arde corporation and are the same as those used in the Delta IV. They consist of an inconel shell wrapped by a composite.

[edit] Launch sequence

Launch sequence (maiden flight example); time scale is in seconds.

The main engine is ignited and throttled to full power while the launcher is restrained and all systems are verified by the flight computer. If the systems are operating correctly, the rocket is released and clears the tower in about seven seconds. First-stage burn lasts about 2:49 minutes. Stage separation is accomplished with explosive bolts and a pneumatically actuated pusher system. See the launch sequence timeline below for more details.

[edit] Launch sites

The Falcon 1 can be launched from five different sites, with the first two flights lifting off from Kwajalein.

• Vandenberg Air Force Base, Pad 3W

Elon Musk has reportedly said the Air Force may evict SpaceX from its Vandenberg launch site because of safety concerns expressed by International Launch Services, which launches Lockheed Martin Atlas V rockets from a neighboring launch site at SLC-3W.^[2]

• Cape Canaveral Air Force Station, Launch Complex 36
• Kwajalein Atoll (Omelek Island), part of the Reagan Test Site
• Kodiak Island
• Wallops Island

[edit] First test flight

The Merlin engine on fire during launch of the first Falcon 1 flight.

The maiden flight of the Falcon 1 was launched on Saturday, 24 March 2006 at 22:30 UTC. It ended in failure about a minute into the flight due to a fuel line leak and subsequent fire. The launch took place from the SpaceX spaceport at Omelek Island in the Marshall Islands.

The launch was postponed several times due to various technical issues with the new vehicle. Scheduling conflicts with a Titan IV launch at Vandenburg also caused delays and resulted in the launch moving to the Reagan Test Site in the Kwajalein Atoll. The first launch attempt on 19 December 2005 was scrubbed when a faulty valve caused a vacuum in the first stage fuel tank which sucked inward and caused structural damage. After replacing the first stage, Falcon 1 launched Saturday, 25 March 2006 at 09:30 local time. The DARPA payload was the United States Air Force Academy’s FalconSAT–2, which would have measured space plasma phenomena.

The vehicle had a noticeable rolling motion after liftoff, as shown on the launch video, rocking back and forth a bit, and then at T+26 seconds rapidly pitched over. Impact occurred at T+41 seconds onto a dead reef about 250 feet from the launch site. The FalconSAT–2 payload separated from the booster and landed on the island, with damage reports varying from slight to significant.^[3]

SpaceX initially attributed the fire to an improperly tightened fuel-line nut. A later review by DARPA found that the nut was properly tightened, since its locking wire was still in place, but had failed due to corrosion.

SpaceX implemented numerous changes to the rocket design and software to prevent this type of failure from reoccurring, including stainless steel to replace aluminum hardware and pre-liftoff computer checks that increased by a factor of thirty. ^{[4] [5]}.

[edit] Second test flight

Fairing separation at Falcon 1 Demo Flight 2. The engine bell of the second stage Kestrel engine is visible at left; the two halves of the payload fairing can be seen falling into the atmosphere at right. Fairing separation took place at T+03:15 at an altitude of around 117 km.

The second mission was launched at 01:10 GMT on 21 March 2007 from Omelek Island with a DemoSat payload for DARPA and NASA. The rocket failed to reach orbit when the second stage Kestrel engine prematurely shut down, due to a loss of control caused by roll excitation, which allowed the remaining propellant to slosh away from the sump, effectively starving the engine of propellant late in the flight.

It was originally scheduled for January, but was delayed due to problems with the second stage. It was then rescheduled for 9 March, but delayed because of range availability issues caused by a Minuteman III test flight which would re-enter over Kwajelen. The launch attempt on 19 March was delayed 45 minutes from 23:00 GMT due to a data relay issue, and then scrubbed one minute and two seconds before launch at 23:45 due to a computer issue, whereby the safety computer incorrectly detected a transmission failure due to a hardware delay of a few milliseconds in the process.

The 20 March attempt was delayed 65 minutes, from an originally planned time of 23:00 due to a problem with communications between one of the NASA experiments in the payload, and the TDRS system. The launch was aborted at 00:05 GMT on 21 March, at the last second before launch, and after the engine had ignited, however the decision to attempt another launch the same day was taken.

The rocket performed well during the first stage burn. However, during staging, the interstage fairing on the top of the first stage bumped the second stage engine bell ^[6]. The bump occurred as the second stage nozzle exited the interstage, with the first stage rotating much higher than expected (a rotation rate of about 2.5 deg/sec vs. expected rate of 0.5 deg/sec maximum), thereby making contact with the niobium nozzle of the second stage. Musk reported that the bump did not appear to have caused damage, and that the reason why they chose a niobium skirt instead of carbon-carbon was to prevent problematic damage in the event of such incidents. Shortly after second stage ignition, a stabilization ring detached from the engine bell as designed^[7]. The rocket reached a final altitude of 289 km and a final velocity of 5.1 km/s, compared to 7.5 km/s needed for orbit.

At around T+4:20, a circular coning oscillation began that increased in amplitude until video was lost. At T+5:01, the vehicle started to roll and telemetry ended. According to Elon Musk, the second stage engine shut down at T+7.5 due to a roll control issue. Sloshing of propellant in the LOX tank increased oscillation. This oscillation would normally have been dampened by the Thrust Vector Control system in the second stage, but the bump to the second nozzle during seperation caused an overcompensation in the correction.^[8] The rocket continued to within one minute of its desired location, and also managed to deploy the satellite mass simulator ring. While the webcast video ended prematurely, SpaceX was able to retrieve telemetry for the entire flight. ^[9]The status of the first stage is unknown; it was not recovered due to problems with a nonfunctioning GPS tracking device.

SpaceX characterized the test flight as a success, having flight proven over 95% of Falcon 1's systems. Their primary objectives for this launch were to test responsive launch procedures and gather data. ^[10]

According to Musk, the SpaceX team intends to have both a diagnosis and solution vetted by third party experts. Musk believes the slosh issue can be corrected by adding baffles to the second stage LOX tank and adjusting the control logic. Although either approach separately should correct the problem (citing the tank of the Atlas-Centaur launch vehicle having no baffles as an example), Musk stated he wants to ensure this problem never shows up again.

Furthermore, the Merlin shutdown transient can be addressed by initiating shutdown at a much lower thrust level, albeit at some risk to engine reusability. Musk believes a good set of slosh baffles, or even another nozzle impact at stage separation should not pose a significant flight risk. The SpaceX team intends to work the problem to avoid a reoccurrance as they change over into the operational phase for Falcon 1. [1]

[edit] Further missions

The third flight will also be from Omelek, carrying a Naval Research Laboratory Tacsat and a Space Services Incorporated space burial payload (which will include remains of James Doohan, Gordon Cooper, and others). This will be the first operational flight. This mission was originally scheduled for 2005, from Vandenberg AFB, but delays due to the Titan launch, and problems with the rocket pushed it into mid-2006. It was then delayed further, as the failure of the maiden flight necessitated a second test mission. It is currently scheduled for September, 2007.^[11]

[edit] Launch log

[edit] Notes

[edit] External links

• SpaceX Falcon 1 details page
• Space Services Inc. space burial page
• Maiden launch details at SpaceFlightNow
• "SpaceX rocket fails first flight", BBC News, 24 March 2006.
• Damage puts first SpaceX rocket launch on hold, Spaceflight Now, 19 December 2005