Posted December 10, 2007
Sorry for the long delay in posting. For the last few months, optional activities such as website updates have gone on the back burner while we finished the regeneratively cooled Merlin 1C engine, got the Falcon 9 first stage integrated, proof tested and fired, signed up our first GTO (geostationary transfer orbit) customer - Avanti Communications Group, and took our COTS system past the big CDR milestone. With all that taken care of, here comes another huge update:
First Falcon 9 Stage Hold Down Firing!
A few weeks ago, we fired an integrated Falcon 9 first stage for first time. This was one of the most difficult steps in the whole F9 development program, as it required that the first stage, test stand, ground support equipment and a Merlin engine all work together as an integrated system.
Over the next three to four months, we will gradually add more engines until reaching the full complement of nine. Once we have all nine engines and the stage working well as a system, we will extensively test the “engine out” capability. This includes explosive and fire testing of the barriers that separate the engines from each other and from the vehicle.
Merlin 1C engine components
It should be said that the failure modes we’ve seen to date on the test stand for the Merlin 1C are all relatively benign – the turbo pump, combustion chamber and nozzle do not rupture explosively even when subjected to extreme circumstances. We have seen the gas generator (which drives the turbo pump assembly) blow apart during a start sequence (there are now checks in place to prevent that from happening), but it is a small device, unlikely to cause major damage to its own engine, let alone the neighboring ones.
Even so, as with engine nacelles on commercial jets, the fire/explosive barriers will assume that the entire chamber blows apart in the worst possible way. The bottom close out panels are designed to direct any force or flame downward, away from neighboring engines and the stage itself.
The first ever engine firing on the big stand
All in all, we’ve found that the Falcon 9’s ability to withstand one or even multiple engine failures, just as commercial airliners do, and still complete its mission is a compelling selling point with customers. Apart from the Space Shuttle and Soyuz, none of the existing launch vehicles can afford to lose even a single thrust chamber without causing loss of mission.
Merlin 1C Development Complete
We officially have completed development of the Merlin 1C engine, another major milestone for SpaceX. This new version of Merlin uses regenerative cooling, wherein the rocket grade kerosene propellant first flows around the combustion chamber and nozzle walls before igniting with the liquid oxygen in the thrust chamber. This active cooling allows for higher performance without significantly increasing engine mass, and represents a huge improvement over the ablatively cooled Merlin, which lofted the first two Falcon 1 flights .
We performed the final test in the development series, a 170 second long mission duty firing, and verified the final design features. In total, across 125 separate hot fire tests, the run time on this engine exceeded 3,200 seconds – equivalent to nearly 19 launches. Quite robust!
A Merlin 1C will power the next Falcon 1 mission early in 2008, and the far larger Falcon 9 will employ nine Merlins on its first stage, and one on the second stage. In its Falcon 9 configuration, Merlin has a thrust at sea level of 95,000 lbs, a vacuum thrust of over 108,000 pounds, vacuum specific impulse of 304 seconds and sea level thrust to weight ratio of 92.
In generating this thrust, Merlin consumes 350 lbs/second of propellant and the chamber and nozzle, cooled by 100 lbs/sec of kerosene, are capable of absorbing 10 MW of heat energy. A planned turbo pump upgrade in 2009 will improve the thrust by over 20% and the thrust to weight ratio by approximately 25%. T he nine Merlins on the Falcon 9 first stage will generate over a million pounds of thrust – four times the maximum thrust of a Boeing 747.
Groundbreaking at Cape Canaveral
Last month, SpaceX along with Space Florida, conducted the official groundbreaking at Space Launch Complex 40, our site at Cape Canaveral. Among those present for the ceremony were the Lt. Governor of Florida, the Commander of Cape Canaveral, the head of the FAA’s space division, the deputy administrator of NASA’s Kennedy Space Center, and the president of Space Florida.
SLC-40 is a world-class heavy lift launch facility, capable of supporting both the Falcon 9 and future Falcon 9 Heavy flights. In operation since 1965, SLC-40 has hosted numerous launches, including the departure of two interplanetary missions; the Mars Observer satellite, and the Cassini spacecraft now exploring the rings and moons of the planet Saturn.
A Titan IV lifting off from Space Launch Complex 40 – the new home of the Falcon 9
NASA COTS Critical Design Review and Our New Hawthorne Building
A few months ago, NASA approved the critical design review (CDR) for the initial flight of our Dragon spacecraft on the Falcon 9 rocket booster. F9/Dragon is intended to provide crew and cargo service to the International Space Station after the Space Shuttle retires in 2010, so passing this review was no small matter. Apart from the flight itself, this was arguably the most important mark of progress in the NASA Commercial Orbital Transportation Services (COTS) program.
Enough room to park a starship – or a lot of Falcon 9s
We held the CDR in our new half million square foot Hawthorne headquarters, which is almost big enough to have its own weather system. Until last year, our building had been used to manufacture Boeing 747 fuselage sections for four decades. It has an unusually large clear span and a 60 foot roof height, making it one of the largest manufacturing buildings by volume in California.
We’ve been talking about how to make use of the giant flat roof – nothing is there right now, but the roof is literally large enough to fit a football stadium. The options depend on permits and costs being reasonable, but it would be really cool to have a wooden deck shaded by our SolarCity photovoltaic panels, where people could have lunch and watch the planes landing at LAX and the Hawthorne airport, which is only a few hundred feet from our building.
In addition, it would be great to have a green park-like eco-roof with sports facilities up there – beach volleyball, basketball and maybe a running track around the perimeter. On the more random side, I like the idea of a small English botanical garden or a Japanese Zen garden. It would be cool to drink tea or coffee while simultaneously ensconced from and in view of greater Los Angeles.
But back to the Falcon 9 review…
Quarter section of the Falcon 9’s 17 foot diameter payload fairing (so shiny)
Dragon Engineering Unit – Aluminum isogrid pressure vessel, heat shield support structure at bottom, Space Station common berthing adapter ring at top, and carbon fiber nose cap at right
In addressing NASA’s requirements, we submitted a package of 486 documents covering every aspect of the F9/Dragon – design, engineering, testing, manufacturing and flight operations. In terms of overall design maturity of the Falcon 9 project, we are ahead of the curve for a typical program of this size. It is unusual for a CDR to feature this quantity of hardware in fabrication, assembly, integration and test phases.
Some progress highlights:
During the three day review, twenty six speakers from our engineering teams gave thirty two presentations on over two dozen different areas: structures, aerodynamics, propulsion, avionics, communication, as well as the Dragon spacecraft design, ground processing, launch, flight operations and recovery, and more.
We addressed and dispostioned all questions, and successfully met all of NASA’s requirements for the review. The feedback overall was quite positive. As I mentioned above, the CDR is the most important COTS milestone, apart from performing the flight demonstrations for NASA, so it is certainly a relief to have that behind us.
Overall, the Falcon 9 program remains on track for demonstration of cargo delivery to the International Space Station by the end of 2009.
Falcon 9 First Stage Mounted in the BFTS (Big Falcon Test Stand)
In preparation for the stage firing mentioned earlier, the F9 first stage had to be hoisted hundreds of feet into the air by massive cranes and placed on our largest test stand at the SpaceX Texas test facility. The BFTS is truly epic in size and is structurally capable of handling thrust levels of up to 3.5 million pounds – almost half that of the Saturn V Moon rocket. Standing roughly 235 feet, the stand is tall enough to require FAA flight warning lights.
Ready for test firing
Falcon 9 Wind Tunnel Testing
Over one hundred years ago, the Wright brothers built small wind tunnels to study the aerodynamics of potential wing designs for their first Flyer. Even in this digital age, where we use computers to perform massive and highly detailed simulations of aerodynamic forces, we still look to wind tunnel data to verify and validate our digital models.
1:33 scale model of Falcon 9 with 17 foot diameter payload fairing
To that end, we recently tested a 5 foot long Falcon 9 model in one of the few remaining wind tunnels capable of moving air at over three times the speed of sound. Built in the 1950’s, the venerable North American Trisonic Wind Tunnel happened to be located just blocks from our old El Segundo headquarters, and provided us with the ability to test a variety of Falcon 9 configurations, including both the large 17 foot fairing design and the Dragon capsule models.
Big Dragon Update
The SpaceX Dragon Spacecraft will carry up to seven crewmembers or over three metric tons of cargo to the International Space Station – and to future private destinations such as those envisioned by Bigelow Aerospace. Like Apollo, Soyuz, and the future Orion spacecraft, Dragon is a capsule design.
Transparent Falcon 9 with cargo carrying Dragon spacecraft
Dragon spacecraft in orbit
Some may wonder if the lack of wings represents a step backwards. Fundamentally, for orbital vehicles spending the vast majority of their time in space, the arguments against wings are strong (although for low energy, sub-orbital craft like SpaceShipOne which spend most of their journey in the atmosphere, there are still good arguments in favor of wings).
Wings have a performance penalty on the way up, are useless in the vacuum of space, and become a hazard on reentry, due to the fragile nature of the high temperature material protecting the wing’s leading surface. Also, returning as a glider gives only one chance at a landing. If any problems develop with the control surfaces, you’re out of luck.
Finally, consider how, with years of Shuttle experience, NASA chose to return to a capsule architecture for the Orion lunar spacecraft. Thus, we favor the capsule design for reliable and economical transport to and from Earth orbit.
Dragon on the Road to the ISS
Several months ago, we completed the first of three phases of review required by NASA’s Safety Review Panel (SRP) to send our Dragon spacecraft to the ISS. Over a series of meetings spanning four days at NASA’s Johnson Space Center in Houston, our engineers presented the Phase I plans for sending the cargo version of Dragon to the ISS.
The review covered twenty-three specific hazards, with extra attention paid to the danger of collision – one of the most difficult hazards to mitigate, and generally considered one of the most difficult areas for “visiting vehicles”.
To date, no other group has passed the Hazard of Collision report the first time through, or completed the overall review in such a short time. The fact that we passed in under a week speaks well of our team’s capabilities.
When we fly the three COTS cargo missions to the ISS, we will also be flight qualifying a huge number of systems that will eventually support passenger space travel. Whether we’re flying cargo or crew, the essential systems for Dragon remain the same:
Overview of the Dragon spacecraft
Dragon with pressurized section filled with cargo
Dragon with pressurized section fitted with seats, people and life support
Draco Thrusters Take Shape
We’re developing a small rocket engine called Draco that generates 90 pounds (400 Newtons) of thrust, using monomethyl hydrazine as a fuel and nitrogen tetroxide as an oxidizer – the same propellants used for orbital maneuvering by the Space Shuttle. Dragon will have a total of 18 Draco thrusters for both attitude control and orbital maneuvering.
Small but efficient – getting around becomes easier once you’re in “zero” gravity
Our propulsion team has completed the first Draco development engine, and it will soon begin testing at our new MMH/NTO vacuum test chamber in Texas.
Dragon Heat Shield Shapes Up
The base heat shield is an extremely important part of Dragon’s design. Although one can do a lot of testing on the ground with plasma torches and arc jets, nothing on the surface of the Earth can test for the actual conditions that are encountered upon reentry at 25 times the speed of sound. Considerable safety margins must be applied to address the model uncertainty, which leads to a relatively heavy heat shield. However, as we are able to anchor our models with empirical flight data, the mass efficiency of the heat shield can be much improved.
Digital modeling of reentry heating for the Dragon capsule - note how the off-axis heating pattern influences the design of the tile pattern in the photos below
A few months ago we completed the full-scale engineering unit of Dragon’s heat shield. Shaped like the heat shields that protected the Apollo capsules during their high-speed returns from the Moon, Dragon’s heat shield uses phenolic impregnated carbon ablator (PICA), the highest heat resistance material known. At heat fluxes that would vaporize steel, PICA is barely scathed.
Developed by the NASA Ames Research Center, PICA demonstrated its abilities in protecting the Stardust sample return mission. Stardust holds the record for the fastest mission reentry speed – nearly 28,000 miles per hour. Dragon will return at under than a third of that speed.
Technicians bond PICA tiles to the Dragon non-flight heat shield engineering model
Completed Dragon heat shield engineering unit with tiles, ready for testing
Dragon Makes a Big Splash
Dragon will return to Earth and land in the ocean (although it can be modified to land on land too). As with the Falcon 9 wind tunnel testing described above, we’re using scale models of our Dragon capsule to verify our digital models of recovery and splash down.
This video clip compares computer simulation of splashdowns with actual drop tests of a Dragon model having corresponding weight, impact speed, and drop angle. The model drop tests confirmed our computer simulations within a few percent.
Dragon will be steerable during reentry, allowing us to hit a target zone of under 1 mile in radius. Initial splashdowns will occur off the California coast.
Next Falcon 1 Launch
Since we decided to use the upgraded Merlin 1C engine on Falcon 1, the next flight has been dependent on finishing the development and qualification testing phases of the engine. With development now over, and only two or three months of qualification and acceptance testing remaining, it appears that Flight 3 will occur in the Spring of 2008.
Flight 3 will be followed shortly afterwards by Flight 4, carrying RazakSAT. Both missions will fly from our Kwajalein Atoll launch site in the central Pacific. Be sure to sign up for our email updates to receive our latest launch progress news. (See the upper right corner of our website.)
In September, Avanti Communications Group PLC of the UK purchased a Falcon 9 launch for its HYLAS Ka band satellite to geostationary transfer orbit (GTO). HYLAS will provide broadband and data communications services to European customers in 22 countries. Of the seven Falcon 9 launches on the SpaceX manifest, this is our first commercial geostationary telecommunications customer. The contract includes options for up to three additional satellite launches, which if exercised, will total approximately $150 million at our standard list prices.
We’re Looking for Great People
At SpaceX we are always seeking world-class people to join our team. Most of our needs are in California, but we’re also growing our Florida team in preparation for increased Falcon 9 activities at Cape Canaveral, and we’re expanding our Texas propulsion and test team.
Since the people we seek can work anywhere they want and tend to be most highly prized by their organizations, SpaceX also offers up to a $5,000 award to anyone who refers a candidate we hire. Besides a competitive salary, comprehensive benefits and significant stock options, joining SpaceX offers the opportunity to help open up space for humanity.