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SpaceX June 2005 through September 2005 Update

Published by Sigurd De Keyser on Sat Oct 8, 2005 2:35 pm
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[October 2, 2005: Target launch date for Falcon I maiden flight is Halloween (October 31) from our island launch complex in the Kwajalein Atoll. The customer for this mission is DARPA and the Air Force and the payload will be FalconSat-2, part of the Air Force Academy’s satellite program that will measure space plasma phenomena, which can adversely affect space-based communications, including GPS and other civil and military communications. For video of the May hold down firing at Vandenberg, click here.]

The History of Falcon 9

About eighteen months ago, a customer approached SpaceX with launch mass and fairing volume needs that exceeded the Falcon 5. We iterated on several different solutions, including upgrading the Merlin engine thrust and adding liquid or solid strap on boosters. All the options held significant drawbacks in cost, schedule or reliability, except one – a nine engine first stage.

By adding an additional four engines on the base and stretching the tanks, we were able to achieve a payload of approximately ten imperial tons to low Earth orbit, which is slightly greater than that of the Boeing Delta IV Medium. Going further and adding two first stages as liquid strap on boosters, like Delta IV Heavy, allowed us to place about 25 tons into LEO – more than any launch vehicle in use today.

This is very significant as it allows SpaceX to lift the full range of commercial and military satellites, as well as service the Space Station with considerably more cargo. It also maximally leverages our investment in avionics, guidance & control, structural design, launch infrastructure and the Merlin engine. Our strategy of using the Merlin engine throughout the Falcon product line is similar to Southwest’s strategy of using only 737s throughout its fleet. However, in our case we get economies of scale in both manufacturing and servicing of the engine.

Some people may wonder why we use exactly the same stage structures on both F5 and F9. From a structural optimization standpoint, it is obviously more efficient to reduce the tank size for Falcon 5. However, that would require considerable additional investment in a different set of tooling, transport and ground support equipment, umbilical tower, aerodynamic calculations, test fixtures, etc. By making use of exactly the same stage structures for F5 and F9, our investment and launch costs are minimized. As those familiar with space transportation know, reliability & cost are the real problem, not squeezing out the last bit of performance.

The Launch Manifest is Growing

In addition to the six Falcon 1 launches, we now have two customers on the Falcon 9 launch manifest, one US government customer in 2007 and then Bigelow Aerospace in 2008. With Falcon 9’s ability to place any size of satellite into geosynchronous orbit, we are seeing considerable interest from the commercial satellite sector. I’m confident that after the launch of Falcon 1, we will be able to add a number of new customers for Falcon 9.

Customer Launch
Vehicle Departure
US Defense
Dept (DARPA)
Q4 2005 Falcon
US Defense
Dept (OSD/NRL)
Q4 2005 Falcon
Q2 2006 Falcon
US Government Q2 2007 Falcon
Q1 2008 Falcon
US Commercial Q2 2008 Falcon
MDA Corp. Q3 2008 Falcon
Swedish Space Corp. Q4 2008 Falcon
US Air Force $100 million contract thru 2010 Falcon

Falcon 1 is Really Important

I want to emphasize that although SpaceX development is now primarily on the Falcon 5/9, Falcon 1 is and will always remain a very important part of our business. All of us at SpaceX really believe in the small satellite market and we will never turn away from it or relegate it to a back corner. I think that once the satellite market has time to adapt to its existence, Falcon 1 may very well see the highest launch rate per year of any rocket in the world.

We have also changed our pricing policy to reflect the all inclusive price of launch to make things really clear. Some people were under the impression that range and 3rd party insurance costs were millions of dollars. Everything is now included, unless you have a really complex spacecraft or require an outside mission assurance process, and it is the same price we’ve had since 2002 – $5.9M for the vehicle plus $0.8M for the launch range, 3rd party insurance and payload integration.

The Island of Dr. Yes

In June, after Titan IV’s launch from Vandenberg was delayed yet again to sometime in late 2005, we decided to switch the maiden launch of Falcon 1 to an island in the Kwajalein Atoll that we are leasing from the US Army. For those unaware, SpaceX has a launch restriction specifying that we cannot fly from our Vandenberg Air Force Base launch site until the multi-billion dollar Titan IV mission departs. In theory, there is a tiny chance that our rocket could go off course and damage the T-IV, which is sitting on its pad, so our ability to launch from there has been put on pause.

The Kwajalein Atoll is essentially a huge reef that occasionally extends above water, forming a chain of islands. The biggest island is also called Kwajalein and contains almost all of the US personnel in the area. Politically, the Kwajalein Atoll is part of the Republic of the Marshall Islands, but is leased by the US Army for use as a missile test range and communications & tracking facility. As a result of hundreds of millions of dollars of investment by the Defense Department over the past several decades, Kwajalein is home to some of the world’s most powerful radar tracking and space communications systems.

Southern part of the Kwajalein Atoll with the main island of Kwajalein in the foreground

Our island in the Atoll is named Omelek and it is about halfway up the island chain on the eastern side. The Atoll’s location is advantageous for a number of reasons. Most significant is its location at 9 deg. N latitude, placing it much closer to the equator than the 28 deg. N latitude of Cape Canaveral, where our other eastward trajectory launch pad is located. That allows us to take more advantage of the Earth’s rotation and deliver increased payload to orbit. It also means that a much smaller plane change maneuver (to 0 deg.) is needed for geosynchronous satellites.

Kwajalein activity had been percolating along for about eighteen months, mostly dealing with regulatory matters, but it became our number one priority in June when we shifted first launch from Vandenberg to Omelek. From having only partially complete concrete foundations in June, the team has kicked butt and we now have the following in place:

  • Launch stand and vehicle erector
  • Vehicle hangar
  • Umbilical tower
  • Helium pressurization system
  • Nitrogen purge system
  • Liquid oxygen storage tanks
  • RP-1 kerosene tanks
  • A liquid oxygen generating plant
  • Dual redundant heavy duty generators
  • Office building (broken into pieces, brought over from another island and reassembled)
  • Fiber optic communications from Omelek to Kwajalein
  • Remote camera systems
  • Remote control of the launch site
  • 10k class clean room for satellite integration

The Army and Kwajalein Range Services have really stepped up to the plate to help get all this done so rapidly and deserve a lot of thanks. In addition to all the physical work that has taken place, a lot of effort has gone into ensuring that the rocket is safe for flight with a fully qualified, independent and redundant thrust termination system. It has also been great working with the Air Force and DARPA as the primary customers, together with NASA in a supporting role, for this first flight.


Our launch control center is located on Kwajalein Island along with guest offices for our customers. The main island also has hotels, shops, a cafeteria and sports facilities. For potential customers out there, I should mention that Kwajalein has some of the world’s best scuba diving and snorkeling! It is literally a tropical paradise.

Omelek pier and landing ramp



Nine Lives

One of the most important questions regarding the Falcon 9 first stage is whether having all those engines helps or hurts. The key question in my view is whether or not true redundancy is achieved. If an engine fails, what are the odds that it will fail in a benign manner? If there is an engine fire or a chamber comes apart, will it be limited to that one engine or will it cause a neighboring engine to fail?

To answer the first question, we can look at US launch failures over the past few decades, for which we have pretty good data. Drawing from the Futron Design Reliability report that looked at failures from 1984 through 2004, there were a total of six failures that were due to liquid rocket engines. Of the six, only one failure was caused by a rupture in the combustion chamber. The other five were either feedline problems or a failure to achieve or maintain full thrust.

Thrust and blocked/frozen feedline issues are no problem for a nine engine vehicle. All it would see is a slight decrease in total thrust, which might result in a slightly lower orbit than desired (if we were at maximum payload). This is definitely a significant advantage compared with a single engine vehicle that would almost certainly be out of luck.

Then there is the question of dealing with the comparatively rare case of a chamber rupture. To protect against this, Falcon 9 will have a blast shield protecting the entire base of the vehicle just above the gimbal joints of the engines. In addition, there will be fireproofed Kevlar fragment containment around each engine, similar to those present in jet engine nacelles. The explosive power of a liquid rocket chamber is actually not exceptionally high – it can be thought of as simply a small pressure vessel containing (in our case) 800 psi hot gas. During the development of Merlin, we saw several of what we refer to as RUD (rapid unscheduled disassembly) events and no fragments have ever penetrated more than 2mm of aluminum. Also, the direction of fragments is in a shallow downward cone away from the vehicle.

As additional measures of protection, all propellant and pneumatic lines have either pre-valves or check valves nested up high in the thrust structure. If anything happens to the engine, the flight computer is able to cut off all propellant and pressurant flow immediately.

Given all of the above, I really believe we have a stage that has considerably higher propulsion reliability than a single engine vehicle.

Moreover, there are examples of multi-thrust chamber vehicles that have outstanding reliability. The Soyuz rocket, which has the longest flight history of any launch vehicle ever and a phenomenal safety record over the past few decades, is the primary form of human transportation to the Space Station. It has thirty-two thrust chambers on the first stage. The Saturn I, which had zero failures, was used for human transportation during the Apollo program. It had eight thrust chambers.

Soyuz with 32 thrust chambers

Saturn 1 with eight thrust chambers

For the stage hold down firing of Falcon 9, we will be using our very large test stand (BFTS) to deal with the roughly 350 metric tons of vertical thrust generated by the nine Merlin 1B engines. We are designing the thrust frame to be able to run to tanks dry with margin, so about 340 tons of net vertical thrust has to be held down. This is no problem for the stand itself, which was designed to handle 1500 tons of thrust! It is quite epic in stature, being about 100 ft tall with ten ft diameter steel reinforced solid concrete legs that extend 70 ft underground.

The elevator is now installed along the one leg and we have the propellant supply tanks in place. Electrical power is in place and fiber communications to the blockhouse will be installed shortly. The next segment of work is digging out the flame diverter at the base, pouring the high temperature concrete and adding the water deluge system. We are hoping to have it ready for a Q2 2006 hold down firing of the F9 flight stage.

Elevator now installed on BFTS


One of the most striking differences between Falcon 1 and Falcon 9 is that, due to the size, almost everything needs a holding fixture and a crane to be moved. Even getting in and out of the tank requires a special drawbridge structure when the manway is at the center of a 12 ft (3.6 m) diameter dome! In contrast, with Falcon 1 at 5.5 ft (1.7 m), two people can easily carry around a dome or barrel section, getting in and out of the tank requires no tooling and transportation of the whole stage is easy, as it fits inside a standard semi trailer.

At this point, we have most of the machinery and tooling built for Falcon 9. All of the domes for the first tank are in house and we are welding up the barrel sections. One significant remaining tool, due to be done soon, is the circumferential stir welding fixture. Once that is complete, Falcon 5/9 will be the only launch vehicle in the world that has fully stir welded tanks. The layup and trim tools for the composite thrust skirt and interstage are done and we are putting together our first 12 ft diameter composite barrel section.

It is astounding to me that so many rockets out there use completely different stage structures for the 1st and 2nd stages. It is a huge cost savings to be able to build the 2nd stage as simply a short version of the 1st stage. All that changes is stringer density and skin thickness.


Engine electronics for the Merlin 1B in Falcon 9 have been simplified down to just three boxes that are responsible for all digital and analog activity. Each set of engine electronics is essentially a self contained plug and play module, dealing with its own activity in accordance with high level commands issued by the flight computer on the upper stage. The only wires between the stage and each engine are an Ethernet cable and a power cable.

The flight computer issues the same steering commands to all engines, except for a slight bias on the outer engines for roll control. Unlike the Falcon 1, where the turbopump exhaust is gimbaled for roll control, the M1B engines on Falcon 9 have a fixed turbine exhaust.

M1B engine showing electronics boxes on the grey panel

The objective with the Falcon 9 avionics is triple redundancy with voting for the flight computer and inertial/GPS navigation system, and dual redundancy for the power system and telemetry, where voting isn’t meaningful. Unlike Falcon 1, Falcon 9 is intended for manned flight one day and all critical systems have to function perfectly for potentially several days of occupied time.

Layout of avionics about the 2nd stage LOX dome

—– Elon —-

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