Posted: Friday, May 9, 2003
Much has happened in the past few months, so there is a lot of good information in the update below. We have had several successful firings of the Falcon main engine (named Merlin), the first stage is almost complete, the second stage is in fabrication, our prototype fairing structure is done and a lot of the small, but important pieces arrived.
In March, we ran a three day Falcon design review for potential customers and the regulatory authorities, which seemed to be very well received. Representatives from NASA, the Dept of Defense and several commercial satellite builders were present on the customer side. On the regulatory front, we had Air Force Range & Safety and the FAA in attendance, and I would like to thank both of those organizations for their continuing support in helping us move Falcon through the regulatory approval process.
At this point, we have a verbal launch commitment from a Dept of Defense customer and a written launch commitment from an international government customer. While still preliminary, this seems to confirm that there is at least modest demand for launching small satellites.
We are starting to have more definite numbers for the payload capability of Falcon and indications are that it will do at least 1,250lbs (570kg) to 200km LEO from Cape Canaveral. This is 25% above our initial target of a 1,000lb payload capability. Pricing for the Falcon remains constant at $6 million per launch.
Also, starting in Q4 2004, SpaceX will offer Falcon with two liquid strap-on boosters in a configuration similar to Boeing’s Delta IV Heavy. Falcon’s capability to LEO would increase substantially to above 4000lbs (1820kg) and enable GTO payloads of approximately 1300lbs (590kg). Pricing and final payload capabilities are not yet determined and a more formal announcement will follow in coming months.
I have been asked several times whether we intend to pursue human spaceflight. The answer is that SpaceX will definitely pursue that market in the long term. In fact, part of the reason why we have spent substantial capital on reliability -- some would argue more than is necessary for satellites -- is that we would like Falcon to be safe enough for human transportation. However, we believe it makes sense to prove reliability with satellites before putting people on the rocket. 99% reliability is considered exceptionally good in the satellite delivery world, but is not very satisfactory for people.
Over the next several months, everyone at SpaceX will be heads down working hard towards our first satellite launch. Before too long, we should be able to release details of those launch plans and the partnership that has come together to make it happen.
Merlin at full thrust with a copper chamber
Merlin with a flight weight ablative chamber
After several weeks of testing, we are at about 94.5% combustion efficiency on a copper heatsink chamber. We will be firing with an ablative chamber in about six weeks, once we correct an issue with the metal insert that joins the injector head to the chamber. That should bump that up efficiency by a few percentage points and put us above our target of 96%. Including gas generator losses, vacuum specific impulse would then be about 310s with a modest expansion ratio.
Also in May, we expect to run the Merlin turbo-pump and verify pressures & flow rates. As mentioned before, our approach is a gas generator cycle, single shaft, single turbine wheel combined LOX/kerosene pump. Like the rest of our development, all components except those used for calibration are at or near flight weight. At 150lbs, the turbo-pump may be the best ever pump in its class for thrust (max 85,000lbf vacuum) to weight.
Stage Primary Structure Arrives
Despite delays due to the transport company truck breaking down on the way to pick up the first stage in Wisconsin, it arrived in time for the design review in good shape. Our shipping fixture with additional bracing from Spincraft did a great job of supporting the stage against lateral loads from the road. We could measure no meaningful deviation from circularity when it arrived, despite the fact that it was shipped unpressurized. This was actually an important practical test of structural stiffness as compared to an Atlas II/III, which requires pressure stabilization in transit to maintain its shape.
Falcon 1st Stage Primary Structure
Ring, Satellite Adapter Cone and Separation System
The vehicle avionics and flight termination system (apart from the linear shaped charges) are mounted on the cone, which is in turn mounted to the top of the second stage. On top of the cone is the satellite release system. We have decided to use a low shock, non-pyrotechnic device called Lightband, with essentially zero debris that could contaminate a satellite or spacecraft’s systems.
Payload Adapter and Satellite Release System on Mounting Tool
Stand Instrumentation and Setup in Texas
The Merlin horizontal pressure fed test stand is now fully set up at our propulsion testing facility in Texas. You can see it on the left under construction in this picture taken in February during a cold snap (that is ice on the ground). The large white pressurant ball, formerly used for wind tunnel tests, is made of one foot thick steel and weighs about 35 tons. In the middle of the picture is the vertical test stand for Merlin and to the right is the Kestrel vertical test stand.
This is intended to be a world class stand on par or better than those in use by Boeing or Northrop, so it is quite expensive and a lot of work to build and check out. In the end, however, we should be able to characterize very accurately the flows, pressures and temperatures throughout the thrust chamber assembly and fine tune the injector for maximum efficiency.
Test Stand Instrumentation and Setup in Texas
The tooling for joining the fairing skin panels, ring frames and stringers has been built and both fairing halves assembled. Our small construction crew, most of whom are former Boeing veterans from Huntington Beach, are doing a great job. They’ve built dozens of fairings in the past for everything from Delta II & IV to the Titan IV.
The first unit is an engineering prototype, which we will place in a test harness and verify all the expected load cases. Depending on how well the physical testing compares to our finite element model predictions, we will consider reducing the aluminum skin thickness in follow on units.
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