SpaceX Update 9 May 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.
Elon
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.
Merlin Turbo-pump
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.
First
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
Avionics
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
Test
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
Payload
Fairing
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.