Skunk Works' End of Year 1998 Summary
During 1998, the X-33 technology demonstrator vehicle jumped from the drawing
board to the assembly floor, and 1999 will be even more dynamic as the X-33 program
enters what managers explain will be an extremely busy period of testing and qualifying
the X-33's cutting-edge components.
Three critical technologies to make single-stage-to-orbit (SSTO) and low-cost
access to space a reality must be developed. These technologies are a rugged, durable,
metallic thermal protection system; an efficient propulsion system ideally suited
to power a lifting body; and most importantly, lightweight yet strong composite cryogenic
fuel tanks and structures to keep vehicle weight down.
Components of these critical technologies have entered the test phase of the
X-33 program, and the thermal protection system already has been declared "ready
for flight."
The first of the two composite liquid hydrogen tanks is close to completing final
assembly and soon will be prepped for shipment to NASA Marshall Space Flight Center,
Huntsville, Ala., for the start of structural and pressure testing.
Successful testing wrapped up Jan. 15 on the first powerpack for the linear aerospike
engine, and engineers are now looking toward full-up engine hot-fires later this
spring.
The metallic thermal protection system panels were declared "ready for flight"
last month after completing an intensive test series that included sessions in high-speed,
high-temperature wind tunnels; combined environments testing; and even a Mach 1.4
flight strapped to the bottom of an F-15.
"We've entered a period of the program almost entirely focused on testing
the technologies critical to making a single-stage-to-orbit space plane a reality,"
said Jerry Rising, vice president of X-33/VentureStar at Lockheed Martin Skunk Works,
Palmdale, Calif. "Now the importance of developing a half-scale prototype becomes
clear. We're learning all the lessons - and some we never would have predicted -
to really understand how to build a space plane of this nature, and how to ensure
all the systems work as planned."
"The Skunk Works has a history of going where aerospace companies have never
gone before, whether we're talking U-2, SR-71 or stealth technology," Rising
added. "X-33 is a similar challenge we're determined to meet."
During the past few months, assembly of the X-33's two composite liquid hydrogen
tanks had been progressing smoothly. While the tank designed for the right side
of the X-33 has completed its eighth and final autoclave cure cycle, the left hand
tank experienced damage to one of its four walls--or "lobe skins"--after
completing a fifth cure cycle.
During a visual inspection, assembly technicians at the autoclave facility at
Lockheed Martin Missiles and Space, Sunnyvale, Calif., noticed bubbles and cracks
on the inner surface of the left hand tank's lobe skin No. 1. The tank had completed
a curing cycle two days earlier to bond stabilization patches to lobe skins No. 1
and No. 4.
A team from Lockheed Martin and Alliant Techsystems, Magna, Utah, maker of the
tank, is currently conducting a full analysis of the situation. Initial assessment
of the situation determined that the lobe skin would have to be completely replaced.
Alliant has begun manufacture of the replacement lobe skin, and crews are in the
process of removing the damaged lobe skin.
Assembly of the right side liquid hydrogen tank is progressing according to schedule.
Crews completed the tank's eighth and final autoclave cure cycle Jan. 11, so all
major elements of the tank are now attached. After the installation of some final
smaller-scale parts, the tank is scheduled to be shipped to Marshall Space Flight
Center in mid- to late-March for final qualification testing.
"No composite cryogenic fuel tanks have ever been done of this size and
complexity. Building and successfully flying lightweight yet strong composite cryogenic
fuel tanks - especially tanks each with a complex geometry that allows them to fit
within the shape of a lifting body - will be an enormous achievement," Rising
said.
"The tanks are one of the toughest technical challenges we've taken on in
a long time. We're working our way through the challenges, and it's all a learning
process that allows us to better develop the full-scale components required for VentureStar,"
Rising added.
Rocketdyne successfully completed testing of the first powerpack for the X-33's
linear aerospike engine on Jan. 16, with its seventh and final successful test on
a stand at NASA Stennis Space Center, Miss. All the tests were conducted without
any shutdowns caused by anomalous engine hardware.
The sixth test, completed Jan. 7, was the first to exceed the planned full engine
duration of roughly three minutes. The test was run for 250 seconds and was successful
in achieving all objectives.
The final test demonstrated operation of the pump at the abort throttle setting
required for "powerpack out" operation. The vehicle would be required to
operate in that mode if one of the two flight engine powerpacks was shut down in
flight due to an anomaly. With a successful demonstration of the "powerpack
out" throttle level, managers have gained increased confidence in the fact that
the two-engine X-33 will be able to continue flying safely to a landing in the event
one engine stops functioning during portions of the ascent.
This powerpack now will be shipped back to Rocketdyne's facility in Canoga Park,
Calif., for disassembly and inspection. Meanwhile, the Canoga Park aerospike team
has begun assembly of the first engine. A second powerpack will be installed on
the Stennis test stand for its upcoming test series. After testing of this unit
is completed, it too will be returned to Canoga Park where it will be installed into
the first engine assembly. Also, major component subassemblies are progressing well
in support of engine build.
Construction of the X-33 launch site, located at Edwards Air Force Base, Calif.,
was completed in December 1998, just a little more than 12 months after groundbreaking
and under budget. This unique complex is designed to minimize operational activities
between test flights and support the program's goal of low-cost access to space.
Taking full advantage of the X-33 single-stage-to-orbit architecture, the complex
provides for maintenance of the vehicle in the horizontal position, rotation of the
vehicle to the vertical position for pre-flight servicing, and vertical launch --
all from the same location, eliminating movement of the vehicle on the ground between
these operations.
One of the most distinguishing features of the launch site is the 90-foot-wide
by 105-foot-long movable building that will serve as an "airplane hangar"
when the X-33 is housed and serviced in the horizontal position. This simplified,
low-cost launch site exemplifies the overall program philosophy of building a reusable
launch system that operates more like an airplane.
Sverdrup Corp. of St. Louis accomplished the design and construction of the site
in record time. "Throughout our company's history we have developed many advanced
technology projects, including many launch facilities," said Ron Williams, Sverdrup
vice president of aerospace. "The X-33 launch site, of which we are very proud,
is a significant advancement in reducing the cost of these systems and their operation."
The X-33 launch site, which encompasses 30 acres, includes 4,000 cubic yards
of concrete, liquid hydrogen and oxygen tanks capable of storing more than 300,000
gallons of cryogenic liquids, and a 250-foot-tall, 250,000-gallon water tower that
will supply the deluge system at launch.
The X-33 Operations Control Center (OCC), located at Haystack Butte nearly a
mile from the launch site, will serve as mission control for the X-33 flight tests.
The OCC is linked to the launch site's data and communications systems through fiber
optics and standard telephone cables. Locations on NASA Dryden Flight Research Center
and Edwards AFB also are connected to the systems.
The X-33 launch site will be decommissioned and returned to a safe and "no-maintenance"
status after the completion of the X-33 flight test program.
The X-33's rugged, metallic thermal protection system successfully passed a rigorous
test series in November that included testing in high-heat, high-speed wind tunnels;
structural and thermal loads testing; and the Mach 1.4 flight aboard a NASA F-15
aircraft. Also, a thermal panel fit test was completed in mid-September at the Lockheed
Martin Skunk Works. This demonstration illustrated the ease of installing TPS panels
and the minimal processing time involved in removing metallic panels for replacement
or to gain access to X-33 systems during flight test operations.
As the X-33 flies through the upper atmosphere, the metallic thermal panels will
protect the vehicle from aerodynamic loads and heat comparable to those the VentureStar
will encounter while re-entering Earth's atmosphere from orbit. The thermal protection
system represents a marriage between aircraft and launch vehicle design, using easy-to-maintain
metallic panels placed over insulating material. Tests have verified that the thermal
protection system will protect launch vehicles from temperatures near 1,800 degrees
Fahrenheit.
NASA expects the metallic thermal protection panels--developed and built by B.F.
Goodrich Aerospace/Aerostructures Group in Chula Vista, Calif.--will dramatically
cut maintenance time and costs associated with more fragile thermal tile systems.
As the metallic panels on the lower surfaces of the X-33 and the rigid blankets on
the upper surfaces make up the vehicle's aerodynamic structural shell, the system
also will result in a significant weight savings over traditional thermal systems
while being much more durable and waterproof.
Manufacture of X-33 TPS flight test hardware is progressing smoothly. The bulk
of the TPS panels will be installed on the X-33 after installation of the vehicle's
two composite liquid hydrogen tanks and surrounding support
structure.
The X-33 Reaction Control System (RCS) verification testing has been successfully
completed by Gencorp Aerojet, Sacramento, Calif. The RCS system utilizes environmentally
benign gaseous oxygen and methane as propellants to power eight rocket engines and
nozzles that will be used to control the X-33's flight at high altitudes.
In December, Aerojet completed a successful mission simulation of an X-33 flight
to Dugway Proving Ground, Utah. The simulation involved regulator switch-over tests
and hot fire testing representative of having five thrusters operating at one time.
All hardware is in excellent post-test condition.
Overview
