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starship-design: FW: SSRT: X-33 schedule slip to Dec. '99
From: firstname.lastname@example.org [mailto:email@example.com] On
Behalf Of Chris W. Johnson
Sent: Monday, November 16, 1998 9:30 PM
To: Single Stage Rocket Technology News
Subject: SSRT: X-33 schedule slip to Dec. '99
The November 2, 1998, issue of Aviation Week & Space Technology included
a story entitled "X-33 Flight Slips Half-Year To December 1999" by
Michael A. Dornheim on pages 26 and 27. Major points from the article
* X-33 should be 69% complete by the end of 1998.
* X-33 is now scheduled for flight in December 1999.
* Liquid hydrogen tank is 50% complete and should be ready by year's end.
* The metallic thermal protection system (TPS) was recently validated in
tests at Langley Research Center.
* Reaction control system has been tested and pronounced flightworthy.
* Edwards launch site construction will be complete this month (Nov. '98).
X-33 will be moved there (sans engine) for tests in July.
* Engine approval is expected in November 1999.
* Lockheed Martin is spending 80% of funds on X-33, 20% on VentureStar.
* Historically, on average, every three months the X-33 schedule has slipped
by one month. If this continues, first flight would actually be July 2000.
* Reasons for the recent delay include a 7 month slip in delivery of the
XRS-2200 linear aerospike engines, and the need to choose a suitable
lining material for the liquid hydrogen tanks.
* Warping forces in the aerospike exhaust nozzle ramp proved challenging.
Its temperature varies from -420F where the liquid hydrogen fuel begins
circulating through it to 5,000F where the full blast from the 10 thrust
chambers is received. Unlike the bell nozzles of conventional rocket
engines, the linear aerospike's ramp attaches directly to the vehicle
structure at multiple points. Problem was known a year ago, and caused a
delivery slip from February to May of 1999.
* Recent difficulties with engine have centered on ramp fabrication. Ramp
is composed of a copper sheet milled with internal cooling passages which
is brazed onto a steel backing. That brazing has proved difficult, but a
successful ramp was produced in September. This problem caused a slip
from May to August or September 1999.
LockMart knew of problem in February, but did not publicize it until
* Another delay was caused by the late delivery by subcontractors of the
XRS-2200 turbomachinery. Tests began October 2 at Stennis Space Center.
* "[D]imensional issues with the thrust chambers have been resolved and
about 10 chambers have been built."
* "Rocketdyne estimates the X-33 engine problems have increased its costs
by $36 million." LockMart expects Rocketdyne to cover those costs.
* First 5 flights will go to Michael AAF on the Dugway Proving Grounds.
Next 2 flights will go to Malmstrom AFB. After that a decision about
flights will be made.
* X-33's mass fraction will be 26.3%. VentureStar's is to be 10%, so a 62%
reduction is required.
* Venture Star's RS-2200 engine is to have a thrust-to-weight ratio of 80,
compared to a ratio of 35 for X-33's XRS-2200. In effect, a 56% weight
reduction is required.
Chris W. Johnson | "Do we realize that industry,
| which has been our good servant,
firstname.lastname@example.org | might make a poor master?"
http://gargravarr.cc.utexas.edu/ | --Aldo Leopold, 1925