Value chain · CLM-0997
In plain terms
The designers said how flat the antenna had to stay: within about half a metre overall, with the surface elements out of true by no more than a twelfth of a degree, under sunlight, gravity and a 24 degree temperature difference across the frame.
The claim as recorded
Rockwell's 1981 antenna structure requirements are a peak out-of-plane deflection of 12 to 48 cm under the worst combination of reflected solar pressure (32.5e-6 N/m2), gravity gradient (32.5e-6 N/m2), microwave pressure (2.5e-6 N/m2) and a thermal gradient of 24 degC peak difference in average temperature of the tribeam caps; a web angular misalignment of +/-0.08 degrees; and, for the reference-phase distribution, aperture flatness of +/-18 cm. The 12 to 48 cm range is stated to be set by "the specific electronic efficiency requirements", and frame mass rises as the allowed deflection falls.
Evidence behind this: T3-contractor requirements databook; requirements, not achieved figures.
Scope and limits
REQUIREMENTS, NOT ACHIEVED FIGURES, FOR ROCKWELL'S TENSION-WEB ANTENNA. The electronic efficiency requirement behind the 12 to 48 cm is not restated on these pages. Boeing's equivalent - 1 arc-minute systematic and 1 arc-minute random subarray tilt for 0.5 per cent loss - is CLM-0981.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Printed 3-95, normalised: "(2) peak out-of-plane deflection 12 to 48 cm - during worst combination of solar pressure reflected - 32.5e-6 N/m2, gravity-gradient load - 32.5e-6 N/m2, microwave pressure - 2.5e-6 N/m2, thermal gradient - 24 degC peak difference in average temperature of tribeam caps, 16 degC sin(beta) difference in X-bracing cables"; also "structural temperature variation across the individual cap of 2-m beams - 110 degC" and differentials of +/-85 and +/-55 degC between cables, bracing and machine-made caps. Printed 3-96, normalised: "the antenna surface deviation from flatness must be compatible with the specific electronic efficiency requirements. The range of these requirements was 12 to 48 cm, as shown." Printed 3-94, from the render: "Web angular misalignment: +/-0.08 degrees under environmentally and operationally induced loads and temperature". Printed 3-60, transcribed from the render: "structural integrity of the array aperture to within +/-18 cm flatness". Printed 3-99, Figure 3.1-82 (pressure only, "THERMAL NOT INCLUDED"): hexagonal frame mass against surface deflection restriction, axis ticks 9 to 48 cm, about 15 to 45 t for a 500 m aperture radius and about 85 to 270 t for 1000 m, the 1000 m curve crossing the top tick (270 t) between the 9 and 12 cm ticks and running on above it. Figure 3.1-83 on the same page (pressure "AND THERMAL GRADIENTS") has axis ticks 12 to 48 cm; its curves are read in CLM-1432.
Basis: cm of out-of-plane deflection; degrees of web misalignment; degC of gradient
Related records
- Answers question
- QST-013 not published in this release
Cite this
energyaperture.com/c/clm-0997
CLM-0997, Energy Aperture, as of 1981.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-582
- CLM-0995The whole ten-kilometre satellite was designed to sway once every fourteen minutes, and the antenna was required to be at least as stiff as...CLM-0996The beams the reference satellite would be built from are specified down to the wall thickness, and two contractors give the stiffness...CLM-0999Rockwell hung a small transmitter above the antenna to give every patch the same timing reference, and each patch corrected its own...CLM-1432Rockwell's chart puts a price in mass on a flatter antenna. The frame for the 1,000 m radius weighs about 85 tonnes if it may deviate by 48...