Value chain · CLM-1432
In plain terms
Rockwell'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 cm and about 226 tonnes if only 12 cm is allowed. The 500 m frame goes from about 16 to about 30 tonnes over the same range.
The claim as recorded
Rockwell's 1981 Figure 3.1-83 plots hexagonal frame mass against the surface deviation allowed under pressure and thermal gradients, for aperture radii of 500, 700, 850 and 1000 m. Graph-read to about +/- 2 t, the mass at the chart's three marked design points of 12, 24 and 48 cm is about 226, 129 and 85 t at 1000 m, 121, 77 and 51 t at 850 m, 79, 53 and 39 t at 700 m and 30, 22 and 16 t at 500 m. The chart prints the beam size b at each point: 86, 80 and 75 m at 1000 m; 71, 67 and 62 m at 850 m; 62, 58 and 56 m at 700 m; 41, 39 and 35 m at 500 m.
Evidence behind this: T3-contractor design chart; the masses and deviations are graph-read by us from the printed curves, while the beam sizes b are printed on the chart.
Scope and limits
GRAPH-READ, NOT PRINTED NUMBERS. The masses and deviations come from the plotted lines and carry about +/- 2 t and +/- 0.3 cm; only the beam sizes b and the axis ticks are printed. A redraw from them reproduces the chart, not the study's underlying data, which the page says is in Volume II Section 3.3, not read here. The dashed curve has no label or legend on the page and its meaning is not stated there. Each b label is attached to the curve whose dot it sits beside; at 24 and 48 cm the 850 m labels sit nearer the dashed curve than the dot. Figure 3.1-82 on the same page is a different chart (pressure only, axis ticks from 9 cm) and its values are not these. The kg x 10^-3 axis is read as tonnes, which fits the 270 t scale of a frame this size; the chart does not say "tonnes".
What it assumes
Linear axes, fitted on the printed ticks (270 to 45 t; 12, 24 and 36 cm, with 0 cm at the vertical axis); a lean of about 0.003 rad in the drawn vertical axis taken out (the dashed verticals at 12, 24 and 48 cm are upright, so the choice moves values at 48 cm by 1 to 2 t, inside the stated precision); each reading is the centre of the printed line.
Where it comes from
PDF p.208 / printed 3-99, zoom-5 crop. Caption: "Figure 3.1-83. Hexagonal Frame Mass Vs. Surface Deviation" (delta). Vertical axis "HEXAGON FRAME STRUCTURE MASS (KG X 10" superscript "-3)", ticks 0 to 270 every 45; horizontal axis "SURFACE DEVIATION" (delta) "(CMS)", ticks 12, 24, 36 and 48, 0 cm at the vertical axis. Legend: (delta) "IS MAXIMUM DEVIATION DUE TO PRESSURE" = 62.5 x 10^-6 N/m2 "AND THERMAL GRADIENTS"; "a & b ARE IN METERS"; curves labelled at the right "a = 1000", "a = 850", "a = 700", "a = 500". Graph-read, t at cm (+/- 2 t, +/- 0.3 cm). a = 1000: 12 226, 15 194, 18 167, 21 145, 24 129, 27 115, 30 106, 36 95, 42 88, 48 85; the curve starts at the 12 cm point. a = 850: 9.8 136, 11 128, 12 121, 15 106, 18 95, 21 85, 24 77, 27 70, 30 65, 36 58, 42 53, 48 51. a = 700: 9.8 87, 11 83, 12 79, 15 71, 18 63, 21 58, 24 53, 27 49, 30 46, 36 42, 42 40, 48 39. a = 500: 9.8 32, 11 31, 12 30, 15 28, 18 25, 21 23, 24 22, 27 21, 30 20, 36 18, 42 18, 48 16. An unlabelled dashed curve lies above the 850 m curve and closes on it towards 48 cm: 10.8 147, 11 146, 15 121, 18 105, 21 92, 24 84, 30 71, 36 63, 42 58, 48 55. All curves end at about 49 to 50 cm. The design points are dots on dashed verticals at 12, 24 and 48 cm, labelled "b = 86", "b = 80", "b = 75" (1000 m); "b = 71", "b = 67", "b = 62" (850 m); "b = 62", "b = 58", "b = 56" (700 m); "b = 41", "b = 39", "b = 35" (500 m).
Basis: t of frame mass (the axis reads kg x 10^-3); cm of surface deviation; m of aperture radius a and beam size b
Related records
- Answers question
- QST-013 not published in this release
Cite this
energyaperture.com/c/clm-1432
CLM-1432, Energy Aperture, as of 1981.
Connected records
Other published records linked to this one. A list, not a judgement.
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