Value chain · CLM-0996
In plain terms
The beams the reference satellite would be built from are specified down to the wall thickness, and two contractors give the stiffness numbers.
The claim as recorded
Boeing's Phase II reference system states its two graphite-composite tri-beams as 38 cm closed and open cap sections of 0.86 and 0.71 mm wall, cap EI of 3.39e8 and 1.80e8 N cm2, beam widths 12.7 and 7.5 m, batten spacing 15.0 and 12.7 m, and 7.48 and 4.11 kg/m, totalling 4.14e6 kg of structure; Rockwell's antenna tribeam girder has a 30.57 m bay length, a geometric moment of inertia of 0.126 m4, modulus 9.65e10 Pa and coefficient of thermal expansion 0.18e-6 per degC in a 60 per cent fibre-volume graphite composite, giving EI of 1.22e10 N m2.
Evidence behind this: T3-contractor reference-system data: a stated beam table (Boeing) and a stated element property table (Rockwell).
Scope and limits
BOEING'S EI IS THE CAP'S, NOT THE TRI-BEAM'S: the tri-beam's stiffness is built from three caps at 12.7 or 7.5 m separation and Boeing does not state it. Rockwell's I = 0.126 m4 is the girder's. Two Rockwell exponents (cap area for mass, tension-web area for inertia) are ambiguous in the scan and are not used. Boeing labels its 7.5 m beam "Type B" on p.21 and "Type C" on p.22. The same Boeing page's prose calls the heavier beams "12.5-meter" where its table prints 12.7 M; this record takes the table.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
printed p.21, raw in the text layer: "3.39 E8", "1.80 E8", "7.48", "4.11", "made up of two sizes of graphite composite tri-beams"; printed p.22: 90,780 m of 12.7 m beams at 7.476 kg/m and 842,320 m of 7.5 m beams at 4.106 kg/m, 4,137,237 kg total. SRC-582 Table 3.1-38 from the render, tribeam girder column: effective area for mass 1.8e-3 m2, for moment of inertia 0.81e-3 m2, radius of gyration 12.48 m, I = 0.126 m4, E = 9.65e10 Pa, alpha = 0.18e-6 per degC, Poisson 0.4, "graphite composite, 60% fiber volume, made up as (0, +/-45, 0)"; the page's text: "The tribeam girder size dimension and bay length dimension are 30.57 m." Consistency: 12.48^2 x 0.81e-3 = 0.126, matching I. 9.65e10 x 0.126 = 1.22e10 N m2.
Basis: N cm2 and N m2 of bending stiffness; kg/m; m4; Pa; per degC
Related records
- Answers question
- QST-013 not published in this release
Cite this
energyaperture.com/c/clm-0996
CLM-0996, Energy Aperture, as of 1981.
Connected records
Other published records linked to this one. A list, not a judgement.
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