Value chain · CLM-0986
In plain terms
The beam-machine speeds in these studies were chosen off a curve, with the operating figure set where going faster stopped helping, and the five metres a minute used elsewhere was a planning assumption that the machine-builders thought could be doubled.
The claim as recorded
Boeing's 1980 briefing selects a composite beam fabrication rate of 1.7 m/min for 1.5 m batten spacing from Grumman curves "since the curve quickly becomes asymptotic above this rate", adds about 30 minutes handling per 104 m beam, applies 75 per cent productivity, and concludes the antenna primary structure needs at least 62 days. The 1978 briefing records the 5 m/min used for timelines as itself a ground rule, with the Grumman (NAS8-32472) and General Dynamics (NAS9-15310) beam-builder contracts projecting 5.7 m/min for 7.5 m beams and 10.5 m/min for 12.7 m beams.
Evidence behind this: T3-contractor briefings; the rates are selections from curves and projections from beam-builder contracts, not measurements.
Scope and limits
THE GRUMMAN CURVE ITSELF (SRC-467 PDF 395) HAS NOT BEEN RENDERED; THE SELECTED POINT IS QUOTED FROM THE TEXT DESCRIBING IT. Three rates - 0.5, 1.7 and 5 m/min - appear across the volumes for different beams and purposes and must not be averaged; 0.5 is the synchronised longitudinal line (CLM-0976, SRC-466 12-78), 5 the mobile machines, 1.7 a composite selection.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
p.397 from the render (the layer renders 1.7 as "I. 7"): "A typical beam building cycle includes about 30 minutes for handling each 104-m long beam... For the required beam batten spacing of 1.5 m, a fabrication rate of 1.7 m/minute was selected since the curve quickly becomes asymptotic above this rate. Using the foregoing data and a productivity rate of 75%, primary structure requires at least 62 days to be assembled." (These data "were developed by Grumman in support of its Phase 1 SPS studies for Boeing-D180-25037-2".) SRC-469 p.128 from the render: "somewhat higher rates may be achieved in fabricating the large SPS structural beams than the 5 meters per minute ground rule used for operations timelines... a production rate of 5.7 meters/min. for the 7.5 m beam, and 10.5 meters/min. for the 12.7 m beam (both composites) can be reasonably expected from a study of growth potentials available in the current technology."
Basis: beam fabrication rate in m/min; days for antenna primary structure
Related records
- Answers question
- QST-015 not published in this release
Cite this
energyaperture.com/c/clm-0986
CLM-0986, Energy Aperture, as of 1980.
Connected records
Other published records linked to this one. A list, not a judgement.