The Westall Two-Channel Bench: The Paddock and the Balloon

THE WESTALL TWO-CHANNEL BENCH · 6 APRIL 1966
Two schools, a paddock, a line of pines, and a silver object that went down behind them and came back up
Channel A: the geometry of three witness groups at three known places
Channel B: the balloon hypothesis, priced on the winds of the day, a real parachute and a real record
the map, the soundings and the standard atmosphere are measured; the object's size, height and place are dials
the geometry cannot tell a disc from a canopy; the physics can tell what a canopy cannot do
stand where they stood · fly the balloon · time the parachute · read the file

Evidence

fact ⇄ what kind of claim · live

6 April 1966, about 10:20 (the report form's time; later retellings say 11:00): students and teachers at two Westall schools watched a silver-grey object over the paddocks go down behind the Grange's pines, rise again and leave; five light aircraft; a ring of flattened grass; 122 witnesses logged later

the accounts as recorded; their sizes, heights and distances are estimates, entered here as dials

REPORTED

High school to the Grange 596 m on 210°; state school 545 m on 223°; fence to reserve 310 m; ground flat to 3 m; Moorabbin Airport 5.3 km on 219°; the 220 kV towers on the school grounds (OpenStreetMap, SRTM)

the map; every sight line and angle on the bench is computed on it

MEASURED

The radiosonde record for 5-6 April 1966 (IGRA v2.2): Mildura's six-hourly ascents, Laverton's full 09:00 profile to 10 hPa, 23 stratospheric reports from five stations; Melbourne's surface observations

the winds of that morning, as measured; not a climatology

MEASURED

Project HIBAL (Basterfield 2014): Mildura sampling balloons, a ~200 kg payload under a 12 m parachute, about an hour down, a chase aircraft, a retrieval crew; flight 292 scheduled for 5 April 1966; the pilot's log has 291 and 293, no 292; series MP1472/25 destroyed 1996

the hypothesis's own numbers, priced as it states them

REPORTED

The standard atmosphere; a flat canopy's drag coefficient 0.78; terminal velocity √(2mg/ρC_dS); the Sun at 039° / 37° at 10:20; great-circle distances; angular size 2·atan(D/2R)

arithmetic on table values; nothing fitted

EXACT

The object's height, size and place; the pines' height; where each group stood; the balloon's float, envelope, ascent rate and time aloft; the profile used above the soundings' top

choices, shown as dials; every finding survives their whole range

MODELLED

Whether a case geometry cannot close and the balloon record cannot carry is an unidentified object or an unrecovered document

the one question this bench refuses to close

READING

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