Flight Computer (Analog E6B)
A faithful, fully interactive analog flight computer: calculator side and wind side with rotating scales, slider and azimuth, usable by touch and mouse with zoom for dense scales.
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Internal prototype: the instrument follows the classic E6-B layout (calculator side, wind side, slide) so its readings can be practised as on a real flight computer; it shows no manufacturer's name, logo or emblem. Publication beyond this test page waits for the remaining release decision on the layout and printed texts.
Calculator side: drag the disc to turn it (Shift, Alt or the Fine button gives one tenth of the motion; arrow keys turn it 0.1°, Shift + arrow 1°, Page keys 10°). The outer scale is fixed, the middle scale and the time ring turn with the disc, and the two windows show the scales printed on the body beneath it: in the AIRSPEED CORRECTION window the pressure altitude is on the body and the temperature on the disc, in the ALTITUDE CORRECTION window it is the other way round, as on the instrument. Tap any scale to put the reading line there; the readout gives the pair under it as the device reads it.
Wind side (Flip): drag the azimuth rim to turn it under the TRUE INDEX, tap inside the azimuth to pencil the wind dot and drag it, drag the slide (or the transparent area) to move the grid. The grommet’s arc is the groundspeed (one continuous grid, 1 kt per arc, labelled 40–260 kt), the drift lines give the wind correction angle (2° apart below 100 kt, 1° above), and the 0–45° scale beside the TRUE INDEX (VAR. EAST / WCA LEFT, VAR. WEST / WCA RIGHT) turns a WCA or a variation into a heading.
Guided procedure: pick a function (every row of the E6-B inventory) and a worked example from the manual; each step highlights the scale, index or window to use and turns green when your setting is within tolerance (about half a degree of disc rotation, one degree of azimuth, one knot of slide). Readings are typed in and checked against what the scale shows at the correct setting. Practice draws the same examples without the steps. Loupe, zoom (wheel, pinch, + / −) and the numeric Set to… entries help with the dense scales; they never replace the instrument.
Every printed position is computed, never traced: a value v of the slide-rule scales sits at 360° × log10(v/10), so turning the disc by θ multiplies every outer reading by 10^(θ/360). The unit arrows sit at the logarithm of their NIST conversion factors from anchors read on the photographs (NAUT 66, U.S. GAL 13, KG 17, FT 14; STAT, KM, IMP. GAL, FUEL LBS, OIL LBS, LITERS, LBS., METERS derived), the 60 RATE and SECONDS indexes at 60 min and 3,600 s per hour. The airspeed window turns the disc by 360° × log10(1/√σ) (σ = density ratio of the pressure altitude and OAT), so its density-altitude pointer reads the exact ISA density altitude and the outer scale reads CAS/√σ — the single ratio the instrument embodies, within 3.5 kt of the manual's answers; the altitude window turns it by 360° × log10(T/T_ISA), which is the manual's true-altitude correction; the Mach index is placed where middle 10 reads the speed of sound.
Readings are shown as the device shows them — rounded to the printed graduation (0.1 from 10 to 15, 0.2 to 30, 0.5 to 60, 1 to 100 per decade; 100 ft at the density-altitude pointer; whole knots and degrees on the wind side). The Exact overlay adds the unrounded values. The procedures are tested by performing them on the same geometry: every setting step must satisfy its own check, every reading must match the manual's example or printed answer within one graduation and equal the digital flight computer's device reading for the same inputs.
Wind side and slide reverse follow the owner’s photograph of the wind side (photo 03): the azimuth ring, cardinal boxes and 16-point names, the TRUE INDEX, the drift / variation scale, the plates and the printed texts are placed at the radii, angles and lengths read on that photo, and the slide reverse is one continuous grid whose arcs and drift lines were measured on it (arcs within 2 px, RMS under 1 px; the 10°, 20° and 30° rays within 0.4°). The grid itself is the vector solution of the manual’s procedure: speed arcs proportional to the speed about one origin and drift lines radiating from it, so the groundspeed under the grommet and the wind correction angle at the dot are exact to the 1-kt / 1° reading.
- E6-B flight computer instruction manual (the published manufacturer's manual of the reference instrument) pp. 4–38: scale description, every procedure, worked examples and printed answers
- Registered photographs of the owner's E6-B flight computer: calculator side and slide front (photos 01, 02), wind side and slide reverse (photo 03); layout, labels, radii and anchor positions; every scale position computed from its ratio, never traced
- NIST SP 811 (unit index ratios); U.S. Standard Atmosphere 1976 / ICAO Doc 7488 (window scales: 1/√σ, T/T_ISA, density altitude); NACA Report 837 (why the window ratio differs from the exact TAS)
- PHAK FAA-H-8083-25C ch. 16 (wind triangle, variation) and AFH FAA-H-8083-3C ch. 9 (crosswind components)