Improved head-up display pitch bar system for aircraft

Details Improved head-up display pitch bar system for aircraft Improved head-up display pitch bar system for aircraft

1993-02-17

1994-08-09

Swarthout, Brent

Communications: electrical

Aircraft alarm or indicating systems

Nonalarm flight indicator

340974, 340980, G01C 2300

Patent

active

053370481

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to head-up display systems for aircraft.
2. Discussion of Prior Art
Known head-up display systems present an aircraft symbol and a pitch ladder display. The pitch ladder is a pattern of bars, each drawn (subject to inaccuracies resulting from the sensors and instrumentation) parallel to the actual horizon and forming a scale against which the position of the aircraft symbol indicates a measure of the attitude (pitch) or climb or dive angle of the aircraft. A central bar in the pattern represents zero climb/dive angle in level flight, and it should overlay the actual horizon as seen through the display whenever the horizon comes within the field of view of the display. It follows that the pattern must be tilted, with respect to the display centerline, by minus the bank angle of the aircraft, and the pattern center so placed that the aircraft symbol position gives the desired climb or dive angle measurement when read against the scale formed by the pitch bars. Only a portion of the pattern will be displayed within the field of view at any instant.
In conditions of poor visibility or in aerobatic maneuvers or high turbulence, climb-or-dive angle information is of vital importance. It is of particular importance that whenever the pilot returns his attention to the display after having any distraction or task requiring him to look elsewhere or after any violent maneuver, the display will give him an immediate and accurate appreciation of the bank angle and climb-or-dive angle presented so as to minimize any possibilities of misinterpretation.
The actual horizon, or the central horizon bar in the pitch ladder naturally forms a particularly useful indication by which the pilot can judge the climb-or-dive angle of his flight, but in a climb-or-dive it will soon disappear from the field of view.
When the climb-or-dive angle changes rapidly the bars in a conventional pitch ladder may appear to be written as multiple images and may all too easily be confused. To reduce these difficulties it was suggested in patent GB2179612B that the spacing of the pitch bars should be varied. The present invention is an improvement on the invention of this patent.


SUMMARY OF THE INVENTION

It is an object of the invention to provide a head-up display system to provide the pilot with very clear analog indications of climb-dive angle which can be immediately appreciated and also to provide a particular indication of chosen climb-or-dive angles .+-..phi..sub.1 which will be useful as references against which climb-or-dive angles may be judged.
According to the present invention a head-up display system includes means for generating a pitch ladder pattern having pitch bars which are straight lines with a central gap, the pitch bars representing climb angles being solid lines and the pitch bars representing dive angles being dashed lines, the pattern having a scale which is unity in a central region and which decreases smoothly from the central region towards the extremes of the pattern, characterized in that: any other bar, and the lengths of the bars decrease according to a relationship with their displacement from the central bar; symbol and the nadir or 90.degree. dive angle is indicated by a distinctive earth symbol, and and two outer regions between the inner regions and zenith and nadir respectively, and the graduation intervals in the outer regions are considerably greater than the graduation intervals in the inner regions, so that the first graduation interval in each outer region is considerably wider than the last graduation interval in each inner region, thus providing distinctive indications of the angles at which the inner regions end and the outer regions begin.
Preferably the zenith star symbol is shown in outline only, and the earth symbol is a circle filled by shading lines.
Preferably the central region extends to .+-.5.degree. and the inner regions extend to .+-.30.degree..
Preferably the graduation intervals in the outer regions are twice

REFERENCES:
patent: 4305057 (1981-12-01), Rolston
patent: 4513509 (1985-04-01), Nordstrom
patent: 4825194 (1989-04-01), Rasinski
patent: 4860007 (1989-08-01), Konicke et al.
patent: 4910513 (1990-03-01), Kelly et al.
patent: 4977401 (1990-12-01), Sjoberg

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