Method and apparatus for guiding a jet aircraft in a noise-abated post-takeoff climb

• US 4,019,702 A
• Filed: 11/13/1975
• Issued: 04/26/1977
• Est. Priority Date: 11/13/1975
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Annin, Gordon D.
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Eisenzopf, Reinhard J.
• Application Number:
  US05/631,525
• Time in Patent Office: 530 Days
• Field of Search: 244/180, 244/182, 244/183, 244/186, 244/187, 244/188, 73/178 R, 73/178 T, 235/150.2, 235/150.22
• US Class Current: 244/182
• CPC Class Codes: G05D 1/0661 specially adapted for take-off

Abstract

A pilot guidance system that computes and displays pitch and speed steering commands is automatically operated during the post-takeoff climb (at specified times clocked from the start of the takeoff run), to present commands that assist the pilot in cutting (and later in restoring) thrust for a predetermined interval to reduce engine noise, and in guiding the aircraft in a safe, gentle climb over the proximate community. The specified times (unique for each model of aircraft, airport, runway and departure flight path), synchronize the thrust cutback interval with the boundaries of the community in line with chosen departure path.

Claims

1. An apparatus for guiding a jet aircraft in a noise-abated post-takeoff climb, comprising:

a flight director having a first circuit means for producing a first electrical signal representing a difference between a sensed longitudinal air speed and a predetermined longitudinal air speed, and having a second circuit means for producing a second electrical signal representing a difference between a sensed vertical speed and a predetermined vertical speed;

signal utilization means including means for commanding a longitudinal air speed and means for commanding a pitch attitude, said means for commanding a longitudinal air speed being connected and responsive to said first electrical signal produced by said first circuit means;

switching means connected between said flight director and said utilization means and having first and second modes, said switching means connecting said means for commanding pitch attitude to receive said first electrical signal produced by said first circuit means when said switching means is in its first mode and connecting said means for commanding pitch attitude to receive said second electrical signal produced by said second circuit means when said switching means is in its second mode; and

timing control means for producing a control signal for operating said switching means at a predetermined elapsed time from the start of a takeoff run, said switching means initially assuming said first mode so that said means for commanding a pitch attitude produces a command that for a predetermined takeoff thrust level causes the aircraft to achieve and maintain said predetermined longitudinal air speed, said switching means being responsive to said control signal to assume said second mode in which said means for commanding a pitch attitude now produces a command in accordance with said predetermined vertical air speed which at said predetermined longitudinal air speed as commanded by said means for commanding a longitudinal air speed requires a reduction in thrust to a level that is substantially less than said predetermined takeoff thrust level.

2. The apparatus set forth in claim 1, wherein said utilization means includes a pitch command indicator means providing said means for commanding pitch attitude and a speed command indicator means providing said means for commanding longitudinal air speed, said pitch command indicator means indicating the amount and direction of pitch change required of the aircraft, said speed command indicator means indicating whether the aircraft is travelling faster or slower than said predetermined longitudinal air speed.

3. The apparatus set forth in claim 1, said timing control means including:

a clock driven by an electrical timer means, said clock visually displaying the elapsed time from said start and said timer means producing said control signal at said predetermined time, and a start control means for automatically starting said timer means in response to predetermined conditions indicating said start of a takeoff run.

4. The apparatus set forth in claim 3, wherein said predetermined conditions are brake release and thrust throttle advance, and said start control means includes means for starting said timer means in response to the coincidence of said predetermined conditions.

5. The apparatus set forth in claim 3, further comprising, manually settable means disposed on said clock for setting said predetermined time.

6. The apparatus set forth in claim 1, wherein said timing control means includes means for terminating said control signal at a second predetermined time from the start of a takeoff run at which said switching means reverts to said first mode.

7. The apparatus set forth in claim 6, wherein said timing means includes means for manually setting the first named predetermined time and said second predetermined time.

8. The apparatus set forth in claim 1, wherein said means for selecting said predetermined vertical speed has means defining a range of selectable speeds from 0 to 1,000 feet per minute, inclusive.

9. The apparatus set forth in claim 1, wherein said first circuit means comprises an angle of attack referenced longitudinal speed command computer.

10. A method of producing electrical control signals bo be displayed by a pilot command indicator for assisting a pilot in guiding an aircraft in a posttakeoff noise abatement flight over a noise sensitive area proximate an airport, comprising:

initially producing a first pitch attitude command signal representing a difference between a sensed longitudinal air speed and a predetermined longitudinal air speed, said first pitch attitude command signal commanding a pilot to pitch the aircraft such that when it is powered at a predetermined takeoff thrust level it will attain said predetermined longitudinal air speed;

producing a control signal at a predetermined time from the start of a takeoff run;

in response to said control signal producing a second pitch attitude command signal representing a difference between a sensed vertical speed and a predetermined vertical speed;

and concurrently with said step of producing said second pitch attitude command signal, producing a longitudinal speed command signal representing said difference between said sensed longitudinal air speed and said predetermined longitudinal air speed, together said second pitch attitude command signal and said longitudinal speed command signal commanding a pilot to pitch the aircraft so that it will assume said predetermined vertical speed and to concurrently reduce thrust to a level substantially below said predetermined takeoff thrust level in order to maintain said predetermined longitudinal air speed.

11. The method set forth in claim 10, further comprising the step of terminating said control signal at a second predetermined time from said start and in response to said termination producing said first pitch attitude command signal, whereby said first named predetermined time and said second predetermined time are preselected to synchronize the timing of the production of said second pitch attitude command signal with boundaries of the noise sensitive area.

12. The method set forth in claim 10, further comprising the steps of displaying said first and second pitch attitude command signals on a flight director pitch command indicator and displaying said longitudinal speed command signal on an indicator showing whether the sensed longitudinal air speed is faster, slower or equal to the predetermined longitudinal speed.

13. The method set forth in claim 10, including the step of selecting said predetermined vertical speed to lie within and inclusive of a range of speeds from 0 to 1,000 feet per minute.