Communications: electrical – Aircraft alarm or indicating systems – Takeoff indicator
Reexamination Certificate
1998-11-10
2001-01-16
Swarthout, Brent A. (Department: 2736)
Communications: electrical
Aircraft alarm or indicating systems
Takeoff indicator
C073S17800T, C340S978000, C701S015000
Reexamination Certificate
active
06175315
ABSTRACT:
BACKGROUND
This invention relates to monitoring an aircraft's acceleration during the takeoff roll up to V1 speed.
Aircraft are certificated by a State's aeronautical licensing authority; such as, the United States Federal Aviation Agency, Transport Canada, the British Air Registration Board, or the European Joint Aviation Authority.
One of the certification requirements involves the aircraft having adequate takeoff performance, such that, with all engines operating, within the available runway distance, the aircraft is capable of accelerating from a standstill to the takeoff decision speed (commonly referred to as the V1 speed or the Go-NoGo speed), where, in the event of an engine failure, the aircraft is capable of either continuing the takeoff safely, or, rejecting the takeoff and stopping within the remaining runway distance available.
The takeoff acceleration is dependent upon eight primary criteria, namely,
a) All-Up Gross Weight of the Aircraft
b) Altitude of the Airfield,
c) Outside Air Temperature,
d) Runway Slope,
e) Wind Component,
f) Engine Power Setting,
g) Wing Flap Setting, and
h) Runway Contaminants; such as, snow, slush, and standing water.
Aircraft manufacturers produce takeoff performance graphs which, when entered with the appropriate criteria, will show the V1 speed and the runway distance required. During takeoff, the aircraft must maintain an acceleration rate such that V1 will be achieved at, or within, the graphed distance.
Let us consider the position of the pilot who has taxied out from the departure gate and has lifted up on the takeoff runway. He knows his V1 speed, and his runway distance required. He commences the takeoff roll. He experiences acceleration that seems satisfactory, but there is no instrumentation system provided to him that directly tells him if the rate of acceleration is in fact satisfactory—that remains, to this day, a “seat of the pants” acquired skill.
Many factors can insidiously retard the required takeoff acceleration rate which may result in having inadequate distance for takeoff, or inadequate distance for the accelerate-stop situation.
Some of the factors that may insidiously retard the required takeoff acceleration rate are: runway contaminants more severe than expected, erroneous engine pressure ratio gauges, engines not delivering rated power, wrong wingflap setting, soft tire(s), dragging brake(s), parking brakes not having been released, etc.
SUMMARY
The object of the invention is to inform the pilot, during the takeoff roll, as to whether the aircraft's acceleration rate is on a schedule that will achieve V1 at the required certificated distance.
In the case of a rotary dial-type airspeed indicator, during the takeoff roll, the pilot is informed of the airspeed the aircraft should be at when acceleration is on schedule, by an additional needle in the airspeed indicator, which is herein referred to as the Howgozit needle.
As the aircraft accelerates during the takeoff roll, the airspeed needle will advance, and the Howgozit needle will also advance. When both needles are registering equally, i.e. one superimposed on the other, then the aircraft's acceleration rate is on schedule. Should the airspeed needle advance ahead of the Howgozit needle, then the aircraft's acceleration rate is better than planned. Should the airspeed needle lag behind the Howgozit needle, then the aircraft's acceleration rate is lagging behind the required schedule.
For distance information, a window in the face of the airspeed indicator will digitally display to the pilot how far in distance the aircraft is presently behind the takeoff roll schedule.
In the case of a tape-type airspeed indicator, the pilot is informed of the airspeed the aircraft should be at when acceleration is on schedule, by means of a needle electronically generated out of the lubber line of the Howgozit Airspeed Indicator, which is herein referred to as the Howgozit needle, as depicted in Sheet 4 of 4 of the Drawings.
As the aircraft accelerates during the takeoff roll, the Howgozit needle will point to the airspeed at which the aircraft should be at, at that particular moment.
If the aircraft is on acceleration schedule as planned, then the Howgozit needle will not be generated, and thus not seen. If however the aircraft is ahead of acceleration schedule, then the Howgozit needle will appear and point down out of the lubber line to the speed the aircraft should be at when on the planned acceleration schedule. On the other hand, if the aircraft is behind the acceleration schedule, as depicted in Sheet 4 of 4 of the Drawings, the Howgozit needle will be generated upward from the lubber line to the speed the aircraft should be at when on the planned acceleration schedule. The further behind schedule, the longer the Howgozit needle will be.
For distance information, a window in the face of the Howgozit Airspeed Indicator will digitally display to the pilot how far in distance the aircraft is presently behind the takeoff roll schedule.
BRIEF DESCRIPTION OF THE DRAWINGS
Sheet 1 of 4 is a speed-vs-time takeoff acceleration graph of an assumed aircraft under assumed conditions, which demonstrates that aircraft acceleration on takeoff is not uniform (i.e., not a straight-line variable) due to factors that vary the thrust and the drag at different speeds; such as, propeller aerodynamic slippage, jet ram effect, tire rolling friction, form and parasite drag.
Sheet 2 of 4 portrays the face of a dial-type Howgozit Airspeed Indicator (showing an aircraft indicating 118 kts, with a required airspeed of 140 kts, and 400 feet behind acceleration schedule).
Sheet 3 of 4 portrays a schematic of the system components' interaction.
Sheet 4 of 4 portrays the face of a tape-type Howgozit Airspeed Indicator (showing an aircraft indicating 118 kts, with a required airspeed of 140 kts, and 400 feet behind acceleration schedule).
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Millard Carl W.
Millard Wayne C.
Gierczak Eugene J. A.
Swarthout Brent A.
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