Exactly How does AUTO PILOT Work?

Question

Is it internal within the plane (Gyro?) or computer or radio type control with a ground system?

Answer 1

The first autopilots operated directly in conjunction with the attitude gyro and the directional gyro.  You dialed a heading into the DG and the autopilot would hold it, while also keeping the pitch and roll attitudes normal.

By the 1960s, there were autopilots that could be coupled with the VOR head to make the autopilot fly a specific radial To or FROM a station.  With improved miniaturization and electronic sophistication, autopilots became increasingly coupled with LORAN, GPS, and Inertial Navigation Systems.

Throughout this time, autopilots were basic servomechanisms that worked by reading, say, a variation in the DG heading and feeding in the necessary control input to correct the drift.  This was usually done by attaching pneumatic actuators to the control cables running to the rudder, elevators, and ailerons.  The autopilot in turn controlled the pneumatics through electric valves.

(I guess that just shows how old I am getting.  The pneumatics go back 40-50 years.  Nowadays direct electric drives are much more common.)

So if, say, the airplane drifts off heading to the left, the circuitry in the autopilot detects this, and sends electric current to the electric valve that admits pressure air to the pneumatic cylinder on the cable for the right rudder.  When the airplane has resumed the correct heading, the autopilot cuts off the current and closes the valve.  (Of course you don't steer with the rudder in coordinated flight, but it works for small corrections, so that was how the first autopilots worked.  Later autopilots are capable of making a coordinated turn, just as human pilots are trained to do.)

Now they are much more complex, and controlled by real computers and microcontrollers so that they can automatically do holding patterns, fly approaches and make a missed approach or go-around, and accomplish numerous other complex tasks.

Answer 2

Lots of good info here, but all of the autopilots I've worked used electric motors to control the trim surfaces. No valves for pneumatics are needed, since the servos are connected to the same wires that are connected to the yoke and rudder cables. With the aircraft hydraulics, only a small force is needed to move the trim surfaces.

On older servos, we had to change the brushes on the motors, but the newer systems have brushless DC motors.

The autopilot is engaged to couple with the nav systems, baro altimeter, or a combination of both. It can also be engaged and the autopilot control panel used in lieu of the yoke and rudder controls.

Answer 3

THere is a dashboard on the top deck of the cockpit.  There are the speed autopilot which can be set and the aircraft would mantain that speed.  The altitude autopilot which is engaged at about 500 feet and automatically climbs the aircraft at inserted fps.  The heading hold switch holds a selected heading.

Answer 4

Basically,  a computer takes incoming information from various sensors on the elevators, rudders and ailerons as well as the gyroscopes, accelerometers, altimeters, compasses and airspeed indicators.

The computer then processes all this information along with various inputs from the pilot, altitude, airspeed and flight plan, then sends signals to servomechanism units (small remote electric/hydraulic motors) connected to the elevators, rudders and ailerons to basically steer the aircraft.

So to summarize, a computer takes input data, processes it and adjusts the plane, takes input data, processes it and adjusts the plane. ect. ect.

Answer 5

THE WORD EXPLAINS ALL. BEARING IS SET . THE VESSEL IS COMMANDED BY THE COMPUTER. IT IS INSIDE THE PLANE OR SHIP. IN THE AIRCRAFT AT THE COCKPIT. ONBOARD SHIPS IT IS AT THE BRIDGE.