PILOT’S GUIDE Retrofit Autopilot Systems

1 PILOT'S GUIDE . Retrofit Autopilot Systems Buyer's GUIDE B y P a u l N o v a c e k Continuing work by the Sperry Autopilots come in many A Little History Corp. during and after the It all began with an invention different forms, but they developed by Elmer Sperry in the war, as well as Minneapolis . Honeywell and other manufactur- all perform the same task, early 1900s the gyroscope. This device uses a spinning ers, further refined the Autopilot , which is to relieve the mass that keeps its orientation making the components lighter, while an airplane moves around smaller and more capable. Over pilot from the sometimes- it, which is the basic principle the years, advances in electron- ics technology made it possible mundane task of flying the underlying today's artificial hori- for autopilots to land an airplane zon gyro. aircraft. They accomplish Originally designed to help under zero-visibility conditions.

2 Ships steer a steady course, In 1964, Smiths Industries devel- this in a few different ways, oped an autoland system for Elmer's son, Lawrence Sperry, but all use the three basic used his father's invention to airliners, enabling landings in successfully launch an aircraft conditions far below previous building blocks of an company specializing in aircraft minimums. Autopilot : sensing position, control Systems . Along the way, Eventually, the Autopilot the Lawrence Sperry Aircraft Co. evolved into the modern flight computing desired goal built the Messenger airplane and management system using fly- by-wire techniques to control and driving flight controls gyro-based instruments that are the aircraft from takeoff through still in use today. Sperry began to achieve the goal. experiments in the early 1920s landing. using gyros to sense attitude and using motors to drive the con- Basic Autopilot Functions trols, resulting in the precursor of An Autopilot 's primary function the modern-day Autopilot .

3 Is to provide stability in one or During the 1930s and 1940s, more axes. Let's use the pitch the Sperry Autopilot was further axis to illustrate this stability developed for use in airliners and function. As an aircraft encoun- as an integral part of precision ters turbulence, the attitude bombsights. The famous Norden indicator sends a signal to the bombsight of World War II used Autopilot computer indicating precision optics, a mechanical the nose has pitched up. The computer and Autopilot technolo- computer processes this signal gy to stabilize the heavy bomber and sends a signal to the pitch during a bomb run. During the servo instructing it to apply down run, the bombardier controlled elevator, thus bringing the aircraft the aircraft through use of the back to level pitch. This stabiliz- Century Flight Systems ' newest Autopilot line, the Triden series.

4 Autopilot . Continued on page 60 . - 58 - Autopilot COMPARISONS. Manufacturer Model Description List Price 20 Roll axis with nav tracking, contained within turn-coordinator $6,400 8,860. Roll functions with altitude hold, trim prompting, contained 30 $10,180 13,980. within turn-coordinator 30 Alt Stand-alone altitude hold, trim prompting $5,440 40 Roll axis, 3 panel mount $6,500 9,000. Roll functions with altitude hold, trim prompting, 3 panel 50 $10,300 15,300. mount S-TEC 55X Full-featured, radio stack mount $17,360 28,980. 60-1 Roll channel, full-featured, 3 panel mount $7,900 60-2 Full-featured, 3 panel mount $14,000. 60 PSS Stand-alone pitch, full-featured $8,200. 65 Full-featured, pedestal mount $24,920 31,760 Yaw Damper Stand-alone or integral $5,200 6,360. Included in MAGIC 2100 Integral part of MAGIC DFCS EFIS package KFC-225 Full-featured for piston singles and twins, radio stack mount $38,000 60,000.

5 Honeywell Full-featured, EFIS compatible for turboprop, pedestal Included in EFIS at KFC-325. mount, RVSM compliant $310,000 (typical). I Roll axis with nav tracking, contained within turn-coordinator $6,750. Century 41 Full-featured, pedestal mount $24,495. 2000 Full-featured, radio stack mount $8,995 19,995. Triden Full-featured, 3 panel mount $12,995 22,995. Full-featured, radio stack mount, single- and multi-engine Chelton AP-3C $14,650 16,150. piston DigiTrak Roll channel, solid-state DG, GPS tracking $1,695 (2 ), $1,745 (3 ). Pictorial Pilot DigiTrack within turn coordinator $2,095 (2 ), $2,145 (3 ). DigiFlight II Panel mount (2 ), GPS tracking with altitude hold $3,850 DigiFlight II G Panel mount (2 ), GPS steering with altitude hold $4,225 Panel mount (2 ), GPS tracking with altitude hold, vertical DigiFlight II VS $4,350 speed and trim prompting DigiFlight II Panel mount (2 ), GPS steering with altitude hold, vertical $4,725 VSG speed and trim prompting TruTrak DigiFlight II Panel mount (2 ), GPS steering with altitude hold, vertical $5,225 VSGV speed, trim prompting and GPS VNAV.

6 DFC-200. Panel (3 ) or radio stack mount, full featured $6,900 ATI/AS. Radio stack mount, full-featured, GPS vertical mode, altitude Sorcerer AS $9,500 preselect, airspeed select Stand-alone altitude hold, vertical speed select with VS. AlTrak / VS $1,695 1,995 model ADI Pilot I Roll Autopilot with ADI, GPS tracking, digital DG $2,795. Roll & Pitch Autopilot with ADI, Alt hold, GPS tracking, ADI Pilot II $3,995. digital DG. Note: The ranges of list prices reflect the different prices for installation kits and optional features. - 59 - Autopilot BUYER'S GUIDE allowing the system to constantly EFIS system as installed in the Continued from page 58 sense and correct the actions Piper Meridian and as Retrofit into ing process repeats itself many until the task is completed. turboprop aircraft. times per second and keeps the As does your body, a gyro All S-TEC Autopilot Systems aircraft balanced around a fixed serves as the Autopilot 's eyes, use hardware, servos and sen- attitude.

7 Or sensors, sensing the current sors common throughout the Once basic stability has been position of the aircraft in relation product line. This commonality achieved around a set point in to the surface of the earth. The gives the aircraft owner signifi- the steady state case, level atti- current position is sent to the cant advantages in serviceability, tude the pilot can change the Autopilot computer, which per- reliability and overall cost. It's set point. This process is called forms all necessary calculations, also the foundation of the S-TEC. homeostasis, in which stability then sends a signal to a motor upgrade/trade-in program, which is achieved around a preset, but that moves the aircraft control gives an Autopilot buyer the resetable point. This homeo- surface. The aerodynamics of option of buying a system today stasis process works for all the the aircraft respond to the control and upgrading it to a system basic Autopilot functions, such as movement and provide feedback with more features and functions heading and altitude hold.

8 To the gyro, which begins the pro- later. An owner can purchase a An Autopilot works in much the cess again. system 20 for just the roll axis, same way as does your body. Depending on the model and then later upgrade using the Your body uses three interrelated capabilities of the particular auto- same servo and mounts, thus Systems to accomplish a task, pilot, either an artificial horizon saving hours of installation time. even as simple a task as taking or turn coordinator gyro is used For the kit-built market, S- a drink of water. Your eyes see as the primary sensor. Additional TEC has a program designed where the glass is on the table, sensors also are used, such to specifically meet the special then your brain processes the as an air pressure sensor, to needs of custom installations. position of the glass and deter- determine altitude, and acceler- The company has specific kits mines what muscles are needed ometers to detect motion.

9 The available for the more popular to lift the glass. An important part computer performs all the com- kit airplanes, such as Lancairs, of this process is the open-loop putations necessary to control Glasairs and others. If S-TEC. feedback that senses your move- the aircraft. The computer output doesn't have an approved kit ments and corrects for any nec- is sent to a servo providing the for a specific kit airplane, the essary adjustments. muscle for each control axis. company will work with avionics While lifting the glass to take shops on a custom installation a drink, your eyes observe the Meggitt/S-TEC or possibly develop a kit for that image of your arm raising the The Meggitt/S-TEC family of specific airplane. glass. This image is sent to your autopilots comprise the basic of S-TEC's newest Autopilot brain, where it is perceived that wing-levelers to fully integrated is borne from the marriage to your arm is not going in the right flight control Systems .

10 For simple Meggitt. The MAGIC 2100 digital direction. A corrective signal is roll control, the system 20 is fully flight control system is an integral sent to your muscles instructing contained in the turn coordinator component of the Meggitt MAGIC. them to move in the proper direc- and roll servo. The upper end of line of control and display units tion. The process, called feed- the S-TEC line, the MAGIC 2100, and is not sold as a stand-alone back, then starts all over again, is an integral part of its Meggitt system ; however, plans are in the works to provide stand-alone capability in the future. The MAGIC 2100 DFCS is a digital attitude based flight control system in an avionics stack-mounted case containing the mode selector/programmer, annunciator, roll, pitch and yaw The entire line of Meggitt/S-TEC autopilots, from simple wing-levelers to full-function flight control computers, including the servo Systems .