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Robert M. Howe, Ph.D. and Professor Emeritus

A Brief Biographical Sketch


Edward J. Fadden, Ph.D.

Chairman of Applied Dynamics International Inc., Board of Directors


A survey article written around 1940 found that desk calculators served the needs for almost all industrial computational tasks except in the telephone and aircraft industries. “Handbook engineering” seems to have been the general approach used for industrial engineering design activities. Why was this the case? Very simply the computer technology to support anything more advanced did not exist prior to WW II. In general, engineering education and practice seems to have been little different in 1940 from what it had been in the late 1920s. Certainly, there was little impetus for change during the depression years of the 1930s.

However, there was one major exception to this situation, namely in the control of large guns for national defense purposes, particularly the guns on US Navy warships. As will be seen below, World War II would bring about an evolution in engineering thinking that took into account control of system dynamics. This led to the need for mathematical modeling and simulation tools for engineers to be able to visualize and predict what would happen in a proposed controller application.

Robert M. (Bob) Howe was born in 1925 and was to become a distinguished leader in this evolution in engineering education and thinking. In 1957, Bob had achieved the status of full Professor in the Aerospace Department of the University of Michigan. In 1957 he would also lead a small group in the founding of Applied Dynamics as part of this engineering evolution.

This document presents a brief biographical sketch of Bob Howe and the role he played both in Applied Dynamics and the U. of M. Aerospace Department. Bob did not live in a vacuum. His life was very much impacted by events, such as World War II, that happened around him and over which he had no control. It’s how he took advantage of the opportunities he was afforded by these events that made him the leader he was. Some of these events that affected not only Bob, but also the US war efforts, Southeastern Michigan, and the U. of M.’s Aerospace Department are presented in the following pages.

Bob Howe lecturing in the 1970s

Bob Howe lecturing in the 1970s

Bob Howe’s Formative Years – 1942 to 1950

Who was Bob Howe and what was his background? Bob was born in Oberlin, Ohio on August 28, 1925. His father, Carl Howe, was a Professor of Physics at Oberlin College. Bob was a very important pioneer in the early development of system simulation and the computational tools for generating solutions to simulation models. But, what was the world like when Bob was still in high school and how would it change in the few years leading to Bob Howe joining the U. of M., Aerospace Department. faculty in 1950?

Bob spent his K through tenth grade in Oberlin public schools. During this period he did so well that he skipped a grade. After he completed the tenth grade in an Oberlin public school, he transferred to Mercersburg Academy1 in Pennsylvania for his last two years of high school. Bob graduated from Mercersburg in 1942 as class valedictorian and enrolled in Oberlin College as a Physics major in June 1942.

The U.S. declared war on Japan on December 8, 1941 following the Japanese attack on Pearl Harbor the preceding day. In 1942, the military services became concerned that they needed many more officers trained in engineering than their military academies and ROTC programs could turn out. In December 1942 a government program was approved to correct this problem. The US Navy began its V-12 college training operation under this new government program on July 1, 1943.

At age 17, Bob applied for and was accepted into this Navy V-12 program as an apprentice seaman at Oberlin College. After five semesters at Oberlin, Bob transferred to California Institute of Technology (Caltech) where he graduated with a BS degree in electrical engineering in 1945. After attending the Navy’s midshipman’s school, he received his US Navy (officer’s) commission as an Ensign. He was then sent to a Naval gunnery school.2 Upon completion of this training, he was assigned as a Gunnery Officer on the USS Dayton, a cruiser that had entered service in 1945. (Note: WW II was over by the time Bob began his service on the USS Dayton, so there was no real need for a Gunnery Officer. Bob was probably very bored during his shipboard time!) He served in this capacity until he was discharged from the Navy in the Fall of 1946. Following his discharge from the Navy, he returned home where he again enrolled in the Physics curriculum at Oberlin College. He graduated with an AB in Physics in 1947.

During the Summers, Bob’s father, Carl Howe, spent time at the University of Michigan working on sponsored research projects that interested him. In the Summer of 1947, Bob joined his father at the U. of M. and they, together with D. W. Hagelbarger (a new Aerospace Dept. faculty member), built DC amplifiers, constructed a small analog computer and used it to explore how this analog computer could be used for various academic and engineering purposes. This work was funded by the US Army Air Force contract called Project Wizard.3

In the Fall of 1947, Bob enrolled at the U. of M. and received an MS in Physics in 1948. He next went to the Massachusetts Institute of Technology (MIT) where he obtained his Ph.D. in Physics in June 1950. He then joined the faculty of the Aerospace Department of the U. of M. as an instructor. (He celebrated his 25th birthday in August 1950!) Bob rose rapidly in the academic ranks becoming an Assistant Professor in 1951, an Associate Professor in 1954, and a full, tenured Professor in 1957.

Bob ‍Howe ‍in ‍the ‍Navy

Bob Howe in the Navy

Naval Gunnery – What Was This All About?

Bob went to gunnery school and became a Gunnery Officer while in the Navy. What impact did this have on Bob’s career? In view of Bob’s high intellectual capabilities, it hardly seems a coincidence that Bob was selected for gunnery school. Going to gunnery school was likely a very fortunate step in Bob’s career development. In order to understand this, we need to find out what was involved with naval gunnery at this point in time and more broadly in engineering technology overall. The following material is taken from: The Pacific War Online Encyclopedia (

“Fire Control

Guns can destroy only what they can hit. This was a difficult problem for long-range gunnery against moving ships which required the gun to place the shell where the ship would be when the shell arrived. At maximum battle range of about 28,000 yards (25,600m or about 16 miles), a 16″ (406mm) diameter shell could take 40 seconds to reach the target, and a target steaming at 25 knots would have moved 560 yards (510m or about 0.33 mile) while the shell was in flight. This was nearly twice the length of an Iowa-class battleship. Long-range fire control proved more difficult for naval engineers to perfect than the construction of guns capable of throwing shells to great distances. However, fire control advanced rapidly during the first part of the 20th century, and by 1939 fire control was one of the most sophisticated of naval technologies.4

Much of the impetus for developing long-range anti-ship gunnery came from the torpedo. Torpedoes could inflict massive damage, and it was felt that gunnery could compete with torpedoes only if guns could hit their targets from outside of torpedo range.”5

By 1940, a variety of very sophisticated mechanical gun control systems had been developed over many years for numerous applications for the US Navy. A ship’s gun control system was not just one unit but consisted of various subsystems that all had to work together. At the top end of this chain of subsystems was the ship’s radar unit that provided the necessary data on the target ship. At the bottom of the chain was each gun’s independent position controller.

A major subsystem was the fire control mechanical differential analyzer, (aka a mechanical analog computer). Constructing the computer subsystem for a large ship was more like building an expensive, hand-made watch than an inexpensive car. The only thing this subsystem had in common with a car was its 3,000 lb. weight. The (only) supplier of this equipment was Ford Instrument Company – no connection to Ford Motor Company. Only one fire control computer was used per ship for the big guns regardless of the number of such guns. Each gun had its own servo positioning system. Thus, the fire control computer had to provide the control input for each gun which would differ from gun to gun. Note: A picture of a typical fire control computer is included a couple of pages below.

The gunnery control discussed above was pertinent to a ship’s offensive weaponry. A ship’s defensive weaponry was essentially for anti-aircraft purposes. The gun controllers needed in this area had to be much faster and more distributed than for the offensive weapons.

“The Mechanical Analog Computers of Hannibal Ford and William Newell”, (, a paper by A. Ben Clymer written in 1993, gives a good picture of the technology that allowed the US Navy to destroy the Japanese Navy.

Clymer’s paper begins as follows:6,7

“For over 40 years mechanical analog computers provided the US Navy (USN) with the world’s most advanced and capable fire-control systems for aiming large naval guns and setting fuze times on the shells for destroying either surface or air targets. A large part of this preeminence can be attributed to the work of Hannibal Ford (founder of the Ford Instrument Company) and William Newell who worked with Hannibal Ford as an employee of the Company. However, the credit has usually been withheld, first because of security classifications and later by the resulting widespread ignorance of even the main facts of their stories.”

At the start of World War II, Ford’s latest product, the Mark 8 was the most advanced fire-control system in the world. Ford had improved on the accuracy of earlier models by adding corrections for deck and trunnion tilt, wind speed, and drift. When the Mark 8’s successor was introduced during the latter stages of the war, the Navy, in keeping with the changes in technology taking place, designated it as the Computer Mark 1. (Note: The addition of these corrections indicates the level of complexity of this mechanical analog computer.)

As noted above, going to gunnery school was a very fortunate happening for Bob’s future career. Why? In order to better understand this, it is useful to consider the following.

In gunnery school Bob had to learn about a complicated system that involved collecting data from various sources, passing this data into the fire control subsystem which solved a complex model consisting of differential and algebraic equations, etc., and sending all the necessary control signals to the various control systems for the individual guns.

A ship’s gunnery system is probably the first really significant example of what eventually become known as “system engineering” and a forerunner of the direction that engineering education and practice would take post WW II. What is important here is to recognize that the situation between “my ship” and the “target ship” was not static; both ships were likely miles apart and had to be assumed to be moving. This was a dynamics problem that could only be described mathematically through the use of differential equations (a branch of calculus), sometimes referred to as “the language of engineering”. The fire control subsystem had to have a differential equation solver which was the mechanical analog computer aspect of this subsystem. The analog computer was the means for simulating the behavior of a physical dynamic system through the use of a mathematical model. This had to be a strong learning experience for Bob given the direction his future career would take.

As a newly commissioned Navy Officer, Bob was assigned as a Gunnery Officer on the USS Dayton. The gun director for the USS Dayton was the Computer Mark 1. This picture shows just how complex the Computer Mark 1 was and why it weighed about 3,000 lbs. This picture is taken from a paper written by Ford Instrument Company for an Analog Museum web site:

The size of the Computer Mark 1 was approximately 62 inches long, 38 inches wide, and 45 inches high. The primary material used in the construction of the above device was an aluminum alloy. The Computer Mark 1 had numerous connection points for ties to external devices which were part of the overall system.

This picture is of the USS Dayton, the ship that Bob served on as Gunnery Officer. This ship was a cruiser class ship in the parlance of the US Navy.

Size wise, a cruiser was larger than a destroyer and smaller than a battleship as typified by the USS Iowa. Cruisers did not carry the huge, 16-inch diameter guns of the battleships. The cruisers were equipped with twelve 15.2cm (6-inch/47 caliber) guns in four triple mounts, twelve 12.7cm (5-inch/38 caliber) guns in six twin mounts, 28 40mm guns, and 10 20mm guns.

Cruisers had a crew of 70 officers and 1,285 enlisted men.

With our naval fleet increasing in size beginning in the late 1930s, the US Navy was concerned that the Ford Instrument Company, manufacturer of the mechanical gun controllers, wouldn’t be able to keep up with the increasing demand for these devices.

An alternative approach, based on the use of electronic amplifiers, was sought as a backup replacement for the mechanical gun controller. The big concern with the use of vacuum tube electronic equipment was that this equipment likely wouldn’t survive in rough seas. Fortunately, Ford Instrument Company was able to keep up with the requirement to supply new ships through the end of WW II. On the other hand, vacuum tube gun directors were used successfully in land based applications which undoubtedly influenced the direction of Project Wizard and other government programs after the war. (See Appendix A for more details)

Interior of the Computer Mark 1

Interior of the Computer Mark 1

Photo# NH 98821 USS Dayton off the Philadelphia Navy Yard, 23 April 1945

Photo# NH 98821 USS Dayton off the Philadelphia Navy Yard, 23 April 1945

Early Analog Computer Concepts and Developments

As noted in footnote 2, the initial purpose of Project Wizard was to develop a defensive guided missile system in 1946. But with the 1947 scale back, the research at the U. of M. in 1947 specified the use of DC amplifiers as the basis of a general purpose analog computer.8 Note: These DC amplifiers became known as “operational amplifiers” or, more popularly as “op amps” and are still called that today.

Simultaneously with the Army Air Force’s Project Wizard, the U.S. Navy launched its own program to develop guided missiles which it named Project Cyclone. The Navy selected Reeves Instrument Company9 in 1946, for “development of a guided missile simulator and the operation of a simulation laboratory [for] research and development on guided missile simulation” and “development and construction of a rapid and precise automatic analog computer suitable for detailed simulation of guided missiles”. The contract’s Task Order II on June 12, 1947, required Reeves to provide “a simulation laboratory, the Project Cyclone Laboratory, which was to be operated by the Reeves Analysis and Computer Group.” Reeves built the lab’s original Reeves Electronic Analog Computers (REACs) in 1947, and a new computing lab of REACs was contracted under Task Order III in 1949. “The guided missile simulator of Task Order II was completed in early 1949 [with a] satisfactory demonstration in February 1949 of the guided missile simulator solving a three-dimensional guided missile problem”.

A commercial version of REAC soon followed, with more than 60 installed by 1950. Why is this important in this document? The Aerospace Dept. of the U. of M. bought a REAC in 1951 to add to its growing analog computer capability.

A research group called Project RAND began within the Douglas Aircraft Company during WW II. On May 14, 1948, Project RAND separated from the Douglas Aircraft Company and became an independent, nonprofit organization. The new entity was chartered in the state of California to “further and promote scientific, educational, and charitable purposes for the public welfare and security of the United States.” Shortly after becoming independent, Project RAND acquired an early model REAC and almost immediately made a number of significant improvements to it, many of which were quickly absorbed by the tiny postwar analog computing industry. Chief among these improvements was a new design for the DC op amp.

In 1949, Prof. L. L. (Larry) Rauch joined the U.of M., Aerospace Dept. from Princeton. In 1950, Prof. Rauch instituted a program of replacing the amplifiers built earlier at the U. of M. with the RAND amplifier design.

One of the problems associated with the DC amplifiers built at the U. of M., starting in 1947, and other such amplifiers, was drift over time in the amplifier output voltage. Rebalancing the amplifiers regularly was a time-consuming necessity. A method for eliminating this drift, called chopper stabilization, was worked out by RCA, and Leeds and Northrup and a patent for this invention was filed in 1949. This was a major step forward in the usefulness of the DC op amp.

Analog computer applications work at the U. of M. began with solving simple, linear, ordinary differential equation models which had time as the only independent variable. This work then progressed to solving a bending beam equation. This equation is a fourth order partial differential equation which has both time and space coordinates as independent variables. The space variable partial differentials were discretized to produce a set of coupled difference/differential equations with time as the only independent variable that had to be solved subject to a set of boundary conditions.

What was the purpose of looking at this example? Well, the wing of an aircraft could be thought of as a bending beam, free at each end, with a pilot controlled fuselage in the center that could insert forces and moments on the beam at that point. This was the subject of several research efforts and reports in the 1948 to1950 period as part of the Project Wizard program.

The 1950s – Bob Howe Establishes Himself as a Leader10

As noted in footnote 2 above, the U. of M. Aerospace Department began working on the Project Wizard contract in 1947. At about the same time the Air Force established the Guided Missiles Training Programs at both the U. of M. and MIT. This program consisted of two years of graduate studies in aeronautical engineering for junior and senior Air Force officers with an emphasis on new courses related to guided missile technology. The Project Wizard work in analog computers in 1947 and 1948 led to the use of analog computers for simulation in the laboratory courses in the Guided Missile Training Program. This in turn led to more government research contracts and had an impact on multiple U. of M. courses and programs.

After receiving his PhD in 1950, Bob returned to the Aerospace Dept. as an instructor teaching courses in flight dynamics and control and resumed his work in developing analog computers. Bob was involved with the Guided Missile Training Program as part of his responsibilities.

Bob Howe studying Couette Flow

Bob Howe studying Couette Flow

Expansion of U. of M. Aerospace Department Programs and Faculty

To handle these new activities, the Aero. Dept. had to add faculty with backgrounds in physics, electrical engineering and applied mathematics to augment its traditional staff of aeronautical engineering faculty. These new members were charged with creating and teaching graduate courses in guided missiles and control systems technology as well as supporting the U. of M.’s newly established Michigan Aeronautical Research Center (MARC) at the Willow Run Airport. (See the section labeled Michigan Aeronautical Research Center in Appendix B.) In 1951 Bob became an Assist. Prof. He rose rapidly as an academician and became a fully tenured Professor in 1957. Bob basically headed the Aero. Dept.’s analog computer facility during much of this period and well beyond.

Aerospace Department Purchase of REAC Analog Computer

The addition of the REAC series 100 analog computer to the Aero Dept. in 1951 provided 20 op amps, four servo-multipliers and four resolvers for coordinate transformation. With this added capability, the department was able to handle nonlinear differential equations involving multiplication of variables and coordinate conversion. Because these multipliers and resolvers utilized servo-driven potentiometers, the useful range of problem frequencies for accurate computation was limited to 1 Hz. or less. The op amps on the other hand, could provide accurate performance for frequencies up to 50 Hz.

Computer System Designed and Built for ONR

In 1951 the Office of Naval Research (ONR) gave the department a contract to study a sound wave application with implications for SONAR signals. The contract also included the design and delivery of an analog computer capable of solving this application. This machine was the first analog computer designed from scratch for delivery to a customer by the U. of M. Aero. Dept. This computer was delivered in 1953.

Tabletop Computer Designed and Built for Aerospace Department Courses

In 1952 Bob Howe developed the first tabletop analog computer specifically for simulation in laboratory courses. At a later date a ten amplifier tabletop analog computer, called the LM 10, was developed for use in Aero. Dept. courses11 and eventually became the first product manufactured by ADI.

Simulation Councils, Inc.

The analog computer was often referred to as an electrical engineer’s sand box. Clever users could devise special circuits to use with an op amp to achieve various kinds of special effects that a less experienced user would not be able to do. There was a need for an organized way for engineers to meet and exchange ideas and techniques. In 1952 a number of analog computer users decided to get together and form a not for profit, professional society to promote the use of mathematical modeling and analog computer simulation. The name selected for this organization was Simulation Councils, Inc. or SCI. (This name was later changed to Society for Computer Simulation.) Regional and national meetings of its members was the initial means for achieving its stated goals. Later, SCI began publishing a monthly magazine for this purpose.

In 1954, Bob started and served as first chairman of the Midwestern Simulation Council (SCI) and in 1957 he served as the first National Chair of the parent SCI organization.

Evaluation of the Computer Section of Flight Training Simulators

In 1953 the Aero. Dept. was given an Air Force contract to look into the computer section of flight training simulators. This study was based on complaints from Air Force pilots that some training simulators did not respond to certain pilot commands in the same way that the actual airplane did. The study was carried out over an 18 month period. Appendix C contains a detailed discussion of this very important project.

The Principal Investigator for this project was Bob Howe. The conclusions and recommendations set forth in the final report were very strong and had a major impact on the future of the training simulator industry as far as the simulation part of the simulator was concerned. Two areas were addressed: The type of electronic amplifiers used (DC amplifiers only, no AC amplifiers); and the need to compare simulation results against actual flight test data for each aircraft – something that had not been done up to that point in time. ( Note: The above recommendations needed to apply to all nonmilitary pilot training simulators also.)

Bob Howe and John McIntosh receiving the McLeod Founders Award from the Society for Computer Simulation (SCS)

Multiplying Two Variables in an Analog Computer Simulation

Starting with the REAC, and for some time thereafter, multiplying two analog variables to get the product was a problem. Appendix D provides an overview of this significant constraint on the usefulness of the analog computer in its early days. As noted in Appendix D, the approach that ultimately prevailed was based on the following equation:

x*y = (1/4)*[(x+y)² – (x-y)²]

This type of multiplier was known as a “quarter square or square law multiplier”.

Bob Howe’s Version of the Square Law Multiplier

In 1959, Bob Howe developed a version of the square-law multiplier based on the following variation of the above equation that used the absolute values of the quantities to be squared:

x*y= (1/4)*[ |x+y|² – |x-y|² ]

Bob’s version was more accurate and used less than half as many components as other available versions. In the early 1960s, Bob would design a much more accurate version of his multiplier as well as a sine/cosine function generator and a logarithmic function generator, all using the same basic approach, for Applied Dynamics. These became “gold standards” for the analog computer industry and were sometimes bought by ADI’s competitors to satisfy their customers’ requirements.

The Founding of Applied Dynamics Inc.

Applied Dynamics was founded in 1957 by four members of the Aeronautical Engineering Department of the University of Michigan (U.of M.). These four were: Prof. Robert M. (Bob) Howe, Assist. Profs. Edward O. (Ed) Gilbert and Elmer G. Gilbert, and J. B. (Jay) King, a mechanical designer. The leader of this group was Bob Howe. Note: Ed and Elmer were identical twins; While they shared an office at the U. of M., the only way to tell them apart was that “Ed is wed and wears a wedding ring”. (The faculty had as much problem as the students did!)

Ed and Elmer Gilbert were born in 1930. In their high school years, they were highly involved as “ham radio” operators to the point of building their own equipment including designing and building their own antenna equipment. In 1948 they entered Western Michigan University where they spent their first two college years. In 1950, they transferred to the U. of M. and graduated in 1952. Their academic records were as follows: B.S.E. Electrical Engineering, University of Michigan, 1952; M.S.E. Electrical Engineering, University of Michigan, 1953; and Ph.D. Instrumentation Engineering12 University of Michigan, 1957. It’s not clear when Ed and Elmer began working with Bob Howe in the U. of M. analog computer lab., but it was probably no later than 1952.

No information is currently available for Jay King’s academic background. but he was a very competent and creative mechanical designer.

ADI started out in Jay’s basement with Jay as its first employee. He was joined later by ADI’s first technician, Peter Barhydt. No one is around anymore who would know how ADI grew in terms of employees, except that at some point Jerry Kennedy was hired as the Company’s first President. Before joining ADI, Jerry had been with Electronic Associates, Inc., where he had been a top salesman for their analog computers.13 Bob, Ed and Elmer, of course continued to be highly involved in product concepts and designs. Likewise, there is no information available on how ADI was funded during its early years. However, ADI did have some outside investors in the 1960s.14

In 1963 Mr. Bill Wood replaced Jerry Kennedy as ADI’s CEO. Prior to joining ADI, Bill had been responsible for the Link and Industrial Controls Division of General Precision, Inc. At that time, Link (the original aircraft pilot training simulator manufacturer) was the largest supplier of aircraft training equipment in the world and Industrial Controls was a prominent supplier of control equipment to the metals and petroleum industries. Bill served as President of ADI until the end of 1968. Bill was a conservative leader who kept ADI out of serious trouble in a very active, but turbulent marketplace for analog computers during his five year tenure. One thing to keep in mind here is that there was virtually no simulation anywhere in the 1940s. The military push for guided missiles in the cold war years, starting after WW II, led to the need for development of control and sampled data system concepts. This, in turn, led to the need to be able to visualize what was going on in a control system to design and tune such a system. Engineering education also underwent a big transformation from being “handbook” based to being much more math and science based.15

Bob Howe’s Book on Analog Computer Components

Bob Howe was a very inquisitive person. He not only wanted to understand how an entity worked, but also what its limitations were when used as a computational device or algorithm in a simulation environment. Error analysis was part of his makeup. Beyond just identifying an error source, Bob wanted to see if there was a reasonable way to reduce or eliminate the error source. With this background in mind, Bob studied how other companies making electronic analog computers were dealing with such issues as multiplying two simulation variables.

In 1958, Bob prepared a “set of notes written by the author to accompany a course on analog computer components given in 1958 for the Research Laboratories of the General Motors Corporation”. Using this set of notes as a starting point, Bob wrote a book entitled: “Design Fundamentals of Analog Computer Components”. This book was published in 1961.

The front of the book’s Dust Jacket has the following message from the Book’s editor:

“Describes the design procedure and philosophy in the development of electronic analog computer components. Presents a practical discussion of the influence of component errors, both static and dynamic, on problem solutions and then gives in detail the design of dc amplifiers, multipliers, function generators and miscellaneous equipment. Many examples of current, commercially-available equipment are presented and illustrated including detailed circuit descriptions.”

The front flap of the dust jacket provides the following message:

“For a complete understanding of the capabilities of an analog computer, considerable knowledge of component details and how they affect computer solutions is necessary. This book brings to those familiar with general-purpose electronic analog computing techniques the understanding they need of why analog computer components are designed as they are and how component errors affect the problems solved by the computer.

The author explores these design considerations with a discussion of overall computer design philosophy, and extensive practical coverage of computer component errors and how dynamic as well as static errors influence problem solutions. There are chapters on dc amplifiers, multipliers, function generators, recorders and miscellaneous equipment. Many helpful photographs and drawings illustrate existing commercial equipment, circuit details, and various components discussed in the book.”

Progress in Analog Computer Technology Over Time

At the time of ADI’s founding, electronic analog computer technology was quite primitive relative to what it would become in the following decade. In 1957 semiconductor logic devices, such as gates, flip-flops, and counters were just beginning to appear in circuit boards.16

Vacuum tube DC amplifiers at the time operated over a +/- 100 volt operating range. It was not possible to duplicate this DC amplifier capability with a solid state equivalent operating over the same +/- 100 volt range until the mid-1960s. Even then there were solid state component reliability problems, referred to as “infant mortality” failures, that took component manufacturers a long time to overcome.

Nonetheless, by late 1966, ADI began to ship its new AD 4 analog computer system which was totally solid state and had no electro-mechanical parts in the computing elements.17 ADI sold its last two AD 4 systems in 1975 and delivered them in 1976 to Government Aircraft Factory in Melbourne, Australia.

An ADI board meeting from the early 1960s. In the seated row, Bob Howe is in the middle with Jerry Kennedy to his left and Larry Fogerty and Bill Wood on his right. Ed and Elmer Gilbert are seated on the far left and far right.

An ADI board meeting from the early 1960s. In the seated row, Bob Howe is in the middle with Jerry Kennedy to his left and Larry Fogerty and Bill Wood on his right. Ed and Elmer Gilbert are seated on the far left and far right.

AD 4 Analog Computer

AD 4 Analog Computer

ADI’s Change From Analog to Digital Computing in 1975

From June 1975 until September, 1992, ADI was a wholly owned subsidiary of a Dutch conglomerate called the Internatio Muller Group (IM) of Rotterdam, The Netherlands. A brief history of ADI in this period is presented in Appendix F. This was a very interesting period for ADI, one in which the Company replaced its analog computer products with high speed, special purpose, digital simulation products. The first of these was called the AD 10. It was also a period of significant growth in size and profitability for the Company.

This change in direction to digital technology opened a whole new area of research for Bob Howe, particularly when ADI began developing a Numerical Integration Processor for the AD 10 around 1977. ADI needed to supply some fixed step-size, numerical integration routines for use with this new processor. The literature provided a number of possibilities. The question was which ones were viable candidates in terms of complexity, computational time required, accuracy, numerical stability, etc.

Bob Howe’s Second Book

Bob Howe was involved in ADI’s decision to switch from analog to digital technology for supplying real time, hardware-in-the-loop, computational power. His research interests quickly turned to investigating and analyzing various aspects of this new technology approach. Eventually some of ADI’s customers began asking Bob to write a book based on this research work. He wrote eleven chapters covering a variety of pertinent topics. These chapters are available on ADI’s web site, To find them, go to the web site and follow the path Resources > Technical Documents > Book “Dynamics of Real Time Simulation” (currently on the bottom of page 3).

In the Introduction to this book Bob states:

“Computational methods in real-time simulation and control are in general not well understood by scientists and engineers, even when they have had extensive experience in non-real-time simulation. In particular, many of the methods used to control dynamic errors and stability in traditional simulation are just not applicable in the real-time case. A vast array of simulation and control tools and other technology have been developed over the past decades that help abstract the complexity of real-time. However, without a deep understanding of the first principles nature of this technology the real-time engineer can fall into many traps. This book is made available to help anyone strengthen their knowledge of the dynamics of real-time and help us all develop better solutions as the world of complex systems becomes increasingly complex.”

Unfortunately, Bob was not able to complete the book. He started on a twelfth chapter, but he was unable to finish it. We will never know whether that would have been the last one or not. Nonetheless, the eleven chapters that are available are a significant contribution to the knowledge of real time digital simulation.

Bob Howe – A Brief Summary From 1960 to 2018

Bob Howe was Chairman of ADI’s Board of Directors from its founding to its sale to Reliance Electric Company in late 1969. Bob became a member of the Reliance Board, probably until the relationship with Reliance came to an end in early 1975. During this period, Bob also served on the US Air Force Scientific Advisory Board from 1971 – 1979. Bob’s first duty, of course, was to his employer, the U. of M. Bob was a highly respected member of the Aerospace Department faculty to the point that he served as Dept. Chair for 15 years during the 1970s and 1980s. Bob retired from the U. of M. in 1991 after he reached the age of 65. During his academic career, he published over 100 papers, and consulted for NASA and various companies. He was also active in several professional societies.

Bob Howe and U. of M. Aerospace Department colleague, Harm Buning, with the Apollo 15 crew.

Bob Howe and U. of M. Aerospace Department colleague, Harm Buning, with the Apollo 15 crew.

Bob continued to be active with ADI over the years wherever he thought he could be of value. This involved both technical and sales areas. He particularly enjoyed visiting ADI customers in support of a sales effort.

In 1991, ADI’s owner, Internatio Muller, was attacked by a group of wealthy investors that was trying to take it over. IM eventually had to sell off a number of its holdings including ADI. IM assisted ADI in having a management buyout and taking ADI private. Bob participated in this buyout by becoming one of the stockholders in the new ADI. At that time, Bob and I became members of the five member Board of Directors of the new ADI. Bob regularly attended the quarterly Board meetings and the annual stockholders meeting and took an active part in these meetings. He had to retire from the Board in August 2017 because of his health. He attended the 2018 stockholders meeting on August 23 of this year just over a week before his death. He was always very interested in ADI from its founding in 1957 to the end of his life.

After I became an employee of ADI in September 1964, I had the pleasure of joining Bob in attending various Simulation Council and other conferences. Bob would often comment on papers presented and/or comments made by other attendees. Whenever one of these speakers or commenters presented a thought or comment that didn’t make sense, Bob would use this “teaching moment” to set matters straight. Once in a while he would end his brief, very logical presentation with the words “I rest my case!”.

Since these conferences were generally held in large hotels, we would stay in the hotel, have dinner there, and often join other attendees in one of the hotel bars after dinner. Occasionally the bar would have a piano. If the piano was unattended, Bob would not let the opportunity go to waste. He would sit at it and entertain those present with his boogie-woogie music at which he was quite good. Sometimes he would keep playing as long as he had an audience even if most of us had already headed off to bed.

In the 1970s and ‘80s, company sponsored user groups were in vogue. ADI established its ADI User Society or ADIUS around 1980 and it was active until the mid ‘90s. ADIUS always had an annual meeting and occasionally there were also some regional meetings. Bob always enjoyed attending these meetings and took an active part in making presentations. His attendance at these meetings highlighted the technical prowess of ADI. In addition to these activities in the U.S., Bob also attended numerous conferences in other countries, e.g., Japan, China, Israel, etc., going back to the 70s, at which he made presentations on behalf of ADI. These conferences led to candidates for the University’s “Visiting Scholars Program,” for which Bob and his wife did a lot of hosting. That program was another instance of cross-fertilization between the University and ADI!

Bob Howe attending a conference in Asia

Bob Howe attending a conference in Asia

When he was in high school, Bob took up cross country running as a sport and continued this on a regular basis until he was no longer able to in his late 80s. Several years ago I made the mistake of asking Bob if he was still jogging. His quick retort was “I don’t jog – I RUN!”

Among things he really enjoyed over the years were going to Michigan football games and reading every edition of Aviation Weekly. He could probably quote statistics for every big commercial and every military aircraft ever built. Bob was also a collector. He collected postage stamps and Frank Sinatra records. Both of these collections were extensive and, in the case of the stamps, expensive. When Bob found an appliance that let him convert his vinyl Sinatra records to CDs, he bought it and converted all his records.

Bob and his family were avid mountain skiers. In 1982, Bob and his wife bought a condo in Vail, CO. They went to the condo several times each year. He finally gave up downhill skiing in his mid-80s. Bob never did anything part way – he was always very competitive until age and health took its toll.

Bob attended the ADI annual stockholders meeting on Aug. 23, 2018 and passed away on Aug. 31, just a few days after his 93rd birthday.

Material extracted from an obituary Bob prepared before his death is presented in Appendix G. Unfortunately, this document was not found among his many papers until months after his death. The family prepared the obituary that was published. Some of the material in Appendix G has been used in above sections of this document.

Bob Howe and a piece of ADI equipment in the 90s

Bob Howe and a piece of ADI equipment in the 90s

Appendix A – Mechanical Analog Computers and Their Electronic Descendants

Mechanical Analog Computers

The concept of a mechanical analog computer or mechanical differential analyzer is virtually unknown today. However, decades before electronic devices of any kind were even dreamed of, people had applications for which they needed a solution.

The history of mechanical analog devices goes back at least to Vitruvius (1st century BC), who described the use of a wheel for measuring arc length along a curve, the most simple integral in space. Many other elementary analog devices were described before the modern period: Differential gears used for adding or subtracting two variables. are usually ascribed to Leonardo da Vinci: and Leibniz is credited for the idea late in the seventeenth century of a similar-triangles device for equation solving or root solving.18

In the 1800s governments in various parts of the US were granting homesteads and surveying was a very important occupation. Surveyors need to determine the area of a piece of land with an irregular boundary, such as a river, that can be depicted as a two-dimensional, closed figure on a piece of paper. From a mathematical standpoint, determination of this area requires an integration process. A device for determining this area is called a planimeter.

The following paper provides documentation of work beginning in 1814 and proceeding to the work of Hannibal Ford relative to the development of mechanical analog computer capabilities. It has lots of colorful illustrations to help the reader understand the concepts.

Cones, Disks, Wheels and Spheres for Area and Integration

This paper begins as follows:


The very first planimeter, invented in 1814 by Johann Martin Hermann in Bavaria, used a cone wheel gear as an integrating mechanism for area measurements. The same principle was implemented in high precision instruments with up to 18 integrators initiated by Vannevar Bush19 for evaluating differential equations in higher physics.

This article presents the history of these instruments and their inventors. It illustrates the rise of a simple kinematic principle from measuring devices to mechanical supercomputers.

1 The First Generation: Cones, Disks and Wheels

It was in the first half of the 19th century when efforts for tax equality and the rise of cadastral authorities in Europe led to an urgent need for devices that could simplify the calculation of areas of real estate.

The first apparatuses were simple analog devices which assisted the calculating clerk in taking the measurements and sometimes multiplying two quantities. These instruments were either only approximating the area or they were restricted in the type of region they could handle.

The simplest devices are so called harp planimeters. Harp planimeters divide the area to be measured into narrow stripes of equal width (much like the strings of a harp). The sum of the lengths of the stripes multiplied by their width gives an approximation for the demanded area.

The first device for calculating the area within a closed curve, was the integrator of B.H. Hermann in 1814. Hermann’s integrator was essentially a wheel pressed against a disk. An early application of such integrators was the integration of force over distance to measure work. Another application was a planimeter to measure the area within a closed curve. In fact. the chief impetus behind the early integrator inventions of the nineteenth century was to get an improved planimeter. James Clerk Maxwell described a ball type of integrating device while he was an undergraduate: it was incorporated in a planimeter design. In about 1863. James Thomson’ conceived an equivalent integrator in which a ball rotates between the disk and a cylinder.

Most of these instruments were cumbersome to operate and none of them could handle arbitrarily shaped areas.

Hermann’s construction dates back to 1814, but since he abstained from publishing it, his invention did not receive closer attention at that time. The prototype of Hermann’s planimeter was disposed as scrap metal, and the inventor’s manuscripts were forgotten for about 40 years.”

This document goes on from here to describe numerous mechanical devices for handling specific applications. By the early 1900s military applications, particularly for naval ship guns, began to get more attention, albeit slowly. By the 1930s the complexity of a mechanical integrator developed for naval gun control by Hannibal Ford is shown in Figure 8, page 25 of the Ben Clymer paper.

The most important use of mechanical analog computers in the 1930s and through 1945 was for US Navy gunnery fire control systems on ships.

A number of educational institutes in the US and elsewhere developed general purpose mechanical analog computers for various studies and demonstration purposes. However, these units were expensive to build, time-consuming to program and slow in operation. As the last paragraph in the paper presented above states:

“Finally, the 18 integrator machine from 1940 marks the culmination as well as the end of the evolution of a simple kinematic principle. The unavoidable destiny of all these differential analyzers was the same as for the very first integrating planimeter of Hermann: It is now scrap metal, dismantled and, if lucky, on show in a museum.”

Electronic Analog Computers

In about 1940 the market for general purpose tools for performing mathematical operations was quite small. Mechanical desk calculators served acceptably for all but the largest problems, such as gun fire control and exterior ballistics.20 When Thornton C. Fry wrote a survey article about the extent of the use of mathematics in industry, he had little to report outside the telephone and aircraft industries. One could not then imagine the explosion of electrical and electronic technologies that would eventually result in a flood of computers available at modest cost.

Two reasons for the lack of effort to develop electrical analog computers for the Navy until the early 1940s was concern that electronic (vacuum tube) systems couldn’t withstand the rugged environment of life at sea21 and that the required parts (resistors, potentiometers, and capacitors) lacked sufficient precision for fire control. The second of these reasons changed rapidly once the Navy decided to invest in the development of the electronic analog computer approach to gun control. While it is very unlikely that any of the details of the electronic gun control units were known for a number of years after the end of WW II for security reasons, the availability of high quality electronic components was a definite benefit for the commercial development of electronic analog computers that occurred at the U. of M. and elsewhere in the years after the war.

DC (direct current) amplifiers had been used since the post-World War I days of radio. They were highly developed in the 1930s by Bell Telephone Laboratories (BTL), which used them for signal amplification in telephony. They were used by George Philbrick at Foxboro, as early as 1937 or 1938, for simulation of linear processes and control systems. Developments of amplifiers for use in simulation were also made by John Ragazzini et al., at Columbia University in about 1940. In fact, the design of the amplifiers constructed at the U. of M. in 1947 was published in an article by Ragazzini et al., in: “Proc. IRE, vol. 35, no. 5, pp. 444-452, May 1947”.

Mechanical analog computer world evolved in two directions in the 1940s, branching into developments in AC analog computers and DC analog computers. AC analog computers were based on AC amplifiers. These amplifiers amplified AC (alternating current) signals but had no DC link between the input signal and the output signal. DC analog computers, on the other hand, incorporated DC amplifiers which did have a DC path connecting amplifier input to amplifier output.

DC Analog Developments

BTL devoted itself to the development of DC vacuum tube amplifiers for use in analog computers for fire control after about June 1940. In November 1940, Western Electric (a member of the Bell Telephone companies) received a contract to develop a model of a DC analog gun director, the T-10. It was to use the BTL-developed DC analog technology. The model was tested successfully in December 1941. The success of the T-10 led to a contract to build the production version, the M-9 Gun Director. It was delivered in December 1942, and it was placed in service in early 1943 for land-based applications. It was used during the V-1 “buzz bomb” attack on London to control the fire of 90-mm guns located along the English coast. During the month of August it shot down 90 percent of the buzz bombs that arrived, and in its best week it shot down 89 of the 91 that arrived. The M-9 was aided by radar and proximity fuzes. A British version of the M-9 (the T-24 directing 4.5 inch AA guns) had its prototype completed by May 1942.

The Mark 8 Fire Control Computer was also developed by BTL during World War II. It was initially requested by the USN Bureau of Ordnance as an alternative to the widely used Ford Instruments Mark I Fire Control Computer, in case supplies of the Mk I were interrupted or were unable to be manufactured in the required numbers. The Mk 8 computer used all electric methods of computation, in contrast to the Mk 1, which performed most computations via mechanical devices. The Mk 8 was found to be more accurate than the Mk 1 and substantially faster in reaching a fire control solution, but by the time it was developed and tested in 1944, supplies of the Mk 1 were found to be sufficient in quantity. The USN extensively tested the Mk 8 and may have incorporated some of its technology into the post war Ford Instruments Mk1A computer. The Mk 8 technology was similar to that used in the M9 gun data computer used by the US Army for coast defense fire control and in the SCR-584 radar system computer.

AC Analog Developments

The principles of AC (alternating current) electrical analog circuits had been known since Steinmetz in the 1880s. Currents entering a node were known to add. The charge on a capacitor was known to be the time integral of the current that had flowed through it. It was known that a servo-driven potentiometer could be “tapped” to yield a function or a product of two variables. This technology was not developed, however, until BTL found application for it in a developmental gun director early in World War II.

The BTL project was to develop an AC analog gun director, the T-15. It was funded in November 1941, and the model was completed a year later and tested in December 1942. The T-15 was never put into production: it was, however, used for research with targets flying trajectories that were not straight lines, i.e., an anti aircraft application. The T-15 led to a proposal to the Navy, in February 1942, to construct an AC analog version of the Ford Instrument Company’s Computer Mark 122. A contract was awarded in September 1942 for development of this “Mark 8 Computer.” Although it proved to be faster than the Computer Mark 1 in completing the initial transient of acquiring and locking onto a target, the Mark 8 Computer was never produced. It had one other feature worth noting: a special electrical integrator that was developed for it.

From 1945 to 1950 the Dynamic Analysis and Control Laboratory at MIT developed an AC analog computer, using 400-cycle AC components in a guided missile flight simulator. This was an activity within Project Meteor. The flight table was mounted on four concentric gimbals so driven as to avoid gimbal lock under all conditions.

While these were interesting applications of the AC amplifier, this type of analog computer did not survive long term. In fact, the work described in the section above entitled “Evaluation of the Computer Section of Flight Training Simulators” and the related material in Appendix C below likely had a lot to do with the demise of the AC amplifier based analog computer.

Appendix B – The Willow Run Complex

Following the end of WW II, the US government established a special relationship with the U. of M. What brought this about?

The story starts in 1931. In that year Henry Ford bought a piece of property just east of the town of Ypsilanti, MI and about 35 miles west of Detroit, and named it the Henry Ford Farm. Ten years later in early 1941, the US government persuaded Ford to take a contract to build B 24 “Liberator” heavy bombers for the Army Air Force under license from Consolidated Aircraft Corporation.23 This was based on Ford’s highly developed and efficient concept for a manufacturing production line. Ford decided to use his Farm for this manufacturing facility and the associated airfield that would be needed. The plant was huge, with over 7 million square feet in an el-shaped configuration. The big leg was over a mile in length. The short leg was at a right angle to the big leg to keep the whole facility within Washtenaw County. Associated with the plant was an airport that had six runways, three hangars, a control tower, a hotel and various other facilities. The biggest hangar could house twenty of the B 24 bombers. The production facility had two identical, parallel, final assembly lines. Most of the parts were manufactured elsewhere. This facility produced 6,972 complete Liberators, ending production in April 1945. At its maximum production rate, one B 24 came out of production every 63 minutes around the clock. It also produced 1,893 knock down kits for a total of 8,685 aircraft. The knock down kits were 80% complete and were shipped by truck elsewhere for final assembly.

The airport, named Willow Run after a little stream that once wandered through the area, covered almost 1,500 acres. It had to be big enough to handle all the crews that had to be stationed and trained there while waiting for their plane to come off the line. Each crew consisted of seven to ten men depending on the particular B 24 model. The history of what happened following this period of B 24 bomber manufacturing is documented in an article written by Bob Howe for the IEEE Control Systems magazine issue of June 2005. This article is titled: Analog Computers in Academia and Industry. The subtitle is: A history of analog computing at the University of Michigan and the founding of Applied Dynamics International.

B-24s under construction at Willow Run

B-24s under construction at Willow Run

Michigan Aeronautical Research Center (MARC)

To paraphrase from this article: “Ownership of the Willow Run Airport that was built as part of the Ford plant was transferred from the US government to the U. of M. (with the proviso that the U. of M. support government sponsored research activities there). This facility gift essentiality required the U. of M. to create the Michigan Aeronautical Research Center (MARC) as an organization for conducting large, government-funded projects. The initial Willow Run program was Project Wizard, sponsored by the US Air Force, (as discussed above). In addition to the transfer of the airport and its associated facilities to the U. of M., the government also named, the U. of M., along with MIT, to establish a two year, graduate level program for military officers in aero engineering with emphasis on the rapidly growing area of missile technology. Bob Howe was involved significantly with this Guided Missiles program after he joined the U. of M. faculty in 1950.

The work that Bob and Carl Howe did during the summer of 1947, mentioned above, for example, was funded under the auspices of Project Wizard.

Note: The Willow Run airport had been built to support the B 24 program. For about two decades after the end of B 24 production, the Willow Run airport continued in operation as Detroit’s primary commercial airport. The airport complex contained facilities from the B 24 manufacturing days that were not needed for commercial airport operation. It was these facilities that were transferred to the U. of M. for its Michigan Aeronautical Research Center (MARC). A number of years later, this research center was renamed the Willow Run Center. In 1972, this center was separated from the U. of M., and established as the: Environmental Research Institute of Michigan (ERIM).

The B 24 production facility today serves as the home of the Yankee Air Force Museum.

Appendix C – Evaluation of the Computer Section of Flight Training Simulators

Two aircraft examples were used for this study: The F-86D fighter and the B 47 bomber. The most difficult area for accurate simulation was the longitudinal or pitch motion. The reason this mode was problematic was that the transient that occurs following a pilot commanded change in altitude consists of two distinct parts: A fast, short term response followed by a slower response called phugoid motion.

The study involved two separate aspects pursued in parallel:

  • The first was to identify pertinent simulator manufacturers, locations of the subject simulators for each selected manufacturer, pilots trained on each of these selected simulators, and the aircraft manufacturers of each of the two selected aircraft. Visits were made and data was collected as detailed in the project’s interim and final reports. All the simulator computer sections studied in this project were based on the AC version of an electronic amplifier.24
  • The second aspect of this project involved expanding the analog computer capability of the Aero. Dept. beyond what was available in the REAC, and other recently built equipment. The goal was to be able to simulate a complete 6 degree of freedom, nonlinear equations of motion model of an aircraft. This meant adding both amplifiers and servo multipliers. Once this expansion was completed, Elmer Gilbert programmed the equations for the longitudinal characteristics of each of the two aircraft mentioned above. This was the area of most difficulty for accurate simulation. His report included strip chart recordings to document the results for a variety of different training simulator situations.

The AC amplifier version used in all the computer simulator sections in this project could not reproduce the fast, pitch mode transient, but Elmer Gilbert’s simulation did. The dynamic performance of these AC amplifiers was definitely inferior to that of the enlarged, DC amplifier based system that the U. of M. now had. Elmer Gilbert’s report provided the evidence needed to make the case against the existing AC amplifier based systems reviewed.

The first recommendation in the final report was that the Air Force should not allow AC amplifiers to be used in any future training simulators bought by the Air Force. Relative to the second point raised above, the recommendation was that in every future simulator procurement the selected vendor would be required to:

  • Obtain or already have the pertinent flight test data for the aircraft type and model from its manufacturer; and
  • Demonstrate that the simulator’s response to certain specified pilot commands was within a certain range – say 25% – of the behavior shown in the flight test data for each such command.

Appendix D – The Multiplication Problem for Early Analog Computers

The initial solution was to use a potentiometer, referred to as a “pot”, where the output of the pot was the product of the voltage across the pot times the setting of the pot. By using a motor to turn the shaft of the pot, the setting of the pot could be changed during the simulation. This in turn required a controller for the motor driving the pot where the input to the controller was a program variable.25 This control operation took time. The time to obtain a solution had to be slow enough so that the error introduced by the pot controller did not substantially affect the overall accuracy of the solution. For aircraft such as the F-86 D and the B 47 real-time simulation was possible in spite of the limitation imposed by the use of servo-multipliers. This was addressed by Elmer Gilbert in his report referenced above.

The need to design servo-multipliers set forth above gave the Aerospace Department valuable insight into practical considerations associated with the design of electromechanical servos. This experience was used later in both lecture and laboratory courses.

All Electronic Approaches for Multiplying Two Simulation Variables

The need to eliminate the electromechanical approach to multiplication eventually led to two all electronic approaches, namely, a time-division concept and a square law concept. Only the square law concept is considered here as it is the one that ultimately prevailed.

In this approach the product, x*y, is obtained from:

x*y = (1/4)*[(x+y)² – (x-y)²]

By using a combination of resistors, diodes and one or more amplifiers it was possible to compute the product without using an electromechanical device with its time delay problem. Several companies came up with versions of this “quarter square” multiplier. Bob Howe’s version became the industry standard in the early 1960s.

Appendix E – ADI’s Historical Competitors

In its first few years, ADI developed a series of small to medium size analog computers that were probably sold to academic institutions and certain research groups such as the AC Sparkplug Division of General Motors. At the same time, companies that would be significant competitors to ADI in the 1960s were both bigger than ADI and further ahead in developing their analog computer products.

  • Reeves Instruments – founded sometime before 1945 – had sold 60 commercial REACs by 1950;
  • Beckman Instruments— founded in the 1930s to manufacture lab instruments – manufactured the EASE (Electronic Analog and Simulation Equipment) from 1953 to at least 1965;
  • Goodyear Aircraft — GEDA – (Goodyear Electronic Differential Analyzer) started dev. in 1948 to support in house missile work. Shipped 1st sys in 1949? Gen 3 started shipping in 1953 – exit ???;
  • Electronic Associates, Inc. (EAI)- founded in 1945 – began shipping analog computers in 1952;
  • Astrodata Comcor – couldn’t find any historical information – was a significant competitor in the 1960s

In the 1960s the three major suppliers of analog computers in terms of numbers of systems sold were: ADI, Comcor and EAI with EAI being the leader. By 1975 the age of the analog computer was essentially over.

Appendix F – A Brief History of ADI in the 1970s and 1980s

In late 1969 or early 1970, ADI was bought by the Reliance Electric Co. of Cleveland, Ohio. Reliance was a manufacturer of industrial products, such as motors, generators, etc. It had two significant subsidiaries, namely Toledo Scales Co. and Haughton Elevator Co. Its soon to retire Board Chairman, Mr. Hugh Luke, sought to diversify its business base by acquiring a high tech company, just as some of its competitors were doing. ADI was not too big and was close to Toledo where Reliance had its two subsidiaries. As it turned out, ADI had some investors who wanted out, so Reliance’s purchase interest was well received. Shares of Reliance (publicly traded on the NYSE) were exchanged for shares of ADI. As part of the deal, Bob Howe became a member of the Reliance Board.

In 1970 Reliance built a facility on Maple Road in Saline, MI to house ADI plus a number of people from Cleveland who had been providing technical assistance for Toledo Scales and Haughton Elevator. Most of ADI’s engineering group headed by Ed Gilbert were reassigned from developing new analog computer products to develop a new digital computer controller for Haughton elevators. I remained with ADI’s Marketing/Sales group primarily to handle ADI’s international activities which were significant in both Europe and Israel.

For the next five years we worked to expand our international market. During this period we sold two systems in Turkey, one in India, at least one in Japan, and worked to develop customers in Australia and elsewhere. As it turned out, one big potential Australian customer, Government Aircraft Factory (GAF) in Melbourne, became a buyer in the Spring of 1975 just when we needed it most. In mid-January 1975, the Reliance CEO, Chuck Ames, who was no fan of high-tech, announced that the Saline facility was to be closed, ADI was to be liquidated, etc. He had no idea what he was doing with regard to ADI with its government contracts, warranty obligations, etc. He simply expected his subordinates to make the problems go away.

Gene Graber had been ADI’s VP of Marketing/Sales from sometime in the early 1960s until early 1970 when he left ADI to become a marketing consultant. After I heard the announcement from Chuck Ames about ADI’s pending demise, I called Gene and told him I thought we should try to find a way to save the Company. Gene contacted Mr. Bram Verwey, who managed ADI’s distributor operations within van Rietschoten und Houwens (R & H) in Rotterdam, The Netherlands. Bram, who was very upset with the adverse impact Reliance’s decision would have on many R & H customers, came to Ann Arbor. Over a period of several weeks, Gene, Bram, and I put together a business plan to have ADI become a subsidiary of the Internatio Muller Group of Rotterdam (IM), R & H’s parent organization. This was presented to Reliance and eventually approved.

One significant delay was caused by the announcement that GAF had chosen to buy its new, very large simulation system from ADI. The hooker was that the order had to be placed with Reliance’s Australian subsidiary and subcontracted to ADI. ADI had to have this business in order to finance the Company until it could reestablish itself in the marketplace as a viable operation. This caused more than a little heartburn for Reliance management, but they finally agreed to accept the situation and go ahead with the sale of ADI to IM.

The change in ADI’s ownership took place in June 1975 and ADI moved to its current location on Stone School Road in Ann Arbor. Gene Graber became CEO, Ed Fadden became Treasurer and VP of Engineering and Marketing, and Ed Gilbert became a consultant to ADI responsible for new product innovation.

With the change in owners, ADI needed a new simulation product to sell. A big problem for analog computers had always been how to handle large data tables, such as lift and drag coefficients for aircraft and missiles. These tables could be functions of two or more program variables, e.g., altitude and Mach number (speed). The use of a digital computer tied to an analog computer to handle the function generation requirement had computational speed limitations. Something new was needed.

Ed Gilbert came up with a concept for a programmable, special purpose, digital unit that was named the AD 10. This could be interfaced to any analog computer through the use of analog to digital converters (ADCs) and digital to analog converters (DACs). The AD 10 used Emitter Coupled Logic (ECL), a very high speed logic family and Static RAM memory devices. This basic product was introduced in 1976 and sold well.

The next step was to add a Numerical Integration Processor to the AD 10 to make it a standalone replacement for an analog computer. It had its own programming language, called MPS 10. It was a fixed point system that had to be scaled. That didn’t solve all the problems of the analog computer, but was accepted by the marketplace in any event. About 150 AD 10s were sold over a several year period.

The answer to the AD 10’s scaling problem was to develop a floating point replacement for the AD 10. This new system was called the AD 100 and it had a much more user-friendly programming language called ADSIM. The AD 100 finally eliminated the scaling problem and provided much more computational power than the AD 10. Its major drawback was that it was very labor intensive to build and thus was expensive. Nonetheless, about 150 of these systems were sold over a several year period in the 1980s.

This picture includes (from right to left): Bob, his wife, Bram, his wife and their daughter

This picture includes (from right to left): Bob, his wife, Bram, his wife and their daughter

Appendix G – Excerpt from Bob Howe’s Prepared Obituary

“In 1952 he developed the first tabletop analog computer specifically for simulation in laboratory courses, as well as an analog computer developed and delivered to the US Navy for the study of underwater sound propagation. In 1953 he became deeply involved in flight simulation training with a USAF (i.e., US Air Force) research contract from the Wright Air Development Center. In 1954 he started and served as first chairman of the Midwestern Simulation Council, and in 1957 became the first president of the national parent Simulation Councils Inc. Also, as a consultant for Link Aviation in 1957, he developed simplified math models used in flight simulators for the DC-8, Boeing 707 and Convair 880 aircraft, the first US jet transports. As a side note, the aero department expertise in analog computers and real-time simulation led in 1957 to the founding by Bob and three of his colleagues, of Applied Dynamics Incorporated. This well known Ann Arbor company developed and marketed analog computers, emphasizing their application to real-time simulation with Bob as chairman of the board for the first twelve years of company existence in addition to his appointment at the University of Michigan. The company continues today as Applied Dynamics International, marketing real-time simulations using digital hardware and software. From 1963-68, Bob served as chairman of the University of Michigan interdepartmental graduate program Information and Control Engineering, and from 1968-82 as chairman of the Aerospace Engineering Department. His many honors include the 1983 AIAA (i.e., US Institute of Aeronautics and Astronautics) deFlorez Training Award for Flight Simulation, the 1978 Award for Meritorious Civilian Service while a member from 1971-79 of the USAF Scientific Advisory Board, and the Society for Computer Simulation International Technical Award, 1978. Bob’s significant additional committee memberships included the NASA Advisory Council Space Systems and Technology Committee (1978-81), Chairman of the Ad Hoc NASA Subcommittee on Shuttle Launched Entry Research Vehicles (1978-81), and Chairman of the Research Advisory Panel, USAF Human Resources Laboratory, Operational Training Division (1979-82). During the last decade of his teaching and research activity in the University of Michigan Department of Aerospace Engineering, Bob participated in flight simulation research jointly with the Psychology Department. Bob officially retired in 1991 as a professor emeritus. During his 41 year career at the University of Michigan he published over 100 technical papers as well as a book on analog computers, and served as chairman of a large number of PhD student committees. In 1947, Bob married Joan (Jo) Craig, whom he met during his last year at Oberlin College. He is survived by Jo, three of his four children and five grandchildren.”


    1  Mercersburg Academy is a selective private, independent, coed college preparatory school for grades 9 to 12 and postgraduate students with boarding capabilities. (

    2  Control of shipboard guns was highly classified and remained that way for many years after the war. To the best of my knowledge, Bob never talked about his gunnery experience. Even though I knew Bob from late 1960, I only found out about it in a conversation with his widow, Jo, in 2019.   

    3  Project Wizard was a post WW II, Cold War-era anti-ballistic missile system to defend against short and medium-range threats of the V-2 rocket type. In March 1946, the US Army Air Force gave a Project Wizard contract to the University of Michigan’s Aeronautical Research Center (MARC). A similar effort, Project Thumper, started at General Electric. Early results demonstrated that the task of shooting down missiles appeared to be beyond the state of the art, and both projects were downgraded to long-term technology studies in the summer of 1947.
Note: The US Air Force became a separate branch of the military on September 9, 1947. Project Wizard and follow on contracts stayed with the Air Force.

    4  The emphasis here is mine.  

    5  The following Notes are pertinent to the above material.
Note 1: The Japanese never connected their ship gun fire control systems to a radar unit.
Note 2: At its slowest speed a torpedo had about the same range as a ship’s guns. However, torpedos were seldom, if ever, fired at the lowest speed; as speed increased so did drag which decreased their range.

    6  This 35 page paper is very detailed. It presents a good history of mechanical devices developed for computational purposes beginning with the invention of a wheel and disk integrator by B. H. Hermann in 1814. It discusses a number of mechanical analog computers for different gun types and both surface and air borne targets. It should be noted that the models that had to be solved in these gun controllers were complex, sophisticated, and involved both algebraic and ordinary differential equations. It also discusses work that went on with investigating and, in some cases, using electronic amplifier replacements for the mechanical analog computers as presented below and in Appendix A.  

    7  The bio at the end of the Clymer paper as written by the author is as follows:
“A. Ben Clymer is a retired consulting engineer who had been in a private practice specializing in simulation and simulators. His interest in mechanical analog computers stems from his employment at Ford Instrument Co. from 1942 to 1945. As a junior design engineer he designed mechanical analog computers used in naval fire-control systems for 5-inch guns and up and an aircraft flight simulator.”

    8    See footnote 2 above.  

    9    Reeves Instrument Company had been involved during the latter part of WW II in developing special purpose electronic systems for radar and other military projects and was known to the Navy as a result.  

    10  In 2005 the IEEE Control Systems magazine dedicated its June issue to:
“A Look Back in Time – The History of Analog Computing”. Bob Howe contributed two articles to this issue. The first is titled: “
Fundamentals of the Analog Computer – Circuits, technology, and simulation”. The second article, which is of particular interest in this document, is titled: “Analog Computers in Academia and Industry – A history of analog computing at the University of Michigan and the founding of Applied Dynamics International”. (Note: Both of these articles are available on ADI’s web site, In addition to this article, which was very useful for this section, Bob Howe’s files which I have had access to since his death also contain much helpful information. I am very grateful to Bob’s daughter, Ms Jackie Hurst, for all her hard work in categorizing and organizing his many files and documents.  

    11  The author, Ed Fadden, taught an introductory laboratory course for seniors and graduate students featuring LM 10s for 6 terms in the early 1960s.  

    12  Instrumentation Engineering was a joint program between the Aero. and Electrical Engineering Departments. My Ph.D. was also in Instrumentation Engineering.  

    13  Jerry was a very energetic man whose motto was “If you’re not the last one on an airplane just before the door is closed, you’re guilty of wasting time at the airport!” This was in the good old days before security lines.  

    14  Ed Gilbert left the U. of M. in 1961 to become V.P. of engineering for ADI to provide the technical leadership it needed to compete in the analog computer marketplace. Ed continued to be involved with ADI over the years until his untimely death from cancer in 1991. Elmer remained at the U. of M. He retired in 1995 as a Professor Emeritus and died in 2019.  

    15  The author, Ed Fadden, notes from personal experience in this area. When I enrolled as a student at Case Institute of Technology (now Case Western Reserve University) in Cleveland in 1954, I was told there was a new degree program available called Engineering Science. Courses would be taught by top faculty people as they wanted to evaluate this program as a significant new way of providing an engineering education. I signed up and have always been happy that I did. In 1958, I took a course in analog computers and was intrigued with its possibilities. I talked to the professor teaching the course and he suggested that I consider the U. of Michigan for a PhD program which I did. Great advice!  

    16  The theoretical basis for semiconductor devices was known for many decades before such devices could be manufactured. For example, patents were granted in two countries in 1928 and 1934 for a device later to be known as a field effect transistor or FET. It was not possible to manufacture a FET in commercial quantities until the 1970s. The first feasibility demonstration that a three terminal semiconductor device could amplify an input signal occurred at Bell Telephone Laboratory in late December, 1947. Commercial bi-polar transistors did not begin to appear until the mid-1950s.  

    17  The computer patch panel which is hanging in ADI’s lobby is from an AD 4.  

    18  Taken from Clymer’s paper.  

    19  MIT in 1931.  

    20  Ballistics, science of the propulsion, flight, and impact of projectiles. It is divided into several disciplines. Internal and external ballistics, respectively, deal with the propulsion and the flight of projectiles. This definition is taken from The Editors of Encyclopedia Britannica.  

    21  The proof of concept that a transistor would work as an amplifying device did not occur until late December, 1947. Solid state amplifiers were not available during WW II.  

    22  A picture of the Computer Mark 1 is provided earlier in this document.  

    23  The B 24 was developed by Consolidated Aircraft Corporation, Ft. Worth, TX. Over 18,000 of these planes were built during WW II at several locations. The main production plant was Willow Run. Each plane had 360,000 rivets which led to the term “Rosie the Riveter” for the production line workers who were mostly women.  

    24  For a discussion of the use of AC and DC amplifiers see Appendix A.  

    25  The controller / motor combination was known as a servomechanism, a pot driven by a servomechanism was called a servo-set pot, and a servo-set pot used to form the product of two program variables was a servo multiplier.  


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