DePauw Univ. Indiana Flying Club; J. Frank Durham; Capt. Frank Hawks; Charles Lindbergh; Weather Broadcasts
Copyright 2011 Franklyn E. Dailey Jr.
Triumph of Instrument Flight
This story of instrument flying is told in the context of progress in United States aviation. The period of closest examination for the transition from flight strictly by visual flight rules to instrument flying will be 1929-39. Near the end of the 20th century, developments of Category 3 landing fields and flight control electronics in aircraft led to the 'autoland' capability.
An instrument flying capability emerged in all industrialized nations in about the same time frame. It was well implemented by the time that war clouds approached in 1939.
In the early years of flying in the United States, most pilots did not fly when the weather was threatening. The more experienced pilots who were flying to accomplish some mission beyond sight of their home airfield learned to avoid weather.
Flying attracted great public interest in the first three decades of the 20th century. The Wright brothers were first in powered heavier-than-air flight in their December 1903 flights at Kitty Hawk, North Carolina. Their achievement was an historic first in aviation's many firsts. The brothers were slow to publicize their accomplishment. Flying emerged as a major news item in Europe before the Wright brothers flight became broadly known in the United States.
Many early aviators, first among them the Wright brothers, brought innovative ideas and practical engineering skills to their objectives. There was not much in the literature available in 1900 about what it would take to fly. The Wright brothers' combination of theory, practical development, testing and risk-taking brought success. A number of aviation pioneers soon followed the Wrights. World War I added great stimulus, not just in airframe and engine development, but in interest on the part of a much wider spectrum of young men who wanted to fly and also wanted to assist their country.
Many would agree that the Wright brothers' breath-taking accomplishment in 1903 was fittingly capped by Lindbergh's historic flight in 1927. By then, the major players were onstage. These were the airframe with its wings, the flight controls, the reliable power plant (engine) and the pilots. Lindbergh was the pilot's pilot - a man who was willing to take a risk but who then did everything possible to improve the odds in his favor. The Wright brothers took risks, but as inventor pilots.
In 1927, a critical element needed to advance aviation, the gyro horizon, was waiting to come onstage to make instrument flying practicable. The change from piston engine to jet engine was further in the future and blind landings would require almost the full century.
By the late 1920s, accumulation of flight experience and achievement of self-defined milestones in speed and endurance by more aviators gave aviation expanded space in newspapers and magazines. The press itself became a sponsor of aviation achievement. Flying the U.S. mail was another daring venture that helped keep aviation in the news in the 1920s and early 1930s. An episode in the history of airmail, along with the formation of airlines, brought attention to the imperatives that would lead to instrument flying.
A few aviators had begun to chafe at the constraints that weather imposed on flight options. Weather was a factor cited by some aviators in their flight attempts to set new point-to-point speed records. On February 5, 1929, Captain Frank Hawks of the Army Air Corps flew a Lockheed Vega monoplane called the Air Express from Mines Field, Los Angeles, to Roosevelt Field on Long Island. His elapsed time was eighteen hours and twenty-two minutes. He told newsmen that he could have made the trip in three hours less except for the storms he encountered. (Standard Quarterly Review, Vol. II, No.1. April 1929 page A-4)
Without any master plan, airframe and engine designers, influenced by pilots, began to add instruments and other aids that responded to a need to know more about their aircraft's performance, helping to improve the pilot's preflight and in-flight decision making.
For farming and other pursuits not directly applicable to aviation, the United States Weather Bureau was regularly upgrading its forecast and reporting capability. One of the outcomes of a radio broadcast capability in the relatively new AM (amplitude modulation) radio frequency band was the addition of weather forecasts. As radio receiver design improved, weather information became accessible to a greater audience. Aviators who followed this progress spread the news of greater flight information availability in aviation discussion groups.
Pilots began to carefully assess newly available flying aids with the realization that knowledge of weather formation and weather movement was important to their flying pursuits. Aviation information relevant to safe flight was being accumulated. In the very early days of heavier-than-air flight, those pilots with more experience would pass along their knowledge to those with less experience. From such sharers of information came a new breed, flight instructors. Eventually, flight school by flight school or flying club by flying club, the pilot cadre and its knowledge-base increased.
The cost of operating an aircraft, even in aviation's earliest days, represented a considerable expense relative to the cost of other extracurricular activities a young man or woman might choose to engage in during aviation's formative years. The pilot-aspirant would often hang around airports, and some would do the dirty jobs that no one else wanted to do. Cleaning up spilled oil was one example. Even if they did not directly get paid for such work, those yearning to fly would hope thereby to get flight time with an instructor at the lowest going price.
Flying clubs helped to drive down the cost of both flying instruction and fees for the use of aircraft. An instructor, often the owner-operator of an aircraft, was a businessman. If a flying club presented him or her with a number of students, and these could be structured into lists and schedules, the instructor would be making best use of time and would price services accordingly. Flying clubs were also an effective means of exchanging information. What one heard or read could be exchanged with others. Early flying clubs represented ground school and flight school bundled together.
J. Frank Durham is a senior practicing attorney in Indiana. In 1924, he spotted his first real airplane on the ground in a field north of Highway 40 between Greencastle and Indianapolis. He places the location west of Plainfield, Indiana. The aircraft was a World War I Jenny. Growing up, Frank built and flew control-line model planes. (With wireless radio control now available, the control line that mechanically transmitted flight control commands to the model flying plane has made its own passage into history.) By 1935, Durham was completely hooked on aviation and with his buddy, Loren McDonald, helped found the DePauw (Indiana) Flying Club. Monthly meetings of the ten members were held at the Delta Tau Delta Fraternity House at DePauw University. Indianapolis Airport was a favorite venue for hangar talk. Listening, and closely examining parked airplanes, substituted for formal ground school. Loren McDonald persuaded a Flight Instructor at the Bloomfield Airport to fly the latter's Taylor Cub over to Greencastle so club members could take turns getting flying instruction. The club student pilots paid $2.50 for a half-hour of in-flight instruction. Frank Durham soloed after four hours of flight instruction.
The law was to become Frank's career, not aviation. Private pilots were going to share the airspace with career aviators, charter pilots, airline pilots and military pilots. By graduation from the University in 1937, Frank had accumulated the grand total of seven hours of pilot flying time. After picking up flight time over a number of years, often in rented aircraft, he received two days of formal instruction at the Acme Flight School in Texas to take and pass the written exam for a Private Pilot's license. A lady pilot checked him out for the flight portion of the requirement. Durham recalls that the flight check occurred in the Cessna 170B he had purchased in 1954, and in which he and his instructor, Chet Hill of Crawfordsville, Indiana, and another attorney-pilot had flown from Greencastle to Texas. Both Frank and the other attorney took their exams and flight tests and earned their Private Pilot certificates on that occasion. Chet returned independently to Indiana and the two newly certificated pilots flew the 170B, legally, back home.
The circumstances of the purchase of the 170B at Indianapolis Airport involved well-known names in early 20th century flying. Chet Hill went with Frank to Indianapolis to assist him on the prospective purchase. The deal was made and ownership was transferred from Mildred Hurt, the owner, to Frank Durham. Mildred had been an early pilot. Her eyes had failed so she resolved to sell her plane. Her husband was in business with renowned aviator Roscoe Turner. Mildred parted from her Cessna with a flourish. Shortly after the acquisition, Frank Durham received a membership in the Aircraft Owner's and Pilot's Association (AOPA). He discovered that it was a gift from Mildred Hurt.
Although J. Frank Durham owns his own plane now and flies from his own airstrip, he recalls many early flights in rented aircraft. There would usually be a number of aircraft available for rent on a given airfield. Depending on an applicant's experience and flight plan, Frank Durham relates that instruction to fly a given plane would be provided by the Fixed Base Operator (FBO) of an airfield. Sometimes a look in the pilot's logbook would be needed and other times conversation alone would suffice. The person responsible for renting the plane to another person would evaluate the applicant's background and make a judgment call on whether oral instruction on the proposed rental aircraft would be sufficient. Pilots were still enough of a novelty so that a person in one airport community already knew something about a person in a nearby community.
Flight powered by an internal combustion engine, with an embarked human operating flight controls, marked the dramatic beginning of piloted flight of heavier than air machines. In the process, the biplane was born. For propulsion, the Wright brothers had provided two propellers for their Wright Flyer, driven through sprocket and chain from one 12 horsepower gas engine. The pilot was conveniently positioned, prone, forward of and between the two propellers. No instrument panel.
The Wrights did not just stumble onto flying with some dumb luck. They were skilled mechanics. They studied the available literature. What had failed to work in the past was evaluated by them and replaced by their contributions to aerodynamics. They did not invent the internal combustion engine but adapted it skillfully to their use, with economy of weight clearly in their mind. They took risk and succeeded. Many who followed were to make enormous contributions, but the Wrights had removed one major obstacle. That obstacle was doubt.
By 1908, just five years after Kitty Hawk, Glenn H. Curtiss was at work advancing the art in first generation aircraft. Military student pilots began training in the United States by 1916 for air combat in the war that the United States would enter in 1917. In addition to their air-to-air combat experience, these men were de facto test pilots in proving a new generation of heavier than air flying machines.
Glenn Curtiss, like the Wrights, began with engineering skill, plus the priceless knowledge from the Wrights' success that flight was possible. Curtiss began with a biplane like the Wright brothers. Though his first craft was still without instrument panel, it had a more coherent look to it. The pilot had a place to sit.
Curtiss began his remarkable career in bicycle repair, then moved on to motorcycles, and then to the design of motorcycle engines. He realized that available engines were not very good. Using an engine of his own design, he set a motorcycle speed record in excess of 130 mph, and for some years was known as the fastest human. Asked to design an engine to move a blimp through the air, he concentrated his engine design efforts on obtaining the highest horsepower per unit weight. This brought him to heavier-than-air craft, and he entered the field of airframe design with the dual motivation to also design appropriate engines to drive propellers for his new aircraft structures.
Glenn Curtiss later launched successfully from the deck of a ship after obtaining some financial support from the U.S. Navy.
Curtiss sat in front of his internal combustion gas engine that turned a propeller which "pushed" the aircraft into the air and sustained it there. His hand wheel, mounted at the top of a "stick," turned the rudder. Back and forth movement of the stick moved the elevator, and Curtiss leaned his body to the left or to the right to add tension to cables which moved his ailerons. Curtiss is credited at the Curtiss Air Museum with the invention of the aileron as a control surface. That control completed the essential air control surfaces in use right down to this day. These control surfaces are the elevator, the rudder, and the aileron.
In the January 1930 issue of the Standard Quarterly Review on page A-32, Dr. William Whitney Christmas is credited as "the inventor of the aileron balancing system which is now used on all planes." Invention claims have been the subject of controversy throughout the history of the U.S. Patent Office. Aviation provided its share of disputed claims. The Wright brothers and Glenn Curtiss were involved in lawsuits initiated by the Wrights.
From France came the third flight surface control modification, putting the aileron under the control of the hand wheel or "yoke," adding rudder pedals to control the rudder, and maintaining the stick for control of the elevators. This configuration settled the control method for aircraft lasting to this day. Without that fairly rapid progression to successful flight controls, flying would have been much slower to advance, holding back successful instrument flying as a subsequent result.
In the next illustration, Curtiss' ailerons can barely be seen as triangles at the tips of the wings. The pilot is forward with the elevators in the far front; a fixed stabilizer is at the rear with a rudder at its center.
This model, atop a pole, greets a visitor at the front of the Curtiss Museum at Hammondsport, New York.
It did not take long for Curtiss to reengineer his craft and put the elevators back with the rudder assembly. Some felt that he was a bit reluctant to put the engine in front of the pilot; his later designs had the engine forward.
In both powerplants and airframes, Glenn Hammond Curtiss was successful, becoming a principal U.S. inventor, of aircraft, and of internal combustion engines to power them. And he was a good pilot as well. He was confident enough to be the first to make the first flight in his own designs and then to pilot them to record after record.
Even without the aileron, the number of Curtiss firsts is incredible: the tricycle landing gear; the seaplane; the amphibian aircraft. He made records for sustained flight, one after another; he was winner of the prize to fly non-stop from Albany to New York. Curtiss was first to fly off a ship and the first to fly off a warship. The latter craft's design, and then its execution as an aircraft of interest to the U.S. Navy, earned him the sobriquet, "father of naval aviation."
For high-speed performance, the inline liquid-cooled engine, a legacy of the automobile, propelled many military fighter aircraft right up to and including World War II.
Glenn Curtiss' experience with engine building for his motorcycles led him to the design of a liquid cooled engine series for aircraft. The first one was known as the Model O. Successively he designed and built models in the OX series, the culmination of which was the OX-5, rated at 90 horsepower. This engine was put into what was then regarded as mass production. This engine powered many different aircraft in the early years. An OX-5 Aviation Pioneers club had active chapters in 2003.
Glenn H. Curtiss eventually put all of his patented designs into the public domain.
The next illustration is the cover page of a patent issued in 1927. Inventor Newton F. Foner depicts the cylinder/crankshaft view (not shown here) of his internal combustion engine on "sheet 1" of his three sheet patent application of 1925. Issued as U.S. patent 1626457, the engine is shown with an aircraft propeller. Like most patent seekers whose objective is to make their novel idea as generally applicable as possible, Foner's patent adds the words, "may be for any purpose for which it is adapted."
Foner's engine was a two-cycle internal combustion engine that the inventor claimed could be operated with several fuels, was liquid cooled, had paired compression and combustion cylinders that the text states had unique cooling advantages, and operated without cam shafts.
The more interesting aspect was the overall layout of the Foner engine. Curtiss' OX-5 and competing engines were inline liquid cooled engines. The eventual winners by 1929 for all but the fastest racing and military fighter aircraft, were the air-cooled radial engines. Foner's engine was liquid cooled but was configured more like the later radial engines.
The only inline vestiges in the Foner engine were the compression-combustion pairs, one behind the other. These were disposed as pairs, but in two geometric planes, radially from the crankshaft. The air-cooled radial engines that powered all successful airline transport planes up to the advent of turbine engines had their cylinder-pairs in the same radial plane. But by then, an in-line look had crept into all radial engines.
As the cylinder count increased, the cylinders could not all be crammed into one radial plan; the solution was that banks of them would be disposed one behind the other. The Pratt & Whitney 4360 that made its appearance at the end of World War II was the last of these, four banks with seven cylinders in each bank, for a total of 28 cylinders. Some called it the "corn cob."
As with other 20th century wars, the end of World War I found war industries at peak production. The excess production of the OX-5 engines at the end of World War I, and their resultant inexpensive availability, found them extensively used in postwar aircraft. A 400-hp Liberty engine was a top horsepower-performing engine that came along at the end of World War I. That engine did not achieve extensive production. Its power was persuasive, but by comparison it was expensive. Cost did not favor its early adoption by aircraft manufacturers.
It took a bit longer for any airframe to achieve mass-production status. One of the first airframe designs to achieve manufacturing scale was the Curtiss Robin. St. Louis-based Curtiss-Robertson built 750 of the single engine Robins before shutting down in 1930, partially a consequence of the Depression.
Three-engine aircraft made a strong, albeit brief, appearance on the aircraft scene. Passengers, paying passengers, occupied the minds of some aircraft designers and manufacturers. For just a few years, three-engine aircraft appealed to some aircraft manufacturers to be a competitive design that would interest those who might be going into the air transport business.
In the first three decades of aviation, aircraft design was partly a `cut and try' effort. It was based on disciplined inspiration. Success improved in steps by learning from what did not work after conducting tests and evaluation of airframes. The wind tunnel became a powerful tool. Aircraft engine design efforts included test- stand testing, and continued to take advantage of knowledge gained in the design of automobile engines.
Putting `best of breed' elements together to create an aircraft system was part of the story of progress. The era in which an aircraft designer was able to design and specify the whole machine, then take delivery of proven results from competing contractors, did not come until much later.
Pilot technique progressed with each generation of aircraft. New aircraft offerings had design failures and pilots who were lost flying them; some pilots lost their lives for the sole reason that they were willing to take a chance on a new craft. Failures as well as successes were teaching experiences. Engines became more reliable, airframes stronger and more aerodynamically efficient. Successful pilots learned the first three essential rules of flying, "keep airspeed, keep airspeed, keep airspeed!"
Technology played a key part in transitioning aviation from the thrill stage to the record-setting stage to routinely successful flight. Training and pilot experience played vital parts. But progress was gained a step at a time with no visionary to claim that he or she saw the ultimate objective and put together the first flow chart to accomplish it.
With the benefit of experience, we can now say that for instrument flying to succeed, advances in aircraft instrumentation were going to be required. Ground radio facilities and weather reporting schedules would be needed. Airframes and engines had to demonstrate reliability. Speed records, distance records, and endurance records would confirm not only the technical advances, but also reliability. Finally, aviation needed aviators whose motivations were akin to explorers bent on conquest.
There is caution. And there is fear. Pilots have fear. Sometimes fear overcomes all the ambitions of a student pilot, and he or she decides not to pursue the pilot objective. After flight with visual earth reference, the next step in flying for many pilots is flight through instruments. Some find that too steep a challenge and drop that ambition. AVWeb is an aviation website. Reporting through the Newhouse News Service in 2001, writer Dru Sefton reported on a question that AVWeb asked one thousand pilots. "Have you ever had to control your own fear serving as a pilot?" 74% admitted that they had. The biggest fears reported by the survey: "weather," followed by, "making a critical error."
This story is developed from a pilot perspective. The infrastructure composite of airport, airways, air traffic control systems and ground instrumentation, weather forecasting and reporting, and communications, will enter these pages mostly from a pilot's perspective. The evolution, from a series of light beacons in the 1920s for night flying, to our present airways route structure, is an essential part of the story of instrument flight.
The early chapters emphasize civil aviation. Many of the basic challenges were confronted and solved in scheduled airline operations. Civil aviation gradually established the statistical basis for safe instrument flight. It accomplished that objective by piling up flight hours accompanied by the steady improvement (lowering the number of accidents and fatalities per passenger mile flown) in accident statistics. The United States government made its mark by insisting that records be kept and then analyzed.
Pilots work hard to make sure that no accident or incident mars their flight records. Unlike the speed, endurance and distance record makers and record breakers to be encountered in Chapter 2, no pilot or group of pilots actually set out with the objective to accumulate a prescribed number of flying hours that supported a claim that instrument flying could at that point be declared safe.
Strict interpreters would argue that "safe" means "freedom from risk" and that flying would never meet that criterion anyway. Many parties with varied backgrounds, academic research, engineering, ground support and of course the pilots themselves, were part of an effort, not always strictly defined, to make flying as safe as it was humanly possible to make it, and to make instrument flying safe in that same context. It was an aggregate of human experience that brought the state of the art from step number one to step number two, the evolution from safe flying to safe instrument flying.
Declarations of safety that cited statistics came after the fact. Government, executive, legislative and judiciary all contributed. An aviation support establishment grew. U.S. pilots and their government participated in an extended shake-down cruise for rules, procedures and equipment that would best insure safe conduct of flight.
The military services made important contributions. They furnished an initial cadre of pilots that had been trained for World War I. In World War II, military pilots, many representing between-the-wars civil aviation, helped extend instrument flying around the globe. Military experiences in instrument flight will be introduced later in the story.
In addition to a pilot bias found here, the reader will also find a geographic bias, the Northern Hemisphere.
A look at polar projection maps of the Northern and Southern Hemispheres is quite revealing. There is very little land-mass between the 50th and 70th southern parallels. There is considerable landmass between the 50th and 70th northern parallels, and parts of it are heavily populated. The northern rims of both the eastern and western hemispheres were a challenge to the early venturing peoples. Man's curiosity, and the linking ingredients, land and water, were passed on to the air faring descendants of the original seafarers to continue the pursuit of passage through these spaces.
Mankind's deadliest wars have occurred in the northern hemispheres. Most of World War II, and the Cold War nuclear standoff that followed, were waged in the Northern Hemisphere.
Travel distance between major population centers is minimized by use of great circle routes. North of the Equator, these routes arch toward the North Pole. In 1940, progress in exploiting strategic aviation advantages of the north Pacific rim lagged behind experience in the North Atlantic.
There have been orderly steps in pilot licensing, as solo pilots, as private pilots, as instrument pilots, multi-engine pilots, commercial pilots and air transport rated pilots. An instructive journey would take one to technology, to safety efforts that would include such steps as seat belts, then shoulder harnesses, on to weather forecasting and reporting, to radio aids and air traffic control, and the composite would be supported with data. None of those approaches, useful and valuable as they might be, would come across a magic day on which it can be categorically stated that the day for instrument flying had arrived.
Many important events in U.S. aviation's formative years have receded into history. Charles Lindbergh's flight from Roosevelt Field, near New York City, to Le Bourget Airdrome, Paris, in 1927 remains an exception. It was then, and is now, recognized as a defining event. Crossing the North Atlantic, The Spirit of St. Louis surmounted or avoided most of the challenges of instrument flight.
Some pilots began to take to the air with flight plans involving forecasts of weather system movements that were conditioned by uncertainty. These pilots understood that they might encounter weather if a weather system moved faster or slower than forecast. Having an alternate airport in mind before taking off became a good prudential rule. Sometimes, despite all precautions, a flight would become immersed in a weather challenge. Pilots who kept their heads and lived to tell the tale brought back information that helped other pilots.
The reader will discover that each form of water, solid, liquid and vapor, has provided its own unique challenge to safe flight. The solid forms would be snow or ice. The vapor could be invisible water vapor, or vapor that had condensed into tiny liquid droplets as in fog.