Development of the DC-1
August 2, 1932, thirty-eight year old Donald Douglas sat in his office reading his mail. One letter he opened would prove to be the most important letter he received in all his years in aviation. Later he called it, “The Birth Certificate of the DC Ships.” The letter, signed by Jack Frye, vice president of operations for Transcontinental and Western Air, Inc. (TWA) was simple and to the point. TWA wanted to purchase ten or more tri-motored transport planes. The letter included general specifications and asked if Douglas was interested. There was also a sense of urgency in the letter because Frye wanted to know how long it would take to have the first plane ready for service tests.
The specifications called for an all-metal, tri-motored monoplane with a gross weight of 14,000 pounds, a range of 1,000 miles, and a top speed of 185 miles per hour. It also called for a capacity to carry twelve passengers, two pilots, and take off fully loaded on two of the three engines. Nowhere in the letter was there mention of cost.The letter intrigued Douglas. He knew the specifications came from questionnaires Frye had sent to his pilots and executives after the Knute Rockne accident.
Frye was an aggressive executive, and proud of his airline. Texas born, Frye was the youngest airline executive in the country, and he had earned his wings. He had been a cowboy, Hollywood stunt flyer, and flight instructor in the early 1920s. Frye saw the need to get people to places in a hurry, and formed his own airline. His Standard Air Lines became a ferry service for Hollywood moguls and stars to their southern California vacation spots. Frye did so well, Western Airlines purchased his airline and when TAT merged with Western Airlines forming Transcontinental and Western Air (TWA), Frye became a vice president.
Although the country was in the midst of the Depression, Douglas had thought about expanding into the commercial market. Even though cars were not selling, banks were failing, and there were thousands of people on unemployment lines, executives were still working and flying, and TWA was looking for a new design. Douglas also had misgivings about entering this market. He would have to gamble the future of his company with no assurance it would be successful. The Depression economy was tenuous. Between 1930 and 1934, he built 162 Army 0-38 observation planes. They were his meat and potatoes. But the narrow profit margins from government contracts were not enough in the difficult times of the Depression. (In 1933 Douglas built his first fighter plane for the Navy, the XFD-1, a two-seater biplane with an enclosed cockpit and fixed gear.) Douglas knew he could not go on building military planes forever, the peacetime military budget was divided among too many companies. (Note: Ironically, military orders continued to be the backbone of the Douglas Aircraft Company. Not until 1958 did civilian orders reach half the amount of government orders.)
Douglas would have to act on Frye’s proposal quickly. He was sure it had gone to the Martin, Sikorsky, and the Consolidated Aircraft companies, and he suspected Curtiss-Wright, Ford, and Fokker were working on new designs also.
A TRAIN TO NEW YORK
A week later, a team emerged with a written proposal, and Raymond and Wetzel boarded a train for New York, with a list of general specifications.
“We traveled by train for two reasons,” said Raymond. “We had much ground to cover, and hundreds of details to lay out. I needed secluded time to work out my performance figures, and, because we really wanted to get there. The ghost of Knute Rockne was still lingering.”8
During this period, the airlines had seen a sharp increase in the number of accidents and neither man wanted to become another statistic. To sum up the state of commercial air travel in 1932, it was expensive, unreliable, and downright dangerous.
Raymond and Wetzel arrived at Pennsylvania Station in New York, and proceeded directly to the TWA office on Lexington Avenue. They laid the three-view drawings before Frye and Richard Robbins, TWA’s president. Frye called in his technical advisor, Charles Lindbergh. Raymond recalled the initial meeting. “Lindbergh looked over the bi-motor proposal. The single engine performance concerned him. Lindbergh said, ‘If an engine should fail on take off, we want to be able to climb out with a full load on the remaining engine.’”
“That didn’t surprise me,” said Raymond. “The requirement was in their tri motor specification, and I mentioned it.”
“‘Correct,’ said Lindbergh. He was very polite to me, but firm. ‘If you’re going to build a bi-motor, as your drawings suggest, we still want the engine-out requirement. We want to be able to climb to an altitude of 8,000 feet, the highest point on our route system, and maintain level flight on the one engine.’”
“I looked at Lindbergh,” said Raymond,” and remembered, we had talked about this back in Santa Monica.”
“Can you do it?” Frye asked.
Raymond’s mind began racing over the formulas. He took out a circular slide rule and started to jot numbers on the side of the drawing. The room was quiet. He immersed himself in the problem but he could feel the tension building.
“Lindbergh broke the silence. He looked at me, and said, ‘If you can do it, we’ll buy the design. If not, we’ll go elsewhere.’”
Raymond knew it was now his decision. The fate of the Douglas Aircraft Company rested not on Donald Douglas but on him. Raymond knew he had to pick up the challenge, or return to Santa Monica empty handed. “I remember looking up from the drawing and straight at Lindbergh. ‘We can meet your requirements’, I said.”
Raymond had moonlighted for four years at Cal Tech giving a weekly course on airplane design. As a thesis subject he had given one of his students, W. Bailey Oswald (Ozzy), the problem of developing a sophisticated method of performance calculation, adaptable to a slide rule.
Oswald developed a set of performance charts, which would help to systematically analyze the many variables of flight: atmospheric density, airplane drag, engine power, and propeller efficiency. (These charts later became a National Advisory Committee for Aeronautics Report.)9 Raymond had used this new analytical method of performance prediction to arrive at his decision.
“Using Ozzy’s method, I concluded a properly designed bi-motor, using the latest state-of-the-art, could probably do the job. The advantages of eliminating the nose engine were obvious, a clear front view for the crew, less noise and vibration, and no fumes in the cockpit.”10
Following the meeting, Raymond called Douglas to bring him up to date. “Doug was pleased and optimistic. I was the one with the butterflies.”
Oswald said later, “Mr. Raymond knew how to use my equations, and found that we could meet TWA’s specifications with a two-engine airplane by shaping it properly. From the calculations we also decided that a stressed skin, all metal construction, with brazen head rivets, and wing flaps was a good way to build it.”
The engine-out requirement still worried Raymond. Oswald’s calculations had a 90 percent assurance factor, with the right engines. It was the other 10 percent that worried Raymond. “We had no idea what we were getting into when we began designing the DC-1,” said Raymond.
“No one could have taken such positive and decisive action as assistant chief engineer responsible for the layout as Mr. Raymond did,” said Oswald. “To my knowledge it had never been done before or afterward.” That’s why Raymond had butterflies. He had put the future of the Douglas Company on the line.
SANTA MONICA - WORK IN PROGRESS
On October 16, 1932, Raymond returned to Santa Monica. The trip greatly affected him, convincing him there was more to designing a commercial airplane than just efficiently carrying cargo and people. “People should not be treated as cargo,” said Raymond.
When Raymond walked into the office he found the team still refining the original design. His phone calls to Douglas kept the team informed and the drawings reflected the progress. “Naturally, we wanted the contract so we were trying to get as far along as possible without spending too much money.”
“Dutch put me in charge of the project and the first thing I did was hire “Ozzy” (W. Bailey Oswald). He was the best man I knew on calculating performance for that engine-out requirement. That still bothered me. I told him we only needed him for a short while but he stayed until he reached retirement age.”15
Oswald recalled, “As proposed, the DC-1 was a bold effort by Ray. He presented in a neat twin engine design what had been earlier envisioned as needing three engines. My job was to see aerodynamically that we did it with two engines.”16
Douglas knew the risk a bi-motor presented, but he also knew they’d have to forget three motors. Kindelberger reminded him, “Who would buy a plane that even looked like a Ford or Fokker?”
BUILD FOR COMFORT AND PUT WINGS ON IT
Raymond discussed his trip with the team. “I knew there was a lot more we needed to consider in building a commercial airplane. If we were going to meet TWA’s specifications, we would have to build a comfortable enclosure, and put wings on it. It would have to be something different, perhaps radical.” WING DESIGN
Raymond knew the size and performance of the proposed airplane plus the comfort of the passengers presented a new set of opportunities. The wing was the biggest question mark in the equation. Most wings in use at the time were merely adaptations of some features of Jack Northrop’s radical new wing design. Northrop joined Douglas in 1923, and played a major role in the development of the World Cruiser. He left Douglas in 1927 for Lockheed, but later resigned to form his own company. In 1931, the Douglas Aircraft Company became a 51 percent stock holder in the Northrop Company.
Jack Northrop had been working with monocoque (pronounced mono-cock) construction, first in wood, then in metal, on a design in which the covering absorbs a large part of the body stresses. The Northrop wing had an innovative new feature, the European-invented cantilever design. It also had several non-parallel aluminum spars that formed a honey-comb effect. The exceptional strength came from individual sections placed together to form a multi-cellular structure, creating a unit stronger than its parts. The traditional wing design of the day had two main truss beams that bisected the body of the aircraft as in the Boeing 247.
Jack Northrop had designed a wing that had a flat center section with removable outer panels. The fuselage of the plane rested on the top of the center section.
Oswald had concluded that in a highly stressed airplane, torsional rigidity of the wing was important in preventing wing flutter at high speeds, and the torsional deflection should be kept at an absolute minimum. After a thorough investigation of various designs, Douglas gave the Northrop multi-cellular wing construction with the NACA refinements final approval. The team also suggested larger and more powerful engines, wrapped in the new NACA cowlings which reduced drag and kept the engines cooler.
The new wing was a major design change, and responsible for a dramatic reduction in the internal cabin noise, and reducing the weight of the airplane. In later accidents involving the DC-3, the wing construction was one reason some aircraft survived crashes that would have destroyed other airplanes.
Making the skin for this radically new aircraft was one of many time-consuming steps to building the DC-1. A sheet metal worker would study the blueprints, and select a piece of aluminum the right size and roughly the right shape. He would scratch out the pattern in the raw stock, and then using blocks and a mallet, shape the metal. There were no hydraulic jacks or presses to shape, form and cut the thousands of pieces needed. The process sometimes took days. To build this single airplane also required large scale retooling in the Douglas factory.
The engineers decided not to use the electrical retraction method for the landing gear (like the Boeing 247) since they felt this apparatus was subject to failure. They decided the gear would be hydraulically activated using a long handle, and retract into the newly developed NACA streamlined nacelles. In the “UP” position, the main gear wheels protruded from the engine nacelles about half their diameter. For safety reasons the engineers decided the wheels would not fully retract. In a wheels-up, emergency landing, the low wing would help shield the passengers, and the half extended wheels would cushion the landing, or so the design logic went. This was a radical departure from the construction techniques common among the multi-engine aircraft in commercial service. Except for the Boeing 247, the Fokkers, Fords and Boeing tri- motors were all high wing, fixed gear airplanes.
The costs for the research directly connected with the project was $325,000 (compared to $250 million for the DC-8). In addition, the airplane also incorporated much of the experience obtained during TWA’s operation of the highly successful, single engine Northrop transports. This alone represented an additional engineering and development cost of roughly $290,000.
WIND TUNNEL ENGINEERING
A large portion of the research cost was the result of the wind tunnel tests, mock up construction and static ground tests of the finished airplane. Without the wind tunnel tests it is quite probable the DC-1 would have been unstable in actual flight, since ordinary mathematical equations showed the original shape was satisfactory.
The engineers put scale models in the wind tunnel more than 200 times at speeds of over 200 miles per hour. The initial tests showed instability. To make the model stable a new untried arrangement of center of gravity, wing sweepback and general reconfiguration was necessary.
The wind tunnel showed the new wing flap design improved lift by 35 percent and increased drag by 300 percent. This would be a significant asset in the landing speed profile. The tests also showed design flaw subtleties that would have gone unnoticed under normal test procedures of the day. These tests also found that adding a fillet between the wing and fuselage increased the top speed by at least 17 miles per hour. By removing the radio mast, and using a trailing antenna instead, engineers added three miles per hour to the DC-1’s speed. A streamlined fairing over the tail wheel added two miles per hour, and the Hamilton controllable pitch propellers added five miles per hour. Minor modifications from the wind tunnel testing also added 27 miles per hour to the speed of the airplane.
Later tests showed the tail wheel fairing did not reduce drag significantly and was undesirable from a maintenance standpoint. The doors covering the wheel wells in the nacelles provided only a negligible reduction in drag. Years later this modification was tried again on the Super DC-3, again with only marginal improvements in speed.
The tests also showed it was desirable to have the engine nacelles ahead of the wing’s leading edge. This enabled the engineers to position the landing gear wheel, forward of the center of gravity, thereby creating greater stability.
“We learned later,” said Oswald, “to use caution in depending fully on wind tunnel tests. Often the test results needed verification. We tried different things and many didn’t work. We found it was very important to get a thorough dynamic test of the machine also. MOCK-UP
As the aerodynamic shape emerged from the wind tunnel tests, engineers made a mock-up with wood frames covered with heavy paper to simulate the metal skin covering. The DC-1 was the first commercial transport designed in full scale mock-up first.
The seats were a comfortable 40 inches seatback-to-seatback, and mounted on anti-vibration rubber pads. Each reclined and doubled as a napping chair. By fitting the cabin floor to the wing center section, the cabin was completely above the wing so there would be no structural member in the cabin.
Engineers installed a complete working control system made of wood, with ropes instead of cables. Every lever, knob, and handle, even such minor ones as the remote control handle for the radio, were tried in countless positions until they found the most practical arrangement. They moved the instruments around until all the related instruments were grouped together.
One phenomena Douglas engineers investigated were reflections and instrument board lighting for night flying. Mirrors in the mock-up replaced windows. They plotted the angle of the mirrors and the corresponding reflections, and developed an arrangement that reduced unwanted reflections. Then they installed a lighted instrument panel and checked it at night for the effect of interior lights on the cockpit. In plotting all possible reflections from ground lights, the engineers missed one critical condition. Later they discovered the nose-mounted landing light created dangerous reflections in fog, snow, and haze, that sometimes blinded or confused the cockpit crew.
HEAT & VENTILATION
Arthur Raymond also wanted to solve the problem of noise. His experience on the Ford Tri-Motor convinced him noise reduction measures were needed. The primary sources of noise in the airplanes of the 1930s were the propellers, engine clatter and vibration (an open aircraft engine on a ground test bed measured 120 decibels). The noise measured inside the typical aircraft of the early 1930s like the Ford Tri-Motor was over 100 decibels.
Dr. Stephen Zand, of Sperry, had begun serious research into aeronautical acoustics in 1932, and he used his early findings in the DC-1. He tested eleven different materials before selecting “Seapak.” The soundproofing consisted of several layers of Kapok next to the duralumin skin, an air space and a layer of filter material. Stretched fabric, and paneling made of a combination of balsa wood and rubber covered the “Seapak.” This soundproofing arrangement reduced the noise level in the DC-1 to 72 decibels at 185 miles per hour. Cruising at 90 miles per hour the DC-1 had a decibel count of 65, and the average sound level in the cabin was lower than in the pilot’s compartment. It ranged from 68 in the rear to 73 in the front. The pilot’s compartment measured an 86 decibel level.22
Raymond also remembered the refrigerator-like Ford and decided to design a reliable heating system. Since the heat would come from the engine, every possibility of gas entering the airplane had to be eliminated. After several arrangements of the components an adequate and safe heating system evolved. Heating the plane in the winter or at high altitudes required an efficient system. A small, 24-pound corrugated steel boiler in contact with the engine exhaust furnished the thermostatically controlled steam heat. There were self-adjusting cool air inlets next to each seat for the passenger’s comfort. Air ducts coupled to a vent in the nose of the plane fed individual seats through grilled floor rests and provided draft-free ventilation. This system provided a complete change of air every 60 seconds, and maintained a temperature of 70 degrees, even when the outside air temperature was below zero.
On March 15, 1933, TWA approved the mock-up fuselage and actual construction began. “As the DC-1 design progressed, it became clear the empty weight was increasing, and moving backward,” reflected Oswald. “Initially the wing platform from the junction just beyond the nacelles tapered both at the front, and back into the smaller chord at the tip, and we sensed it was no longer a good design.”
The wing span was initially 80 feet, but designed for growth. As the airplane design progressed, it got heavier, increasing from 14,000 to 17,000 pounds gross weight. “When the weight grew,” Oswald said, “the center of gravity moved back. Since it had a good span, it was easier to sweep the wing back than move the entire wing. We increased the span to 85 feet, with the outer wing panel tapered backward to show a straight trailing edge. The increased span made it possible for the DC-1 to fulfill its critical single engine requirement. It was really an expedient, but it worked out beautifully and made the airplane easy to recognize.”23
The contract had called for an empty weight of 14,600 pounds, and some engineers said the heavier plane would not get off the ground. Raymond was confident since he had talked to Al French, the West Coast representative for the Hamilton Standard Propeller Company. French told him about the new controllable pitch propeller they were developing. It would allow the pilot to adjust the angle of the propeller to take larger bites of air at take-off. It would also be more efficient at high altitudes. “That prop will bail us out,” Raymond told Douglas. “WE SHOULD GET ONE HELL OF AN ENGINE”
During construction of the airframe, Douglas tested engines from two manufacturers. The dilemma Douglas engineers faced was that both engines were good, but both also had problems. The Wright “Cyclone” engine had a cylinder head cooling problem and the Pratt & Whitney engine burned too much oil.
Competition to capture the engine contract was intense. One day in April, Douglas and Ivar Shogran, chief of the power plant section walked through the plant.
As they walked the plant Douglas noticed a line painted down the aisle. He asked Shogran, “Why the line?” Shogran replied, “It separates ‘no-man’s land.’”
The Wright Engine Company, the company that built the engine for Lindbergh’s “Spirit of St. Louis,” set up camp on one side of the line. The Pratt & Whitney crew was on the other side. There were large screens hiding their respective engines from the sight of the other camp. The two crews wore clean white jump suits with the name of their company in bold letters on the back of the uniform. The two groups would not speak to each other and no one crossed the line from the other camp. Each was trying to come up with the better engine. It would mean a big contract to the winner. Shogran told Douglas, “We should get one hell of an engine out of this rivalry.” They did.
After intensive testing, the Wright Company reengineered the cylinders, adjusted the price downward, and the “Cyclone” won the contract. Two years later, the Pratt & Whitney Company successfully introduced their 1,000 hp “Wasp” engine specifically designed to compete with the Wright “Cyclone”
As a result, about two-thirds of the commercial DC-3s had Wrights, and the others had the Pratt & Whitney engine. All military C-47s had Pratt & Whitney engines, so, as Arthur Raymond put it, “Pratt & Whitney came out ahead in the end, as they were in the habit of doing.”
The Douglas DC-1
On June 22, 1933, Donald Douglas rolled the new DC-1 out of the hangar. The sleek, silver fuselage had a fish-shaped body, oval-like in cross-section, and large square windows. It was the largest fuselage land plane ever built in the country as a bi-motor monoplane design. One old barnstormer remarked it was so big it would never fly.
The Scientific American reported, “The DC-1 represents the acme of design, both in relation to aerodynamic efficiency and to comfort features for the passenger.”
The DC-1 was larger than the Boeing 247, had all the aviation and passenger improvements the Boeing had, and a few new ones. Two Wright “Cyclone” engines on the airplane each delivered 710 hp, more horsepower than the original Ford Tri-Motor engines combined. It had split flaps under each wing that acted as air brakes, helping to reduce the landing speed to 58 miles per hour, lower than the TWA requirement.
In exceeding TWA’s specifications on the DC-1, Douglas had set the foundation for the success of the DC-3. In retrospect, some have said the DC-3 was over-engineered. If one accepts that, then it began with the DC-1.
Arthur Raymond doesn’t agree. “The absence of sophisticated tests for stress on parts, and limited experience with all metal design may have led us to pick stronger materials than we needed. We didn’t go about it to make it conservative, we wanted to make it safe, and there wasn’t much experience with design.”2
THE FIRST FLIGHT
On the day of its first fight, everyone connected with the DC-1 was anxious. After many days of fine tuning and adjusting the engines, everything seemed ready.
Carl Cover, vice president of sales, and chief test pilot for Douglas, would pilot the plane, and Fred Herman would act as copilot. The two men were both good pilots and they were all business as they climbed aboard.
Douglas had set the takeoff time for the lunch hour so his employees could see the fruits of their labor. About eight hundred people (employees and general public) were present.
The sun was shining, and the sky was clear, and the offshore Pacific Ocean breeze had blown away any clouds. The temperature was a comfortable 76 degrees. The two men in the airplane knew the future of the Douglas Aircraft Company depended on how well they flew the DC-1.
After reviewing the preflight check list, Cover was ready. The mechanic standing beneath the cockpit on the left side waved that all was clear. Cover pressed the starter switch, and the propeller began to turn lazily. Suddenly, the whining engine coughed, and the propeller spun into life.
Cover repeated the procedure for the starboard engine, and synchronized them. The DC-1 was ready to go. The mechanic pulled the wheel chocks, and Cover taxied into position.
Cover ran up the engines, and checked the instruments again. Everything looked okay. The engines were sending vibrations, and sounds echoing through the hollow fuselage. Carl Cover and Fred Herman hardly noticed. Cover applied left rudder and swung the plane onto the runway. Again he ran up the engines, keeping his feet firmly on the brakes. The aircraft strained at the invisible leash.
Cover released the brakes and the plane began to roll. As the plane gathered speed, Cover aborted the take off. He eased off on the power, and began taxiing. He was rechecking the instruments and getting the feel of the aircraft. The Douglas employees were watching intently. Some were puzzled. There was a murmured concern running through the crowd. Donald Douglas watched calmly.
Cover reached the end of the runway, turned the plane around and taxied back again. When he reached the takeoff point he turned the nose into the light west wind blowing off the ocean, pushed the throttles forward and roared down the runway. The gathering speed caused the tail wheel to rise and the plane assumed its natural flight characteristics. On July 1, 1933, at exactly 12:36 PM, 332 days after Douglas received Frye’s letter, the main gear of the DC-1 left the ground. It was the beginning of the end for the Condors and other wood, fabric and wire airplanes. Douglas looked at Raymond. “Well she’s off,” he said calmly.
Cover pulled back gently on the control stick. The nose lifted as the propellers chewed away at the air. The roaring Cyclone engines pulled the Douglas into the air without the slightest strain. A loud cheer went up in the crowd. The take off was perfect.
The plane was not more than a hundred feet off the ground when the left engine sputtered, and quit. Alarm registered in Cover’s brain. A moment later, the right engine did the same. The crowd below was watching intently and saw it happen too. Most were silent, just staring up at the drama unfolding before them. Douglas overheard someone say, “She’s going to crash.” His stomach knotted. The crowd expected a disaster.
Arthur Raymond recalled what he saw from the ground. “Those of us who watched the first flight got a thrill. The takeoff from Clover Field was toward the ocean, and the land beyond the runway dropped off sharply. After gaining a bit of altitude, the plane began to sink as it went into a left turn, and dropped out of sight. Our hearts nearly stopped, but the turn continued. We saw it again, gaining some altitude. Again it sank and rose. Obviously Carl could get a little higher each time, so we relaxed.”
They weren’t relaxing in the cockpit. Cover looked at Herman. He knew they had a problem, but how serious a problem, that he did not know. He needed some altitude to maneuver. Gently he lifted the nose skyward. As the plane started to respond, both engines sputtered.
There was silence in the cockpit, and there was silence on the ground. All eyes were riveted skyward on the sleek silver plane. The silence was ominous, even in the cockpit. Cover’s mind raced over his options. He had only seconds to react. He was an experienced pilot, and his reflexes saved him. He pushed the control stick forward to gain airspeed. Both engines suddenly cut back in. Now his reasoning took over his reflex action. He pulled back on the wheel, and started to climb, very slowly, and very carefully.
Cover coaxed the plane up to 1,000 feet and started to pull the nose up. Again the engines sputtered and quit. He was pushing it now, he thought. He put the nose down and the engines came back to life. That settled it, Cover thought. He didn’t know what was wrong, but he had to land the plane immediately and safely. He couldn’t risk the plane, or the life of his copilot.
Carl Cover had earned his salary on that twelve minute ride. He landed the plane, taxied into the hangar, and climbed down to a waiting crowd. Cover later described the flight to Douglas, as flying on a dotted, wavering line.
Raymond recalled the events that followed. “Carl walked straight over to Ivar Shogran who was our chief power plant engineer. Shogran looked puzzled. He was bewildered and thought there may be a problem from contaminated fuel.”
Engineers from Wright swarmed over the engines. “Everything looked okay. The fuel was clean. We had a real puzzle, so we grounded the DC-1 until we could work it out.” said Raymond.
The DC-1, like the Wright brothers’ “Flyer” made its exciting debut without fanfare or ceremony. Although almost 800 people showed up, the Thirteenth National Air Races were in the news. Roscoe Turner, one of America’s speed aces, had just set a new transcontinental speed record of 11 hrs, 40 minutes. Italo Balbo, a famous Italian pilot, was flying across the Atlantic with a squadron of seaplanes, in the first mass-trans ocean flight. Like the Wright “Flyer,” there was little mention of the DC-1 in the newspapers. The public wanted to read about Turner and Balbo’s adventures.
Shogran worked his engineers around the clock for a week, checking every system. They ground-tested the engines for hours without a failure. The trouble seemed to disappear without a hint as to the cause.
“Carl’s familiarity with the plane in the moment of the crisis led to the answer,” said Raymond.
He suggested they look at the carburetors, but the Wright Engine Company engineers objected. They had other suspicions. When they finally relented they discovered Cover was right. The carburetors were mounted backwards so, when the plane assumed a nose up attitude, the carburetor floats would cut off the fuel flow to the engines. When the engineers turned the carburetors 180 degrees, the trouble cleared.
On July 7, they made another test flight. The engines performed perfectly, but Cover discovered the plane flew like a shark, fishtailing through the sky.
Douglas sent design engineer Eugene Root and Bailey Oswald up to ride in the rear of the plane to learn what was wrong. Root said, when the plane landed, “It was like being on the ‘Crack-the-Whip Ride,’ at a carnival.”
Oswald described it as the tail trying to get ahead of the nose. They adjusted the rudder linkage, flattened out the sides of the rudder and extended the surface area. The next flight found the plane completely stable.
The DC-1 was probably subjected to more testing than any other known passenger or military plane of its time. Because of this many neglected variables and uncertainties of flight testing were eliminated. Douglas engineers kept in mind the objective; to decide not the peak performance under ideal conditions, but the performance that could be maintained daily, under airline conditions.
Over 200 flying hours and 15,000 gallons of gasoline went into the actual flight tests. Among the tests were those for speed, stability, and general performance. Accurate landing speeds, take off distances, and initial climb angles were plotted, checked and correlated to motion picture records. The airplane was tested for structural strength under static loads, and dynamic loads in-flight. After flight testing the DC-1 at various altitudes, the engineers tried every possible engine speed, propeller pitch, and various loadings, in all weather conditions. Douglas asked Cover what he thought of the DC-1’s flight characteristics. “She was born to fly,” he said, “and she belongs up there with the angels.”4
SINGLE ENGINE TEST
September 12 was the day of the all-important single engine test. Were Oswald’s calculations correct? On board were test pilot Eddie Allen, TWA copilot Tommy Tomlinson, Douglas flight engineer Frank Collbohm, and Dr. W. Bailey Oswald.
The engine run-up was normal, and Allen taxied the airplane onto the runway at Winslow, Arizona, carrying water ballast for a full 18,000 pounds of gross weight.
The contract had stipulated a test flight from, “Los Angeles, eastward . . . , or Winslow, westward . . .”5 either way, it would take the flight over the highest mountains on TWA’s routes.
The team chose Winslow, Arizona, because of its demanding environment. At an altitude of 4,256 feet, it had daytime temperatures near 100 degrees. These conditions would influence the flight characteristics, and handling of the aircraft.
As the plane started down the runway, Tomlinson called the airspeed, and runway markers. The plane bounced lightly as it began to un-stick from the runway surface.
“Gear up!” Allen suddenly called.
The idea was to get the gear up as quickly as possible to reduce the drag on the plane. When Tomlinson began pumping the gear handle, Allen reached over and shut down the right engine.
The plane sagged and struggled to maintain flight. Observers said the propellers came within inches of the ground. Then slowly, the plane began to climb. The controllable pitch propellers acted as Hamilton Standard’s vice president, Al French, said they would at high altitudes.
Allen did not follow the conservative engine-out procedure planned. When the landing gear struts were fully extended meaning the wings were supporting the weight of the plane, Tomlinson was to start pumping the gear up. Then Allen should have started reducing power. Instead he had told Tomlinson to begin retracting the gear a moment before he cut power to the starboard engine. He had gone beyond the intent of the contract that called for successful single engine operation, “...failure of either engine at anytime during take off, after traversing 4/10ths of the runway or not less than 1,000 feet . . .”
Allen had shut the engine down at the most critical point in the take off, when the wheels had just barely left the ground, and before the wings had enough lift. Allen had a great deal of confidence in the airplane and the Wright engines, but he had also worked closely with Bailey Oswald.
Raymond put it this way. “Allen worked with Ozzy in the development of a series of charts, and the conclusions they drew from the calculations were that airplanes should be flown at higher altitudes; they should do it faster, to get the most efficient results. So along with Ozzy, he came to have a feeling for this one engine out flight that I don’t think other people naturally had. It was seat-of the pants information other people worked with. The supercharged engines, and adjustable pitch propellers, also influenced Allen’s actions.”
“Allen had flown some single engine airplanes for Northrop, which had some similar design characteristics so he knew from personal experience what the airplane could do. It was a combination of people who knew certain parts of this thing all getting together, talking and reaching a conclusion.”
“We made sure everyone understood the attitudes of the airplane leading to the best performance with an engine inoperative.” said Oswald. “When Allen cut the engine, he put the operating engine downward and the fuselage straight forward. It was much more efficient to get the side force on the wing. Eddie knew all those things. He was an engineer’s dream.”
The plane climbed to 8,000 feet, maintained 130 miles per hour, and cleared the Continental Divide at Gallup, New Mexico. Two hours later, it landed at Albuquerque, on one engine. It was as if nothing were out of the ordinary. Ford’s “Tin Goose” became a dead duck.
On September 13, 1933, after the successful one-engine test, the DC-1 became part of the TWA fleet.
Later the capability of the DC-3 to fly well and under good control turned out to be of more than a professional interest to Oswald. “We were on a flight to Washington, D.C., in the company’s DC-3. Aboard were Douglas, several vice presidents, and Arthur Raymond. The airplane was flying over the mountains of Pennsylvania and several times the copilot came into the cabin and peered out the window at the right nacelle. The copilot informed us there was an indication of an engine fire. They didn’t want to dispense the extinguisher because the engine could not be restarted. So they feathered the propeller and turned the airplane back to Columbus. Investigation later showed the warning system to have a short circuit due to moisture.”
On one early test flight, the DC-1 nearly met disaster. Allen and Tomlinson were landing the plane when there was a breakdown in communications.
On previous flights, Frank Collbohm had operated the landing gear’s hydraulic pump. This flight was a landing test and Collbohm wanted to watch the three-point landing. He went to the rear, pulled the door open and laid down on the floor to watch the tail wheel’s impact. Bailey Oswald had gone along to help with the instrument calibrations. Oswald stepped up to Collbohm’s spot between the two pilots, when Collbohm went to the rear. Pilots Allen and Tomlinson didn’t notice the switch as they were busy setting up for the landing. Assuming that Collbohm would activate the gear, they did not vary from their routine. No one had told Oswald he was supposed to lower the gear.
Collbohm saw the tail wheel touch the ground, sparks began to fly and he got a face full of dirt. The plane scraped along the runway on its belly. The under side of the plane was scratched, dented, and the propellers were bent. There was no structural damage, however, a clue to the strength of the future DC-3.
Fifty-four years later, Oswald described the character of Donald Douglas as it related to that incident, “Nobody ever called me in and said I was responsible for the wheels up landing. That is the way Doug was. He just asked, ‘What happened? What will it take to fix it, and how long will it take?’ He didn’t waste time fixing the blame.”
“I wanted flush riveting, and full gear retraction,” said Oswald, “but during that landing test, I really did appreciate the safety of the partially retracted gear.”9
THE TWA TEST — FOR REAL
On November 15, 1933, Donald Douglas had his first ride aboard the DC-1. Cover and Tomlinson were flying Douglas from Santa Monica, to Newark, New Jersey, to meet with TWA’s president to renegotiate the DC-1 contract. President Roosevelt had taken the country off the Gold Standard, and technically the contract was void. It had called for “$58,000 payable in gold in ten monthly installments.”10 Douglas was looking to raise the price to $65,000, the equivalent in paper money. As the airplane climbed over the Andais Pass, one of the highest points along the Continental Divide, one engine failed. Douglas later said, “Here was the TWA requirement, for real, but you could hardly tell back in the cabin. It was like nothing happened.”
Carl Cover made a 180 degree turn, and landed at Albuquerque. They fixed the problem, and the rest of the flight was uneventful.
The DC-1 later became known as TWA’s flying laboratory. During the early part of 1936, after TWA had withdrawn it from passenger service, they used it for high altitude research. The engines were changed to Wright GR-1820-F55 “Cyclones” with two-speed blowers, with Hamilton Standard constant speed propellers. The flight crew used oxygen masks and auto-pilot (since visibility through the frost-covered windows at 20,000 feet was impossible) to test deicing boots for the wings, and alcohol mixes for the propellers. Howard Hughes, the largest stockholder in TWA, thought so much of the DC-1 that he later bought it, and considered using the plane for a planned record breaking round-the-world flight. At the last minute Hughes opted for a twin engine Lockheed 14, and the DC-1 faded into the background.
A gentleman aristocrat, Viscount Forbes of England, bought the machine and planned to fly it across the ocean. However, at the last minute caution caused him to transport the machine on the deck of a freighter.
Once in England it was registered as G-AFIF. The prototype DC-1 remained in England only four months before being purchased in October, by a French aviation broker. It later turned up in Spain as EC-AGJ registered to the Spanish Republican government. In 1940 it was registered as EC-AAE by the Nationalist Government. From there it went to Iberia Airlines as “Negron” and soon found itself in the middle of the Spanish Civil War. Remarkably, it survived the war undamaged.
THE LAST FLIGHT
On a bright, sunny December morning in 1940, fate finally caught up with the DC-1. There was nothing unusual about the morning, or the flight. As usual, the DC-1 rolled down the runway at Malaga, Spain, and left the ground effortlessly. Immediately after the wheels left the ground, the port engine quit. The plane began to mush. The pilot, perhaps not knowing the aircraft could fly on one engine, opted for a wheels up landing.
The plane crunched to a stop, and when the dust cleared the DC-1 lay battered and broken with a heavily damaged airframe. All the passengers and crew escaped from the battered fuselage.
According to the Captain, Rodolfo Bay, there were no spares available so the Spanish Air Force mechanics stripped the plane of parts and left the fuselage to rot.11
In the early days of World War II, Communist mobs set fire to many of Malaga’s churches, and religious symbols. One item destroyed was a wooden Andas, a stretcher-like platform used to carry the statue of the Madonna during religious ceremonies. Felipe Ezquierro, a Spanish aviation historian, claimed that while he cannot confirm the legend that a replacement Andas came from the wreckage of the DC-1, “I think we can accept the beautiful legend that the famous aircraft at the end of its days became a throne for the procession through the streets of Malaga as the representative image of the Mother of Christ, who for Spanish Catholics has the name, “Queen of the Skies.”12 Carl Cover was right, the DC-1 belonged with the angels.