Gone from the airways for the duration, unless a miracle occurs, are the giant four-motored "307-B's," more popularly known as the Stratoliners. Today, these pioneers of over-weather flying for airline passengers wear the dun color of the United States Army Air Forces. Civilian America, given a taste of high flying comfort, again rides in Douglas DC-3's, content in the thought that the Stratoliners are doing their job for Uncle Sam in all parts of the world.
In passing, the "307-B's" have left their mark on the domestic skyways. Farseeing TWA, the airline which co-operated with Douglas to give the nation the first DC-2, has proved the four-motored planes are practical for airline transportation and that they will serve as civilian transports when the war is over.
Proof of what they have done lies in the operations report on NC-1940, carrying TWA's number "401." This plane is one of the five which TWA operated transcontinentally for 19 months, from July 8, 1940, until drafted by the Army Air Forces in January, 1942, only a few weeks after the debacle at Pearl Harbor.
No 401 and her sister ships showed that supercharged cabins functioned well, making it possible for flights as high as 20,000 feet without discomfort in breathing. Previous to this, 12,000 feet was considered the transport ceiling without oxygen. They demonstrated that over-the-weather flight not only avoided almost all storms but that rough air, the bane of most passengers, was left far below. And too, they proved that cross-continent schedules could be cut to 15 hours, and at the same time made special runs in 11 hours, also showing what could be done in the future. From a standpoint of economy, they revealed that in spite of increased size and therefore increased original cost and operation expense, the actual expenditure per seat-mile was almost exactly that of the commercially successful Douglas sleeper transports.
The original cost of No 401 was $351,990 as against $118,000 for the DC-3s. With a wingspread of 105 feet and height at the tail equal to that of a seven-story building, it weighed 30,000 pounds empty, carried a crew of five and 33 passengers. The Douglas DC-3, fully loaded, weighs 24,500 pounds, carries a crew of three and 21 passengers on day flights. Carrying a full load, the gross weight of Stratoliner "401," is 38,368 pounds.
Experiments which made "401" possible started in 1935, when Jack Frye, president of TWA, asked Boeing for an over-weather plane. Frye knew such a plane was feasible because of experiments in high altitude flying made by D W "Tommy" Tomlinson, TWA chief engineer and test pilot over a period of years, under Frye's sponsorship.
No 401 had a lot of gadgets (which were not to be found on the DC-3, or any other transport plane) in addition to her supercharged cabin, into which air was "packed" to give passengers 8,000 foot comfort at 16,000 feet, and 12,000 foot comfort at 20,000 feet. Among these were the gyro-stabilized compass, an instrument combining the function of an artificial horizon, magnetic steering compass and directional gyro with coordinated readings to eliminate the faults of all three; remote transmitting compass, supplementing the gyro-stabilized compass, situated in the extreme rear of the fuselage free from electrical and magnetic disturbances, and flight analyzers which recorded the elevation and radio contacts at any point during flight. And, for the first time, celestial navigation was utilized, making flight off airways possible, with the only limitation being the necessity to refuel every 1,500 to 2,000 miles.
No 401 with her four 1,100 hp motors, hung up a few records for herself. Fully supercharged, they drove her with an assisting tail wind 349.95 mph from Columbus to New York. The run, 521 miles, was covered in one hour and 49 minutes. She went easily to better than 25,000 feet.
No 401 was turned over by Boeing to TWA on May 10, 1940. A TWA flight crew took over at Portland, OR, and flew the big plane to Kansas City via Denver, CO. For many months a TWA factory inspector and his assistants had watched her go together so that they knew every nook, cranny and gadget, and how everything on board functioned.
At Kansas City, more tests were run. Nearly 100 items designed for passenger comfort were installed. TWA engineers estimate that on "401" and her sister ships, such items weigh 29 pounds per passenger. Being scientifically minded, however, the engineers include the weight of the two stewardesses in this figure. Well, they do aid passenger comfort, do they not? They weigh a total of 260 pounds.
In addition to this, minor operational installations and changes to special TWA equipment were made before the plane was put on scheduled flights.
Once ready to go, "401" and her four sisters were in for some hard work. In 19 months of operation between Burbank, CA, and LaGuardia Field, NY, they ran up the amazing total of 25,125 hours, covering 4,522,500 miles without injury to anyone. They hauled 110,000 passengers, of which "401" carried her share.
From May 10, 1940, until March 9, 1942, "401" flew 5,674:09 hours. This is approximately 3,096 hours per year, 258 hours per month, eight hours per day. These figures prove conclusively that modern transports can keep going day in and day out, spend little time in the shops. No. 401 flew 1,031,320 miles and carried 21,808 passengers during her commercial service.
Flying enthusiasts like to say that you can operate a plane as cheaply as a car. That isn't true when you discuss the costs of putting 4,400 hp and more than 38,000 pounds into the air. It would be better to compare it with a streamliner or an ocean liner.
For one thing, there's crew cost. By the hour, this comes a trifle high. Your captain, first officer, flight engineer and two stewardesses require an investment of $22.61 for each 60 minutes. With "401" operating 258 hours each month, paychecks run to $5,833 for that period. And for her entire commercial life, we get $128,289, or a little more than one-third of the original cost of the craft!
Four motors drink a lot of gasoline. In flying as far and as high as she did, "401" burned 1,096,784 gallons of gasoline at an average cost of 30 cents per gallon. Set the cash figure at $350,000 and you find that the craft gulped practically her own cost in gasoline. Add 24,398 gallons of oil at approximately $1 per gallon $24,398.
Passengers have to eat and on the Stratoliners they ate food specially prepared by Dave Chasen, Hollywood restaurateur, a favorite of the movie stars. Approximately 27,260 meals were served aboard "401." Figuring $1.46 per meal Chasen catering comes high the investment was $39,799. Take Chasen's word for it that he delivered nine and one-half tons of meat and 18,000 gallons of coffee to "401." If the 21,808 passengers had drunk all the coffee they wouldn't have slept very well, but you have to figure that TWA always has "more than enough" and that pilots and crew are coffee lovers, too.
As an advertising gesture, TWA sent out commemorative silver lucky pieces the size of a half-dollar to the first few thousand Stratoliner riders. They were great souvenirs. This evidently had a salutary effect on the customers, who did little pilfering. The loss in silverware on "401" was very small, as no insignia is on it. Same goes for towels. But TWA encourages the "lifting" of salt and pepper shakers. This goodwill venture, on "401," cost the company $920.
Twenty-five mechanics comprised the ground crews which kept each DC-3 in the air. TWA found that by adding only five men, making it 30, they had a sufficient ground personnel. Cost of this crew amounted to $70,398, approximately one-fifth of the purchase price, over the operating period. No 401 was pretty well behaved and went into repair shops along the line on only a few occasions. However, she did get a careful check every 20 hours, which meant that she was rolled into the hangar 284 times in the course of her service. Some items of expense in this connection: A small matter of 1,656 spark plugs, costing $4,388. (Remember that each full replacement calls for 112 plugs.) Five sets of replacement tires, costing about $1,000. Tires are guaranteed for 1,000 hours of flight, which means about 300 take-offs and landings. Nine major overhauls at an individual cost of about $478 per operation. Multiply by four to get the price for four motors.
An item which you'd probably overlook is the cost of cleaning and laundering sheets, pillow cases, head rests, carpets and other items, as well as their replacement due to wear and tear. Overall cost of laundry was $2,200. Life of blankets and sheets, due to the fact that TWA buys only the finest and lightest obtainable, is sometimes three or four years. So the equipment for the 16 berths didn't wear out. Head rest covers, napkins, hand towels and pillow cases, which are soiled or stained more easily (Lady, watch that lip rouge!) last only six or eight months. Carpets are removed and cleaned with each 20-hour operational check, which means that they met up with the vacuum cleaner 284 times. Replacement on all of the above amounted to $486.27.
TWA maintenance crews report that passengers are neat, clean and careful. They respect equipment. The main damage, believe it or not, is holes torn in seat covers. The cost of repair is negligible. No 401 never went back to the factory for any kind of modernizing or repair work. The reason for this is that she stood up well. Another is that TWA's repair and maintenance facilities are so complete that it is possible to do everything but actually build the planes.
For instance, consider upholstering. Upholstery work is based on the condition of each individual seat some seats are more popular with passengers than others and are therefore sat in more often and the work is done at the TWA Kansas City depot. It is estimated that "401" was completely upholstered once at a cost of $8,800.
Just about all of TWA's specially qualified roster of 42 pilots flew "401." She never left her three-stop transcontinental route. She seldom changed her dress with the seasons, except that in winter she donned her special de-icing equipment, which included de-icers on wings, stabilizers, propellers, windshields, carburetors and pitot masts. In the case of the last three items, these were installed for the first time on "401" and her sister ships necessities for high-altitude flying.
There is an adage that a good airplane is never finished, not even after it is placed in operation. There are always improvements to be made as months and years pass. And "401" was no exception. During her period of commercial operation she got the aforementioned gyro-stabilized compass, remote transmitting compass, celestial navigation equipment and flight analyzers. She also drew a pitot static blowdown system which allows lines connecting air speed indicators to be cleaned during flight, preventing the accumulation of moisture. Her fuel quantity measuring system was perfected. Supplementing this, fuel flow equipment was installed to permit a constant reading of the weight of fuel the engines consumed.
In the fall of 1940, our "401" received completely new and modernized carburetor and fuel systems. These systems included auxiliary fuel pumps to replace former hand operated pumps, and a dual type fuel system, separate and interchangeable for each engine. Had she continued in service, this list would have been much longer.
All in all, while her cost was only $351,990, more than $750,000 was spent in all departments to keep her operating. But she made a lot of money. She hauled a lot of passengers, mail and express. And she and her sisters opened the curtain of the future to give us a glimpse of the better things which are coming after the war is ended.
This article was originally published in the December, 1942, issue of Flying including Industrial Aviation magazine, vol 31, no 6, pp 30-32, 82. The original article includes 4 photos.
Photos are not credited.