Once upon a time, the world moved at a slower pace than it does today. No mass media, no 24-7 news channels, and no next-day mail delivery service were available. But with the advent of the aircraft as a functional operational machine, the world changed completely in an instant. In the past, mail was delivered on horses, trains, boats and even primitive automobiles and/or four-wheeled trucks, these methods of delivery took days, weeks or even months in some instances; but with the invention and development of the airplane, mail delivery reached a new dimension. Thus the airplane had a direct effect on how people could communicate throughout great expanses of territory. They shortened, not the distance between sender and receiver, but the time the mail took from getting from the originating party to the end user. In the course of the early aircraft-supplied mail delivery system, four very distinct aircraft stood out from the pack. These four represented the epitome of air cargo delivery in an age of constant development and improvements.
In the spring of 1911, an early sample of the Wiseman-Cooke airplane was the first flying machine to deliver mail in the United States, when pilot and aviation pioneer Fred Wiseman carried a pack of letters from Petaluma to Santa Rosa in California. The complete eighteen-and-a-half mile trip was covered by Wiseman in two full days. Many mechanical difficulties, common on those early flying machines, delayed his trip. When he was airborne, the Wiseman-Cooke plane could only muster speeds just short of seventy mile per hour. Slightly built and very similar in airframe construction to the famous Wright Brother’s Flyer, the Cooke was powered by a Hall-Scott V8 engine modified to give the 670 lbs airframe enough speed to clear the ground. The next generation of mail delivery airplanes instituted a big move forward with the inception of the Curtiss JN-4, also called the Jenny. The Jenny was an advanced version of an early Curtiss JN model used mainly as a training aircraft during the Great War by the British Royal Flying Corps. Introduced in mid 1915, the JN-4 had a fuselage of 27′-4″ in length with a height of 9′-10.5″. Total wing area for the Jenny was 352 sq ft. A Curtiss designed OX5 in-line piston engine, capable of generating nearly seventy miles per hour, powered the JN-4. After the War ended in August 1918, the United States Postal Office adopted the Jenny as it’s first official air mail carrier plane. But the Jenny’s relatively small operational range, (it could operate only about one hundred and seventy five miles without refueling and maintenance); made it ill-suited for long-range mail delivery. It also did not help that the Jenny’s payload capacity was only three hundred pounds. Soon after its incorporation into the US Mail System, the Jenny was retired from front line service in less than a year.
When the US Postal Service bought the JN-4s, they also acquired a small group of de Havilland DH-4 airplanes from the US Army Signal Corp supply depot. The Airco, (or de Havilland), DH-4 was a two-seater daylight medium bomber produced in Great Britain. The DH-4 had an airframe 30′-8″ in length and a height of 10′-5″. When in combat, the DH-4 was armed with a single 7.7 mm Vickers machine gun mounted on the front of the cockpit, and another Vickers gun placed in the back of the fuselage for defensive cover – features removed for civilian operations. The DH-4 could carry up to 460 lbs of bombs internally, making the cargo payload a more manageable one. The plane was powered by one Roll-Royce Eagle VIII Vee piston engine capable of providing the aircraft with top speeds of just under 143 mph. The de Havilland’s operational range was an improvement over the other aircraft examples utilized by the Postal Service; it could operate at a range of 435 miles without any stops. As soon as they arrived, and after re-fitting, the DH-4 entered front-line service with the Postal Office. This plane was exactly what the mail service was looking for. It could carry a relatively large payload for long distances. But, as with all of the aircraft of the time, it fell victim to the newer, improved and less expensive aircraft coming along.
These two above mentioned aircraft represented a leap forward in aviation design. They were basically a tubular frame covered by sheets of canvas. The first departure from this design concept adopted by the Service was an impressive, albeit, dangerous one. The first US Postal Service all-metal aircraft was Germany’s Junkers JL-6 plane. First developed for military use in March 1917; the aircraft never saw significant combat in the Great War. A civilian version was introduced in the spring of 1919. It were to be the world’s first all metal monoplane use to ferry civilian passengers, doing so from the mid 1920 onward. But the JL-6 was a flawed design. Its electrical wire system was not properly insulated causing the plane to catch fire on mid-air. Many attempts were made to correct the problem, and all were unsuccessful, this fact lead the Postal Service to retire the JL-6 from front line service in the summer of 1921.
Today, the United States Postal Service utilized the latest commercial aircraft available and the best that technology can offer, this with the sole purpose of providing the customer with the best delivery capability the Service can offer. But in pioneer days of aviation, the Service needed to adapt promptly to new technology, new operational system, and by trial and error; they did. These four distinct planes, each of one served the Service in its own capability, proved that the aircraft was indeed, a practical and affordable mean of mail transportation, and on those days, this was a leap forward.
– Raul Colon