Tag Archives: Air Mail

15 May 1918

Curtiss JN-4HM “Jenny), S.C. 38262, at Potomac Park Polo Field, Washington, D.C., 15 May 1918 (National Postal Museum, Smithsonian Institution)

15 May 1918: The United States Post Office Department began regularly-scheduled transportation of the mail by air. After a short delay the first flight departed from Potomac Park Polo Field, near Washington, D.C., at approximately 11:45 a.m., heading to Philadelphia, Pennsylvania, on the first leg of a relay to New York City, New York. Among many spectators and government officials, there to observe was Thomas Woodrow Wilson, the 28th President of the United States of America.

Potomac Park Polo Field

The weather was described as “fair,” with the air temperature at 70 °F. (21 °C.). The first airplane scheduled to depart was a Curtiss JN-4HM “Jenny,” Signal Corps serial number S.C. 38262. Its pilot was Second Lieutenant George Leroy Boyle, Aviation Section, Signal Officer’s Reserve Corps, United States Army.

S.C. 38262 was a brand new airplane. It had been shipped by railroad from the Curtiss Aeroplane and Motor Company’s plant in Hammondsport, New York, to Hazelhurst Field,¹ Long Island, New York. The airplane was uncrated and assembled, then flown to Bustleton Field, about 15 miles (24 kilometers) from down town Philadelphia.

Major Reuben H. Fleet, at left, with 2nd Lieutenant George Leroy Boyle, at Potomac Park Polo Field, the morning of 15 May 1918. (National Postal Museum, Smithsonian Institution )

On the morning of 15 May, Major Reuben H. Fleet flew S.C. 38262 to Washington, D.C., arriving there at 10:35 a.m. Major Fleet met with Lieutenant Boyle to discuss the actual mail flight and assist him with charts for the route. With all the hurried activity, refueling the Jenny was overlooked. When it was time, Boyle was unable to start the airplane’s engine. There was no gasoline available at the polo fields, so some was siphoned from the other airplanes.

Lieutenant Boyle was finally airborne at approximately 11:45 with his load of U.S. Mail.

2nd Lieutenant George Leroy Boyle takes off in Curtiss JN-4HM S.C. 38262, at approximately 11:45 a.m., 15 May 1918. (Smithsonian Institution SI 2000-6150)

After taking off, though, Lieutenant Boyle turned toward the south—the wrong direction for Philadelphia.

Boyle soon realized that something was wrong and he landed to try to orient himself. he took off again, but once again recognized that he was lost and landed again, this time, near Waldorf, Maryland. Landing in a soft field, S.C. 38262 nosed over and the propeller was damaged.

Coincidentally, a house near Boyle’s landing site was the home of Assistant Postmaster General Otto Praeger, about 20 miles (32 kilometers) from Washington. Boyle was able to call Washington and report in. He and the mail were driven back to Potomac Park.

Major Fleet wanted to replace Boyle, but was overruled by Post Office officials.

Lieutenant Brady’s flight report, Form 220B, 15 May 1918. (National Archives and Records Administration, via Tim Brady, Embry-Riddle Aeronautical University)
Reverse of (National Archives and Records Administration, via Tim Brady, Embry-Riddle Aeronautical University)

S.C. 38262 was repaired, and on 17 May, Lieutenant Boyle and his load of mail, all of which had been stamped to indicate the first day of air mail service, once again took off on schedule at 11:35 a.m., for Philadelphia. This time, though, Boyle was escorted as far as Baltimore, Maryland, by another pilot. (Sources vary. Some say it was Major Fleet, while others say it was Lieutenant James Edgerton, flying S.C. 38274.) From that point, Boyle had been told, he was to simply follow the shoreline of Chesapeake Bay to Philadelphia.

But, once again, Lieutenant Boyle turned the wrong way. At about 2:45 p.m., low on fuel, he landed near Cape Charles, Virginia, about 125 miles (201 kilometers) to the south of Washington, D.C. Boyle was able to borrow gasoline from a farmer and at 4:15 p.m., was airborne once again.

Darkness approached and Boyle’s fuel was running low. Uncertain of his position, at 7:05 p.m., he landed at the Philadelphia Country Club, which was about 15 miles (24 kilometers) short of his actual destination at Bustelton Field. The airplane struck an obstacle and Lieutenant Boyle was thrown from the cockpit, though he suffered only minor injuries. The Jenny, though, was in worse shape. Its left lower wing was torn off, and its upper wing damaged. The airplane would be repaired, but did not return to service until 10 July 1918.

A member of the club drove Boyle and his load of mail to Bustleton Field, where it was loaded on a train for New York City.

Postal Department officials wanted Lieutenant Boyle to continue flying the mail, but Major Fleet refused. This time, rather than being overruled, he was supported in his decision by Secretary of War Newton Diehl Baker Jr.

Curtiss JN-4HMs S.C.38274 and S.C. 38262 at Potomac Park Polo Field. (Benjamin Lipsner Collection, National Postal Museum, Smithsonian Institution A.2006-12)

On 1 March 1918, the U.S. Postal Department and the United States Army agreed that the Army would fly the mail, beginning 15 May 1918. Major Reuben Hollis Fleet, Aviation Section, Signal Corps, was placed in charge of the project by Secretary of War Baker. The Signal Corps ordered 18 airplanes for the purpose: six Curtiss Aeroplane and Motor Co, JN-4HTs, serial numbers S.C. 37944, 38262, 38274, 38275, 38276, 37278; six Liberty-powered Curtiss R-4Ls, S.C. 39362–39367; and six JR-1Bs, serial numbers 1–6, from the Standard Aircraft Corporation, Plainfield, New Jersey. Fleet told Curtiss to modify the Jennys by removing the seat and flight controls from the forward cockpit, and to add a hopper to hold the mail. The airplanes were also given increased fuel and lubricating oil capacity. The airplanes were redesignated JN-4HM.

Major Fleet was told to select four pilots, while the Post Office Department would choose another two. He chose 1st Lieutenants Howard Paul Culver, Walter Miller and Torrey H. Webb, and 2nd Lieutenant Stephen Bonsal, Jr.

2nd Lieutenant James C. Edgerton, Aviation Section, Signal Corps, United States Army.

The two Army pilots chosen by the Post Office were 2nd Lieutenant George L. Boyle and 2nd Lieutenant James C. Edgerton. These two officers had just completed flight training and had only about 60 hours flight time, each.

But George Boyle was engaged to Miss Margaret Grundy McChord, the daughter of Judge Charles Caldwell McChord, Chairman of the Interstate Commerce Commission. Lieutenant Edgerton was the son of James A. Edgerton, the purchasing agent of the Post Office.

Not much is known about George Leroy Boyle. He was born at Fort Scott, Kansas, during October 1891. He was the first of four children of Louis C. Boyle, a lawyer who had been born in Canada, and Gertrude Boyle, of Illinois. George had three younger sisters,  Catherine G., Clara L., and Gertrude Boyle.

Boyle may have studied at the University of Missouri, Columbia, in 1912, and/or the Kansas City School of Law, Kansas City Missouri, as a member of the Class of 1915.

Boyle is believed to have attended ground school at Princeton University, Princeton, New Jersey, from 17 November 1917 to 26 January 1918. He was commissioned as a second lieutenant in the Aviation Section, Signal Corps, United States Army, and ordered to report to Park Field at Millington, Tennessee, for primary flight training. He then completed advanced flight training at Ellington Field, Houston, Texas.

Ellington Field, near Houston, Texas, 1918. (Signal Corps, United States Army)

One month following his unfortunate beginning as an air mail pilot, George Leroy Boyle married Miss McChord. The ceremony was held at 5:00 p.m., 15 June 1918, in the Red Parlor of the New Willard Hotel, a luxurious Beaux-Arts-style hotel near the center of Washington, D.C. The wedding, “One of the most notable of the June weddings in the capital,” was officiated by Rev. Walter Everett Burnett.

Lieutenant Boyle’s military career seems to have come to an end at about this time. In 1920, he and Mrs. Boyle (along with her father, Judge McChord) were residents at the Willard, and Boyle was a practicing attorney.

Mrs. Boyle gave birth to a daughter, Josephine Fairchild Boyle, in Washington, D.C., 15 April 1921.

By 1924, the Boyles were living apart. George Boyle was practicing law in Kansas City, Missouri, while Mrs. Boyle and her daughter remained in Washington, D.C.

Nothing else seems to be known about George Leroy Boyle.

Major Fleet and Lt. Boyle with S.C. 38262, at Potomac Park polo Field, 15 May 1918. The woman in the photograph may be Miss Margaret McChord, Lieutenant Boyle’s fiancée. (National Postal Museum, Smithsonian Institution)

There is another interesting story associated with George Boyle and the First Day of U.S. Air Mail service.

The Post Office Department issued a new 24-cent postage stamp for air mail. The stamp was issued on 10 May 1918. Due to an error in printing, the blue portion of the image, the airplane was printed inverted in reference to the red portion. Only about 100 stamps are known to have been printed this way. Known as the “Inverted Jenny,” this is one of the most famous and valuable postage stamp errors known.

The airplane on the stamp, a Curtiss Jenny, is marked with the serial number 38262—Lieutenant Boyle’s airplane.

An example of this stamp sold at auction in 2016 for $1,351,250 (including buyer’s premium).

“The Inverted Jenny” 24¢ postage stamp, issued 10 May 1918. (U.S. Postal Service)

The Curtiss JN-4 “Jenny” was a single-engine, two place, two-bay biplane, designed and built by the Curtiss Aeroplane and Motor Company, Hammondsport, New York, and used primarily as a training aircraft. It was also produced by five other manufacturers under license: the Fowler-Howell & Lesser Co., San Francisco, California; Liberty Iron Works, Sacramento, California; Springfield Aircraft Corporation, Springfield, Massachusetts;  St. Louis Aircraft Corporation, St. Louis, Missouri; and the U.S. Aircraft Corporation.

Side elevation erection drawing of the Curtiss JN-4D Jenny, 1917. (rcgroups.net)

The JN-4 was 27 feet, 4 inches (8.306 meters) long, with an upper wing span of 43 feet, 7-3/8 inches (13.294 meters) and lower span of 33 feet, 11¼ inches (10.344 meters). The height of the airplane in flight attitude was 9 feet, 10-5/8 inches (3.013 meters). The JN-4H variant had an empty weight of 1,625 pounds (737 kilograms), and gross weight of 2,269 pounds (1,029 kilograms).

Front elevation erection drawing of the Curtiss JN-4D Jenny, 1917. (Smithsonian Institution, National Air and Space Museum, NASM-NAM-A-42215-C)

The wings had a chord of 4 feet, 11½ inches (1.551 meters), and vertical gap of 5 feet, 1¼ inches (1.556 meters). The lower wing was staggered 1 foot, 4 inches (0.406 meters) behind the upper. The wings had 2º angle of incidence and 1° dihedral. There was no sweep. The ailerons were on the upper wing. The total wing area was 353.06 square feet (32.80 square meters).

While the most common variant of the JN-4, the JN-4D, was equipped with the Curtiss OX-5 engine, the JN-4H was powered by a Wright-Hispano, or more commonly, the “Wright-Hisso,” a design licensed by the Wright-Martin Aircraft Corporation, New Brunswick, New Jersey, from the Société Française Hispano-Suiza. Many sources state that the engine of the JN-4H was a Wright-Hisso E, but almost universally, they indicate that it was rated at 150 horsepower. The Model E, however, was rated at 180 horsepower, while the 150 horsepower engine is identified as the Model A. There was also an improved 150-horsepower Model I. Wright-Martin began producing the Model E in September 1916, All three of these engines are very similar. It is uncertain which model was actually installed in the JN-4HM mail planes.

Wright-Martin Model E SOHC V-8 aircraft engine, licensed version of the Société Française Hispano-Suiza V-8, in the collection of the Smithsonian Institution, National Air and Space Museum. (NASM 2014-04437)

The Wright-Hispano Models A, E and I were liquid-cooled, normally-aspirated, 717.629-cubic-inch-displacement (11.760 liter) single overhead camshaft (SOHC) 90° V-8 engines. All were direct drive.  The A and I variants had a compression ratio of 4.72:1, while the Model E ratio was 5.33:1. The Model E was designed to operate 300 r.p.m. faster than the A or I, and was strengthened for the higher loads. The Models A and I were rated at 150 horsepower at 1,540 r.p.m. at Sea Level. The Model E produced 185 horsepower at 1,750 r.p.m., and 195 horsepower at 1,850 r.p.m. The dry weight of the Model E was 470 pounds (213 kilograms).

The Curtiss JN-4HM had a cruise speed of 75 miles per hour (121 kilometers per hour) and maximum speed of 91 miles per hour (146 kilometers per hour). Its service ceiling was 7,500 feet (2,286 meters) and the airplane’s range was 155 miles (249 kilometers).

A Curtiss JN-4D in the collection of the Smithsonian Institution, National Air and Space Museum. (NASM SI-2007-13553)

¹ On 15 July 1918, Hazelhurst Field was renamed Mitchel Field in honor of James Purroy Mitchel, mayor of New York City, 1914–1917. The name change was officially approved in April 1919. James Mitchel had joined the Aviation Section, Signal Corps. on 6 July 1918, he was killed when he fell from an airplane near Gerstner Field, Louisiana.

© 2019, Bryan R. Swopes

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28 April 1937

Pan American Airways' Martin M-130, China Clipper, at Macau, 1937.
Pan American Airways’ Martin M-130, China Clipper, at Macau, 1937.

28 April 1937: The first transpacific flight by a commercial passenger airliner is completed when Pan American Airways’ Martin M-130, China Clipper, arrived at Hong Kong. The flight had departed San Francisco Bay, California, on 21 April with 7 revenue passengers and then proceeded across the Pacific Ocean by way of Hawaii, Midway Island, Wake Island, Guam, Manila, Macau, and finally Hong Kong. The Reuters news agency briefly reported the event:

AIR LINK AROUND WORLD FORGED.

China Clipper Lands At Hong Kong.

Hong Kong, April 28.

The Pan-American Airways flying boat China Clipper landed at 11:55 this morning from Manila and Macao. This links the Pan-American and Imperial Airways, completing the commercial air link round the world. —Reuter.

The Straits Times, 28 April 1937, Page 1, Column 4.

Pan American Airways' China Clipper, a Martin M-130, NC14716, over San Francisco, California.
Pan American Airways’ China Clipper, a Martin M-130, NC14716, over Oakland, California. (Unattributed)

The China Clipper, NC14716, was the first of three Martin M-130 four-engine flying boats built for Pan American Airways and was used to inaugurate the first commercial transpacific air service from San Francisco to Manila in November, 1935. Built at a cost of $417,000 by the Glenn L. Martin Company in Baltimore, Maryland, it first flew on 20 December 1934, and was delivered to Pan Am on October 9, 1935.

The airplane was operated by a flight crew of 6 to 9, depending on the length of the flight, plus cabin staff, and could carry 18 passengers on overnight flights or a maximum 36 passengers.

Martin M-130 China Clipper, NC14716, at Honolulu, Ohau, Hawaiian Islands. (Unattributed)
Martin M-130 China Clipper, NC14716, at Honolulu, Oahu, Hawaiian Islands. (Unattributed)

The Martin M-130 was 90 feet, 10.5 inches (27.699 meters) long with a wingspan of 130 feet, 0 inches (39.624 meters). It was 24 feet, 7 inches (7.493 meters) high. Its maximum takeoff weight was 52,252 pounds (23,701 kilograms).

The flying boat was powered by four air-cooled, supercharged, 1,829.389-cubic-inch displacement (29.978 liters) Pratt & Whitney Twin Wasp S2A5-G engines. These were two-row, 14-cylinder radial engines with a compression ratio of 6.7:1. The S2A5-G was rated at 830 horsepower at 2,400 r.p.m., and 950 horsepower at 2,550 r.p.m. for takeoff, burning 87-octane gasoline. They drove three-bladed Hamilton Standard Hydromatic constant-speed propellers through a 3:2 gear reduction. The engine was 3 feet, 11.88 inches (1.216 meters) in diameter and 4 feet, 8.75 inches (1.441 meters) long. It weighed 1,235 pounds (560 kilograms).

The airplane had a maximum speed of 180 miles per hour (290 kilometers per hour), and a cruise speed of 130 miles per hour (209 kilometers per hour). The service ceiling was 10,000 feet (3,048 meters) and its range was 3,200 miles (5,150 kilometers).

Martin M-130, NC14716, China Clipper, moored at some distant exotic locale.
Martin M-130, NC14716, China Clipper, moored at some distant exotic locale. (Unattributed)

© 2019, Bryan R. Swopes

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22 November 1935

Pan American Airways’ Martin M-130 flying boat, China Clipper (NC14716), leaving the Golden Gate enroute to Honolulu, 22 November 1935. Photographed by Clyde Herwood Sunderland, Jr. (1900–1989).

22 November 1935: The Pan American Airways flying boat, China Clipper, a Martin M-130, NC14716, departed Alameda, California (an island in San Francisco Bay) at 3:46 p.m., Friday, and arrived at Honolulu at 10:39 a.m., Saturday, completing the first leg of a five-day trans-Pacific flight to Manila.

The aircraft commander was Captain Edwin Charles Musick, with First Officer Robert Oliver Daniel (“Rod”) Sullivan. The navigator was Frederick Joseph Noonan, who would later accompany Amelia Earhart on her around-the-world flight attempt. There were also a Second Officer and two Flight Engineers. The cargo consisted of 110,000 pieces of U.S. Mail.

Captain Edwin Musick and R.O.D. Sullivan, at the center of the image, next to the China Clipper before leaving San Francisco Bay with the first transpacific airmail, 22 November 1935. The three men at the right of the image are (left to right) Postmaster General James Farley; Assistant Postmaster General Harllee Branch; and Pan American Airways’ President Juan Trippe.

Pan Am personnel called the Clipper “Sweet Sixteen,” referring to its Civil Aeronautics Board registration number, NC14716. The airplane and Humphrey Bogart starred in a 1936 First National Pictures movie, “China Clipper.”

NC14716 was the first of three Martin M-130 four-engine flying boats built for Pan American Airways and was used to inaugurate the first commercial transpacific air service from San Francisco to Manila in November, 1935. Built at a cost of $417,000 by the Glenn L. Martin Company in Baltimore, Maryland, it was delivered to Pan Am on October 9, 1935. The airplane’s serial number was 558.

The M-130 was operated by a flight crew of 6–9, depending on the length of the flight, plus cabin staff, and could carry 18 passengers on overnight flights, or a maximum 36 passengers.

Cutaway illustration of Pan American Airways’ Martin M-130 China Clipper. Detail from larger image. (National Air and Space Museum SI-89-1216-A)
Martin M-130 3-view drawing. (Flight)

The Martin M-130 was 90 feet, 10.5 inches (27.699 meters) long with a wingspan of 130 feet, 0 inches (39.624 meters). It was 24 feet, 7 inches (7.493 meters) high. The total wing area was 2,315 square feet (215 square meters), including the “sea wings”. Its maximum takeoff weight was 52,252 pounds (23,701 kilograms).

The flying boat was powered by four air-cooled, supercharged Pratt & Whitney Twin Wasp S2A5-G two-row 14-cylinder radial engines with a compression ratio of 6.7:1.  They had a normal power rating 830 horsepower at 2,400 r.p.m., and 950 horsepower at 2,550 r.p.m. for takeoff. They drove three-bladed Hamilton Standard Hydromatic constant-speed propellers through a 3:2 gear reduction. The S2A5-G was 3 feet, 11.88 inches (1.216 meters) in diameter, 4 feet, 8.75 inches (1.441 meters) long, and weighed 1,235 pounds (560 kilograms).

Martin M-130 NC14716, right rear quarter view.

The airplane had a cruise speed of 130 miles per hour (209 kilometers per hour) and a maximum speed of 180 miles per hour (290 kilometers per hour). The M-130’s service ceiling was 10,000 feet (3,048 meters). Its range was 3,200 miles (5,150 kilometers).

Martin M-130, NC14716, China Clipper, moored at some distant exotic locale.
Martin M-130, NC14716, China Clipper, moored at some distant exotic locale. (Unattributed)

© 2018, Bryan R. Swopes

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3 November 1926

Chief Pilot Charles A. Lindbergh in the cockpit of Robertson Aircraft Corporation’s modified De Havilland DH-4, Number 109, 15 May 1926. (Swenson Studio)
Charles A. Lindbergh, circe 1926. (SDA&SM)
Charles A. Lindbergh, circa 1926. (San Diego Air & Space Museum)

3 November 1926: Charles Augustus Lindbergh, chief pilot of the Robertson Aircraft Corporation, St. Louis, Missouri, was flying a night air mail route between St. Louis and Chicago, Illinois. His airplane was a modified De Havilland DH-4B, U.S. Postal Service Airmail Plane Number 109.

Lindbergh was flying Contract Air Mail Route 2, or “C.A.M. No. 2.” He departed St. Louis at 4:20 p.m. and made his first stop at Springfield, Illinois, at 5:15 p.m. He then continued on the second stage, Springfield to Peoria, Illinois.

Visibility was poor, about a half-mile (800 meters) in fog. Lindbergh flew at 600 feet (183 meters) but was unable to see the ground. Near the air field at Peoria, he could see lights from 200 feet (61 meters) altitude, but was unable to land.

After circling for 30 minutes, he continued toward Chicago. Lindbergh occasionally saw lights on the ground through the fog, but with his fuel running low, he decided that he was going to have to abandon his airplane. He headed out over more open country and climbed to 14,000 feet (4,267 meters).

Robertson Aircraft Corporation Dh-4 No. 109. The airplane's fuselage is painted "Tuscan Red" and the wings and tail surafces are silver. The lettering on the side is white. (Minnesota Historical Society)
Robertson Aircraft Corporation DH-4 No. 109, 15 May 1926. (Swenson Studio/Minnesota Historical Society)

At 8:10 p.m., the de Havilland’s fuel supply was exhausted and the engine stopped. Lindbergh switched off the battery and magnetos, then stepped over the side. He immediately pulled the ripcord of his parachute and safely descended to the ground.

Airmail Plane Number 109 crashed on the farm of Charles and Lillie Thompson, near Covell, a small town southwest of Bloomington, Illinois. Lindbergh had been unable to find the wreck in the darkness, but in daylight, it was clearly visible just 500 feet (152 meters) from the Thompson’s house.

This was the fourth time that Charles Lindbergh has used a parachute to escape from an airplane. The last time was just six weeks earlier.

Charles A. Lindbergh (fourth from left) with the wreckage of Robertson Aircraft Corporation DH-4 No. 112, 16 September 1926. (Yale University Library)

He resigned from Robertson Aircraft and formed a group to finance and build the Spirit of St. Louis. Charles Augustus Lindbergh flew his new airplane across the Atlantic Ocean, non-stop, solo, 20–21 May 1927.

Robertson Aircraft Corporation's four de Havilland DH-4s, numbers 109, 110, 111, and 112.
Robertson Aircraft Corporation’s four de Havilland DH-4s, numbers 109, 110, 111, and 112. The airplanes’ fuselages are painted “Tuscan Red” and their wings and tail surfaces are silver. The lettering on their sides is white. No. 112 is the last airplane in this group. “Lucky Lindy” bailed out of it on the night of 16 September 1926.

The Airco DH.4 was a very successful airplane of World War I, designed by Geoffrey de Havilland. The DH.4 (DH-4 in American service) was a two-place, single-engine, two-bay biplane with fixed landing gear. The fuselage and wings were constructed of wood and covered with doped fabric. The airplane was produced by several manufacturers in Europe and the United States.

The DH-4 was 30 feet, 5 inches (9.271 meters) long with a wingspan of 42 feet, 8 inches (13.005 meters) and height of 10 feet, 6 inches (3.200 meters). It had an empty weight of 2,391 pounds, (1,085 kilograms) and gross weight of 4,297 pounds (1,949 kilograms). Fuel capacity was 67 gallons (254 liters).

Army Air Service DH-4s were powered by Liberty 12 aircraft engines in place of the Rolls-Royce Eagle VII V-12 of the British-built DH.4 version. The L-12 was water-cooled, normally-aspirated, 1,649.34-cubic-inch-displacement (27.028 liter), single overhead cam (SOHC) 45° V-12 engine. It produced 408 horsepower at 1,800 r.p.m. The L-12 as a right-hand tractor, direct-drive engine and it turned turned a two-bladed fixed-pitch wooden propeller. The Liberty 12 was 67.375 inches (1.711 meters) long, 27.0 inches (0.686 meters) wide, and 41.5 inches (1.054 meters) high. It weighed 844 pounds (383 kilograms).

The Liberty 12 aircraft engine was designed by Jesse G. Vincent of the Packard Motor Car Company and Elbert J. Hall of the Hall-Scott Motor Company. This engine was produced by Ford Motor Company, as well as the Buick and Cadillac Divisions of General Motors, The Lincoln Motor Company (which was formed by Henry Leland, the former manager of Cadillac, specifically to manufacture these aircraft engines), Marmon Motor Car Company and the Packard Motor Car Company. Hall-Scott was too small to produce engines in the numbers required.

The DH-4 had a maximum speed of 124 miles per hour (200 kilometers per hour), service ceiling of 19,600 feet (5,974 meters) and range of 400 miles (644 kilometers).

Many DH-4s were rebuilt as DH-4Bs. These can be identified by the relocated pilot’s cockpit, which was moved aft, closer to the observer’s position. The an enlarged fuel tank was place ahead of the pilot’s cockpit. Following World War II, many were rebuilt with tubular metal frames for the fuselage, replacing the original wooden structure. These aircraft were redesignated DH-4M.

The prototype American DH-4, Dayton-Wright-built airplane, is in the collection of the Smithsonian Institution National Aviation and Space Museum.

Wreck of Robertson Aircraft Corporation's de Havilland DH-4, Number 109. (San Diego Air and Space Museum Archives)
Wreck of Robertson Aircraft Corporation’s de Havilland DH-4, Number 109. (San Diego Air and Space Museum Archives)

© 2016, Bryan R. Swopes

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1 October 1947

A Los Angeles Airways Sikorsky S-51 helicopter takes off from the roof of the Terminal Annex Post Office, 1 October 1947. The Los Angeles Times published this photograph 2 October 1947 with the following caption: “NEW MAIL SERVICE — Los Angeles Airways helicopter shown landing on the roof of Terminal Annex Post office yesterday to inaugurate helicopter air-mail service, the first of its kind in the United States. Two flights daily are planned on this run with another to start Oct. 16.” (Los Angeles Times Photographic Archive/UCLA Library)

1 October 1947: Los Angeles Airways began regularly scheduled air mail service in Los Angeles, using the Sikorsky S-51 helicopter.

“. . . the U.S. Civil Aeronautics Board awarded LAA the route authorities to operate local air mail services in Southern California using the Sikorsky S-51. Before long, LAA was operating a twice-a-day mail service between the main downtown post office and Los Angeles International Airport along with a small package air express service.

“With a fleet of five S-51s, LAA’s first year of operations resulted in 700 tons of mail being carried with approximately 40,000 landings throughout the Los Angeles metropolitan area. The small operation maintained a 95% reliability rate and by the time it began its small package air express service in 1953, it was annually moving nearly 4,000 tons of mail a year.

“In July 1951 the CAB awarded LAA’s reliable helicopter operation the rights for passenger services which started in November 1954 with larger Sikorsky S-55 helicopters while the smaller S-51s continued the mail and small package services. . . .”

Tails Through Timehttp://aviationtrivia.blogspot.com/2010/06/on-1-october-1947-los-angeles-airways.html

The S-51 was a commercial version of the Sikorsky R-5 series of military helicopters. It was a four-place, single-engine helicopter, operated by one pilot. The cabin was built of aluminum with Plexiglas windows. The fuselage was built of plastic-impregnated plywood, and the tail boom was wood monocoque construction. The main rotor consisted of three fully-articulated blades built of metal spars and plywood ribs and covered with two layers of fabric. (All metal blades soon became available.) The three bladed semi-articulated tail rotor was built of laminated wood. The main rotor turned counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right.) The tail rotor was mounted on the helicopter’s left side in a pusher configuration. It turned clockwise as seen from the helicopter’s left.

The helicopter’s fuselage was 41 feet, 7.5 inches (12.687 meters) long. The main rotor had a diameter of 48 feet (14.630 meters) and tail rotor diameter was 8 feet, 5 inches (2.565 meters), giving the helicopter an overall length of 57 feet, 1 inch (17.399 meters). It was 13 feet, 1.5 inches (4.001 meters) high. The landing gear tread was 12 feet (3.7 meters). The S-51 had an empty weight of 4,050 pounds (1,837 kilograms) and maximum takeoff weight of 5,500 pounds (2,495 kilograms). Fuel capacity was 100 gallons (378.5 liters).

The helicopter was powered by an air-cooled, supercharged, 986.749-cubic-inch-displacement (16.170 liter) Pratt & Whitney Wasp Jr. T1B4 (R-985 AN-5) direct-drive, nine-cylinder radial engine which was placed vertically in the fuselage behind the crew compartment. This engine was rated at 450 horsepower at 2,300 r.p.m., Standard Day at Sea Level. The R-985 AN-5 was 48.00 inches (1.219 meters) long, 46.25 inches (1.175 meters) in diameter and weighed 684 pounds (310.3 kilograms) with a magnesium crankcase.

The S-51 had a maximum speed (Vne) of 107 knots (123.1 miles per hour/198.2 kilometers per hour). Range was 275 miles (442.6 kilometers). The service ceiling was 14,800 feet (4,511 meters). The absolute hover ceiling was 3,000 feet (914.4 meters).

Of 220 helicopters in the S-51 series built by Sikorsky, 55 were commercial models.

Los Angeles Airways Sikorsky S-51 (Viewliner)
A Los Angeles Airways Sikorsky S-51. The main rotor hub is covered. (Viewliner)

© 2016, Bryan R. Swopes

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