Curtiss JN-4

The Curtiss JN-4 "Jenny" was one of a series of "JN" biplanes built by the Curtiss Aeroplane Company of Hammondsport, New York, later the Curtiss Aeroplane and Motor Company. Although the Curtiss JN series (the common nickname was derived from "JN") was originally produced as a training aircraft for the U.S. Army, the "Jenny" continued post-World War I as a civil aircraft as it became the "backbone of American post-war [civil] aviation." Thousands of surplus Jennys were sold at bargain prices to private owners in the years after the War and became central to the barnstorming era that helped awaken America to civil aviation through much of the 1920s.

Design and development
Curtiss combined the best features of the model J and model N trainers, built for the Army and Navy, and began producing the JN or "Jenny" series of aircraft in 1915. Curtiss only built a limited number of the JN-1 and JN-2 biplanes. The design was commissioned by Glenn Curtiss from Englishman Benjamin D. Thomas, formerly of the Sopwith Aviation Company.

The JN-2 was an equal-span biplane with ailerons controlled by a shoulder yoke located in the aft cockpit. It was deficient in performance, particularly climbing, because of excessive weight. The improved JN-3 incorporated unequal spans with ailerons only on the upper wings, controlled by a wheel. In addition, a foot bar was added to control the rudder. The 1st Aero Squadron of the Aviation Section, U.S. Signal Corps received eight JN-2s at San Diego in July 1915. The squadron was transferred to Fort Sill, Oklahoma, in August to work with the Field Artillery School, during which one JN-2 crashed with a fatality. The pilots of the squadron met with its commander, Capt. Benjamin Foulois, to advise that the JN-2 was unsafe because of low power, shoddy construction, lack of stability, and overly sensitive rudder. Foulois and his executive officer Capt. Thomas D. Milling disagreed, and flights continued until a second JN-2 crashed in early September resulting in the six remaining JN-2s being grounded until mid-October when two new JN-3s were delivered and the grounded aircraft had been upgraded to the new design. In March 1916, these eight JN-3s were deployed to Mexico for aerial observation during the Pancho Villa Expedition of 1916–1917.

After the successful deployment of the JN-3, Curtiss produced a development, known as the JN-4, with orders from both the US Army and an order in December 1916 from the Royal Flying Corps for a training aircraft to be based in Canada. The Canadian version was the JN-4 (Canadian), also known as the "Canuck", and was built with a control stick instead of the Deperdussin control wheel used in the regular JN-4 model, as well other changes including ailerons on all four wings, a somewhat larger and more rounded rudder, and a lighter interior structure.

Operational history
The Curtiss JN-4 is possibly North America's most famous World War I aircraft. It was widely used during World War I to train beginning pilots, with an estimated 95% of all trainees having flown a JN-4. The U.S. version was called "Jenny", a derivation from its official designation. It was a twin-seat (student in front of instructor) dual control biplane. Its tractor prop and maneuverability made it ideal for initial pilot training with a 90 hp Curtiss OX-5 V8 engine giving a top speed of 75 mph and a service ceiling of 6500 ft. The British used the JN-4 (Canadian) (along with the Avro 504) for their primary World War I trainer using the Canadian Aeroplanes Ltd. indigenous variant. Many Royal Flying Corps pilots earned their wings on the JN-4, both in Ontario and later in winter facilities at Camp Taliaferro, Texas.

Although ostensibly a training aircraft, the Jenny was extensively modified while in service to undertake additional roles. Due to its robust but easily adapted structure able to be modified with ski undercarriage, the Canadian Jenny was flown year-round, even in inclement weather. The removable turtle-deck behind the cockpits allowed for conversion to stretcher or additional supplies and equipment storage, with the modified JN-4s becoming the first aerial ambulances, carrying out this role both during wartime and in later years. Most of the 6,813 Jennys built were unarmed, although some had machine guns and bomb racks for advanced training. With deployment limited to North American bases, none saw combat service in World War I.

The Curtiss factory in Buffalo, New York, was the largest such facility in the world, but due to production demands, from November 1917 to January 1919, six different manufacturers were involved in production of the definitive JN-4D. Production from spare or reconditioned parts continued sporadically until 1927, although most of the final orders were destined for the civil market in Canada and the United States. The final version of the aircraft was the JN-6, powered by a 150 hp (112 kW) Hispano-Suiza 8 V-8, first ordered in 1918 for the US Navy. A seaplane version was built for the Navy which was so modified that it was essentially a different airframe. This was designated the N-9. In U.S. Army Air Service usage, the JN-4s and JN-6s were configured to the JNS ("S" for "standardized") model. The Jenny remained in service with the US Army until 1927.

After World War I, thousands were sold on the civilian market, including one to Charles Lindbergh in May 1923 in which he then soloed. Surplus US Army aircraft were sold, some still in their unopened packing crates, for as little as $50, essentially "flooding" the market. With private and commercial flying in North America unhampered by regulations concerning their use, pilots found the Jenny's slow speed and stability made it ideal for stunt flying and aerobatic displays in the barnstorming era between the world wars, with the nearly identical Standard J-1 aircraft often used alongside it. Some were still flying into the 1930s.

JN-4 airframes were utilized to produce early Weaver Aircraft Company / Advance Aircraft Company / Waco aircraft, such as the Waco 6.

Notable firsts
Between 1917 and 1919 the JN-4 type accounted for a number of significant aviation "firsts" while in service  with the US Army Signal Corps Aviation Section and the United States Marine Corps (USMC) including flying the first U.S. Air Mail in May 1918.

In a series of tests conducted at the U.S. Army's Langley Field in Hampton, Virginia, in July and August 1917, the world's first "plane-to-plane" and "ground-to-plane, and vice versa" communications by radiotelephony (as opposed to radiotelegraphy which had been developed earlier) were made to and from modified US Army JN-4s by Western Electric Company (Bell Labs) design engineers Lewis M. Clement and Raymond Heising, the developers of the experimental wind generator powered airborne wireless voice transmitter and receiver equipment.

In early 1919, a United States Marine Corps (USMC) JN-4 was also credited with what is believed to be the first aircraft to successfully execute a "dive bombing" attack during the United States occupation of Haiti. Marine Corps pilot Lt Lawson H. Sanderson mounted a carbine barrel in front of the windshield of his JN-4 (previously, an unarmed trainer that had a machine gun mounted in the rear cockpit) as an improvised bomb sight that was lined up with the long axis of his aircraft, loaded a bomb in a canvas mail bag that was attached to the JN-4's belly, and launched a single-handed raid at treetop level, in support of a USMC unit that had been trapped by Haitian Cacos rebels. Although the JN-4 almost disintegrated in the pull-out, the attack was effective and led to Sanderson in 1920 developing further pioneering dive-bombing techniques to provide Marine pilots with close aerial support to infantry comrades.

Variants


Although the first series of JN-4s were virtually identical to the JN-3, the JN-4 series was based on production orders from 1915–1919.
 * JN-4A — Production version of the JN-4, 781 built.
 * JN-4B — This version was powered by an OX-2 piston engine, 76 built for the U.S. Army, nine for the U.S. Navy.
 * JN-4C — Experimental version, only two were built.
 * JN-4 (Canadian) Canuck — Canadian-built version, 1,260 built by Canadian Aeroplanes Ltd. for the RFC in Canada/RAF in Canada and USAAC. Independently derived from the JN-3, it had a lighter airframe, ailerons on both wings, different shaped wings, stabilizer, elevators and rudder. Its use by the USAAC was curtailed as the lighter structure was claimed to cause more accidents than the US built aircraft, although no air fatalities were attributed to the structural integrity of the type.
 * JN-4D — Improved version, adopting the control stick from the JN-4 (Canadian) 2,812 built.
 * JN-4D-2 — One prototype only, the engine mount being revised to eliminate the down thrust position.
 * JN-4H — two-seat advanced trainer biplane, 929 built for the U.S. Army. Notable for introducing the use of the Hispano-Suiza 8 V-8 engine for greater power and reliability.
 * JN-4HT — Two-seat dual-control trainer version.
 * JN-4HB — Bombing trainer version.
 * JN-4HG — Gunnery trainer version.
 * JN-4HM — communications conversion of JN-4HT, powered by Wright-Hisso E 150 hp (112 kW); six converted. Used to fly the first US Air Mail (May–August, 1918)
 * JN-5H — One-off advanced trainer biplane, only one was built.
 * JN-6 — Improved version of JN-5 trainer biplane series notably used four ailerons. A total of 1,035 built for the US Army and five for the U.S. Navy.
 * JN-6H — Improved version of the JN-6.
 * JN-6BH — Bomber trainer version.
 * JN-6HG-1 — Two-seat dual-control trainer version; 560 built from JN-6 production, 34 for US Navy.
 * JN-6HG-2 — Single-control gunnery trainer; 90 delivered.
 * JN-6HO — Single-control observer trainer version, 106 delivered.
 * JN-6HP — single-control pursuit fighter trainer version.
 * JNS ("standardized") — During the post-war years of the early 1920s, between 200 and 300 U.S. Army aircraft were upgraded to a common standard of equipment and modernized.

"Specials" and one-offs

 * Allison Monoplane — Conversion of JN-4 (Can) G-CAJL by the Allison Company, Kansas, that mounted a parasol wing in place of the biplane configuration; only one conversion made.
 * Curtiss Special (1918) — A smaller, custom-built single-seat variant for Katherine Stinson, powered by a 100 hp (74.5 kW) OXX-6.
 * Ericson Special Three — Some reconditioned aircraft built by Canadian Aeroplanes Ltd. were fitted with a third cockpit.
 * Hennessey Monoplane — 1926 monoplane conversion by James R. Hennessey, three-place transport; 90 hp (67 kW) Curtiss OX-5; span: 36 ft (11 m) length: 25 ft (7.6 m).
 * Severski 1926 biplane — A JN-4 modified with a roller / ski undercarriage, one experimental aircraft converted by the Seversky company.
 * Sperry Monoplane — Conversion offered by the Sperry Company that mounted a parasol wing in place of the biplane configuration.
 * Twin JN — Enlarged twin-engined version of the JN-4, powered by two OXX-2 piston engines. Built in 1916 as the JN-5 for an observation role, among the many other modifications was an enlarged wingspan and new rudder adapted from the Curtiss Model R-4. Two of the series saw action with the US Army on the Mexican border in 1916–1917. A total of eight Twin JNs were built, with two in US Navy service.

Military operators

 * Argentine Naval Aviation
 * Australian Flying Corps
 * No. 3 Squadron AFC - Used for training.
 * Central Flying School AFC at Point Cook, Victoria.
 * 🇨🇦 Canada
 * Royal Canadian Air Force
 * Cuban Air Force
 * Royal Flying Corps
 * No. 24 Squadron RFC
 * No. 25 Squadron RFC
 * Royal Naval Air Service
 * United States Army Signal Corps Aviation Section (1915)
 * United States Army Signal Corps Aeronautical Division (1915–1918)
 * United States Army Air Service (1918 et seq.)
 * United States Marine Corps
 * United States Navy
 * United States Army Signal Corps Aviation Section (1915)
 * United States Army Signal Corps Aeronautical Division (1915–1918)
 * United States Army Air Service (1918 et seq.)
 * United States Marine Corps
 * United States Navy

Civil operators

 * 🇨🇦 Canada
 * Elliot Air Service, Red Lake, Ontario

Survivors
About 50 Jennys survive in museums and with private owners.
 * JN-4C C227 is displayed at the Canada Aviation and Space Museum, Rockcliffe, Ontario.
 * JN-4C C308 is flown on a regular basis at the Pioneer Flight Museum, Kingsbury, Texas.
 * JN-4C C496 is exhibited at the Historic Aircraft Restoration Museum, Creve Coeur Airport, St. Louis, Missouri.
 * JN-4C C1122 is airworthy with Skeeter Carlson, Spokane, Washington.
 * JN-4C 10875 owned by John Shue, York, Pennsylvania.
 * JN-4C C-AAI is part of the Reynolds-Alberta Museum, in Wetaskiwin, Alberta, Canada.
 * A 1917 JN-4D is on permanent display at the Museum of Science and Industry in Chicago.  It is displayed upside down next to a wraparound balcony, and details of the cockpit can readily be seen.
 * JN-4D U.S. Army Air Corps 1282 is on display at the Western Antique Aeroplane & Automobile Museum (WAAAM) in Hood River, Oregon.
 * JN-4D, USAAC 2805 is on display at the National Museum of the United States Air Force in Dayton, Ohio. It was obtained from Robert Pfiel of Taylor, Texas in 1956. The aircraft is displayed in the Museum's Early Years gallery.
 * JN-4D Signal Corps 2975, c/n 450, built 1918, is on display at the Virginia Aviation Museum, Richmond, Virginia, on loan from Ken Hyde, Warrenton, Virginia.
 * JN-4H, restored as U.S. Navy 6226 (ex-[[USAAS] "38262")], powered by a rare Hispano-Suiza 8, V-8 engine, on display at the Old Rhinebeck Aerodrome in Rhinebeck, New York. It is still flightworthy and occasionally flown during airshows.
 * JN-4D U.S. Army Air Corps "2525" on display at the Call Aviation Field Memorial Exhibit at Kickapoo Air Park in Wichita Falls, Texas. It is flown on the first Saturday of each month, weather permitting.
 * JN-4D c/n. 4904. EAA AirVenture Museum, Oshkosh, Wisconsin.
 * The Cradle of Aviation Museum on Long Island has two Jennys on display. One is the aircraft owned by Charles Lindbergh in which he barnstormed long before his transatlantic flight. Lindbergh purchased this aircraft in Americus, Georgia for $500 in May 1923, and sold it to a flying student of his in Iowa the following October. It was restored by the late George Dade in the 1970s and is on loan from the Long Island Early Fliers Club.
 * A JN-4D built in 1917 has been fully restored to flying condition and is on display, as well as being available for flights at the Golden Age Air Museum at Grimes Airport, Bethel, Pennsylvania.
 * A JN-4D built in 1918 fully restored to flying condition and is on display at the Flying Heritage Collection at Paine Field in Everett, WA.. It is U.S. Army Air Corps "3712" based at March Field, CA.

The "Inverted Jenny" stamp
The "Inverted Jenny" (C-3a) is a 24 cent 1918 US Air Mail postage stamp printing error in which the blue central vignette of US Army Curtiss JN-4HM #38262, the nation's first mailplane, appeared as "inverted" on a single sheet of 100 stamps owing to an inadvertent error made by the operator of a hand rolled spider press by printing the red frame impression upside down after the vignettes had already been printed on the sheet on another press. As the Jenny vignette was only inverted on one sheet, this stamp represents the rarest and most valuable known USPOD printing error of all time. A single example (sheet position 57) sold at auction in 2007 for $977,500.00.



Notable appearances in media
In 1921, Lee De Forest made a short film Flying Jenny Airplane in his Phonofilm sound-on-film process. The film depicted a JN-4 flying, and recorded the sound of the Jenny as well. The short documentary was the first production of the De Forest Phonofilm company.

Among many later films depicting the barnstorming era where the Jennys "ruled supreme" and played a feature role, was The Spirit of St. Louis (1957) and The Great Waldo Pepper (1974). In The Court Martial of Billy Mitchell (1955), authentic OX-5 Jennys were showcased as United States Army Air Service training aircraft.

Broadcast on April 15, 1987, by PBS, the National Geographic special entitled "Treasures from the Past" featuring the restoration and first flight by Ken Hyde of a JN-4D that would go on to win the "Lindy Award" at the EAA AirVenture Oshkosh '87.

Notable musician Al Stewart refers to the Jenny in his song "The Immelman Turn" (2005) in which a barnstorming acrobat falls to his death from a Curtiss Jenny attempting the maneuver in a 1923 airshow.