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Curtiss Jenny (Model JN)
The Curtiss Jenny (Model JN) was the most important American primary trainer of the First World War, and played a major role in the development of civil aviation after the end of the war.
The Model JN developed from the separate Model J and Model N designs. These were very similar tractor biplanes, designed by the British engineer B. Douglas Thomas. Both used the same Curtiss OX engine and had the same fuselage, but the Model J wings used the Eiffel 36 aerofoil and the Model N the RAF 6 aerofoil. There were some differences in the controls. After the appearance of the Model JN, the J series was dropped, although work continued on the Model N (or at least the name was used for two later designs).
There does not appear to have been an official JN or JN-1. The second Model J, Army Signal Corps aircraft No.30, was used as a prototype for the JN, and is sometimes called the JN or JN-1. Some confusion has been caused by the US Navy’s aircraft. In their 1917-1935 numerical list aircraft A149 and A150 are listed as either JN-1Ws or the Curtiss S-4 and S-5. Putnam’s detailed book on Curtiss aircraft lists A149 as the S-4 (Model 10A), a triplane twin float plane, and A150 as the S-5 (Model 10B), a triplane with a single main float. A198 is also sometimes listed as a JN-1. However A198 was probably the second of two Twin JNs acquired by the Navy.
The Model JN was originally ordered in 1914 as an observation type. However the vast majority of them were produced as trainers, and it is said that 95% of all US and Canadian pilots trained during the First World War used the Jenny at some point. It was also ordered in large numbers by the British, and was built in larger numbers than any other American aircraft before their entry into the war in 1917.
Only eight JN-2s were built, all for the US Army. Two of them were lost at some point before late 1915, when the surviving six were given the same wings as the JN-3. The JN-3 itself was originally ordered by the British, early in 1915, and just over 90 were ordered for the RNAS. Two were ordered by the US Army in August 1915, perhaps to replace the two lost JN-2s. All eight JN-2/ JN-3s in US service took part in Pershing’s Punitive Expedition to Mexico in 1916, but performed badly, and only one survived the experience!
The JN-4 was the only existing American design to be ordered into mass production after the US entry into the war in April 1917. After April the US Army ordered 7,166 aircraft, of which 6,070 were delivered. This included 4,895 produced by Curtiss and the rest from six other firms. The US Navy also acquired 134 Jennies during the war, probably from Army production.
At first the Jenny was used as a primary trainer. However the Army soon decided that the best way to produce advanced trainers would be to find a more powerful engine to the JN-4. This produced the JN-4H, using a 150hp Hispano-Suiza engine licence built in the US. This, and the very similar JN-6H, were used a bombing trainers, fighter trainers, gunnery trainers and observation trainers, each with a different configuration.
After the end of the war the Army soon withdrew its 90hp engined aircraft. These aircraft powered by 150hp engines (JN-4H and JN-6H) remained in Army service after the war. These more powerful aircraft remained the Army’s main primary trainer until 1925, when newer designs became available. Many of these aircraft were reconditioned after the war, and given the new designation of Curtiss JNS. This programme lasted until 1925.
In 1919 the Army still had 3,285 Jennies in service. By 1927 this had dropped to only 37, and they were withdrawn in September 1927.
In November 1919 the Navy had 76 Jennies in service. They gained another 216 Jennies from the Army in 1920-23. However by the end of 1926 only 22 were still in service.
In mid 1926 the National Guard had 112 JN-4s in service, along with seven TW-3s. The Guard was about to purchase it’s first Douglas O-2s.
In the immediate aftermath of the war surplus Jennies were quite pricy, but as time went on they became increasingly cheap, until eventually you could get one for £50. At the same time the US had no regulations for aircraft, so even the most dangerous ‘crate’ could be flown.
The first half of the 1920s became known as the ‘Jenny Era’, and it was used extensively by the barnstorming showmen of the era. Most of these aircraft were surplus 90hp JN-4s as the high powered aircraft remained in Military service until they were ready to be scrapped. The Jenny was particularly famous for its use by wing-walkers, who liked its level wings, many inter-wing struts and the king posts above the outer struts. It also helped that the United States didn’t sign up to the 1919 agreement on aircraft registration and airworthiness, which meant that for many years there were no rules surrounding American aviation.
One side effect of the lack of regulation was that it was easy to make significant modifications to the Jenny. One of the most common was to replace the short lower wings with a spare set of upper wings, installed upside down. A number of companies also developed completely new wings for the Jenny, including lower drag biplane sets and parasol monoplane wings (including Sikorsky and Sperry).
The Jenny began to fade out of use from 1925, when the first post-war designs began to appear. The real end came in 1927, when the US Government finally introduced licensing requirements for aircraft and pilots. Very few Jennys were able to pass the new airworthiness tests. Some gained ‘C’ licences, allowing limited use, while others flew in states that hadn’t adopted the Federal rules, but by 1930 it was illegal to fly the Jenny in most of the United States.
The last major use of the Jenny was in Hollywood, where they formed a significant part of the Hollywood Squadron, making appearances in many movies, often in the guise of other types.
The JN-2 was the first version to be produced, although only eight were built. They used the Curtiss OX engine, and had equal span wings with the Eiffel 36 aerofoil and four ailerons controlled by Curtiss’s shoulder yoke system. Late in 1915 they were given the same wings as the JN-3, and more powerful OXX engines, but all of the surviving aircraft were lost during the Punitive Expedition to Mexico in 1916.
The JN-3 was an improved version of the aircraft, originally produced for the British RNAS from March 1915. The US Army later brought two, perhaps to bring their total force back up to eight. The JN-3 used the unequal span wings used on the modified Model J, with ailerons on the upper wings. They were given a new Deperdussin control system, which has a wheel for aileron control and a foot bar for the rudder. The American aircraft were also lost in Mexico, but the British aircraft were used as trainers.
The JN-4 was the most important productive version, and was built in vast numbers for the US Army, as well as for the US Navy, the British and private customers. The first JN-4s were produced in 1916, and were virtually identical to the JN-3. However the type evolved through several variants, with the best probably being the JN-4H, with a more powerful Hispano-Suiza engine. The JN-4A became the Model 1 in Curtiss’s 1935 designation system.
Curtiss JN-4Can ‘Canuck’
The JN-4Can ‘Canuck’ was a parallel development to the JN-4, and was designed in Canada to satisfy British demands. Many of its features were later adopted in the JN-4.
The designation JM-5 was briefly attached to the twin engine version, and was then give to the prototype of an advanced trainer variant that never entered production.
The JN-6 was similar to the JN-4, but with ailerons fitted on both wings. Just over 1,000 were built, almost all as specialist advanced trainers.
The JNS was the designation given to aircraft that were rebuilt to a standardized design after the war, and stood for JN Standardized. The most obvious change was the removal of the ailerons from the lower wings of the JN-6.
Curtiss Twin JN
The Twin JN was a two-engine version, produced in 1916. It was an observation type, but only about ten were ever produced.
The N-8 of 1915 was very similar to the JN-3 and early JN-4, but used the same RAF 6 aerofoil as the original Model N. Only a handful were produced.
The Curtiss N-9 of late 1916 was a floatplane trainer produced in large numbers for the US Navy. It was very similar to the JN-4, but perhaps with the RAF 6 aerofoil.
Engine: Curtiss OX-5 inline
Crew: 2 pilots
Span: 43ft 7 3/8in
Length: 27ft 4in
Height: 9ft 10 5/8in
Empty weight: 1,390lb
Gross weight: 1,920lb
Maximum take-off weight:
Max speed: 75mph
Cruising speed: 60mph
Climb Rate: 2,000ft in 7.5 min
Service ceiling: 6,500ft
Engine: Wright-Hispano A
Crew: 2 (pilot and gunner)
Span: 43ft 7 3/8in
Length: 27ft 4in
Height: 9ft 10 5/8in
Empty weight: 1,625lb
Gross weight: 2,269lb
Maximum take-off weight:
Max speed: 91mph
Cruising speed: 75mph
Climb Rate: 2,000ft in 3.3 minutes
Service ceiling: 7,500ft
Armament: One fixed forward firing Marlin gun, one or two flexibly mounted Lewis guns