Sparrowhawk - Curtiss F9C - Varpushaukka

The Curtiss F9C Sparrowhawk was a light 1930s biplane fighter aircraft that was carried by the United States Navy airships USS Akron and Macon. It is an example of a parasite fighter, a small airplane designed to be deployed from a larger aircraft such as an airship or bomber.

An F9C-2 captures the trapeze aboard Macon in 1933
Although designed as a pursuit 'plane or fighter, the Sparrowhawk's primary duty in service was reconnaissance, enabling the airships it served to search a much wider area of ocean. The Sparrowhawk was primarily chosen for service aboard the large rigid-framed airships Akron and Macon because of its small size (20.2 ft (6.2 m) long and with only a 25.5 ft (7.8 m) wingspan), though its weight, handling and range characteristics, and also downward visibility from the cockpit, were not ideal for its reconnaissance role. 

The theoretical maximum capacity of the airships' hangar was five aircraft, one in each hangar bay and one stored on the trapeze but, in the Akron, two structural girders obstructed the after two hangar bays, limiting her to a maximum complement of three Sparrowhawks. A modification to remove this limitation was pending at the time of the airship's loss. Macon had no such limitation and she routinely carried four airplanes.

To achieve launching and recovery from the airship in flight, a 'skyhook' system was developed. The Sparrowhawk had a hook mounted above its top wing that attached to the cross-bar of a trapeze mounted on the carrier airship. For launching, the biplane's hook was engaged on the trapeze inside the airship's (internal) hangar, the trapeze was lowered clear of the hull into the (moving) airship's slipstream and, engine running, the Sparrowhawk would then disengage its hook and fall away from the airship. For recovery, the biplane would fly underneath its mother ship, until beneath the trapeze, climb up from below, and hook onto the cross-bar. 

The width of the trapeze cross-bar allowed a certain lateral lee-way in approach, the biplane's hook mounting had a guide rail to provide protection for the turning propeller (see photo), and engagement of the hook was automatic on positive contact between hook and trapeze. More than one attempt might have to be made before a successful engagement was achieved, for example in gusty conditions. Once the Sparrowhawk was securely caught, it could then be hoisted by the trapeze back within the airship's hull, the engine being cut as it passed the hangar door. Although this sounds tricky, pilots soon learned the technique and it was described as being very much easier than landing on a moving, pitching and rolling aircraft carrier. Almost inevitably, the pilots soon acquired the epithet "The men on the Flying Trapeze" and their aircraft were decorated with an appropriate unit emblem.

Once the system was fully developed, in order to increase their scouting endurance while the airship was on over-water operations, the Sparrowhawks would have their landing gear removed and replaced by a fuel tank. When the airship was returning to base, the biplanes' landing gear would be replaced so that they could land independently again.

For much of their service with the airships, the Sparrowhawks' effectiveness was greatly hampered by their poor radio equipment and they were effectively limited to remaining within sight of the airship. However, in 1934 new direction finding sets and new voice radios were fitted which allowed operations beyond visual range, exploiting the extended range offered by the belly fuel tanks and allowing the more vulnerable mother ship to stay clear of trouble.

One interesting use of the Sparrowhawks was to act as 'flying ballast'. The airship could take off with additional ballast or fuel aboard instead of its airplanes. Once the airship was cruising, the aircraft would be flown aboard, the additional weight being supported by dynamic lift until the airship lightened.

No airplanes were lost when the Akron went down but the Macon took four with her to her watery grave. Her wreck was discovered at its underwater resting place with four F9C-2s in their hangar. 
These are known to have been BuAer number 9058 - 9060.


Only one Sparrowhawk survives today. BuAer number 9056 was pending write-off at NAS Hampton Roads in 1939 when it was transferred to the Smithsonian Institution. In later years it had been rebuilt, using parts from the surviving F9C-2 (BuAer number 9057) and the XF9C-2 (9264). It was previously at the National Museum of Naval Aviation, at NAS Pensacola, and is currently displayed at the Steven F. Udvar-Hazy Center of the Smithsonian's National Air and Space Museum collection, wearing the markings of F9C-2 A9056 of USS Macon.

Specifications F9C-2
Crew: 1
Length: 20 ft 2.0 in (6.147 m)
Wingspan: 25 ft 6.0 in (7.772 m)
Height: 10 ft 6 in (3.2 m)
Wing area: 172.79 sq ft (16.053 m2)
Empty weight: 2,089 lb (948 kg)
Gross weight: 2,776 lb (1,259 kg)
Powerplant: 1 × Wright R-975-E3 9-cyl. air-cooled radial piston engine, 438 hp (327 kW)
Maximum speed: 176.5 mph (284 km/h; 153 kn)
Range: 297 mi (258 nmi; 478 km)
Service ceiling: 19,200 ft (5,852 m)
Rate of climb: 1,700 ft/min (8.6 m/s)
Wing loading: 16 lb/sq ft (78 kg/m2)
Power/mass: 0.086 hp/lb (0.259 kW/kg)

Armament: 2 × .30 in (7.62 mm) Browning machine guns
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Curtiss F9C Sparrowhawk (suom. Varpushaukka) on kevyt kaksitasoinen hävittäjälentokone, joita oli sijoitettu Yhdysvaltain laivaston USS Akron (ZRS-4) ja USS Macon (ZRS-5) ilmalaivoihin 1931–1935.

Curtiss F9C suunniteltiin alun perin Yhdysvaltain laivaston 10. huhtikuuta 1930 julkistamaa pienen laivastohävittäjän suunnittelukilpailua varten, muut osallistujat olivat General Aviation (aiemmin Fokker) XFA-1 ja Berliner-Joyce XFJ-1 koneillaan.

XF9C-1 (laivaston sarjanumero A8731) tilattiin Curtissilta 30. kesäkuuta 1930. Se teki ensilentonsa maaliskuussa 1931. Koneessa oli metallinen itsekantava runko ja pyrstö, sekä kankaalla verhoillut metallirunkoiset siivet, laskutelineissä ei ollut muotosuojia. Moottorina oli 420 hevosvoimainen Wright R-975C (J-6-9) Whirlwind -tähtimoottori.
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Neljä seitsemästä Sparrowhawkista menetettiin onnettomuudessa, kolmesta jäljelle jääneestä koneesta poistettiin niitten tarttumakoukut ja ne uudelleennimetttiin XF9C-2:ksi. Kaksi niistä romutettiin San Diegossa 1936. Ainoa jäljelle jäänyt kone siirrettiin laivaston lentotukikohtaan Anacostiaan, Marylandiin. Vuonna 1939 se lahjoitettiin Smithsonian-instituutille tarttumakoukun jäljitelmällä varustettuna.

USS Macon-ilmalaiva
XF9C-2 oli Curtissin yksityisesti rakentama toinen prototyyppi, sen moottorina oli 438 hevosvoimainen R-975E-3-moottori, sen ylätaso oli kiinnitetty kymmenen senttiä korkeammalle kuin ensimmäisessä prototyypissä ja laskutelineissä oli muotosuojat.

Laivaston pienten laivastohävittäjien suunnitelmaa ei toteutettu ja Sparrowhawkit olisi poistettu käytöstä, ellei niille olisi löytynyt uutta tehtävää.

Yhdysvaltain laivasto tilasi 6. lokakuuta 1928 kaksi jäykkärunkoista ilmalaivaa, USS Akronin ja Maconin, ja jo suunnitteluvaiheessa ne oli tarkoitus varustaa lentokoneitten kuljetusmahdollisuudella. Suunnitteluvaiheessa ei kuitenkaan ollut vielä olemassa tehtävään sopivia hävittäjiä. Sparrowhawk todettiin ihanteelliseksi ilmalaivakäyttöön pienen kokonsa vuoksi.

Koneen ylätasoon kiinnitettiin tarttumakoukku, jolla kone kiinnittyi ilmalaivan "trapetsiin", minkä jälkeen se vedettiin ilmalaivaan. Koneet varastoitiin ilmalaivan rungon sisään, mistä ne laukaistiin kiinnittämällä trapetsiin ja laskemalla rungon ulkopuolelle, minkä jälkeen hävittäjän lentäjä vapautti koneen kiinnityskoukun. Ilmalaivalta toimiessaan Sparrowhawkien laskeutumistelineet yleensä poistettiin ja korvattiin ylimääräisellä polttoainesäiliöllä lentoajan ja toimintasäteen pidentämiseksi.

Kumpikin ilmalaiva pystyi kuljettamaan neljä hävittäjää runkonsa sisällä ja yhtä rungon ulkopuolella.

Vaikka Sparrowhawkien tarkoitukseksi yleensä mielletään ilmalaivojen puolustus, niiden pääasiallinen tehtävä kuitenkin oli tiedustelutoiminta ja siten pidentää meritiedusteluun tarkoitettujen ilmalaivojen tehokasta toiminta-aluetta.

Ilmalaiva USS Akron (ZRS-4), 1931-1933.
USS Akron oli ensimmäinen Yhdysvaltain laivaston kahdesta jäykkärunkoisesta ilmalaivasta. Se rakennettiin Akronissa, Ohiossa ja otettiin palveluskäyttöön lokakuun lopulla 1931. Sitä käytettiin jäykkärunkoisten ilmalaivojen teknisen ja operationaalisen laivastokäytön tutkimiseen.

Akron joutui 4. huhtikuuta 1933 ankaraan myrskyyn New Jerseyn rannikolla ja pian keskiyön jälkeen se syöksyi pyrstö edellä mereen. Vain kolme aluksen 76:sta miehistön jäsenestä selvisi onnettomuudesta hengissä.

USS Macon, Akronin sisaralus rakennettiin myös Akronissa. Se teki ensilentonsa vuoden 1933 huhtikuussa, vain muutama viikko sisaraluksensa tuhoutumisen jälkeen. Lentotestien jälkeen se otettiin palveluskäyttöön kesäkuussa 1933.


Ollessaan 12. helmikuuta 1935 palaamassa meriharjoituksista tukikohtaansa Moffett Fieldiin, Kaliforniaan, USS Macon joutui Point Surin edustalla myrskyyn, jonka aiheuttamien vaurioiden seurauksena se vaipui mereen. Onnettomuudessa menehtyi vain kaksi miehistön jäsentä, mutta ilmalaiva upposi mereen, päättäen samalla Yhdysvaltain laivaston kokeilut jäykkärunkoisilla ilmalaivoilla.

IMAM Ro.37

The Meridionali Ro.37 Lince (Italian: "Lynx") was a two-seater Italian reconnaissance biplane, a product of the Industrie Meccaniche Aeronautiche Meridionali (IMAM) company. It appeared in 1934 and had a composite structure of wood and metal. 
The aeroplane first saw operational duty in Spanish Civil War, and during the Second World War it saw duty on almost all fronts, except for Russia and the English Channel. It followed the Ro.1 as the main reconnaissance aircraft for the Italian army.

A contest was held by the Regia Aeronautica for a light reconnaissance aircraft and a heavier aeroplane. The first should have 350 km/h (190 knots/220 mph) maximum speed, five hours endurance, three machine-guns and a bomblets dispenser, armour, and the capability to operate from improvised airfields. The heavier one should have 325 km/h maximum speed, at least 1,300 km (810 mi) endurance, 7,000 m (22,750 feet) ceiling, climb to 5,000m (16,000) in 19 minutes, three crew, five weapons, high wing and other details.

Limited production of the IMAM Ro.30, an improved Ro.1 with a defensive turret and better engine, resulted. It was rejected by the Regio Esercito and not chosen for production, being only capable of 200 km/h (110 knots), five hours endurance, a climb rate of 4,000 m (13,000 feet) in 20 minutes, and had three weapons.

IMAM did not give up after the modest success of the Ro.30 and so designed a new aircraft, the Ro.37, which first flew in 1933.
This was a biplane aircraft of mixed construction, with two seats, and a 560 hp Fiat A.30 inline engine. It reached 300 km/h (162 knots) and perhaps even more with this engine, the same as that of the Fiat CR.32. The Ro.37 had a 7,000 m ceiling, 3,000 m climb in 11 minutes, over 1,200 km (750 mi) endurance, three machine guns (two in the nose and one dorsal), twelve 15 kg bombs, and good agility. It was similar to the Hawker Hind, rather than a light army aircraft, and its performance was similar to the later Westland Lysander, but the contemporary British design was the Hawker Hector.

The Ro.37 was later fitted with the 600 hp Piaggio P.IX radial engine. The better reliability of this engine was considered more desirable and so this was the main version produced.
The Ro. 37 served as standard equipment in observations units, for many years. But during WWII, and particularly on the African front, the aeroplane was used in other roles, including tactical support and fighter duty. 103 Squadron was equipped in mid-1935 and swiftly employed in Ethiopia. In December this unit was sent to Somalia, and eventually another four squadrons went to this theatre: 105, 108, 109, and 110 Squadrons, for a total of ten Ro.37 and forty-one Ro.37Bis.
With the end of operations, 110 Squadron remained in the theatre, deployed in counterinsurgency tasks and serving as reinforcement for isolated garrisons.

In the meantime, the R.37 also served in the Spanish Civil War, with the first ten arriving in late 1936. Another 26 (possibly 58) went to this theatre and were used for many missions and tasks. They were used as assault aircraft, even though they were unarmoured. The results were satisfactory and some were even converted to a single-seat machine for use as attack fighters. The two-seat versions were used as heavy fighters, providing protection for S.81 bombers from Republican I-15s.

It is not known if there were any air-to-air victories.

The Ro.37 was generally liked by pilots, and the only complaint was that aircraft was prone to damage to the undercarriage, and had some engine faults.

The aircraft was produced until 1939 with a total of 569 (237 + 332bis) produced, and as late as 1940 there were provisions to have 17 Squadron equipped with this machine. In fact, the Ro.37 continued to be used as reconnaissance aircraft for years, since its replacement, the Caproni Ca.311, proved unsatisfactory.

Ro.37 were also quite widely exported (ten to Uruguay, sixteen to Afghanistan, fourteen to Hungary, eight to Austria, and one to Ecuador) and around 280 were in service in 1940, in thirty squadrons consisting of 215 aircraft.

Some were in service up to 1943 and perhaps even later. They were very vulnerable, but in the war Italy did not have sufficient resources to produce a better observation aircraft, not even the Ro.63, a superior aircraft, similar to the Storch, but with more endurance.

Ro.45
The last of the classic biplanes made by IMAM was this machine, an enhanced Ro.37. It was 10.37 m length, with a 12.32 m wingspan. First flight was on 10 December 1935.

The 820 hp Isotta-Fraschini Asso XI.RC40 engine boosted maximum speed to 350 km/h, ceiling to 8,000 m, and endurance to 2,250 km. Destined for long-range reconnaissance and light bombing, it remained a single prototype for unknown reasons: perhaps it was rated too costly or the improvements over the Ro.37 were not enough.

General characteristics
Crew: 2
Length: 28 ft 1 in (8.56 m)
Wingspan: 36 ft 4 in (11.08 m)
Height: 10 ft 4 in (3.15 m)
Wing area: 337.46 sq ft (31.35 m²)
Empty weight: 3,494 lb (1,585 kg)
Max. takeoff weight: 5,335 lb (2,420 kg)
Powerplant: 1 × Piaggio P.IX RC.40, 9-cylinder, air-cooled, radial, piston engine, 560 hp (418 kW)
Maximum speed: 205 mph (330 km/h)
Cruise speed: 155 mph (250 km/h)
Range: 696 miles (1,120 km)
Service ceiling: 23,620 ft (7,200 m)
Armament: Two 7.7mm (0.303in) fixed forward firing Breda-SAFAT machine guns
One 7.7mm (0.303in) flexible mount machine gun in rear cockpit
397 lb (180kg) of bombs on underfuselage racks

Polikarpov I-15

Polikarpov I-15 ja I-15bis ja niistä edelleen kehitetty I-153 olivat neuvostoliittolaisia kaksitasoisia hävittäjälentokoneita, joita käyttivät tasavaltalaiset Espanjan sisällissodassa, Kiina sodassa Japania vastaan ja Neuvostoliitto toisessa maailmansodassa. Niitä valmistettiin 905 kappaletta. 

Talvisodassa erityisesti I-153 oli vaarallinen Suomen ilmavoimien päähävittäjää Fokker D.XXI:tä vastaan.

The Polikarpov I-15 (Russian: И-15) was a Soviet biplane fighter aircraft of the 1930s. Nicknamed Chaika (Russian: И-15 Чайка, "Seagull") because of its gulled upper wings, it was operated in large numbers by the Soviet Air Force, and together with the Polikarpov I-16 monoplane, was one of the standard fighters of the Spanish Republicans during the Spanish Civil War, where it was called Chato (snub-nose) in the Republican Air Force, or "Curtiss" (because its resemblance to Curtiss F9C Sparrowhawk) in the Nationalist Air Force.

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Nikolai Nikolaevich Polikarpov

Dmitri Grigorovitšin ja Nikolai Polikarpovin suunnitteleman I-5 -koneen ensimmäinen prototyyppi lensi 29. huhtikuuta 1930 nimellä VT-11 ja toinen prototyyppi 22. toukokuuta 1930. I-5:n sarjavalmistus alkoi vuonna 1932. Kahdessa vuodessa I-5-konetta rakennettiin 803 kappaletta. Koneen moottorina oli 480 hv:n M-22 -moottori, joka oli lisenssillä valmistettu versio 9-sylinterisestä Bristol Jupiter -tähtimoottorista.

I-5-konetta kehitettiin edelleen ja uuden version prototyyppi TsKB-3 lensi ensilentonsa lokakuussa 1933. Koneen yläsiipi oli ns. lokkisiipi ja moottorina oli 630 hv:n Wright Cyclone. I-15:ksi nimetyn koneen sarjatuotanto alkoi vuonna 1934. Moottorina oli aluksi M-22 mutta myöhemmin Cyclonesta kehitetty 635 hv:n M-25. I-15-hävittäjää valmistettiin 733 kpl.

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The design for the 14th fighter for the VVS, the I-14, started as an advanced (for the era) monoplane under the direction of Andrei Tupolev. He grew concerned that the design would not mature, and ordered two backup biplane designs as the I-14A and B just to be safe. Polikarpov had just been released from prison in August 1932, and was handed the I-14A project. When both the I-14 and I-14A were ordered into production, Polikarpov's design, a development of the I-5 fighter became the famous I-15.

The first flight was made in October 1933 with V.P. Chkalov at the controls, powered by an imported Wright R-1820 Cyclone engine. The I-15, also known by its development name TsKB-3, was a small biplane fighter with a gulled upper wing. The single bay wings were of wooden construction, while the fuselage was of mixed steel and duralumin construction, with a fabric covered rear fuselage.

Production started in 1934, initially being powered by the M-22, a licensed built version of the Bristol Jupiter radial engine. While less powerful than the Cyclone, the M-22 powered aircraft were still superior to the I-5 which it replaced, demonstrating excellent manoeuvrability. Production switched to the 515 kW (700 hp) M-25 engine (a license built Cyclone) in late 1936. A total of 671 I-15s were built, 284 in the Soviet Union and a further 287 under license by CASA in Spain.

The gulled upper wing of the I-15 was unpopular with some pilots, as it was felt to restrict visibility, so Polikarpov's design bureau produced a revised version, again powered by the M-25, with a longer span un-gulled upper wing. This version, the I-15bis, commenced production in 1937, a total of 2,408 I-15bis' being delivered by the time production finished in 1940

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Lokkisiipi haittasi lentäjän näkyvyyttä ja se korvattiin suoralla yläsiivellä. Moottoriksi asennettiin 725 hv:n M-25V, joskin tuotantoversioissa tavattiin myös 760 hv:n M-25A:ta ja 775hv:n M-25B:tä. Moottorin painon kasvun myötä rakenteita jouduttiin vahvistamaan. Uutta versiota kutsuttiin I-152:ksi ja I-15bis:ksi ja sen valmistus aloitettiin syksyllä 1937. 

I-152 -konetta rakennettiin Neuvostoliitossa 2 408 kappaletta, joista 186 kappaletta vietiin Kiinaan vuodenvaihteessa 1937–1938. Lisäksi Espanjan tasavaltalaiset rakensivat lisenssillä 231 konetta vuosina 1937–1938.

Koneen kehittäminen ei jäänyt tähän, vaan sitä kehitettiin edelleen Espanjan sisällissodan kokemusten perusteella. Yläsiiveksi asennettiin lokkisiipi ja alasiipeen sisään vedettävät laskutelineet. Prototyyppi valmistui lokakuussa 1938. Koneen tuotanto alkoi nimellä I-153 keväällä 1939 ja päättyi vuoden 1940 lopulla 3437 koneen valmistuksen jälkeen. Koneessa oli 850 hv:n M-62-moottori, joka sekin oli kehitetty Wright Cyclonesta. 

Ensi kerran I-153 osallistui sotatoimiin Khalkin-Golissa Japanin hyökättyä Neuvostoliittoa vastaan heinäkuussa 1939. 

Koneessa oli aseistuksena neljä 7,62 mm ShKAS-konekivääriä, joiden yhteenlaskettu patruunamäärä oli mahtava, 5 000 kappaletta. 

Aseistuksen heikkoutena pysyi loppuun asti mekaaninen liipaisin, joka oli vailla minkäänlaista tehostinta, vaikka se oli sijoitettu ohjaussauvaan. Liipaisin oli niin raskas käyttää, että monet koneet huojuivat rajusti aseita käytettäessä tahattomien sauvanliikkeiden vuoksi, ja osumistarkkuus oli vajavainen.

Koeversioissa kokeiltiin paineistettua ohjaamoa, turboahtimia ja kiihdytykseen käytettäviä rakettimoottoreita.

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General characteristics

Crew: 1

Length: 6.10 m (20 ft)

Wingspan: 9.75 m (32 ft)

Height: 2.20 m (7 ft 3 in)

Wing area: 23.55 m² (236 ft²)

Empty weight: 1,012 kg (2,231 lb)

Loaded weight: 1,415 kg (3,120 lb)

Powerplant: 1 × M-22 radial engine, 353 kW (473 hp)

Maximum speed: 350 km/h (220 mph)

Range: 500 km (310 mi)

Service ceiling: 7,250 m (23,800 ft)

Rate of climb: 7.6 m/s (1,490 ft/min)

Wing loading: 65 kg/m² (13 lb/ft²)

Power/mass: 0.25 kW/kg (0.15 hp/lb)

Armament: 4 × fixed 7.62 mm PV-1 mg or 2 × fixed 12.7 mm BS mg

Up to 100 kg (220 lb) of bombs or 6 × RS-82 rockets
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Variants:
TsKB-3bis
Prototype.

TsKB-3ter
Prototype fitted with the more powerful M-25V radial piston engine..

I-15
First production series.

I-15bis

Single-seat fighter biplane, armed with four 7.62 mm (0.30 in)PV-1 or ShKAS machine guns, plus up to 150 kg (330 lb) of bombs. The I-15bis was powered by the more powerful 570 kW (775 PS) Shvetsov M-25V radial piston engine. It had a straight upper wing. A total of 2,408 machines were built.
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In August 1937, the Chinese Kuomintang Government signed a non-aggression pact with the USSR. And, in autumn of the same year, the Soviet Union commenced to ship I-15s as a part of a programme of military aid to the Chinese Air Force (CAF) in its defensive war against Japan. More than 250 Soviet pilots volunteered to fly the 255 I-15s supplied to China in autumn 1937. By 1939, the total number of Polikarpov biplanes delivered to CAF reached 347 I-15/I-15bis. The I-15bis saw a great amount of action in Manchuria and in the various border clashes between the Soviets and the Japanese. In 1937, I-15s in the hands of the Chinese Nationalist Air Force fought against invading Japanese, where the tough biplane began to meet its match in some of the newer, faster Japanese monoplanes.

In 1939 Polikarpov fighters were extensively used during the Battles of Khalkhin Gol fought around the Khalkha River in Dornod Province. The battles were fought during 11 May–16 September 1939, and involved more than 600 planes. When hostilities commenced, the only I-15bis in the area were 14 aircraft of 70th IAP. Their number increased in the following weeks: on 23 May, 35 I-15bis a from 22nd IAP arrived from the Trans-Baikal region. However the Polikarpov pilots had been hastily trained and they suffered heavy losses against the more experienced Japanese. During this conflict, Soviet Union and Japan lost more than 200 aircraft each. Mongolian People's Army Air Force- deliveried 10 aircraft in middle July 1939 and trained flight personal for rear air defence. Afterwards, they received more than 30 aircraft in March 1942.

The I-15 was used in combat extensively by the Republicans in the Spanish Civil War and proved to be one of the best fighter biplanes of its time. The first batch of 25 Polikarpovs arrived in Cartagena, Spain, on 28 October 1936, with 15 pilots, led by future ace Pavel Rychagov. Few days later a further group of 10 pilots and 15 aircraft arrived in Bilbao. The Soviet pilots soon entered in action. They had their baptism of fire on 4 November. 

On that day, I-15s shot down two Junkers Ju 52/3ms together with two CR.32s, over Madrid, and forced to crash-land a third Ju 52 and a Heinkel two-seater. No losses were reported among the Soviet pilots. During the next two days, Chato pilots claimed 12 more victories, at the cost of two I-15s lost. But on 16 November, while dogfighting with Fiat CR.32s over Madrid, future ace Rychagov was shot down and four days later the number of combat-ready Polikarpov in the central area had fallen to 15 aircraft: seven had been lost in combat, two had force-landed and one was undergoing repair.

In December 1936 and January 1937 two more shipments of 30 Polikarpovs arrived in Spain, making it possible to form a complete combat unit of four I-15 squadrons. Until the spring of 1937, central Spain was the main war theatre of the I-15s. And in May 1937, another batch of 31 Polikarpov landed in Spain, taking the total number of I-15s delivered to Republicans to 116. The exact number of I-15s lost during the Spanish War is difficult to determine as the Republicans destroyed a number of them while retreating and because there is little reliable data about the final stages of war. Chato losses were comparable to those of its principal rival, the Fiat CR.32. 

By 1 January 1939, 197 Polikarpovs had been lost: 88 shot down by enemy aircraft and nine by anti-aircraft artillery, 27 destroyed on the ground and 67 written off in accidents.

More than 1,000 I-15bis fighters were still in Soviet use during the German invasion when the biplane was employed in the ground attack role. By late 1942, all I-15s and I-15bis' were relegated to second line duties.

Curtiss XA-14

The Curtiss XA-14 was a 1930s United States airplane, the first multi-engine attack aircraft tested by the United States Army Air Corps. Carrying a crew of two, it was as fast as the standard pursuit aircraft in service at the time.

Originally built as an in-house venture as the Curtiss Model 76, powered by two experimental Wright XR-1510 radial engines, flight testing was sufficiently impressive that after the USAAC appraisal the Model 76 was returned to Curtiss and fitted with two 775 hp (578 kW) Wright R-1670-5 Cyclone engines with constant-speed propellers. 
This configuration was accepted by the Army with the designation XA-14. It had standard Army markings with the serial number 36-146.

The Model 76 was of all-metal construction with an oval section semimonocoque fuselage, described as "pencil slim". The XA-14 was extensively tested, at one stage being fitted with a 37 mm (1.46 in) nose cannon.

In July 1936, 13 developed versions, re-engined with two Wright R-1820-47 Cyclone twin-row radials, were ordered into production as the Y1A-18.

Specifications XA-14
General characteristics
Crew: two
Length: 40 ft 3 in (12.3 m)
Wingspan: 59 ft 5 in (18.11 m)
Height: 10 ft 9 in (3.3 m)
Max. takeoff weight: 11,750 lb (5,330 kg)
Powerplant: 2 × Wright R-1670-5 radials, 775 hp (578 kW) each
Maximum speed: 254 mph (221 kn, 409 km/h)
Range: 825 mi (717 nmi, 1,328 km)
Service ceiling: 27,100 ft (8,260 m)
Armament: 4 × 7.62 mm M1919 Browning machine guns forward-firing
1 × 7.62 mm machine gun aft-firing + 650 lb (295 kg) bombs in internal bay

Douglas DB-8 or Northrop A-17

The Northrop A-17, a development of the Northrop Gamma 2F was a two-seat, single-engine, monoplane, attack bomber built in 1935 by the Northrop Corporation for the U.S. Army Air Corps.

The Northrop Gamma 2F was an attack bomber derivative of the Northrop Gamma transport aircraft, developed in parallel with the Northrop Gamma 2C, (of which one was built), designated the YA-13 and XA-16. 

The Gamma 2F had a revised tail, cockpit canopy and wing flaps compared with the Gamma 2C, and was fitted with new semi-retractable landing gear. It was delivered to the United States Army Air Corps for tests on 6 October 1934, and after modifications which included fitting with a conventional fixed landing gear, was accepted by the Air Corps. A total of 110 aircraft were ordered as the A-17 in 1935.

The resulting A-17 was equipped with perforated flaps, and had fixed landing gear with partial fairings. It was fitted with an internal fuselage bomb bay that carried fragmentation bombs and well as external bomb racks.

Northrop developed a new landing gear, this time completely retractable, producing the A-17A variant. This version was again purchased by the Army Air Corps, who placed orders for 129 aircraft. By the time these were delivered, the Northrop Corporation had been taken over by Douglas Aircraft Company, export models being known as the Douglas Model 8.

Operational history
A-17A cockpit
United States
The A-17 entered service in February 1936, and proved a reliable and popular aircraft. However, in 1938, the Air Corps decided that attack aircraft should be multi-engined, rendering the A-17 surplus to requirements.

From 14 December 1941, A-17s were used for coastal patrols by the 59th Bombardment Squadron (Light) on the Pacific side of the Panama Canal.

The last remaining A-17s, used as utility aircraft, were retired from USAAF service in 1944.

Other countries
Argentina purchased 30 Model 8A-2s in 1937 and received them between February and March 1938. Their serial numbers were between 348 and 377. These remained in frontline service until replaced by the I.Ae. 24 Calquin, continuing in service as trainers and reconnaissance aircraft until their last flight in 1954.

Peru
Peru ordered ten Model 8A-3Ps, these being delivered from 1938 onwards. These aircraft were used in combat by Peru in the Ecuadorian-Peruvian war of July 1941.
The survivors of these aircraft were supplemented by 13 Model 8A-5s from Norway (see below), delivered via the United States in 1943 (designated A-33). These remained in service until 1958.

Sweden
The Swedish government purchased a licence for production of a Mercury-powered version, building 63 B 5Bs and 31 B 5Cs, production taking place from 1938 to 1941. They were replaced in service with the Swedish Air Force by SAAB 17s from 1944.
The Swedish version was used as a dive bomber and as such it featured prominently in the 1941 film Första Divisionen (sv).

The Netherlands
The Netherlands, in urgent need of modern combat aircraft, placed an order for 18 Model 8A-3Ns in 1939, with all being delivered by the end of the year. Used in a fighter role for which they were unsuited, the majority were destroyed by Luftwaffe attacks on 10 May 1940, the first day of the German invasion.

Iraq
Iraq purchased 15 Model 8A-4s, in 1940. They were destroyed in the Anglo-Iraqi War in 1941.

Norway
Main article: Douglas A-33
Norway ordered 36 Model 8A-5Ns in 1940. These were not ready by the time of the German Invasion of Norway and were diverted to the Norwegian training camp in Canada, which became known as Little Norway. 

Norway decided to sell 18 of these aircraft as surplus to Peru, but these were embargoed by the United States, who requisitioned the aircraft, using them as trainers, designating them the A-33.
Norway sold their surviving aircraft to Peru in 1943.

Great Britain
In June 1940, 93 ex-USAAC aircraft were purchased by France, and refurbished by Douglas, including being given new engines. These were not delivered before the fall of France and 61 were taken over by the British Purchasing Commission for the British Commonwealth use under the name Northrop Nomad Mk I.

South Africa
The RAF assessed the Northrop Nomad Mk Is as "obsolete" and sent them to South Africa for use as trainers, serialed AS440 to AS462, AS958 to AS976 and AW420 to AW438.

Canada
The Royal Canadian Air Force received 32 Nomads that had been part of a French order of 93 aircraft. When France fell in 1940, this order was taken over by Great Britain who transferred 32 of the aircraft to Canada where they were used as advanced trainers and target tugs as part of the British Commonwealth Air Training Plan. These were serialed 3490 to 3521; all were assigned to No. 3 Training Command RCAF.

Specifications A-17
General characteristics
Crew: two pilot and gunner
Length: 9.67 m
Wingspan: 14.54 m
Height: 3.62 m
Wing area: 33.7m²
Empty weight: 2,211 kg
Loaded weight: 3,328 kg
Powerplant: 1 × Pratt & Whitney R-1535-11 Twin Wasp Jr two-row air-cooled radial engine, 750 hp (560 kW)
Maximum speed: 332 km/h
Cruise speed: 274 km/h
Range: 1,046 km
Service ceiling: 5,915 m
Rate of climb: 6.9 m/s
Armament 4 × 7.62 mm forward Browning mg+ 1 × 7.62 mm rear mg
Internal bay for bombs
External wing bomb racks 544 kg)

Vickers Vildebeest

The Vickers Vildebeest and the similar Vickers Vincent were two very large two- to three-seat single-engined British biplanes designed and built by Vickers and used as light bombers, torpedo bombers and in army cooperation roles. While first flown in 1928, it remained in service at the start of the Second World War, with the last Vildebeests flying against Japanese forces over Singapore and Java in 1942.

Designed against Air Ministry Specification 24/25 for the RAF, for a land-based torpedo bomber to replace the Hawker Horsley, the prototype Vildebeest, the Vickers Type 132, was first flown in April 1928, powered by a Bristol Jupiter VIII radial engine. After initial evaluation, the Vildebeest was shortlisted for evaluation with the Blackburn Beagle and Handley Page Hare. As the Jupiter VIII was prone to vibration, a second prototype, the Vickers Type 204 was fitted with an Armstrong Siddeley Panther engine, and after further testing, the Vickers design was confirmed as the winner of the contest. Engine problems continued, however, which were solved by fitting a new version of the Jupiter, which later became known as the Bristol Pegasus.

The Vildebeest had an all-metal, fabric-covered airframe, with single-bay unstaggered wings. An initial production order was placed in 1931 for nine aircraft, with the first production aircraft flying in September 1932. More production followed, with major production being of the Vildebeest III version, which added a third crewmember, with 150 built for the RAF. 

The Mark IV introduced the much more powerful (825 hp (615 kW)) Bristol Perseus sleeve valve radial engine enclosed in a NACA cowling, which significantly improved performance, maximum speed increasing to 156 mph (251 km/h) and rate of climb to 840 ft/min (4.3 m/s). 
The Perseus had overheating problems, and was unsuitable for tropical service, and production was limited to 18 aircraft, which served with the home based squadrons.

In 1931, Vickers designed as a private venture a General Purpose version of the Vildebeest to replace the RAF's Westland Wapitis and Fairey IIIFs, supporting the Army in the Middle East. Successful trials were conducted in the Middle East, Sudan and East Africa with a converted Vildebeest I in the General Purpose role during 1932–1933, and Specification 16/34 was drawn up around the modified Vildebeest, which was named the Vickers Vincent. Differences from the Vildebeest were minimal, with the torpedo equipment replaced by provision for an auxiliary fuel tank instead. It had a three man crew, and was powered by a 660 hp (490 kW) Bristol Pegasus IIM3. Between 1934 and 1936, 197 Vincents were built for the RAF or converted from Vildebeests.

The Vildebeest was purchased in moderately large numbers by the Royal Air Force from 1931 and used as a torpedo bomber. It entered service with No. 100 Squadron at RAF Donibristle in Scotland in October 1932, replacing the Hawker Horsley. 
Four frontline torpedo-bomber squadrons were equipped with the Vildebeest, two at Singapore (100 Squadron, which moved from the United Kingdom in 1933 and 36 Squadron, which replaced its Horsleys in 1935), and two more in the United Kingdom.

The Vincent entered service with No. 84 Squadron RAF at Shaibah, Iraq in December 1934, re-equipping General Purpose squadrons throughout the Middle East and Africa. By 1937, it equipped six squadrons in Iraq, Aden, Kenya, Sudan, and Egypt.

At the outbreak of the Second World War, 101 Vildebeests were still in service with the RAF. The two British-based squadrons flew coastal patrol and convoy escort missions until 1940 when their Vildebeests were replaced by the Bristol Beaufort. 
The two Singapore-based squadrons were still waiting for their Beauforts when Japan invaded Malaya in December 1941 and the obsolete biplanes had to be deployed against the Japanese attackers, making an abortive torpedo attack on a Japanese cruiser off Kota Bharu on 8 December.

The Vildebeests continued to attack the Japanese as their forces advanced down Malaya, sustaining heavy losses from Japanese fighters, particularly when no fighter cover could be provided. On 26 January 1942, the Japanese landed at Endau, 250 miles from Singapore, and 12 Vildebeests of 100 and 36 Squadrons were sent to attack the landings. Despite an escort of Brewster Buffalo and Hawker Hurricane fighters, five Vildebeests were lost. The attack was repeated later that day by eight Vildebeests of 36 Squadron and three Fairey Albacores, resulting in six more Vildebeests and two Albacores being shot down. The surviving Vildebeests were withdrawn to Java on 31 January and attacked another Japanese landing force off Rembang, claiming eight ships sunk but sustaining further losses. The final two Vildebeests of 36 Squadron attempted to escape to Burma on 6 March but were lost over Sumatra. The last Vildebeests in RAF service, operated by 273 Squadron at Ceylon were retired in March 1942.

While the Vincent had started to be replaced by more modern aircraft such as the Vickers Wellesley and Bristol Blenheim bombers, 84 remained in service with the RAF on the outbreak of the Second World War. Vincents were used for bombing missions against Italian forces in the East African Campaign and for coastal patrols from Aden, one attacking the Italian submarine Galileo Galilei. Other Vincents bombed Iraqi forces during the Anglo-Iraqi War of 1941. The last frontline Vincents retired in January 1943, with the type continuing in second line service (which included pesticide spraying against locusts in Iran) until 1944.

The Vildebeest was ordered by the Spanish Republic in 1932 and licence production of 25 Vildebeest for the Spanish Republican Navy was undertaken in Spain by CASA most receiving the Hispano-Suiza HS 600 inline engine, though some other engines were also used. Around 20 survived to fight with the Spanish Republican Air Force on the loyalist side of the Spanish Civil War, some equipped with floats.

A Vildebeest was the first victim of Francoist ace Joaquin Garcia-Morato.

12 Vildebeests were purchased by the Royal New Zealand Air Force in 1935 for coastal defence, with a further 27 acquired from RAF stocks in 1940-41. In addition, 60 or 62 of these machines, (depending on source), were passed on to the RNZAF.

New Zealand Vildebeests were also used for photo mapping. A few were used for maritime patrols against German surface raiders, and Japanese submarines, (a handful were based in Fiji in December 1941), but the main wartime role of the New Zealand aircraft was as particularly unwieldy pilot trainers, until replaced by North American Harvards in 1942.

Specifications: Vildebeest III
Crew: three, pilot, navigator, and observer
Length: 11.18 m
Wingspan: 14.94 m
Height: 4.47 m
Wing area: 67.7 m²
Empty weight: 2,170 kg
Loaded weight: 3,864 kg
Powerplant: 1 × Bristol Pegasus II-M3 air-cooled radial engine, 635 hp (474 kW)
Maximum speed: 230 km/h
Range: 2,010 km
Service ceiling: 5,800 m
Rate of climb: 3.2 m/s
Wing loading: 57.1 kg/m²
Power/mass: 0.122 kW/kg
Armament: 1 × fixed 7.7 mm vickers mg, and 1 × flexible,7.7 mm lewis gun
Bombs: 500 kg of bombs or 1 × 18 in (457 mm) torpedo

Me Bf-109X

After the success of the demonstration at the meeting of Zürich in 1937, Udet was receptive to the idea of developing an export version of the Bf 109 but with a different engine than the DB 601. 

The engine chosen was the P&W "Twin Wasp" SC-G of 1200 hp. The Messerschmitt company received a contract from RLM/LC on 13 June 1938 to fit the P&W Twin Wasp on the Bf 109 V21 (21st prototype) Werknummer 1770 (D-IFKQ). 

Even the maiden flight date is not known; it is established that Hermann Wurster flew it at Augsburg on 17 August 1939. In September 1940 it was part of the DVL (Deutsche Versuchsanstalt für Luftfahrt) at Brauschweig-Völkenrode with the Stammkennzeichen code KB+II. Its end is not known.

As the BMW 801 radial engine became available, a Bf 109F, Werknummer 5608, callsign D-ITXP was converted with a BMW 801 A-0. 

This aircraft became a prototype for the Bf 109X. 

The fuselage had a wider cross-section, and a new canopy was fitted. 

The wing tips were akin to that of the Bf 109E. 

The prototype was first flown by Flugkapitän Fritz Wendel on 2 September 1940, and the test flights continued despite troubles with the BMW 801A powerplant. Development was stopped in early 1942.