Boeing Stearman Model 75, part seven. The Stearman in America, part four. USAAC, USN and USAAF users

 

The Boeing Stearman Model 75 is an American biplane of which 10,626 exemplars were manufactured from 1934 until the mid 1940s. 
It served as a primary trainer for both the United States Army Air Forces (USAAF) and the United States Navy (USN) throughout World War 2. 

During late 1933 Mac Short, Harold W. Zipp and J. Jack Clark, engineers at Stearman Aircraft, took a Lloyd Stearman's design made back in 1931 and added cantilever landing gear and adjustable elevator trim tabs to come up with the Model 70, which was able to withstand +12g  and -9g forces. 
This initial Model 70 was powered by a single 210 hp Lycoming R-680 radial engine and flew for the first time on 1st January 1934, with additional test flights being performed later at Wright Field, Naval Air Station (NAS) Anacostia and NAS Pensacola. The performance pleased the USN and requested a similar model to be built under similar specifications, including a 200 hp Wright J-5 engine. This model was designated as NS-1 by the USN and 41 were ordered, with enough spares to build additional 20 machines.

In 1934 Stearman became a subsidiary of Boeing and therefore its aircraft were known as Boeing-Stearm. It was during the summer of that year when Stearman engineers improved the Model 73 (the internal denomination for the aforementioned NS-1) into the Model X75. This lead to the United States Army Air Corps (USAAC) to evaluate the plane that autumn. The Model X75 was powered either by a 225 hp Wright R-760 or a 225 hp Lycoming R-680. The USAAC accepted the model and ordered in July 1935 26 machines powered with the Lycoming engine, designated at PT-13A (PT stands for 'Primary Trainer') with the USN ordering twenty more. In August 1936 the USAAC ordered fifty PT-13As more with thirty more being ordered in October that same year and twenty-eight more in December. 

On 6th June 1941 the US Government approved the civilian version of the Model 75, designated as Model A75L3 (PT-13) and Model A75N1 (PT-17), with around 60 being sold to civilian flight schools such as Parks College of Engineering, Aviation and Technology, the export market and the many British Flying Training School Program across the USA.

This program was established at the beginning of World War 2, when the United Kingdom recognized the need to train a large number of pilots, so a large number of flying and aircrew training schools were set up across the British Empire and some neutral nations like the USA, where pilots could be trained without the risk of enemy interference. 

The British Flying Training Schools were also set up in the United States from 1941 onwards as a result of the Lend Lease Bill. Seven schools were opened (numbered from one to seven, two in Texas, two in Oklahoma and one in California, Arizona and Florida) and of those, at least five of them were equipped or had the PT-13A/PT-17 in their ranks at some point. 

On 15th March 1941 Boeing delivered its 1000th trainer to the USAAC and the 1001th trainer to the USN. Later, on 27th August 1941 the 2000th trainer was delivered to the USAAC. This feat was followed on 27th July 1944 when the company delivered the 10,000th primary trainer.

After World War 2, thousands of surplus PT-17s were sold to civilians and former military pilots. Many were modified as crop-dusters with a hopper for pesticide or fertilizer fitted in place of the front cockpit. Additional equipment included pumps, spray bars and nozzles placed below the lower wings. 

Sources:

1st https://en.wikipedia.org/wiki/Boeing-Stearman_Model_75

2nd https://en.wikipedia.org/wiki/British_Flying_Training_School_Program

Curtiss SBC Helldiver, part two. The Helldiver with the USMC.

 

The Helldiver was also used by the United States Marine Corps (USMC). A single SBC-3 was received in 1938 by the VMF-2 which was employed as a squadron hack at Naval Air Station San Diego, California. That machine was sent to Battle Fleet Pool in June 1939. 

The prototype of the SBC-4, called XSBC-4, was also used as a staff transport for Headquarters Marine Corps. This machine survived until 31st August 1944 when it was written off the inventory while serving at NAS Kodiak, Alaska.

Later, in January 1940, the USMC had four SBC-4 in inventory. Two of them were based at Marine Corps Air Station (MCAS) Quantico, Virginia, one was assigned to VMF-1 and the second was serving with Marine Utility Squadron 1 (VMJ-1). The other two were based at NAS San  Diego. One SBC-4 was assigned to VMF-2 and the second to VMJ-2. 

By 7th December 1941, the USMC had a total of 23 SBC-4 in inventory, twelve of them assigned to observation squadrons (VMO).

Marine Observation Squadron 151 (VMO-151) was sent to Tafuna airfield, in the American Samoa, on 9th May 1942, fully equipped with the SBC-4. It was there, at Tafuna where a second observation was formed, the VMO-155 on 1st October 1942 by taking half of the VMO-151's personnel and machines. This new squadron, however, was sent back to the United States on 8th December 1942 to be reformed and the remaining personnel was sent to Guadalcanal Island.

The SBC-4s in VMO-151 were replaced in December 1942 by the Douglas SBD Dauntless and by June 1943 they were fully equipped with the Dauntless. By that time they had moved to Uvea island, in Wallis Group, New Caledonia, leaving their SBC-4s behind. 

The last report of a SBC-4 serving with the VMO-151 was dated on 1st June 1943.

Sources:

1. https://en.wikipedia.org/wiki/Curtiss_SBC_Helldiver

2. Signal Squadron - Aircraft In action 151 - SBC Helldiver in Action

3. https://www.valka.cz/Curtiss-SBC-Helldiver-t45473

Pics re-drawn from:

http://wings-aviation.ch/53-Military-Aircraft-in-Detail/Curtiss-Helldiver/Attack.htm

Curtiss SBC Helldiver, part one. The Helldiver in the US Navy

 

A contract was signed in August 1936 by the US Navy for the delivery of 83 SBC-3 (Curtiss Model 77A - according to the internal denominations given by Curtiss). On 17th July 1937, their delivery process began, with the first aircraft being deployed with Scouting Squadron Five (VS-5) assigned, theoretically, on board of USS Yorktown (CV-5), however, as Yorktown was commissioned until 30th September 1937, they remained on land, while the ship underwent sea trials. It wasn't until 10th December that same year when the VS-5 was embarked on the Yorktown, where the Helldivers served until 1940 when they were replaced by the Douglas SBD-3 Dauntless. 

By June 1938 three of the five scouting squadrons assigned to aircraft carriers (USS Enterprise -CV-6, USS Yorktown - CV-5 and USS Saratoga - CV-3), were equipped with the Helldiver, while the other two were equipped with the Vought SBU-1. 

A single SBC-3 was kept by Curtiss and re-engined with a 750 hp Wright R-1820-22 nine cylinder radial engine. It received the denomination of XSBC-4, which served as the prototype for the SBC-4. 

An initial contract was signed for a batch of 58 SBC-4, on 5th January 1938, followed by two additional contracts, one for 31 Helldivers on 27th July 1938, and a third one for 35 more on 13th August 1938, making a total of 124 contracted aircraft, powered all of them by the Wright R-1820-24 radial engine, yielding 850 hp of power.

Scouting Squadron 2 (VS-2), on board of USS Lexington (CV-2) was the first one to receive the SBC-4 Helldiver, replacing their Vought SBU-1s. By 26th June 1939, VS-2 was completely equipped with 21 SBC-4s. The Lexington was the only carrier to actually fly the Helldiver, during military maneuvers, as they were replaced by Douglas SBD-2 and SBD-3 Dauntless dive bombers in 1941, prior to Pearl Harbour. 

Given the expanding aviation training programme, most of the SBC-4s, with other training aircraft, were assigned to Naval Reserve Air Bases (NRAB), to allow reserve US Navy and US Marine airmen assigned to reserve scouting squadrons, and maintain their proficiency. 

As time went by, the US Navy acquired more modern aircraft and both SBC-3 and SBC-4s were replaced by, mainly the Douglas SBD Dauntless. By 7th December 1941, both US Navy and US Marines, had a total of 69 SBC-3 and 118 SBC-4s, based at Naval Air Stations (NAS), NRABs and the Naval Aircraft Factory in Philadelphia, Pennsylvania. The largest group was based at NAS Miami, in Florida, where they were used for intermediate flying and dive bombing training.

The carrier USS Hornet (CV-8) was also equipped with SBC-4, at the time of Pearl Harbour. This carrier was undergoing sea trials on the Atlantic Ocean on 7th December and the two squadrons equipped with the Helldiver kept them until the ship sailed to San Diego, California, in March 1942. By that time, both squadrons had transitioned to the Dauntless, though their aircraft were not replaced yet, making the Hornet the last ship to operate the Helldiver aboard and aircraft carrier. 

The last SBC-4 Helldiver was built in May 1941 and, by 1944, the last SBC-3, was seriously obsolete and they were stricken off the inventory. The longest surviving one were a group of 12 aircraft, based at NAS Jacksonville, Florida, which were stricken on 31st October 1944.

Sources:

1. https://en.wikipedia.org/wiki/Curtiss_SBC_Helldiver

2. Signal Squadron - Aircraft In action 151 - SBC Helldiver in Action

3. https://www.valka.cz/Curtiss-SBC-Helldiver-t45473

Pics re-drawn from:

http://wings-aviation.ch/53-Military-Aircraft-in-Detail/Curtiss-Helldiver/Attack.htm

Grumman J2F Duck, part two

 

When the last production Grumman JF-3 rolled out the factory on 18th October 1935, Duck production was halted for a time until March 1936, when a completely new design was ordered.

Instead, Grumman decided to revise their G-20 design and, the result, called G-15 by the company, was given the designation of J2F by the US Navy. The J2F differed from the previous JF in many ways. It was powered by a 750 hp Wright R-1820-20 air-cooled radial engine with a short chord engine cowling. The float was extended forward by one foot (0.3048 meters), making the design longer than the regular JF Duck.

The J2F also was able of carrying more additional equipment to make the aircraft more multi-role, like target-towing, smoke-laying and photographic survey and reconnaissance, apart from medical evacuation as one stretcher could be fitted in the passenger compartment, in place of the usual two seats. It could also serve in the typical light-transport role. The airframe remained basically the same as the JF, with the exception of the longer float, and wings remained unchanged. 

The first J2F-1 flew on 3rd April 1936 and was delivered to NAS Anacostia, in Washington DC. It was equipped with fittings for a single 0.30 in machine gun, bomb racks on the lower wing, and a tailhook to operate from carriers. By 1937 a total of twenty-nine J2F1 were completed. 

The first J2F-1 was hold at Anacostia for testing purposes, one of which involved the installation of full span flaps on the trailing edges of the upper wing, to try and lower the landing speeds to 65 mph (104.607 km/h). This aircraft was unofficially known as the J2F-1A.

In 1938 Grumman was tasked with the manufacture of thirty J2F-2. This variant was powered by a 790 hp Wright R-1820-30 radial engine and was armed with a single forward-firing 0.30 in machine gun, plus a flexible one placed at the rear cockpit. This variant was mainly built of the Unites States Marine Corps.

During the next two years, nine J2F-2s were stationed at Charlotte Amalie, Saint Thomas, American Virgin Islands, as part of the neutrality patrols over the Caribbean Sea. Those J2F-2A Ducks belonged to VMS-3 and were modified with twin rear machine guns and two additional bomb racks under the lower wings. 

Twenty unarmed J2F-3s were ordered in January 1939 destined for the US Naval Attaches and the Commander of the US Naval Academy, prepared for VIP use. Those "admiral barges" (as they were commonly known) were plush and painted in dark blue and silver. The J2F-3 was powered by a 790 hp Wright R-1820-36 engine, driving a three-bladed constant-speed propeller.

During late 1939 and early 1940, as war was getting closer to the United State's borders, new military outposts were established. Therefore more Ducks were needed to support the extended patrol areas. The J2F was ideal for operating from those improvised outposts, which were usually shallow inlet facilities, or single ramp docking facilities. In September 1939 production of thirty-two J2F-4s began at Grumman. This version was the same as all previous variants, with minor modifications in cockpit instruments and engine operation.

Sources:

1. https://en.wikipedia.org/wiki/Grumman_J2F_Duck

2. Squadron Signal - Aircraft in Action Mini 7 - Grumman JF Duck

Grumman JF Duck

 

The Grumman JF Duck was an American single-engine amphibious biplane manufactured by Grumman during the 1930s decade.

The Duck was designed in 1932, inspired by the designs of previous amphibious aircraft like the Loening OL and was one of the first designs of the, back then, newly created Grumman. 

The prototype, XJF-1, flew for the first time on 24th April 1933, in Farmingdale, Long Island with Paul Hovgard at the controls.

The XJF-1 was a compact single-bay biplane with a crew of two, seated in tandem under an enclosed canopy. It was powered by a single Pratt & Whitney R-1830-62 radial engine and was armed with a single .30 in caliber flexible machine gun placed at the rear, operated by the observer. It could also carry a single 100 lb (45 kg) bomb under each lower wing. In the rear of the float, two passengers could be accommodated side-by-side. This compartment was accessed through a set of folding doors located in the floor of the rear cockpit. The float was faired into the fuselage, like previous Loening models did. The main landind gear retracted into the float, while the non-retractable tailwheel, mounted at the rear of the main float, acted as a water rudder too. It was also equipped with an arresting hook, which was mounted at the rear of the fuselage. 

The XJF-1 was delivered to the US Navy and underwent evaluation at NAS Anacostia, in Washington DC on 4th May 1933. As a result, the vertical tail surfaces were changed because the original triangular ones resulted in some longitudinal instability. The surfaces were redesigned to the broader squarer vertical surfaces found in the production models of the regular JF Duck. The XJF-1's tail was redesigned, redelivered and accepted into service. Unfortunately, the XJF-1 crashed in the James River on 8th March 1934 when operating with VX-1D5, a naval test and development unit, based at NAS Norfolk in Virginia.

The Duck was ordered into production in 1934. The production version differed from the prototype in having a different rudder, fin and its armament deleted (although it still had provision for a defensive machine gun) with a third crew member (a radio operator) was added. The US Navy issued a contract for twenty-seven JF-1 and the first JF-1 entered into service at NAS Norfolk, Virginia in May 1934. The US Marine Corps (USMC) also undertook the type during February 1935. In the US Navy the JF-1 served in VJ-1 (Utility Squadron 1), attached to USS Wright (AV-1) with detachments aboard the main carriers of the time, USS Saratoga (CV-3), USS Lexington (CV-2) and USS Ranger (CV-4) and also aboard USS Heron (AM-10) in the Asiatic Fleet.

It was also assigned at the Navy's main shore bases like Coco Solo in the Panama Canal Zone, Pearl Harbor in Hawaii and the Navy Yard, at Cavite in the Philippines. 

The JF-2 was a development of the JF-1 built in 1934-1935 for the US Coast Guard. The JF-2 were powered by a single Wright R-1820-102 rated at 700 hp. The JF-2 were equipped with a radio direction finder loop antenna placed on the fuselage spine behind the canopy and it lacked arrestor gear. The JF-2 served with the US Coast Guard from land bases in New Jersey, Washington, Florida, North and South Carolina, Mississippi, and California, as well as aboard USCG cutter Taney (WHEC-37), in Honolulu, Hawaii, the USCG icebreaker Spencer (WPG-36) in Cordova, Alaska, where it also served in the Bering Sea Patrol unit. Four JF-2 were transferred to the US Navy. 

The JF-3 was a further development built both for the US Navy and USMC reserve units in 1935. Only five of them were built and were powered by a single 750 hp Wright R-1820-80 engine. Like the JF-2 it also lacked the arrestor hook. A single JF-3 was delivered to each of the major reserve bases at NRAB Brooklyn, in New York, NRAB Seattle in Washington, NRAB Long Beach, California and NRAB Opa-Locka, in Florida. 

The JF Duck also had one foreign customer: Argentina. In 1937 Argentine Government bought eight Grumman model G-20 Ducks directly from Grumman. The G-20 was similar to the JF-2 used by the US Coast Guard. The first Argentine G-20 flew for the first time in December 1936 and by February 1937 they were all delivered. They replaced the outdated Vought O2U-1As in the Escuadrón de Observación Naval (Naval Observation Squadron). They operated from BAN (Base Aérea Naval - Naval Air Base) Comandante Espora, other Argentine Navy's bases like BAN Puerto Belgrano and aboard the cruisers ARA Almirante Brown (C-1) and ARA Veinticinco de Mayo (C-2). They served until 1948. 

Sources:

1. https://en.wikipedia.org/wiki/Grumman_JF_Duck

2. Squadron Signal - Aircraft in Action Mini 7 - Grumman JF Duck

3. https://www.valka.cz/topic/view/160020/Grumman-JF-1-Duck

4. http://wings-aviation.ch/51-Profiles/G/G-Basis-en.htm

5. http://elmuan.blogspot.com/2011/08/1937-grumman-g-15-y-g-20-duck.html (translated)

6. http://www.histarmar.com.ar/Armada%20Argentina/AviacionNaval/REC-AT-GrummanDuck.htm (translated)

Douglas B-23 Dragon

 

The Douglas B-23 Dragon is an American two-engined bomber developed by Douglas Aircraft Company as a successor of the B-18 Bolo.

Douglas proposed some modifications thought to improve the performance of the B-18. Initially, the XB-22 (the original project to re-engine the B-18 with Wright R-2600-1Twin Cyclone radial engines) was considered a redesign. The complete B-18 redesign was considered to have enough promise by the United States Army Air Corps (USAAC) to modify the original contract, and manufacture the last remaining 38 B-18s as the B-23 standard. The design incorporated a larger wingspan, with a wing design similar to that of the Douglas DC-3, a fully retractable undercarriage and improved defensive armament. In fact, the B-23 was the first American bomber equipped with a glazed tail gun position. It was equipped with three 0.3in machine guns set in various defensive positions plus a single 0.5in machine gun placed in the tail which was operated from the prone position by a gunner using a telescopic sight. It had a payload of 2.000 lb (910 kg), just like the Bolo, but it had a range of 1.400 milles (2.300 km) and was also faster. 

The prototype flew for the first time on 27th July 1939 and a total of just 38 machines were manufactured at Douglas' factory in Santa Monica, California, when production ceased in September 1940.

Even if it was faster, better armed and had a longer range than the Bolo, the B-23 couldn't be compared to other medium bombers of the time like the North American B-25 Mitchell and Martin B-26 Marauder. That's why the B-23 was never used in combat overseas, even if, for a brief period of time, they were employed as patrol aircraft operating in the west coast of the United States. The B-23s were relegated to training duties, although some were converted to transports and redesignated to UC-67. 

The B-23 was also used as a testbed for different engines and it was used for supercharger development by General Electric at Schnectady, in New York. 

After World War 2 all of them were sold to private owners and used as either passenger airplanes or executive transports, with pertinent internal modifications having been carried out and, therefore, many of them have survived. Thanks to the wartime experience with the type, General Electric bought and used five of them, and Howard Hughes had a converted one as his personal transport.

Some converted aircraft were sold to foreign countries like Ecuador, where its national airline, Ecuatoriana de Aviación, bought a single UC-67 in the late 1950s which was even used as that country's presidential transport. Another machine is known to have been sold to the Greek airline Scholai Delta and used at Hellenikon airport in Athens, as an instructional stationary airplane during the 1970s until it was completely broken off in the 1980s.

Sources:

1. https://en.wikipedia.org/wiki/Douglas_B-23_Dragon

2. https://www.valka.cz/Douglas-B-23-Dragon-t31133

3. https://es.wikipedia.org/wiki/Ecuatoriana_de_Aviación (translated)

4. https://www.airhistory.net/photo/8266/N86E

Douglas B-18 Bolo, part one

 

The Douglas B-18 Bolo was an American medium bomber which served with the United States Army Air Corps (USAAC) during the late 1930s and early 1940s. 

In 1934 the USAAC requested a bomber with double payload and range than the Martin B-10 which, was just entering service as USAAC's standard bomber. The next year an evaluation was carried out at Wright Field, Ohio, where Douglas showed their DB-1 design and competed with the Boeing Model 299 (which would eventually be improved into the Boeing B-17 Flying Fortress) and the Martin 146. 

Boeing's candidate was clearly superior, however, as pilots forgot to unlock controls when taking off causing the prototype to crash, it was removed from consideration and its high price per unit ($58.500 vs $99.620 of the Model 299 - $1.105.142 and $1.881.953 adjusted for inflation in the past year) also played a big factor in making the DB-1 as the chosen bomber. Therefore the DB-1 was ordered into mass production in January 1936 as the B-18.

The DB-1 design was basically the same as the DC-2 with many modifications. The wingspan was 4.5ft - 1.4m larger, the fuselage was deeper to better fit bombs and the six-men crew, the wings were fixed in the middle of the cross section instead of the bottom because of the deeper fuselage. It was equipped with three turrets, placed in the nose, ventral and dorsal positions, with this last one being retractable. Each turret was equipped with one Browning 0.3in machine gun. It could also carry a normal payload of 2.000 lb (910 kg) of bombs, however, it could be overloaded up to 4.400 lb (2.000 kg) at maximum. 

Sources:

1. https://en.wikipedia.org/wiki/Douglas_B-18_Bolo

2. https://www.valka.cz/Douglas-B-18-t72780

3. http://www.aviation-history.com/douglas/b18.html

Vought XSO2U

During the late 1930s the U.S. Navy developed a set of specifications for a new scout-airplane capable of operating from cruisers in the reconnaissance and gunnery spotting roles. This new machine was intended to replace the Curtiss SOC Seagull biplane. This aircraft was required to have folding wings, a superior range and speed to that of the Seagull, it had to be powered by the Fairchild Ranger V-770 inline engine.
Both Vought-Sikorsky and Curtiss-Wright submitted their designs. Vought's design, named internally as Model 403, was identical to the Vought Kingfisher, which was back then in development, intended to replace the Seagull on Battleships, but had its wings moved higher on the fuselage, when compared to the Kingfisher, and it was different in the attachment method used by its single floater landing gear. Additionally, the radial engine of the Kingfisher was replaced by the Ranger V-770 inline engine which yielded 450 hp of power.
The XSO2U was capable of operating both on floats as a seaplane, or with a conventional fixed undercarriage, as a landplane. It was entirely made out of metal with the exception of its control surfaces which were fabric-covered. The wings could be folded to rear for storage in a way similar to those of the Grumman TBF Avenger torpedo bomber.
The aircraft had diving bombing capabilities and could be fitted with a single bomb or depth charge on hardpoints under each wing. It was armed with two M2 0.5 in (12,7 mm) Browning machine guns, one forward firing through the propeller using synchroniser gear and the other in a flexible position in the observer's cockpit for defensive purposes.
The XSO2U flew for the first time in July 1939 in the landplane configuration and it wasn't until December that year that it flew with floaters. Flight testing showed that the aircraft lacked directional stability, but the addition of a larger ventral fin, connecting the rear of the float to the tail, helped to solve the problem.
It also suffered from engine problems as the Ranger engine wasn't known for its reliability. It was particularly prone to overheat and a solution for that problem could never be found. The prototype's original engine, V-770-4 was replaced by a XV-770-6 which featured a repositioned oil cooler, but the problem persisted.
In spite of the engine's overheating problems, it was considered superior to the competing Curtiss XSO3C-1 Seamew. However, Vought's manufacturing capacity was already taken by the Kingfisher and the F4U Corsair fighter (the first version of which was already into production in 1942), so the XSO3C-1 was considered as the winner of the contract and entered, therefore, into production.
After the competition, the XSO2U was used as a general utility aircraft and hack by the US Navy, before being given to the Ranger Engine Corporation in July 1942 for testing the V-770 engine. This testing was intended to help debugging for the Bell XP-77 light fighter and the Edo XOSE floatplane. The engine kept on being problematic and, after two years of testing, it was returned to the US Navy. As the airplane had no use for the Navy, it was therefore written off on 6th July 1944 and was subsequently scrapped.

Sources:
1. https://en.wikipedia.org/wiki/Vought_XSO2U
2. Mc Farland - United States Naval Aviation, 1919-1941
3. Signal Squadron - Aircraft In action 119 - Vought OS2U Kingfisher in Action

Vought OS2U Kingfisher, part five

The Vought OS2U Kingfisher was designed by Vought's main designer Rex B. Beisel as he was tasked with designing an observation monoplane aircraft for the US Navy that could commit many tasks like directing Battleship fire. By replacing the standard Vought O2U Corsair biplane, Beisel incorporated production innovations as it was the first production type to be assembled with spot welding, a process developed jointly by both Vought and Naval Aircraft Factory in order to create a smooth fuselage resistant to buckling and with less drag. Biesel also introduced high-lift devices, spoilers and deflector flaps and drooping aillerons located on the trailing edge of the of the wing. This arrangement was unique to the Kingfisher, and were deployed to increase the camber of the wing creating, therefore, additional lift.
It was armed with a single 0.30 in Browning machine gun, with the receiver mounted low in the right front cockpit, which fired between cylinder heads, with another one, mounted on a flexible Scarff ring, for the radio operator/gunner. It could also carry two 100 lb bombs or two 325 lb depth charges. Additionally, the Kingfisher (as it was designated), was used as a trainer in both landplane and seaplane variants.
The prototype flew for the first time in 1938 and was powered by a 450 hp Pratt & Whitney R-985-4 Wasp Junior radial engine. The first variants, called OS2U-1, were powered by the Pratt & Whitney R-985-48 air-cooled radial engine which yielded 450 hp of power. The second variant, was powered by a slightly improved variant of that same engine, P&W R-985-50 and was named OS2U-2 , the third variant, OS2U-3 was powered by a P&W R-985-AN2 and some of them, manufactured by the Naval Aircraft Factory, received the denomination of OS2N-1. All of them yielding 450 hp of power. A fourth variant, OS2U-4 was in the works, with narrow-chord and high-aspect ratio wings, fitted also with full-span flaps, however it wasn't developed.
A total of 1519 machines were manufactured of every variant at Vought-Sikorsky Aircraft Division's factory in Stratford, Connecticut and the Naval Aircraft Factory in Philadelphia.

Sources:
1. https://en.wikipedia.org/wiki/Vought_OS2U_Kingfisher
2. Signal Squadron - Aircraft In action 119 - OS2U Kingfisher in Action
3. https://www.valka.cz/topic/view/141347/Vought-OS2U-1-Kingfisher
4. https://www.valka.cz//topic/view/1179

Vultee P-66 Vanguard

During the late 1930s Vultee Aircraft Division conceived what later would be the Vultee Vanguard from a set of common wings ,aft fuselage and tail assemblies. Four designations were assigned by the company, V-48 for a single-seat fighter, BC-51 for a double-seat basic combat trainer, B-54 for an advanced combat trainer (where BC-54D would be the basic trainer variant). Eventually, the BC-51 became the Army Air Corps BC-3 and the BC-54D became the Vultee BT-13 Valiant.
Therefore, in 1938, Richard W. Palmer, designed the V-48 fighter. It featured a metal-covered, semi-monocoque fuselage and fully retractable landing gear. It was powered by a 1200hp Pratt & Whitney R-1830 radial engine. When the first prototype was being constructed, a decision was taken to lengthen the propeller shaft and install a tight cowling to provide a pointed nose to reduce drag. That way, the first prototype made its maiden flight in September 1939 piloted by Vance Breese. Nicknamed "Vanguard", on the 9th May 1940, when performing a test flight, the prototype collided with a Lockheed Sirius, while landing at Vultee airfield, severing one of the undercarriage legs. However, Breese managed to skillfully land the fighter with little additional damage. The prototype was subsequently rebuilt with the orthodox cowling that was employed in the subsequent exemplars.
Flight testing revealed inadequate cooling, however, measures to modify the cooling ducting were of little avail. The design was re-evaluated and it was reached to the conclusion that the insignificant drag reduce wasn't worth the added weight and ducting problems. The second prototype, named V-48X was modified with a conventional cowl, and the first aircraft was subsequently modified.
It flew for the first time on 11th February 1940 and, as result of flight tests, changes were made to the design including substantially increasing the areas of the horizontal and vertical tail surfaces.
On 6th February 1940 the Swedish government ordered 144 Vanguards which were labelled as the V-48C. The production prototype flew later on 6th September 1940. The model V-48C was similar to the V-48X except for the engine which was a later version of the R-1830 engine with a better high-altittude performance and provision for four 0.30in (7.92mm) machine guns in the wings and two 0.50in (12.7mm) machine guns in the fuselage.
When the aircraft was placed into production in September 1941, the U.S. Government placed an embargo on exporting the aircraft to Sweden. After the attack on Pearl Harbor and the subsequent reorganization of the U.S. Army Air Corps, they were given the designation of P-66. Production ended in April 1942 with around 50 aircraft were retained by the USAAF and used them mainly at pursuit training bases in the Western U.S. assigned to the 14th Pursuit Group in defensive roles. Pilots were impressed by the P-66s handling, however it was considered less than robust and a tendency to ground-loop destroyed more than 15 aircraft in landing accidents.
The British government took possesion of 100 P-66s which named them as Vanguard I with the intention of using them as advanced trainers in Canada. However, they reliquished the aircraft to China where 104 Vanguards, some of them being USAAC's machines, were shipped under lend-lease program. They were originally intended to serve with the 3rd American Volunteer Group (AVG), but plans for additional groups were discarded after the attack on Pearl Harbor.
In late 1942 the Chinese received the machines via India and they were pushed into service with USAAF insignia and serials as well as Chinese markings and Vultee serials on factory models.
It didn't have a distinguished career in China due to problems that began back in transit towards China when some were destroyed in tests in India and others were lost while en route to China. Most of the assembled P-66 were not marked as airworthy and were abandoned in Karachi, with just 12 Vanguards serving in Kunming with the 74th Fighter Squadron, 23th Fighter Group where they barely saw any action at all.
Two Chinese squadrons from the 3rd and 5th Groups, based at An-Su, saw some combat action with the Vanguard from August 1943 onwards. However, many P-66s were shot down on the ground during Japanese attacks and many others were shot down by friendly fire when they were mistaken for the Nakajima Ki-43 and Ki-44. Even if the P-66 had a decent top speed of 340mph (550Km/h), it wasn't a rival for the agile Japanese fighters in high-g maneouvers and they had to employ hit-and-run tactics against the Japanese.
In Chinese service, the P-66 was replaced by the Curtiss P-40 in 1943. Some few P-66s were placed in storage at caves for use in the upcoming civil war against the Chinese communists. However, as late as 1947 they were still in their crates and it's not known that they were using after World War II.

Sources:
1. https://en.wikipedia.org/wiki/Vultee_P-66_Vanguard
2. Salamander Books - The Complete Book of Fighters

Boeing P-26

The Boeing Company funded the project to produce the Boeing Model 248 in September 1931, with the US Army Air Corps supplying the engines and instruments. The design included an open cockpit, fixed landing gear and externally braced wings and it was the last of such design procured by the USAAC as a fighter aircraft. The original Model 248 had a very high landing speed which caused many accidents, so in order to remedy that, flaps were fitted to reduce landing speed. The USAAC ordered three prototypes, under the name of Boeing XP-936 with the first flight taking place on 20th March 1932.
The prototype was still hard to land and sometimes, due to its short nose, it rolled onto its back and would flip forward, injuring, or even killing, the pilot. The prototype's unarmed headrest offered virtually no protection in such cases, so the production model, called Model 266 (Boeing P-26A) had a taller armoured headrest installed.
The P-26A version was powered by a single Pratt & Whitney R-1340-27 "Wasp" with a power of 600hp while subsequent versions, the P-26B and C were powered by the R-1340-33 fuel-injected engines. The C version had modified and optimized fuel systems and all of them were armed with two 0.30in (7.92mm) M1919 Browning machine guns or one 0.30in and one 0.50in (12.7mm) calibre machine guns and could carry up to 90Kg (100lb) of bombs.
Back in the early 1930s it was the fastest American fighter aircraft to serve with the USAAC. However, as the aircraft technology was developing very quick, it soon became obsolete with wire-braced wings, fixed landing gear and open cockpit. For comparison purposes, the Dewoitine D.500 flew for the first time the same year as the P-26 and the Soviet Polikarpov I-16 was already flying with retractable landing gear by 1934, just two after the P-26. By 1935, just two year after the P-26 was designed, the Curtiss P-36, the Messerschmitt Bf.109 and the Hawker Hurricane, were all flying with enclosed cockpits, retractable landing gear and cantilever wings. However, as the P-26 was easy to flight, it remained in service with the USAAC until the United States entered the World War II.
It was delivered to the USAAC's Pursuit Squadrons in December 1933 with the last production aircrafts rolling out of the factory in 1936, under the designation of P-26C. Twenty-two squadrons flew the P-26, with peak service being six squadrons in 1936. They were the frontline fighter of the USAAC until 1938 when the Curtiss P-36 and the Seversky P-35 began to replace the P-26. Twenty of them were lost in accidents between 1934 and 1941, but only five before 1940.
They were also assigned to overseas deployment to supplement the Seversky P-35 at Wheeler Field, in Hawaii between 1938 and 1940 and, while some of them remained there as trainers, others were sent to Albrook Field, in the Panama Canal Zone, were nine of them were active in December 1941. They also served with the 3rd Pursuit Squadron of the 4th Composite Group, based in the Philippines and they were sold between 1937 and 1941 to the Philippne Army Air Corps.

Sources:
1. https://en.wikipedia.org/wiki/Boeing_P-26_Peashooter
2. Salamander Books - The Complete Book of Fighters.

Curtiss SOC Seagull, part two

The first ship to receive the SOC Seagull was the light cruiser USS Marblehead (CL-12) in November 1935 and, by the end of that decade, it had replaced completely its predecessor troughout the fleet. Production ceased in 1938 as the Vought OS2U Kingfisher was chosen as its replacement.
So, by 1941 most battleships had transitioned towards it and cruisers were expected to replace their Seagulls with the newly arrived Curtiss SOC Seamew.
However the Seamew suffered from a weak engine and plans to adopt it as a replacement were scrapped. Therefore, the SOC Seagull continued to be employed in observation and artillery spotting missions, despite belonging to an earlier generation.
Through the first six months of service, it was known as XO3C-1, but its designation changed when it was decided to merge its scouting and observation roles. It wasn't until 1941 that it received the Seagull nickname, when the US Navy began adopting popular names for aircraft in addition to the alpha-numeric designations. The name Seagull was also previously given to two civil Curtiss aircraft, Model 18 and Model 25 both of them converted from Curtiss MF flying boats.
When it operated from cruisers, as a seaplane, the returning ones landed on the smooth ocean surface created on the sheltered side of the vessel, as it made a wide turn, after which the aircraft would be winched back onto the deck.
When it was replaced by the OS2U Kingfisher, most aircrafts were converted into trainers and remained in service until 1945. When the SOC3 Seamew failed, many SOC Seagulls that had been relegated to second line duties, were returned to frontline units from late 1943 onwards and saw service aboard warships in combat zones for the remaining of World War II. It has been one of the cases where an older aircraft type, that was retired or pushed back to a secondary role, replaced the new aircraft that was intended to replace it.

Sources:
1. https://en.wikipedia.org/wiki/Curtiss_SOC_Seagull
2. https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=832
3. http://www.pacificwar.org.au/Midway/RalphWilhelm/SeagullIndex.html

Curtiss SOC Seagull, part one

The Curtiss SOC Seagull was an American single-engined scout observation aircraft, which was designed by Alexander Solla when he was working for the Curtiss-Wright company for the United States Navy. It served on board of Battleships and Cruisers in a seaplane configuration, being launched from catapults and recovered from sea landings and also by the United States Marine Corps which used them, limitedly, in the scout role, specially in the years previous to America's entry into World War II.
The wings could be folded back to be storaged aboard the ship and floaters could be replaced by fixed landing-gear to make it operate from shore bases or carriers.
A total of 285 SOC aircraft were manufactured, from every variant from SOC-1 to SOC-4 with the production beginning in 1935 and the SOC-3 being the basis for the Naval Aircraft Factory SON-1 variant of which 64 of them were delivered in 1940.
The prototype flew for the first time in 1934 and every versions were powered by a single Pratt & Whitney R-1340-18 nine-cylinder air-cooled radial engine which yielded a power of 550hp. It had a crew of two, and was armed with one fixed forward-firing 0.3in (7.62mm) Browning M2 AN plus one defensive rear-firing 0.3in Browning M2 AN. It could also carry a payload of 650lb (295Kg) of bombs carried under lower wings.
It was ordered for production by the United States Navy in 1933 and entered service in 1935. The first production order was of 135 SOC-1 models, followed by 40 SOC-2 variants with fixed landing gear for landing operations both carriers and shore bases. A third variant known as the SOC-3 was built by the Naval Aircraft Factory, as we told before and received oficial denomination of SON-1.

Sources:
1. https://en.wikipedia.org/wiki/Curtiss_SOC_Seagull
2. https://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=832

Curtiss O-52 Owl

The Curtiss O-52 Owl was an American observation aircraft which was used by the United States Army Air Corps and some others just before the American entry into World War 2.
It was developed in 1939 and it was the last 'heavy' observation aircraft developed for the USAAC as the concept of an observation aircraft with two seats dated back to the World War 1 and, in 1940 the USAAC ordered 203 O-52s for observation duties. However, by 1941 it was already outdated and was no match for modern combat aircrafts.
Just after delivery, it was used in military maneouvers with the USAAC, but after America's entry into World War 2, it was deemed as outdated by the USAAF, specially for operations in overseas areas, therefore, it was relegated to courier duties within the USA and short-range anti-submarine patrols over the gulf of Mexico and Atlantic and Pacific Oceans. Apparently it was used briefly in the frontline in the battle of Luzon, in Philippines during Japanese offensives in 1941-1942.
It was the last "O" type aircraft manufactured for the USAAC and, after the Japanese attack on Pearl Harbour, that designation was discontinued and was replaced by the "L" series for liaison type.
It seems that the Brazilian Air Force adquired some of them in 1942 but they remained there and weren't sent to Europe with the Brazilian Expeditionary Force. However, as we couldn't find any proof of this aircraft serving with Brazil, the drawing should be considered as speculative.
It was powered by a Pratt & Whitney R-1340-51 radial engine which yielded a power amount of 600hp (447Kw) and was armed with a single forward-firing Browning 0.3in (7.62mm) machine-gun and another one in defensive position.
In November 1942 the USSR ordered 30 O-52s through the lend-lease programme with 26 of them being shipped but with just 19 of them being actually delivered as seven of them were lost in the Arctic Convoy Route. Of those 19, only 10 of them were accepted into service and were used operationally for artillery fire spotting and general photographic and observation duties in north and central areas of the Eastern Front during spring-summer 1943 with one of them being shot-down by the Luftwaffe. It was generally disliked by Soviet pilots, although some of them were still active during early 1950s with the Aerogeologiya organization which was a branch of the Soviet ministry for Geology that performed aerial geological surveys, specially in the vast Siberian region.

Sources:
1. https://en.wikipedia.org/wiki/Curtiss_O-52_Owl
2. https://www.sas1946.com/main/index.php?topic=26029.0

Bell YFM-1 Airacuda

Materializing many innovative features and designed by Robert J. Woods, the Airacuda was a five-seat long-range bomber destroyer. It was powered by two engines in a pusher configuration and it accommodated two gunners in forward extensions of the engine nacelles. Those crew members were provided with wing crawlways in order to reach the main fuselage in the event that it was needed to evacuate the nacelle gun positions.
The first prototype XFM-1 was powered by two 1150hp Allison V-1710-13 12-Cylinder liquid-cooled engines which drove three-blade propellers via 64-in (1.62m) extension shafts and flew for the first time on 1st September 1937.
Twelve further evaluation models were ordered, nine as YFM-1 and other three YFM-1As which was different just in having tricycle undercarriage. The engines kept being two 1150hp Allison V-1710-23s, but three of them were fitted with the V-1710-41 of 1090hp as YFM-1Bs. The 12 YFMs were delivered to the United States Army Air Corps between February and October 1940 and they were armed with one 37mm T-9 cannon in each gun nacelle with 110 rounds each, plus one 0.3in (7.62mm) M2 machine gun with 500 rounds in each of the retractable dorsal turret and ventral tunnel positions and one 0.5in (12.7mm) M2 gun firing from each of the port and starboard beam positions. Twenty 30lb (13.6Kg) bombs could be fitted internally.
During flight testing performed by Bell, many problems and flaw were encountered with two of them being lost to accidents and most of them being damaged. The most accident occurred to an YFM-1A on a flight between Chanute Field, Illinois and Keesler Field, Mississippi when a broken oil line sparked a fire due to some serious fuselage vibration encountered during the flight. As there wasn't any way of extinguishing the fire, both pilot and crew chief agreed to bail out. The pilot was killed as his parachute didn't open. That was the only fatality occurred during the testing of the Airacudas.
In spite of all those problems, a full operation Airacuda squadron was assembled and operated from 1938 to 1940. Funds were appropriatted but never released for the purchase of two further groups of Airacudas. However, as the continued problems persisted, the aircraft received the reputation of "hangar queens". Near the end of the aicraft's operational life they were flown mainly for photo oportunities and always accompanied by a chase plane for security purposes. It was decided eventually to disperse the aircraft through various airfields to give pilots the chance to add the unusual aircraft to their log books, so they were sent to Langley Field, Virginia, Maxwell Field, Alabama, Hamilton Field, California and Wright Field, in Dayton, Ohio. One of them was displayed at the 1940 New York World Fair finished with the colours of the 27th Pursuit Squadron but during this time the aicraft saw limited flight time as pilots weren't interested in flying the unusual aircraft.
Many plans were made to modify them to make them operational, including the modification of the airframe and adding more powerful engines but all of them were rejected. In early 1942 despite the danger of enemy attacks against American bombers, the Airacuda was rejected.

Sources:
1. Salamander Books - The Complete Book of Fighters
2. https://en.wikipedia.org/wiki/Bell_YFM-1_Airacuda