Curtiss BF2C Goshawk (1933)

USN Carrier Fighter 1934-1936 (164 built)

Curtiss last naval fighter

The Curtiss BF2C Goshawk (Model 67) was a 1930s naval land-based biplane fighter that was the last of a long series made by the Curtiss for the Navy. It was also distribtuted internationally as the Model 68 Hawk III. Developed from the very similar F11C-2 featuring a land-based undercarriage, the latter was used by several squadrons in the Navy, was considered sturdy enough for carrier operations, but the undercarriage was also a source of drag. Thus the USN, wanted, if possible that Curtiss integrated a retractable undercarriage on the F11C-2 as it possessed development potential. Grumman, which had some experience back then on these, was tasked to to procure a retractable landing gear to match the Curtiss Goshawk.

proto

This variant had still the same wooden wing with a flat-bottomed Clark Y airfoil. It was first tested as the XF11C-3 by the Navy, internally the Curtiss Model 67. Its main gear retraction system was inspired by the Grover Loening system of the Grumman XFF-1 prototype. It was simple, rugged, but manually operated. The prototype was tested by the USN in May 1933 with a Wright R-1820-80 radial engine (700 hp/520 kW) and showed 17 mph (27 km/h) faster but with a decrease in maneuverability. For production the wing was replaced by an all-metal frame biconvex NACA 2212 airfoil. The XBF2C-1 (or Model 67A) as tested was was thought to be tough enough to be used as figher and doubling as dive bomber.

⚠ Note: This post is in writing. Completion expected in September 2026.

In the ensuing weeks of testing however a slew of issues appeared and thus, only 27 of the final BF2C were ordered by the Navy. It was deployed from late 1934 to VB-5B, on USS Ranger (green tail). However performances were mediocre and the manually lowered landing gear was a major distraction for the pilots which also needed to keep sight with the flight deck, a task already made difficult by the long nose. The very production machine flew by October 1934 and the last by December. But in 1935, after barely a year in operation, and with alternatives proposed by Grumman itself, the FF and its announced F2F fighter which flew already in 1934 as the XF2F-1 and was demonstrated to the Navy, not only Grumman soon became its primary supplier of the USN, but the BF2C Goshawk became the last Curtiss fighter of the USN.

Only 27 of these, retired after unflattering Comparisons with the F2F in early 1935. In 1936, the B2FC was relegated to its Naval Air Station. There, the BF2C-1 Goshawk was still the primary aircraft flown by VB-5B, but the Navy had been fed up with its "Vibration" Issue coming from its landing gear and wing structure during steep dive-bombing runs. Following a fatal structural failure during an exercise, the U.S. Navy entirely withdrew the BF2C-1 from frontline fleet service after only a few months of operations. It seems they were parked for training, until a better model, also from Curtiss, the SBC Helldiver biplane, showed more potential as dive bomber.

The last Navy "Hawk"

Until December 1932, Curtiss and Boeing were the primary suppliers of single-seat carrier-based fighters to the U.S. Navy. Initially, when the Navy operated the USS Langley and fielded just two carrier-based fighter squadrons, there was virtually no competition between the two firms. The military purchased aircraft in small quantities from both, aiming to support both alternative sources equally. But the situation changed in 1927, with the commissioning of the new, large and fast USS Lexington and Saratoga. Each could accommodate up to 90 aircraft verus at best 34 on Langley. These became the first true fleet carriers, arguably ones of the best worldwide. The number of carrier-based fighter thus squadrons tripled, and so the Navy’s minimum fighter requirements, estimated at 120–150 aircraft. As the cost of a fighter at the time ranging from $13,000 to $15,000 (Boeing F4B-1 $15,000. Curtiss P-6E $13,000), the total contract value could exceed $2 million.

For this new lucrative contract Curtiss and Boeing turned into ruthless rivals and in the end Boeing won with its F4B-1. and the onset of the Great Depression in 1929 dealt the final blow to Curtiss. Boeing remained with an absolute monopoly and sold the Navy more than 230 F4Bs of various models. Then Grumman entered the chat by December 1932. It started to challeng Boeing's position through the FF-1 all-metal carrier-based fighter with retractable landing gear. The latter was designed by the company.

So by 1933, as Grumman worked already on ts F2F fighter, Curtiss had Navy officials praising the promising F11C Goshawk fighter. 29 modified ones were to be ordered as F11C-2 and to consolidate its position and expand deliveries, Curtiss decided to purchase Grumman's retractable landing gear, into the F11C design. This became the "Curtiss Model 67". The Navy followed this development and approved of it. Engineers were assigned the 5th production F11C-2 (serial 9269). Its main landing gear installed was the same as the design patented by Grumman without much change but to fit the Curtiss model. The wheels retracted into dedicated recesses underbelly, which forced the adoption of a bulgy appendice past the engine.

This was the only way, and broke the streamliness for lowring the drag. The pilot had to operate it, through a chain drive from a cockpit handle. To accommodate these recesses and retraction mechanism plus the landing gear proper, the forward fuselage was much deepened, and its structural weight took 104.4 kg. Balance was reclaculated and for this, the upper wing was shifted slightly forward. The other novelty was a semi-enclosed cockpit, thanks to a small sliding canopy. The pilots usually hated enclosed cockpits, but this one could be left open and gave any good visibility all around.

So 1934, a similar canopy was installed on the BFC-2 fighter-bomber variant. By the spring of 1933, he Navy designated the final prototype XF11C-3 after which it made its first flight in April 1933. On next May 27, it was handed over to the Navy for final evaluation trials, from which a report from naval pilots recorded notably a takeoff weight of 2,181 kg and top speed of 348 km/h, altitude of 2,439 m thanks to its 700 hp Wright R1820-80 9-cylinder air-cooled radial with standard Hamilton all-metal fixed-pitch propeller. Curtiss worked on a ground-adjustable pitch propeller for better flight performance but it was never done. The XF11C-3 outperformed the former F11F-2, by 22.5 km/h in top speed tanks to the lower drag and more powerful engine.

Trials led to modifications such as controllable trim tabs plcaed on the ailerons and rudder and new flights showed all major issues had been ironed out. Thus by February 26, 1934 at last, the Navy ordered twenty-seven F11C-3, to be deployed on the brand new aircraft carrier USS Ranger. However, plans were for Boeing F4B-4 aircraft as fighters and the Curtiss were instead rebranded as fighter-bombers (BF2C-1). For this, the upper wings, with its original wooden structural framework was replaced with a lighter metal one. There was a new mounting point that could be used to release either a 227 kg bomb or 189-liter fuel tank. This new recess sat between the landing gear retraction fairings. There was no fork enabling to sling the bomb below the propeller's radius though, so the dives were never full vertical but always at an angle where gravity took care of the bomb's path,clearning the propeller's arc.

Curtiss's "Flying Jackhammer"

However Curtiss was never far away for bad news. In flight testing on September 24, 1934 at NAS Hampton Roads (Virginia), the sole XFB2C-1 crashed on takeoff after an engine failure. The Navy did not reported on this badly as it had previous logged some 254 hours testing. So the order was maintained and the first left the factory floor on October 7, 1934 with its final engine, a R1820-04 radial engine rated for 700 hp at 2,438 meters. Each unit cost the Navy (and American taxpayers) $18,000 and the engine itself represented a third of it.
The first arrived at VB-5B belonging to USS Ranger, the first landings and take-offs for qualifications being performed in November 1934. This was the first time the Navy had a versatile aircraft, capable of operating in the same mission as fighter and dive-bomber. In the fighter configuration its takeoff weight was 2,068 kg for a top speed was 362 km/h but when carrying a bomb it took 241 kg, and was still able to reach 346 km/h.

However if Navy tests pilots were please with the model on land, with enough rotations on USS Ranger, a report lambasted the model. Pilots roasted the Goshawk. They expressed their frustration on the report on a major issue:
In cruising flight, wings would vibrate so much the BF2C-1 received the nickname of "flying jackhammer". This was never identified in flight tests and could only be reproduced in dedicated trials. In the end, it was solved. The liquid-cooled V1570 inline engine mounted in front had its airflow affecting the airframe but the tests proceeded with a smaller, earlier engine and these oscillations never occur. There was a resonance between natural frequencies of the engine and wings.
The second issue was common to it and the earlier model, and was related to the poor view from the cockpit, notably to land on any deck. An issue solved by Grumman and partly solved by Curtiss on the SBC dive bomber.
The third issue was a tail assembly vibration when a load was carried on the centerline pylon. This was fixed with an annular airflow stabilizer mounted ahead, looking like a retractable oil cooler.

To fix the wing vibration issue, Curtiss engineers attached weights to the wingtips to alter the harmonic oscillation frequencies. But flight tests showed that now the overloaded struts and bracing wires started to to fail. The test pilot had to land quickly to avoid all cables to part. Curtiss then proposed to swap the new metal-structured wings for export models (Hawk III) wooden wings which never shown such oscillation. However the Navy reclined at the cost of such conversion. Months went on as all this happened, and in between the Navy ordered a large batch of Grumman F3F fighters. Plus, the Navy ordered from Curtiss a deidicated dive bomber, the SBC Helldiver (the first one).

Design

"The aircraft was a single-engine, single-seat, carrier-based fighter-bomber of mixed construction featuring retractable landing gear. The fuselage was functionally divided into three sections: forward (nose), middle (center), and aft (tail).

Specifics

The fuselage utilized a truss structure, a characteristic feature of all the company's previous fighters. The trusses consisted of welded steel tubing. Duralumin L-section stringers were used for the longitudinal members of the center and aft fuselage sections. The engine, along with its instruments and fuel and oil system components, was mounted on an engine mount in the forward fuselage. The engine was enclosed by a quick-release duralumin NACA-type cowling. Located between the cockpit and the engine were the oil tank, two fuel tanks, the main landing gear retraction wells, and the machine guns with their ammunition boxes.

The landing gear retraction and extension mechanism was mounted on a structural bulkhead. On the underside, in the landing gear installation area, the fuselage featured a central recess equipped with mounts for an external fuel tank or a 227 kg bomb. The forward fuselage was enclosed by quick-release duralumin panels, providing convenient access to the machine guns, oil and fuel tanks, and the main landing gear retraction mechanism. The semi-enclosed cockpit was located in the central section of the fuselage.

A windscreen consisting of three rectangular Plexiglas panels protected the pilot from the front. A telescopic sight was mounted on two struts ahead of the windscreen. The pilot's head was shielded on the sides by a canopy section that could slide rearward when necessary. The height-adjustable pilot's seat consisted of two contoured duralumin sections. The seat's headrest featured a soft, leather-covered cushion. There was no armor protection.

The main landing gear units were of the pyramidal type, equipped with oleo-pneumatic shock absorbers. The retraction and extension system was typical of early American aircraft with retractable gear from the first half of the 1930s. Retraction was achieved by pulling the gear legs into the fuselage using a chain drive operated by a hand crank on the left side of the cockpit; the wheels stowed into dedicated recesses in the fuselage side panels. The landing gear struts were attached to a reinforced structural bulkhead that also served as a firewall. The main landing gear wheels were equipped with pneumatic shoe brakes. The strut for the free-swiveling tailwheel featured rubber shock absorption.

Instrumentation was located on the central instrument panel and on the lower central panel—the so-called "beard." Some controls and equipment (such as the throttle lever and the stabilizer incidence control wheel) were positioned along the cockpit sidewalls. The mid-fuselage section was fabric-covered. The tail section of the fuselage began immediately aft of the cockpit. Its upper portion formed a fairing (or dorsal spine) covering the area behind the pilot's headrest, enclosed by duralumin panels.

Navy standard survival gear—including an inflatable rubber raft, food and drinking water supplies, and signal flares—was stowed beneath a removable panel in this fairing. Radio equipment units were installed in the lower part of the aft compartment; a rectangular, quick-release access hatch in the left fuselage side allowed for their maintenance.

Lifting surfaces

The aircraft featured a biplane configuration with an all-metal structure. The upper wing consisted of a center section and outer panels. The wing's internal structure comprised two spars and a series of ribs. The wing spars were of the duralumin box-girder type. The ribs were also made of metal. Special compartments at the wingtips housed flotation bags—containers made of rubberized fabric designed to keep the aircraft afloat during a forced water landing. The pilot could inflate these bags with compressed air using a valve located to the right of his seat. The trailing edge of the upper wing's center section featured a cutout to improve upward visibility.

The lower wing consisted of right and left panels and was similar in construction to the upper wing. Each lower wing panel was equipped with two racks for 45-kg bombs. The upper and lower wings were interconnected by two N-struts; similar struts attached the upper wing to the fuselage. A Pitot-static tube for the airspeed indicator was mounted on the right wing strut. The wing bracing consisted of paired steel cables. Ailerons were located only on the upper wing. Aileron control was achieved via a rigid linkage system using push-rods extending from the lower wing. The wings were fabric-covered, while the ailerons featured duralumin skinning.

The tail unit was of mixed construction. The structural framework—comprising spars and ribs—was made of aluminum alloy, while all tail surfaces were fabric-covered. The rudder featured aerodynamic horn balancing. Trim tabs were installed on both the rudder and the elevators. The stabilizer design allowed for the adjustment of its incidence angle via a screw mechanism. To ensure structural rigidity, the stabilizer and fin were braced against each other with tension cables. The flight control surfaces are cable-operated.

Engine & Performances

The aircraft's powerplant consists of a Wright R-1820-04 Cyclone nine-cylinder air-cooled engine. Most aircraft of this type lacked an exhaust manifold; instead, each cylinder was equipped with an individual exhaust stack that directed exhaust gases away from the fuselage and into the airflow. Engine control was managed via a throttle lever mounted on the left side of the cockpit. The aircraft were fitted with Hamilton Standard two-blade, variable-pitch metal propellers. Fuel was carried in two unprotected fuselage tanks with a combined capacity of 418 liters.

The forward lower tank (209 liters) was located immediately behind the main structural bulkhead and the main landing gear wheel wells. The rear upper tank, of equal capacity (209 liters), was positioned slightly above and behind the forward one. They were not interconnected and featured separate filler necks. Fuel was consumed alternately from the forward and rear tanks. Their placement near the center of gravity ensured that the aircraft's balance and handling characteristics remained unaffected. An additional 189-liter external drop tank could be mounted on the underside of the fuselage. A 34-liter oil tank for the engine was installed immediately behind the engine, forward of the fuel tanks.

Armament

The BF2C-1 carried an armament of two 7.62mm Brownings and made provision for a single 215kg bomb or up to four 53kg bombs. The aircraft's armament comprised both bombs and guns. The latter consisted of two synchronized fuselage-mounted 7.62 mm Colt-Browning machine guns, each with an ammunition supply of 600 rounds. Four bomb racks carried small bombs weighing 45.3 kg or 52.6 kg, while a single 227 kg bomb could be carried on the central under-fuselage hardpoint.

⚒ Curtiss BF2C specifications 1934
Dimensions	Wingspan 9.60 m (32 ft 6 in), fuselage 7.01 m (23 ft); Height 3.30 m (11 ft 10 in)
Wing area	24.34 m2 (261.99 sq ft)
Weight, empty	1,529 kg (3,371 lb)
Weight, Max TO	2,066 kg (4,555 lb)
Propulsion	Wright R-1820-04 Cyclone 9-cyl. AC radial: 700 hp
Propeller	2-bladed constant-speed propeller
Speed, max.	362 km/h (225 mph)
Ceiling	39,500 ft (12,000 m)
Climb Rate	2,303 ft/min (11.70 m/s)
Range	917 km (570 miles)
Wing load	17.4 lb/sq ft (or 84.8 kg/m²) based on its gross weight
Power/mass	0.17 hp/lb (or 278 W/kg) on its gross weight
Armament:	2 × 0.3 in (8 mm) Browning MGs, Bombs/drop tank (3 racks)
Crew:	One Pilot

The Goshawk in the U.S. Navy

As seen above, 27 Curtiss BF2-C Goshawk were ordered, and deployed on USS Ranger as fighter bombers in on VB-5 from October 1934. In addition to their central payload harpoint, and two 0.30 cal. Browning machine guns furing though the propeller arc they had two more hardpoints for 500 lb (230 kg). But as soon as carrier pilots flew it, they noted serious issues. The wing vibration was so bad, pilots were constantly adjusting the output to avoid resonance with the engine, and no standard cruise speed could be sustained as they would result in such shaking the flighter would just dislocate itself apart. That, plus the underpylon vibration issue, the bad visibility when landing, and the issue of manually lowering the undercarriage, which kept the pilot busy at a critical phase, made it unpopular very quickly. The served just for a couple of months before being withdrawn. Boeings F4Bs took their place until the F3F came in.

No more BF2C-1s were ordered. They were being reassigned to shore-based units. In comparison the older F4B-4 was still better in many areas. The remainder operated on land; at the naval air station for training, with the last withdrawn from service from VB-5B in February 1935. The F4B-4 was soon itself replaced by the Grumman F3F. The underdog company had definitely solidified its entry as primary provider of the Navy, dethroning Boeing and Curtiss. Still, this was a failure overall for Curtiss (one of many to come, that with cripple the company's reputation after WW2).

This had serious repercussions as the Navy Department expressed its frustation as Curtiss being not able to provide a carrier-based fighter meeting operational standards. Curtiss still was not done and in 1935, proposed the BF2C-1 for training but the conversion was rejected. The previous fixed undercarriage model also had issues of its own. By contrast the Grumman F2F and F3F had everything the Navy wanted and needed. The comparison was damning.

Exports: The Hawk III's success

But what Curtiss lost to the Navy, it gained on the export market. Indeed, the "land-based" F11C-3 was distributed as the "Hawk III". It had no arresting hook, the new three-bladed propeller and a simpler, cheaper wooden wing structure with metal was used for the aileron frames but was powered by the same Wright SR-1820F-53 engine used in the F11C-2. It was never designed for sive bombing but was sold as capable to do so. By April 1935, a single F11C-3 was sold to Turkey for evaluation, but rejected. The latter purchased previously its Hawk II with fixed undercarriage. Deliveries of 24 aircraft to Thailand (Siam) from August 1935 was its greates achievement. The next year in 1936, Argentina in turn purchased ten of these. The same year, Cutiss continued to propose upgraded variants of its bird of prey, with the Model 79 Hawk IV demonstrator. It had now a completely enclosed cockpit and 790 hp (590 kW) R-1820-F56 engine, but never saw success.

Chinese Hawk IIIs

The Model 68 Falcon III thus had wood/Clark Y wings, a 770 hp (570 kW) R-1820-F53 engine, and its best customer overall was China. China acquired the largest number of Hawk IIIs starting in 1936. In all 102 were delivered. They arrived disassembled and were assembled by local aviation workshops. The result was sometimes not great and they had issues, but the pilots were pleased with their performances. From August 1937 indeed they started to duel with both IJA (Imperial Japanese Armed force) IJN (Navy) models. They took a big part in the Battle of Shanghai and Nanjing, and were viewed as the Patriot Chinese Flying corps' as "cutting edge interceptor" that did well ongside the Falcon IIs, Boeing Model 281 Peashooters and Fiat CR.32s. Col. Gao Zhihang for example shot two Mitsubishi A5M "Claude" over Nanjing in an afternoon on 12 October on his model number "IV-I" as wing Commander.

On August 14, Chinese Hawk IIIs engaged a force 13 times their size and managed to down many Japanese bombers. The first day of the war, Hawk IIIs shoot down three Mitsubishi Type 96 "Nell" (G3M2) bombers at once flying without fighter escort, lacking self-sealing fuel tanks. Against the latest Japanese fighters however, the Hawk III was hard-pressed, often due to a Japanese huge numerical advantage. Good pilots could holed their area against prececessors of the A5Ms like the Nakajima A3M, but already the Nakajima Type 95 (A4N1) nearly a ton lighter and 30 hp more powerful managed to out-turn the Hawk in every engagement and gained complete air dominance in a couple of months. When the A5M arrived in turn en masse, they completed this close to shore, the IJN assigned repsonsibility, when IJA fighters like the Nakajima Ki-27 "nate" completed this dominance inland. Only when USSR provided I-16, I-15, and I-153s the situation started to redess, and all remaining Hawk III fighters were relegated to training. Mos were destroyed by 1941.

Thai Hawk IIIs

In mid 1935, Thailand put ordered 24 Curtiss Falcon IIIs for 63,900 Baht each as well as paid a construction licence. The initial 12 Hawk IIIs were shipped to Thailand in August that year, and 12 more arrived later, named "Contender Type 10". In addition Thailand managed to build in a workshop fifty additional Hawk IIIs from 1937 to 1939. And unlike the Argentinian ones, they saw action, against the French in the Franco-Thai War and after that intercepting incoming Japanese aircraft by December 194 when the country was occupied, turned into a client state. The Hawk III remained active until modern Japanes emodels were purchased, and they were turned to local flying schools. A portion was still used by 1949. One of these, KH-10 was saved from scrapping and sent to the Royal Thai Aviation Museum, the only surviving Hawk III and by extension, BF2C Goshawk.