Hawker Osprey (1932)

FAA: 144 built 1932-44.

The Hawker Osprey was the navalised carrier-borne version of the Hart, a versatile model powered by a Rolls-Royce Kestrel II engine for 168 mph (270 km/h). 103 were built, the last still used in the fleet air arm by 1944 as a trainer. Those deployed in Malta for ASW and reconnaissance were still active in 1941-42. Other versions developed specifically for the Swedish Air Force (Cruiser HSwMS Götland), Portuguese Naval Aviation and Spanish Republican Air Force, seeing action in the civil war.

The Hawker Osprey was the naval-ized carrier-borne version of the Hawker Hart. The Osprey had a single Rolls-Royce Kestrel II engine, and had a max speed of 168 mph. Its armament consisted of a single forward .303 in Vickers MG and one .303 in Lewis. The Osprey joined the Fleet Air Arm in 1932, with 103 being built, and ended its career in 1944 after serving as a trainer for FAA pilots during WWII. By December 1936, Ospreys were being deployed by 701 Squadron based at RAF Kalafrana in the anti-submarine and anti-piracy role - from pinterest

Development

About the hawker Hart

Among all British aeronautical champions of the interwar, Hawker, which started with assets from the defunct, but world famous Sopwith of WWI, became a household name for the whole interwar, creating before WW2 the war-winning Hurricane, the fighter bombers Tempest and Typhoons and did it again in the cold war with the VTOL superstar, the Harrier. However the company was less prevalent in naval matters, compared to the likes of Fairey, Blackburn, Short or Supermarine. Still the company was in 1930, on a non-ending stride of success under the leadership of its lead designer, Sydney Camm. Hawker with the Fury arguably made the finest biplane fighter of 1931, an era-defining model, which "looked right, few right". 275 were made and exported.

Hawker Hart in formation

The fuselage construction and profling which made for excellent performances also thanks to very capable inline V12 Rolls-Royce engines was also applied to other models, just scaled up. One was the Hind, a light bomber, and another was the Hart, a "heavy fighter/bomber/reconnaissance" model, essentially a scaled up Fury with reinforcements, two seats and a better engine. Camm, which worked on 52 aircraft designs during his long career, ending with the Harrier, made with a Hart an unremarkable but highly succesfull jack of all trades capable of mixing any roles in a single package. It was the greatest export success of the company, and arguably of Britain on the international market back then. For more "stuff" on Hawker and Sydney camm, see the page on the Sea Hurricane.

In the Interwar, with Germany our of the way and only Fokker as a serious rival left in Europe, the US only having an anemic home market, both France and Britain amsbolutely dominated the world's aircraft export market for military aircraft. In France in 1925 as it entered service the Potez 25 soon became a major export success, with some 3,500 produced and exported. In Britain, this was arguably the Hart, with more than 1,000 manufactured through many variants and also widely exported. However, the Hart arrived a bit later, on a different schedule defined by the Air Ministry.

The Hart predated indeed this famous lineage and the Hawker Fury. It all started in 1926 when the Air Ministry stated a requirement for a 2-seat "high-performance" day bomber of all-metal construction. Top speed was to be no less than 160 mph (260 km/h; 140 kn). Hawker, Avro and de Havilland answered the tender. Fairey was not proposed the tender at first. Hawker under Sydney Camm worked on a panel of novel construction solution in order to deliver a workable prototype. The all-metal nature of the airplane was indeed groundbreaking still in 1926 when most designed relied still largely on wood and canvas. The speed setup at the time was for fighters only. That meant a potentially large fighter with a second seat and able to carry bombs. Thanks to a Rolls-Royce inline V12 and excellent profiling taking advantage of metal panelling, the aircraft, albeit sitll a biplane, was very smooth. It had the best results in a wind tunnel.

Technical details of the Osprey

The prototype Hart (serial J9052) first flew in June 1928, in time to be tested by in-house pilots of the Aeroplane and Armament Experimental Establishment at RAF Martlesham Heath, from 8 September. Pilot were impressed: In straight line, the Hart did better than the specified speed at 176 mph (283 km/h; 153 kn) and even managed 282 mph (454 km/h; 245 kn) in a dive. It could carry an observer/rear gunner with an excellent view, was safe to fly, stable if needed, accelerated quickly and proved agile enough to do some fighting if needed. It could also carried a reasonable bomb load under wings. All in all, this was the winner design, when chosen in April 1929. Its competitors, the de Havilland Hound abd Avro Antelope were both rejected, the first due to handling problems when landing and still largely wooden structure the second loosing only on a more complicated and costier maintenance compared to the Hart. The Fairey Fox IIM was presented too late and also rejected.

Long story short, the Hart became an instant success, with large orders for the RAF, 992 produced as the Hart Mark I and it became the standard bomber/recce/escort fighter in Britain between 1931 and 1935 when replacement started. It was the perfect blend of qualities for this austere post-1929 conditions and a good complement to the absolute banger that was its interceptor cousin, the Fury. Hawker was for five years, at the top of the mountain. Exports came from all over the world as well, Estonia, South Africa, Sweden, among others, and new versions were developed like the Hawker Hind and Audax light cooperation bombers, the Demon heavy fight, the tropicalized Hardy and finally... the Osprey.

Design of the Osprey

The Hawker Osprey was a derivative of the Hart, navalized to equip the the Fleet Air Arm branch on aircraft cariers in the Royal Navy. They replaced notably the WWI era Sopwith 1 1/2 Strutter still around. These carriers in 1931, the Argus, Hermes, Eagle, Furious, Glorious and Courageous, all needed a modern flighter/reconnaissance model capable of doing the bulk of its work aside dedicated torpedo bombers, in cramped hangars. British carriers had to content with small air groups and asked more of its models. Later example of these jacks of all trade would be the fairey Fulmar, later replaced by the Firefly.

The Osprey could be considered as their predecessor. The base recipe was the same technically as the Hart, but with specific fleet additions: A small inflatable raft and survival kit, flares inside a compartment aft, better navigation equipments and radio sets, reinforced undercarriage and tail hook to land on carrier decks. The only issue was their lack of folding wings initially, solved on the later Marks and soon retrofitted. There were also floats for the seaplane conversion, and all undercarriage models had Kiddle-Lux floatation bags attached to the upper plane wings. The "Osprey" is a marine bird of prey.

General Layout and Structure

General structure of the Hart, essentially identical to the Osprey src

The Osprey was Two seat fleet fighter reconnaissance landplane or seaplane

Wing: Unequal span, single bay, staggered biplane. Centre section carried above fuselage on splayed out structs. One set of N type struts on each side of fuselage. Wing structure mainly stainless steel, covered with fabric. Frise type ailerons on top planes. The Fuselage was a rectangular stainless steel structure, faired to an oval section and covered with fabric. The tail Unit was of the monoplane type. It was of the stainless steel framework, covered with fabric. Balanced rudder and elevators. The Osoprey was sold to the FAA as a convertible. The underbelly had fixation points either for a land undercarriage of cross axle Vee type, or a pair of single step metal floats with a W style attachement.

Engine

The Osprey was equipped by the late model Rolls-Royce Kestrel XVI, 21-litre, 1,295 cu V12 water-cooled inline. It was first developed as an Air Ministry project to replicate the single-block architecture of the 18-litre American D-12 Curtiss during 1925-6. Kestrel variants could generate between 500 (IB model) and 600 hp (V model), and as much as 750 horsepower in the supercharged Peregrine derivative. This was the direct predecessor of the legendary 27-litre 1,650 cu (1,100 hp) P.V.12 (Merlin), utilized in the Hawker Hurricane, Supermarine Spitfire and North American Mustang.

Armament

The Hart and Osprey were both armed with two fixed machine guns firing forward through the propeller with an interrupter gear, like most fighters of the day, and one machine gun on a scarff mounting in the gunner's or observer cockpit, equipped with a Mk. III Lewis gun. In the nose there were .303 Mk. II Vickers gun with C. C. synchronizing gear, allowing them machine gun to be fired directly through the aircraft propeller. Their own loading system however was too low and forward compared to the pilot's position to be "un-jammed" if it happened. Aft, this was the Hawker style Scarff ring for the observer’s Lewis gun, with graduations and an optional ruptor when directly facing the tail. There were also up to 520 lb (234 kgs) bombs under wings, but only available for the land-based carriage version. This consisted of three 85 Ibs (39 kgs) bombs in racks of there underwing. They were absent from the floatplane configurations due to the weight of the floats, potentially used as extra fuel tanks.

Osprey Mark I in seaplane configuration, author unknown, pinterest. Note the bomblets underwings.

⚙ Hawker Osprey IV specifications
Empty Weight	3,503 lb
Max Takeoff weight	4,790 lb
Lenght	29 ft 4 in
Wingspan	37 ft
Height	11 ft
Wing Area	339 sq ft
Engine	Rolls-Royce Kestrel V12 WC: 640 hp
Top Speed	176 mph at 13,120 ft
Range	Est. range of 470 mi (760 km; 410 nmi).
Climb Rate	Climb to 10,000 ft/3000m in 8.65 minutes
Ceiling	22,000 ft
Endurance	3 hours
Equipments	Land undercarriage/metal floats
Armament	Two fixed machine guns firing forward through the airscrew and one machine gun on a mounting in the gunners cockpit
Crew	Pilot cockpit below cut out in trailing edge, gunner/observer cockpit behind.

Variants

HMS Sussex showing crane, catapult, and Hawker Osprey

Osprey I

2-seat fleet spotter/reconnaissance aircraft, 630 hp (470 kW) Rolls-Royce Kestrel IIMS inline piston engine: 37 built.

Osprey II

2-seat same, 630 hp (470 kW) Rolls-Royce Kestrel IIMS, redesigned floats: 14 built.

Osprey III

2-seat same, 630 hp (470 kW) Rolls-Royce Kestrel IIMS, dinghy stowed away starboard upper wing: 26 built.

Osprey IV

2-seat fleet same, 640 hp Rolls-Royce Kestrel V: 36 delivered 1935. Last variant.

Service

The Osprey joined the Fleet Air Arm (FAA) in 1932. Some 103 by then had been built for british use only. The Mark IV entered service in 1935 and thus, ended their career in 1944, as trainers for FAA pilots. By December 1936, a new 701 Squadron, based at RAF Kalafrana in Malta was created with these Ospreys, for anti-submarine and anti-piracy role. They would take an important role in 1940-42. But well before that, the first Osprey Mark I were accepted in Flights No. 404 and 409 in November 1932, and No. 407 (seaplane) Flight had its Fairey IIIFs replaced by Ospreys for work with the cruisers of the Home Fleet.

Ospreys also served in Flights 403, 406, 407, 443, 444, and 447. They also soon joined Squadrons 800, 801, 802 and 803 as re-formed in 1933. Alongside new fighters squadrons for the FAA were created with Hawker Nimrods in the the 800s, FSR (Ospreys) the 810s and TSR (Horsleys) as the the 820. All arrived with their original factory colors, all metal and light canvas plus squadron colour-coded bands linked to various aircraft carriers such as:
-Red for Courageous
-Blue for Furious
-Yellow for Glorious
-Green for Eagle
-Black for Hermes.

At the beginning of 1936 Courageoust had three Ospreys as Furious and Glorious, but six on Eagle. In addition there was a "pool" of 34 seaplanes on some 29 warships, cruisers and battleships of the RN, for a total of 144 Ospreys for the entire production, not just the 132 of the FAA). The Late generation Ospreys still were used on HMS Ark Royal in 1939, until replaced by the Blackburn Skua. That makes 132 Ospreys in the FAA, some converted as seaplanes, and the latter as trainer aircraft until 1944. But this is not all, the full count should also integrated those purchased by Sweden, and by Portugal, plus a one-off to Spain, from British stocks.

Captain Richard Bell Davies, back to the Royal Navy after the RAF was created, criticized the Osprey as unsuitabie as a seaplane. He believed thay a slower and more robust, specialized aircraft would be better. By the 1930s enthusiasm for shining new tech started to get traction over wartime learning and experience. The latter tended to be forgotten. The Admiralty attempted to simplify requirements down to a Torpedo, Spotter, Reconnaissance (TSR), and fighter/dive-bomber with in addition seaplanes. The pure naval fighter role was just cancelled. This will came back to haunt the FAA in 1939...

Technical homogeneity in this 1930s disarmament with the Air Ministry control of production meant the FAA was fiorced to be concept with imperfect aircraft, kjacls of all trades and masters of none, and the excellence of the Hawker design was a perfect example of this. As a single seat fighter it coulmd not compete against the Fairey Flycatcher, then Hawker Nimrod, and as a two seat bomber/spotter/reconnaissance or seaplane it was not rugged enough, and lacked range. The torpedo bomber Horsley was necessary alongside. By 1935, Hawker aircraft became the entire RAF and most of the FAA. Sydney Camm weanwhile came close to his dream of efficiency of a single aircraft suitable of every role. But hard operational realities flew into the face of this concept.

Nevertheless the Opsrey remained operational until WW2 broke out. In 1934 one RAF squadron had four Ospreys for communications, later HMS Sussex sailed to Melbourne for the Centenary celebrations and flew its Osprey. By mid-1935 the Second Cruiser Squadron also was issued Ospreys. One of the last cruiser equipped was HMS Ajax which like so many received two for service with the Mediterranean Command. These remained in service until 1939 late. The Swedish ones stayed active until 1945. The fate of the single re-engineered Spanish Osprey, part of a batch of 57 aicraft for the Republicans, is uncertain. The new engine was to match local maintenance capabilities: The Hispano-Suiza was actually built and serviced in Spain at the time.

The Swedish S.9s were not without critics: It took 30 min. to hand-crank start the NOHAB Mercury engines for example as there was no facility on board Gotland to do the job. The electric curcuit had to be modified to change this ultimately. Also each machine had a different radio set, and many elements did not tolerated seawater spray and were hit by rust. Wooden and fabric components also had a hard time with saltwater and warmer climates. The pilot’s neck support made of thin sheet metal, buckled during catapult launches and needed to be changed. But that was about it. In 1943 they were retired as Gotland was converted as an AA cruiser. Their fates are varied but they were planed on wheeled undercarriages and went as target tugs for a time.

Exports

Portuguese Osprey

Two Osprey III were saold, tailored for Portugal with the Kestrel IIMS engine and delivered in 1935. Six more were delivered in 1939, all in seaplane configuration.

Spanish Osprey

One powered by a Hispano-Suiza 12Xbrs engine was delivered to the Spanish Republican Air Force in 1937.

Swedish Osprey

Swedish Version. Had a 600 horsepower (450 kW) NOHAB Bristol Mercury radial, interchangeable wheel/float landing gear. 6 built as S9 for the aicraft cruiser Götland.