OS2U-1

This page is about the American hydroplane bomber OS2U-1. For the other version, see OS2U-3.

OS2U-1

360://https://wiki.warthunder.com/images/4/4e/Cockpit_os2u_1.jpg

OS2U-1

USA

I Rank

Battle rating:

AB	RB	SB
1.0	1.0	1.0

Class:

Bomber

Light bomber

Hydroplane

Research:2 900

Purchase:700

Show in game

Description

The OS2U-1 "Kingfisher" was built by Vought-Sikorsky Aircraft Division as a catapult-launched observation floatplane designed to be used by various cruisers and battleships employed by the US Navy. It was a revolutionary design for its time, using spot welding construction, creating a smooth fuselage with reduced drag. The first prototype flew in 1938 and production started in early 1940. While its performance was modest, it soon replaced the previous Curtiss SOC Seagull thanks to its more modern airframe. The production model used a Pratt & Whitney R-985-48 radial engine. The OS2U-1 had a limited maximum range compared to the OS2U-3, which was improved in said version with the fitting of additional self-sealing fuel tanks in the wings.

As an observation aircraft, the OS2U-1 Kingfisher lacks the performance and armament to be very effective in frontline battles. It is not recommended to engage in direct combat with enemy fighters, instead opting to attack undefended ground targets. Following its intended role, it is very effective as a reconnaissance aircraft in naval matches.

It has been in the game since the start of the Open Beta Test prior to Update 1.27. It was previously made unavailable after it was removed from the research tree in Update 1.57 "Battle March", however, in Update 14.11.18 it was returned, available for research after researching Rank II of American naval forces. In Update "Winged Lions", the OS2U-1 also became available as a shipboard reconnaissance aircraft, able to be launched by some American naval vessels, listed below.

Ships that carry the OS2U-1 as a ship-launched reconnaissance aircraft

• HMS Enterprise
• USS Alaska
• USS Baltimore
• USS Brooklyn
• USS Cleveland
• USS Fargo
• USS Mississippi
• USS Nevada
• USS Tennessee
• USS Trenton

General info

Flight performance

Max speed

at 1 700 m296 km/h

Turn time33 s

Max altitude5 950 m

EnginePratt & Whitney R-985-48

TypeRadial

Cooling systemAir

Take-off weight3 t

Even for aircraft of its battle rating, the OS2U-1 Kingfisher has relatively poor flight performance. When stock, this aircraft has a meagre rate of climb and turn rate. Spading it with all of the performance modifications will boost these values, but not significantly enough to compete against other aircraft it may encounter. As with most hydroplanes, the OS2U-1's performance is hindered by its floats. Another item that will weigh down the Kingfisher is the mounted 100 lb AN-M30A1 bombs. It is recommended to ditch these bombs when attempting to manoeuvre in combat.

It is highly recommended to begin a dive from altitude when entering the midsection of the map to keep up speed and stay away from enemy interceptors. Since this aircraft is not equipped with a bombsight, maintaining high altitudes may not be beneficial for its mission anyway. If enemy fighters do attack, it will likely be a struggle to escape due to the OS2U-1's low acceleration and manoeuvrability. If the wings or engine take damage, the aircraft might not be able to fly effectively and it may even crash just because of the loss of power and lift.

Notably, the angle of incidence between the chord line of the wing and the longitudinal axis of the fuselage is relatively large compared to some other aircraft. In other words, the wing of the OS2U-1 is angled upward compared to the angle of its nose. Therefore, placing the gunsight on the horizon will hold the wings at a higher angle of attack and slow the aircraft down. A pitch attitude that may first appear to be significantly nose-down can be held to increase cruising speed. Pitch attitude can be checked using the attitude indicator in the aircraft's cockpit or the virtual cockpit.

Characteristics	Max Speed (km/h at 1,700 m)		Max altitude (metres)	Turn time (seconds)		Rate of climb (metres/second)		Take-off run (metres)
	AB	RB		AB	RB	AB	RB
Stock	284	273	5950	34.8	38.5	5.3	5.2	305
Upgraded	310	296		31.1	33.1	9.9	6.8

Details

Features
Combat flaps	Take-off flaps	Landing flaps	Air brakes	Arrestor gear
✓	✓	✓	X	X

Limits
Wings (km/h)	Gear (km/h)	Flaps (km/h)			Max Static G
		Combat	Take-off	Landing	+	-
405	350	337	308	160	~15	~15

Optimal velocities (km/h)
Ailerons	Rudder	Elevators	Radiator
< 200	< 200	< 240	> 306

Survivability and armour

Crew2 people

Speed of destruction

Structural0 km/h

Gear350 km/h

• No armour protection
• One self-sealing fuel tank in the fuselage

The survivability of the OS2U-1 Kingfisher is suboptimal as there is no armour protection for important modules or crew. The large radial engine may be able to stop enemy fire from the front from damaging the pilot, but it will take damage itself, reducing flight performance. The tail gunner is unprotected and can be knocked out quite easily, either because of enemy bullets flying directly into the turret or punching through the tail itself. Due to their size, the floats will likely soak up damage and can even fall off of the aircraft when destroyed. The fuselage fuel tank being self-sealed means that after a certain period of time after taking damage, the fuel tank will be able to seal the holes to stop itself from leaking out.

Modifications and economy

Repair costBasic → Reference

AB97 → 131

RB139 → 187

SB160 → 216

Total cost of modifications2 820

855

Talisman cost190

Crew training200

Experts1 000

Aces20

Research Aces96 000

Reward for battleAB / RB / SB

20 / 30 / 60 %

100 / 100 / 100 %

Modifications

Flight performance	Survivability	Weaponry
Fuselage repair Research: 150 Cost: 45 40 Radiator Research: 150 Cost: 45 40 Airframe Research: 220 Cost: 65 60 Compressor Research: 220 Cost: 65 60 Wings repair Research: 250 Cost: 75 70 Engine Research: 250 Cost: 75 70 Cover Research: 240 Cost: 75 65 Engine injection Research: 240 Cost: 75 65	EFS Research: 240 Cost: 75 65	bmg30_belt_pack Research: 150 Cost: 45 40 Mk.41 bmg30_new_gun Research: 220 Cost: 65 60 bmg30_turret_belt_pack Research: 250 Cost: 75 70 bmg30_turret_new_gun Research: 240 Cost: 75 65

One order of research for the OS2U-1 is as follows:

• Mk.41: This modification will allow 2x 100 lb bombs to be carried, adding another weapon to the Kingfisher's ground attack arsenal.
• Offensive 7 mm and New 7 mm MGs: The former modification will expand ammunition choices for the offensive 7.62 mm machine gun. The latter modification will decrease weapon spread and overheating rate.
• Flight Performance: These modifications will help to increase the OS2U-1's meagre performance by slightly increasing its speed and manoeuvrability. Some of these modifications will also help to increase the durability of the airframe.
• Turret 7 mm and New 7 mm MGs (turret): Researching these modifications will help to increase the stopping power of the tail gunner.
• EFS: Although taking damage is often the end for the Kingfisher, this modification can be useful in the rare case that the aircraft's engine is set on fire while it is also able to successfully disengage. After using it, the engine will be unusable, but it may slightly increase the chance of gliding back to the airfield, instead of burning the aircraft down.

Armaments

Offensive armament

Weapon 17.62 mm Browning machine gun

Ammunition500 rounds

Fire rate1 000 shots/min

The OS2U-1 is armed with:

• 1 x 7.62 mm Browning machine gun, nose-mounted (500 rpg)

Suspended armament

List of setups (1)

Setup 12 x 100 lb AN-M30A1 bomb

The OS2U-1 can be outfitted with the following ordnance:

• Without load
• 2 x 100 lb AN-M30A1 bombs (200 lb total)

Defensive armament

Turret7.62 mm Browning machine gun

Ammunition600 rounds

Fire rate1000 shots/min

The OS2U-1 is defended by:

• 1 x 7.62 mm Browning machine gun, dorsal turret (600 rpg)

The offensive and defensive armament of the OS2U-1 both consist of 7.62 mm Browning (.30 cal) machine guns. These rifle-calibre machine guns may be adequate when fitted in large numbers to other aircraft, but in single mounts, they are not particularly effective against vehicles of any type. With the OS2U-1 being an observation aircraft by nature, these weapons are intended for emergency self-defence and light ground attack. It is not recommended to use these weapons to hunt enemy aircraft, especially those that are metal-skinned or are bombers because of their resistance to damage from rifle-caliber weapons. Although 500 rounds may seem like much, this ammunition pool will soon run out after engaging just a few ground targets.

The tail gunner has significant blind spots, including directly behind the aircraft, meaning that enemies can only be engaged when flying above and slightly to the side of the aircraft. This can be inconvenient in battle, as many fighters will attack from below and behind.

The two 100 lb AN-M30A1 bombs will cause a performance penalty but can be useful in destroying armoured targets that the machine guns won't damage. They are mounted on the wings and drop separately. Due to their small size, they will have to be dropped as accurately as possible to cause significant damage.

Usage in battles

Air Battles

The OS2U-1 Kingfisher is classified as a bomber, and as such it spawns at altitude. Despite this, it is highly recommended to primarily use it in the low-altitude light ground attack role. If possible, Kingfisher pilots can fly outwards towards the edges of the battlefield to stay out of sight of the enemy and take indirect routes to desired targets.

The single forward-facing 7.62 mm Browning machine gun is capable of destroying artillery, AAA (stationary and on trucks), landing craft, and light armoured cars. Beware of ammunition remaining during and after engaging enemy units. Since tanks and light pillboxes cannot be destroyed with such a small MG calibre, the player will have to resort to bombs to destroy them.

Due to its relatively poor flight performance and light weaponry, it is ill-advised to attempt to engage enemy aircraft with the OS2U-1. Its gun will likely not do significant damage against enemy aircraft, especially if they are larger and/or have multiple engines. As such, it is recommended to entirely avoid confrontations in the OS2U-1. If an opponent is approaching from the rear, the tail gunner can be used to fire shots towards them, hopefully deterring a further attack. Note the gunner's large dead zones directly behind the aircraft.

Ground Battles

Bombs will almost always be a part of the OS2U-1's primary loadout in Ground Realistic battles. A tactic that can be used is to loiter outside of the battlefield and wait for an enemy to drive into a capture point, move into position, bomb them, and then fly away. Alternatively, the Kingfisher can be used in the reconnaissance role, scouting out the positions of enemy ground forces. In Simulator battles, the OS2U-1 also serves well in the recon role since the cockpit has a relatively good view of the surrounding area.

If enemy SPAAs begin engaging, it is recommended to leave the area as quickly as possible. Without armour and having poor flight performance, the Kingfisher becomes a sitting duck at low altitudes. Getting engaged by anti-aircraft guns can also alert enemy fighters to your position, following their tracers.

Naval Battles

With the OS2U-1's small size and speed relative to ships, it can be used to quickly gather information about the enemy fleet's positions with minimal interference. If necessary, it can land in the water to avoid being fired on by enemy anti-aircraft guns. The bombs will not cause significant damage to most larger ships but can be used effectively against small boats as long as the Kingfisher can get close enough to drop them accurately. It is recommended to stay away from vessels with significant anti-aircraft defences as even small and medium calibre guns will do significant damage to the airframe. Damage to the floats will affect the ability to float on water and could cause the aircraft to sink upon landing.

Manual Engine Control

MEC elements
Mixer	Pitch	Radiator			Supercharger	Turbocharger
		Oil	Water	Type
Not controllable	Controllable Auto control available	Not controllable Not auto controlled	Controllable Not auto controlled	Combined	Not controllable 1 gear	Not controllable

Pros and cons

Pros:

• Machine guns are reliable and resistant to overheating when used properly
• Can carry bombs
• EFS can increase survivability after experiencing an engine fire
• Ability to land on water
• Speed combined with cockpit visibility can be helpful when performing recon roles, increasing loiter time
• In Naval modes, its slow speed allows the plane to skim smoothly across the water, thus making capturing points easier
• (Ship-launched) Usually comes in a pair aboard ships, meaning it is more expendable compared to other naval floatplanes
• Bomber air spawn gives an altitude advantage and can be traded to maintain speed

Cons:

• Very slow, it can struggle to reach its top speed or take off from water
• Poor manoeuvrability and energy retention
• Weak offensive, defensive and suspended armaments
• Large dead zones for the tail gun, no ability to shoot enemies directly behind, below, or above the aircraft
• Important components are unarmored and there are significant performance penalties after receiving heavy damage to wings
• No wheels for landing on land

History

The OS2U Kingfisher, built by Vought-Sikorsky Aircraft Division, was a catapult-launched observation floatplane designed by Rex Beisel (a design engineer responsible for Vought F4U Corsair). The Kingfisher was assembled using spot welding construction which increased aerodynamics compared to previous methods. It also had several innovative features, such as deflector plate flaps and drooping ailerons used to create additional lift at low speeds, improving control of the aircraft.

Prototype XOS2U-1 flew in 1938 and the first production variant was delivered in early 1940. Despite its modest performance it gradually started replacing the previous Curtiss SOC Seagull biplane and ended up as the U.S. Navy's main ship-launched scout plane during WW2. The OS2U stayed in use much longer than expected because its successor, the Curtiss SO3C Seamew suffered from various issues, most notably severe engine issues. The later OS2U-3 variant first flew on 17 May 1941. The main difference from its predecessor the OS2U-1 was additional self-sealing fuel tanks in the wings and improved armour protection for the pilot.

The OS2U Kingfisher had a 450 hp (336 kW) Pratt & Whitney R-985-AN2 radial engine (all Kingfishers were powered by different versions of this engine). It was armed with a 7.62 mm Browning machine gun in the nose, hidden inside the engine compartment, and another 7.62 mm Browning machine gun in a dorsal turret on a flexible ring mount. It was also able to carry light suspended armament, including 100 lb (45 kg) bombs and 325 lb (147 kg) of depth charges. The OS2U-3 was the most produced variant of the series with just over 1,000 units built. It was the only exported variant and served in many countries from Uruguay to Australia and even the Soviet Union aboard the cruiser Murmansk (former USS Milwaukee). The last of the Kingfishers were withdrawn from service with Cuba in 1959.

While some versions were deployed to land bases (OS2U-2s installed with wheels instead of floats and were mostly used for training) most Kingfishers were operated from the catapults of the U.S. Navy's cruisers and battleships. This rather violent launch was done into the wind over the sides of the vessel, with the catapult being powered by an artillery shell. Landing required the ship to make a turn to create a patch of relatively calm sea surface where the Kingfisher could land and then taxi to the "sled" system used to pull it closer to the ship's crane, after which it would be hoisted back on deck.

In the early 1940s, seaborne radar was a rarity and still primitive, the eyes and ears of a fleet of warships were limited at best. This is where the observation aircraft was imperative. A battleship would launch a Kingfisher seaplane and the aircraft could then patrol the surrounding seas for hundreds of miles for hours at a time. Depending on the threat, the Kingfisher might be looking for anything as huge as an enemy fleet or as small and deadly as a single enemy submarine. In the case of the latter, the Kingfisher had teeth of its own: even with its limited payload, the Kingfishers assisted in the sinking of U-boats U-576 and U-176. Simply finding a target or enemy fleet was of immense use to the bridge crew of a warship, but the Kingfisher could do more. Once an enemy fleet was identified it was almost inevitable that an engagement would take place – even in the 1940s, naval guns were well capable of firing shells over 20 miles. The Kingfisher could fly over an enemy fleet and report directly back to the bridge crew of any warship within its fleet, giving real-time feedback on the accuracy of fire and corrections to bring tremendous firepower onto a target. Furthermore, the importance of naval gunfire did not stop with engaging other vessels: carrying some of the largest guns in the entire world on a mobile platform, battleships were the ultimate fire support during an amphibious assault. As US Marines fought their way from beachheads all across the Pacific theatre, the guns of the fleet were often there to eliminate concentrations of enemy troops and heavy defensive positions. Again, the Kingfisher was ideally placed to ensure this supporting fire was accurately and efficiently delivered.

Even though it was used in many different roles, as trainer, bomber, anti-submarine platform in the Atlantic, scout, naval gunfire spotter etc. one of the Kingfisher's most respectable roles was Search and Rescue missions, where it was involved in saving downed airmen in the Pacific. On one occasion in 1942 over Pacific a B-17D became disoriented, ran out of fuel and ditched. After drifting for several weeks without food and water, the crew and passengers were rescued by a Kingfisher. With all the survivors on its wings, it could not take off and started taxing to the nearest island before being relieved by a torpedo boat. On another occasion, Kingfisher of USS Indiana rescued two downed airmen off of Guam in 1944, despite being exposed to fire from several nearby Japanese artillery positions. The only confirmed kill scored with the Kingfisher happened on 16 February 1945 at Iwo Jima where Lieutenant D.W. Gandy of the US Navy shot down a Zero fighter.

Archive of the in-game description

In March 1937, the Chance-Vought company, then part of United Aircraft Corporation, obtained an order from the US Navy to design a catapult reconnaissance-spotter float plane to replace the obsolete Curtiss SOC biplane. A year later, in March 1938, the first prototype XOS2U-1 took to the air in a version with non-retractable landing gear, and two months later the first takeoff from water took place. Due to new technology, the prototype showed a considerable improvement in its main performance characteristics compared with its predecessor. It had longer range, a higher service ceiling and a considerably lower takeoff weight. In spite of the fact that a less powerful and lighter engine had been selected, the speed was unchanged and the mean rate of climb was even somewhat higher. However, the more up-to-date design of the monoplane caused the designers a few headaches. By comparison with the SOC, its takeoff and landing characteristics were considerably worse. They had to give up on a central float designed by Vought itself and use an EDO design instead. After several minor improvements, the aircraft was put into series production and accepted by the Navy under the designation "Kingfisher" (the name of a tiny bird which lives on small lake fish). The production aircraft were fitted with the Pratt & Whitney R-985-48 "Wasp Junior" engine, nominal power 450 hp, with a two-bladed propeller. Up to the end of 1940, 54 OS2U-1s had been built, 18 of which were sent to re-equip battleships based at Pearl Harbor and Alameda.

Media

Skins

• Skins and camouflages for the OS2U-1 from live.warthunder.com.

See also

Related development

• OS2U-3

Aircraft of a similar configuration or era

• F1M2
• Po-2M
• S17BS

Aircraft of a similar role

• Shipboard reconnaissance aircraft

External links

Ship-launched reconnaissance aircraft
USA	O3U-1 · OS2U-1* · SOC-1
Germany	Ar 196 A-3*
USSR	KOR-1
Britain	Osprey Mk IV · Walrus Mk.I
Japan	E7K2 · E8N2 · E13A1 · F1M2*
Italy	Ro.43
France	GL.832HY · Loire 130С
	*Available standalone in tech tree