BI

BI

BI

USSR

V Rank

Battle rating:

AB	RB	SB
6.7	6.7	6.3

Class:

Fighter

Jet fighter

Purchase:Bundle or Gift

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Description

The BI is a gift rank V Soviet jet fighter with a battle rating of 6.7 (AB/RB) and 6.3 (SB). It was introduced during Update "Raining Fire" as a reward for the 2020 Wargame "Strategist" event, and is currently available for sale on the Marketplace.

General info

Flight performance

Characteristics	Max Speed (km/h at 4,500 m)		Max altitude (metres)	Turn time (seconds)		Rate of climb (metres/second)		Take-off run (metres)
	AB	RB		AB	RB	AB	RB
Stock	793	787	12000	21.2	21.2	84.9	79.4	400
Upgraded	807	800		20.8	21.0	116.4	100.0

Details

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

Limits
Wings (km/h)	Gear (km/h)	Flaps (km/h)			Max Static G
		Combat	Take-off	Landing	+	-
920	420	N/A	N/A	320	~9	~3

Optimal velocities (km/h)
Ailerons	Rudder	Elevators	Radiator
< 400	< 410	< 550	N/A

Engine performance

Engine			Aircraft mass
Engine name		Number	Basic Mass	Wing loading (full fuel)
Isaev D-1a		1	924 kg	233 kg/m2
Engine characteristics			Mass with fuel (no weapons load)		Max Takeoff Weight
Weight (each)	Type		0m fuel	1m fuel
300 kg	Liquid-fuel rocket		1,134 kg	1,629 kg	1,650 kg
Maximum engine thrust @ 0 m (RB / SB)			Thrust to weight ratio @ 0 m (100%)
Condition	100%	WEP	0m fuel	1m fuel	MTOW
Stationary	1,121 kgf	N/A	0.99	0.69	0.68
Optimal	1,121 kgf (any speed)	N/A	0.99	0.69	0.68

Survivability and armour

• 5.5 mm steel behind the pilot.
• 5.5 mm steel plate installed in the nose.
• 64 mm bulletproof glass in front of pilot
• Self-sealing fuel tanks* (7 under the cannon barrels, 8 behind pilot, 3 in rear fuselage)

*The fuel tanks are cylinder-shaped, not rectangular, like most planes' fuel tanks, allowing for more fuel tanks.

Armaments

Offensive armament

The BI is armed with:

• 2 x 20 mm ShVAK cannons, nose-mounted (45 rpg = 90 total)

Usage in battles

How to climb and get best battle endurance with the correct fuel management

Using fuel management will allow your endurance to increase from 1 minute 57 seconds to over 13 minutes, only use the fuel you need to use.

To get the longest endurance out of it's limited fuel amount, climb from the airfield at an angle of 70-80 degrees, at full throttle and as you hit 3000 meters, change the angle of the attack and throttle back to 30%. Adjust your climb angle to make sure speed is still increasing whilst the height increases too. This will allow you to travel to 5000 plus meters without burning much of your preciouses rocket fuel. This fuel, you will need for later in the battle. Once you have hit 5000 meters, throttle back to 14% and continue to climb and adjust your climb angle again to roughly 16 degrees. You can continue to climb at this angle until you see it fit not to do so.

When you hit the altitude you like, you can throttle back to 0% and just glide, with only minor adjustments to the throttle to keep in you level flight.

Descending

The key to descending without locking up and crashing is, not to point your nose straight down unlike other aircrafts, the BI is able to gain a lot of speed even in a little descent. When, the BI speed starts going over 700 Km/h pull up slowly and lose it, when you push the nose back down push the rudder all the way to the left or right. If you aren't losing speed fast enough, shift the plane 45 degrees to the left or right, with full rudder movements. This will slow you down.

Due to the BI being able to go over 900 Km/h with ease and locks up at Mach 0.76, descending from height from 5000 meters needs to be calculated based on the battle conditions in the match. If you descend to fast, due to a high angle of attack, you will lock up and crash into the ground, because you will be unable to pull out in time.

A high angle of attack for a descent is around -70 degrees, even using the ruder and shifting the BI to the left and right will not be enough.

A good angle of attack to descend is around -30 to -60, the steeper the angle faster you will go. When you descend keep your throttles at 0%, only when you are pulling out of the dive at the very end, after losing speed, they should be opened carefully.

Engaging in combat

The BI is similar to the He 162 A-2 - small amounts of fuel and ammo (low flight endurance) but has astonishing performance, being able to climb 80 degrees vertically. As such it excels in the interceptor role, climbing at a extremely high rate of up to 116.4 meters per second in AB and 100.0 meters per second in RB. Able to shoot down bombers and fighter bombers before exhausting the fuel supply and landing again. Don't be rused by its acceleration into thinking it has a high top speed - the wings and elevators will lock up at mach speed: 0.76 Thus making any manoeuvres and climbs impossible. Flying full throttle at 8000 Meters, will see you rip your wings off in level flight.

Do not try to outrun enemies, in turn fights but instead use your manoeuvrability and acceleration to fight them, your speed & small size will be your only zenith. The BI only has 90 rounds of ammo, 45 rounds per gun. This is not a lot of ammo, you can get up to two kills, without having to reload with well placed shots.

Engaging fighters

Fighting fighters in combat, aim for the wings and tail, aiming for wings with the limited ammo which the BI has will cause the wing fuel tanks to catch on fire. Aiming for the tail, will see that the tail gets cut clean from the fuselage, unlike a bomber a fighter is smaller and lesser space for fired ammo to miss critical elements.

The enemy fighter, may see you sneaking on him or her, they will bank left or right, do not follow them in the turn, the BI cannot turn fight with out losing it's advantageous speed. Instead, disengage, throttle up, climb and come back around for another pass.

Engaging Bombers

Fighting bombers, aim for the wings and engines, aiming for the fuselage will unlikely cause any critical hits unless you can hit the flight deck. Aiming for the wings, increases the odds of hitting a wing spar and seeing the wing get ripped off with a short one second salvo. Aiming for engine, will knock the engine out and possibly set fires inside of the wing installed fuel tanks. The larger area with more critical elements increase the odds of doing critical damage with the limited rounds which you have.

Do not stay behind the enemy bomber, their gunners will hit your rocket fuel tanks and will see the BI set on fire. If it is on fire, break off the attack and dive as fast as you can, this will put the fire out. Then head back to the airfield and repair, and refuel.

Landing

To land the bi, you need to keep about 5 to 10 seconds of fuel in case you need to go around due to a missed approach. When on approach, you will need to lose speed fast, which it can do. This is due to the BI not using the sleek low profile aerodynamic wings, as you find on other jets. However, to do this, you must reduce the speed down to under 420 km/h or your gear will be ripped off making the odds of crashing on landing very high.

To land the BI, flip the plane on it's side, use the rudder during the turns to help cause more fiction with the air, which will start reducing it's speed. Due to the shape of the BI which features great guilder aerodynamics, it is able to fly at high speeds and keep the momentum even without any throttle being active. As soon as the BI touches the ground, apply the breaks and turn the rudder hard left and right to help slow it down.

Landing on short runways, should be avoided or risk crashing at the end, the reason for this if you come into fast or high the BI will bonce, it will bonce to 150 meters or more. Ideally you should head back to the main airfield which has the long landing strip to land on.

Modules

Tier	Flight performance	Survivability	Weaponry
I	Fuselage repair		Offensive 20 mm
II		Airframe
III	Wings repair		New 20 mm cannons
IV	Engine	Cover

Pros and cons

Pros:

• Amazing acceleration.
• Great roll rate.
• Excellent manoeuvrability.
• Takes off is very fast.
• Incredible climb rate.
• Very strong airframe.
• Very small size, makes successfully engaging it very hard.

Cons:

• Not very well armoured or crew protection
• Only has landing flaps
• Can reach rip speed (Mach 0.81) while travelling in a straight line
• Very hard to pull out of a dive, due to it's great speed.
• Maximum fuel load is only 1 minute and 57 seconds.
• Limited armament, only two ShVAK cannons with 45 rounds each.

History

The BI was a short range interceptor prototype designed by  A. Ya. Bereznyak and A. M. Isaev. When operation Barbarossa started the project suddenly became very important which led to Bereznyak and Isaev making a more detailed design which the finished in a mere three weeks. On July 9th Bolkhovitinov and his team met with Andrey Kostikov the head of RNII. Dushkin was not happy about the idea of bypassing his fuel pump design, but they backed the plan and cosigned a letter that was eventually shown to Joseph Stalin. After giving a report at the Kremlin, they were ordered to build the aircraft and were given only 35 days to do so. The official order was dated August 1st, but work began in late July. The engineers were given leave to visit their families, and then literally lived at the factory until the aircraft was finished.

The new design was called "BI" for Blizhnii Istrebitel (close-range fighter), but the letters were also understood by everyone to stand for its inventors: Bereznyak and Isaev. The original plan to include four machine guns was replaced by a design with a pair of 20 mm (0.79 in) ShVAK cannon. The new aircraft was a low-wing monoplane 6.4 m (21 ft) long, with a wingspan of 6.5 m (21 ft) and an estimated take-off mass of 1,650 kg (3,640 lb) (dry mass 805 kg (1,775 lb) and had a maximum propellant load of 705 kg (1,554 lb). The D-1-A-1100 engine was capable of throttling between 400 kg and 1,100 kg and with 705 kg (1,554 lb)) of propellant, the engine could burn for almost two minutes.

Working around the clock, local furniture workers were employed to build the first two prototypes (BI-1 and BI-2). The skin was 2 mm (0.08 in) plywood with a bonded covering of fabric. The ailerons, elevators and rudder were fabric covered, and the flaps were duralumin. In the forward section were 5 compressed air tanks and 2 kerosene tanks. In the aft were 5 compressed air tanks and three nitric acid tanks.

Pressurized to 60 bar (6,000 kPa), the tanks were made from a high-strength chromium-manganese-silicon steel ("Chromansil") that was not especially resistant to corrosion. Thus, the acid tanks had to be replaced periodically. Compressed air was also used to retract and deploy the landing gear and to power the built-in cannon.

On 1 September 1941 the BI-1 was completed and ready for gliding tests by pilot Boris N. Kudrin as Dushkin's engine was still not ready. A few weeks later, rival aircraft designer A.S. Yakovlev took it upon himself to tow the prototype to TsAGI for windtunnel testing. This alarmed Bolkhovitinov's team, because their patron had a rocky history with Yakovlev, but Alexander Sergeevich and aircraft designer Ilya Florov studied the test results and gave them sound advice for improvements. Yaw instability was corrected by enlarging the rudder and adding two circular plates to the tail horizontal stabilizer.

Test Flights

In October, both OKB-293 and RNII were evacuated to the Urals, along with most of Moscow's war industry. Bolkhovitinov's team was stationed in Bilimbay, and Dushkin's team in Sverdlovsk, about 60 km (37 mi) away. A test stand was built on the shore of frozen lake Bilimbay, with a dynamometer cradle to hold the BI-1 during engine testing. A new test pilot, Grigory Yakovlevich Bakhchivandzhi, was assigned to the team. Dushkin was increasingly absorbed by other work, including RNII's own rocket aircraft project, the Kostikov-302. He assigned his engineer Arvid V. Pallo to oversee the installation and testing of the rocket engine.

Nitric acid presented a constant problem, corroding parts and causing skin burns and respiratory irritation. Tanks of sodium carbonate solution were kept around to neutralize acid spills. On 20 February 1942, the engine exploded during a full system test. The nozzle section was blasted into the lake, and the engine head struck the back of the pilot's seat, knocking Bakhchivandzhi against the instrument panel and injuring him slightly. Pressurized nitric acid from a broken propellant line drenched Pallo. Fortunately, quick thinking mechanics dunked him head-first into a tank of soda solution. His face was yellow from the characteristic acid staining, but his glasses saved him from being blinded. To protect the pilot in the future, a 5.5 mm (0.22 in) steel plate was added to the back of the seat.

By April 1942, BI-1 was ready for testing at nearby Koltsove airfield. A test commission was formed, with representatives from OKB-293, RNII and the NII VVS. On 2 May the pilot let the aircraft lift off to 1 m (3 ft 3 in) under low thrust.

On 15 May at 19:02 (UTC), Bakhchivandzhi made the first real flight of BI-1, reaching an altitude of 840 m (2,760 ft) and a maximum speed of 400 km/h (220 kn; 250 mph). The mass of the aircraft had been reduced to 1,300 kg (2,900 lb) (only 240 kg (530 lb) of nitric acid and 60 kg (130 lb) of kerosene loaded), and the engine was de-rated to 4.9 kN (1,100 lbf). The pilot shut the rocket engine off after about one minute, when a light indicated it was overheating. On landing, the aircraft descended too rapidly because of insufficient forward speed, breaking the main-landing-gear on touchdown. The pilot was unhurt and reported that, aside from the rough landing, the aircraft handled well. The flight lasted only 3 minutes and 9 seconds.

In July, Dushkin recalled Pallo to help work on the "302" rocket-aircraft project, meanwhile Bolkovitinov asked Isaev to take over and master the technology of liquid fuel rocket engines. Isaev got permission to visit Valentin Glushko, the leading Soviet expert on rocket engines, who was then working in a special lab for political prisoners. Glushko taught Isaev the complex techniques of chamber-wall heat transfer calculation and engine design, developed by himself and Fridrikh Tsander in the early 1930s. Isaev's propellant feed system was simple, but it produced an uneven fuel pressure that diminished as compressed air was used up. Bolkovitinov and his engineers wrestled with this problem, designing pressure regulators and even a piston fuel pump driven by compressed air, but none of these improvements were realized.

Too damaged by acid to fly safely, BI-1 was retired and the second prototype BI-2 was made ready. Backchivadzhi made the second flight on 10 Jan 1943, reaching 1,100 m (3,600 ft) but with the engine still throttled back for a maximum speed of 400 km/h (220 kn; 250 mph). The first flight had been with landing gear kept down, and some vibration was observed. For the second flight the landing gear was retracted, and no vibration was observed at the same speed.

On 27 March, during a low-altitude test flight, BI-1, piloted by Backchivandzhi, entered a 45-degree dive and crashed into the ground, killing Backchivandzhi. The accident put a halt to flight tests, and a lengthy investigation began. Eventually, after wind tunnel testing, it was determined that BI-1 lost control due to transonic effects on the pitch controls / stabilisers. Estimates of Backchivandzhi's final velocity range from 800 to 900 km/h (430 to 490 kn; 500 to 560 mph), but the recording instruments were too damaged by the crash for a reliable measurement. The 27 March is considered a black day in Soviet aviation history, also being the date that Yuri Gagarin died in a MiG-15UTI crash. In 1973, Backchivadzhi was posthumously elevated to Hero of the Soviet Union.

Media

Skins

• Skins and camouflages for the BI from live.warthunder.com.

Videos

Most unusual aircraft discusses the BI at 3:44 - War Thunder Official Channel

A BI... to fly - Napalmratte

The Shooting Range #218 - Metal Beasts section at 00:28 discusses the BI.

See also

Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:

• reference to the series of the aircraft;
• links to approximate analogues of other nations and research trees.

External links

• [Devblog] Crafting Event “Strategist”: Bereznyak-Isayev