Soviet prototype fighter aircraft family
I-21
|
|
Role
|
Jet
fighter
Type of aircraft
|
National origin
|
Soviet Union
|
Manufacturer
|
Alekseyev
OKB-21
|
Designer
|
Semyon Alekseyev
|
First flight
|
Late 1947
|
Retired
|
1947 after test flight.
|
Status
|
Prototype
|
Number built
|
3
|
Variants
|
Alekseyev I-212
|
The
Alekseyev I-21
was a Soviet
twin-engined
jet
fighter
, built in the late 1940s. Two
prototypes
were constructed with the designation of I-211, of which one was converted into the I-215 with more powerful engines. A third aircraft was built to evaluate the
bicycle landing gear
arrangement for use in other aircraft. The fighter was not accepted for production as it was inferior to the
swept-wing
fighters like the
Mikoyan-Gurevich MiG-15
.
Development
[
edit
]
After working as
Lavochkin
's right-hand man during
World War II
, Semyon Alekseyev was appointed as Chief Designer of
OKB
-21 (design bureau) at
Gor'kiy
. The
Council of the People's Commissars
directed Alekseyev and other designers to develop jet fighters using more powerful engines than the captured German
Jumo 004
and the
BMW 003
and their Soviet-built copies. The result of Alekseyev's efforts was the I-21 (Russian:
istrebitel
(fighter)), which was planned to be produced in several variants.
[1]
The I-21 was a twin-engined, all-metal,
single-seat
jet fighter, with straight
laminar flow
wings, mid-set on a circular fuselage. The fighter's 1,500-
kilogram-force
(15
kN
; 3,300
lbf
)
Lyul'ka
TR-2
turbojet
engines were mounted below the wings much like those on the German
Messerschmitt Me 262
fighter. Underneath the engine
nacelles
were
hardpoints
that could carry 250-kilogram (550 lb) bombs or
drop tanks
. The slightly swept tail unit was cruciform in layout with the tailplane set at approximately half-fin span with slight
dihedral
. The aircraft's structure was generally constructed from high-strength B-95
duralumin
, although high-strength steel and "Elektron"
magnesium
alloy
were used for some components. A hydraulically retractable
tricycle undercarriage
was fitted, using twin wheels for the nose and main landing gear. Hydraulically actuated
airbrakes
were fitted either side of the rear fuselage.
[1]
Alekseyev initially planned to arm the aircraft with three 37-millimeter (1.5 in)
Nudelman N-37
autocannon
, each with 30
rounds
, but later decided upon a pair of 23 mm (0.91 in)
Nudelman-Suranov NS-23
autocannon with 75 rounds per gun.
[2]
Design work on the I-210 (I-21 version 0) was concurrent with the I-21, probably as a fall back for any lack of availability of the latter's TR-2 engines. The only significant difference was the substitution of 800 kgf (7.8 kN; 1,800 lbf) BMW 003 engines (or the reverse-engineered RD-20), but the ex-German engine's significantly inferior thrust rating meant that it would never meet the I-21's speed requirement. Even replacing the BMW 003 with the slightly more powerful (900 kgf (8.8 kN; 2,000 lbf)) Jumo 004 would not allow the I-210 to meet the speed requirement and the project was cancelled before any metal was cut.
[3]
Construction of the first two airframes, designated as the I-211 (I-21 version 1), began at the end of 1946, under extreme pressure by the Ministry of Aircraft Production to complete initial flight testing by 1 August 1947, to enable the aircraft to take part in the Aviation Day Flypast at
Tushino
on 18 August. While one of the two airframes initially produced was used for static testing, the other was fitted with 1,300 kgf (13 kN; 2,900 lbf)
Lyul'ka TR-1
turbojet engines because the intended TR-2 was not available. The engines were mounted in the middle of the wing, with the wing
spars
continued by banjo rings around the engines, much like those on the British
Gloster Meteor
fighter. Despite pressure from above, the I-211 was unable to participate in the Tushino display.
[4]
Flight testing started in late 1947, but only six test flights had been carried out before the I-211 struck a
pothole
on landing, which collapsed the undercarriage. Even the limited amount of flight testing showed it to be faster than the
Sukhoi Su-11
which also used the TR-1 engine. Repairs were carried out and the opportunity taken to replace the troublesome engines with imported 1,590 kgf (15.6 kN; 3,500 lbf)
Rolls-Royce Derwent
V engines. Alekseyev took the opportunity to upgrade the aircraft to the I-215 configuration which had been in development since before the first flight of the I-211. The substitution of the
centrifugal-flow
Derwent for the
axial-flow
TR-1 forced the redesign and enlargement of the nacelles to accommodate the larger engine. Other modifications included increasing the fuel capacity from 2,000 kg (4,400 lb) to 2,300 kg (5,100 lb), provision for a ranging
radar
in the nose, and better protection for the pilot. The armament was revised to the originally specified N-37 guns, although the ammunition capacity was marginally increased to 35 rounds per gun. Despite good results from flight testing, the I-215 lost out in production orders to the newer generation of swept-winged fighters.
[5]
A second I-215 was built to an order from
OKB-1
as the I-215D (
dooblyor
, second prototype), to evaluate the bicycle or tandem landing gear configuration. It used wider-diameter paired wheels in a tandem arrangement that retracted into the fuselage, along with small outrigger wheels under the engine nacelles which retracted into fairings. The main undercarriage of the I-215D also incorporated a kneeling feature which could increase the
incidence
of the aircraft by 3° to assist take-off. Trials with this undercarriage arrangement were successful and paved the way for its use in other Soviet aircraft, including Dr.
Brunolf Baade
's
Aircraft 150
, then under development.
[6]
Variants
[
edit
]
- I-210
- The initial version with BMW 003 or Tumanskii RD-20 engines, project only.
[3]
- I-211
- The first flyable example completed as the I-211 with Lyul'ka TR-1 engines, rebuilt as the I-215.
[7]
- I-211S
- I-211 with swept wing and unswept tail, project only.
[7]
- I-215
- The re-built I-211 with Rolls-Royce Derwent V engines and other minor modifications.
[8]
- I-215D
- Bicycle-undercarriage I-215 built to order of OKB-1.
[6]
Specifications (I-211 as tested)
[
edit
]
Data from
Early Soviet Jet Fighters
[9]
General characteristics
- Crew:
1
- Length:
11.54 m (37 ft 10 in)
- Wingspan:
12.25 m (40 ft 2 in)
- Wing area:
25 m
2
(270 sq ft)
- Airfoil
:
I-S10-11
- Empty weight:
6,890 kg (15,190 lb)
- Gross weight:
7,400 kg (16,314 lb)
- Fuel capacity:
2,000 kg (4,400 lb) (internal), 2,500 kg (5,500 lb) (with drop tanks)
- Powerplant:
2 ×
Lyul'ka TR-1
axial-flow turbojet, 12.8 kN (2,870 lbf) thrust each
Performance
- Maximum speed:
950 km/h (590 mph, 510 kn) at sea level
- Ferry range:
1,550 km (960 mi, 840 nmi)
- Service ceiling:
13,600 m (44,600 ft)
- Rate of climb:
27.78 m/s (5,469 ft/min)
- Time to altitude:
5,000 m (16,000 ft) in 3 minutes
Armament
See also
[
edit
]
Aircraft of comparable role, configuration, and era
Related lists
References
[
edit
]
- ^
a
b
Gordon & Kommissarov 2014, pp. 405?06
- ^
Gordon & Kommissarov 2014, p. 415
- ^
a
b
Gordon & Kommissarov 2014, pp. 406?07
- ^
Gordon & Kommissarov 2014, p. 410
- ^
Gordon & Kommissarov 2014, pp. 410?11, 414?16, 422
- ^
a
b
Gordon & Kommissarov 2014, p. 422
- ^
a
b
Gunston 1995, pp. 16?17
- ^
Gordon & Kommissarov 2014, pp. 416?18, 422
- ^
Gordon & Kommissarov 2014, pp. 405?06, 415
Bibliography
[
edit
]
Further reading
[
edit
]
- Green, William & Swanborough, Gordon. "The Complete Book of Fighters". London: Salamander Books. 1994.
ISBN
1-85833-777-1
External links
[
edit
]