La-5FN-1.cdr

Power: 1xASh-82FN 1,850 hp (1,379.16 w), Shvetsov 14 cylinder radial, air cooled
Unladen weight:  .....................................................6,173 lb (2,805 kg)
Laden weight:  ........................................................7,406 lbs (3,359 kg)
Max Speed (21,325 ft):  ..........................................403 mph (650 k/ph)
Climbing Rate:  .......................................................16,405 ft in 5 min 0 sec
Max range:  .............................................................475 miles (765 kms)
Service Ceiling: ......................................................36,090 ft (11,000 m)
Wingspan:  ..............................................................32ft 2 in (9.8m)
Length:  ...................................................................27ft 10.2in (8.5m)
Height:  ...................................................................9ft 3in (2.84m)
Wing Area:  .............................................................189.34 sq ft
Armament: 2x20 mm ShVAK cannon (200 rounds per gun), nose

After designing the LaGG-3, the designers split on how to

increase is performance. Improved production and experimental
variants of this aircraft with water-cooled engines did not provide a
satisfactory solution. Then a radical solution came with the suggested
installation of the M-82 14-cylinder radial air-cooling engine, which
was lighter and much more powerful than engines of M-105 family.
What was also ideal was that M-82 production was well set and huge
stocks of this engine were available. Created to power single-engine
bombers of the Su-2 class, it just waited for another airframe to be
fitted to. V.P.Gorbunov and M.I.Goudkov came up with their
solutions, slightly different by the degree of modifications to the
LaGG-3. But their conversions (LaG-5 and Gu-82) had only limited
success.

S.A.Lavochkin also managed to modify the LaGG-3 to

accept this engine, despite the lack of official support. Lavochkin's
Factory N°153 (Novosibirsk) was taken over by A.S.Yakovlev (the
Yak-1 was in production there in parallel with the LaGG-3). He was
left with only a nucleus of his team in Tbilisi. He was so out of official
favor that the factory director refused to cooperate with this potential
saboteur and enemy of the people. So the La-5 prototype was
assembled and kept out in the 'open' and was ready at the very end of
1941. After factory trials the La-5 was evaluated by the military in
May 1942 and approved for pre-production.

Ten pre-production aircraft were found to be 40 to 50km/h

slower than the prototype. A specially assigned group of TsAGI
aerodynamic experts traced the problem to gaps in the engine cowling
and it was quickly cured. Vibration problems caused by the lack of
propeller blade balance were also fixed. But when two aircraft were
lost in fatal accidents due to wing failure, the test flights were halted.
Only after exhaustive searching and ground tests did Lavochkin find
the cause. Factory workers had been enlarging the holes for the wing
attachment bolts to make them easier to assemble - but this weakened
the wing and caused its failure. After the positive conclusion of its
trials the La-5 was rushed into production and front line service. The
first regiments were manned by factory pilots and arrived at Stalingrad
in September1942. As many as 1129 were assembled during 1942

This aircraft used the same delta-wood technology as the

LaGG-3 and shared a lot of its components. The La-5 also had a
retractable tail wheel (it was fixed on the LaGG-3). Early batches even
had a 2-layer nose section, one (inner) inherited from the LaGG-3 and
another (outer) just an aerodynamic transition from the large diameter
M-82 cowling to the slim LaGG-3 fuselage. Without production
interruptions, numerous changes were made. Delta-wood relied on
imported epoxy, and was gradually replaced by thicker (but less dense)
pine parts - and later by metal ones. From 1943 on the fuselage behind
the cockpit was lowered, providing a better view for the pilot.

The flow of cooling air was provided by a pair of large

adjustable louvers on each side of fuselage. This solution proved to be
no less efficient than commonly used 'all-round' cooling gills, but
more technological and reliable. It became a common feature for the
entire line of Lavochkin's piston engined fighters. On the La-5 these
louvers had an articulated fairing (covering the large diameter joint
exhausts). This was deleted in later aircraft of this type. Other 'marks'
of production of the La-5 were a step-shaped nose intake - pushed up in
later models with supercharged engines.

In 1943 more powerful engines were fitted. Experiments

with the M-71 were officially discouraged. The boosted M-82F was
installed on some batches of production aircraft. Those differed by a
Cyrillic 'F' painted on the engine cowling. All M-82F powered aircraft
had a cut-down upper fuselage. Those aircraft are often referred to as
the La-5F. But this is not an official designation and a number of
'Lavochkins' with an all-around canopy had an original M-82 engine.

Like all Soviet aircraft, the La-5 offered little in the way of

cockpit sophistication and pilot comforts. In the Summer time cockpit
ventilation was insufficient, and pilots complained about excessive
heat coming from the engine. But as a fighting aircraft, it was
exceptional. The La-5 inherited the 2-level neutral gas protection of
the fuel tanks that was used on the LaGG-3. With less vulnerable radial
engines the La-5 was a very hard-to-kill aircraft. And the Pilot was
protected by a 10mm armor seat back.

Built in a few different variants, the La-5 is often poorly

represented by Western sources. Designations used are often wrong or
misused, like the Lag-5. Some sources mix the La-5 with La-5FN and
even with La-7.

During the offensive stage of the Battle for Stalingrad the

new Lavochkin aircraft made its debut. In the Summer of 1943 the La-
5FN was delivered in substantial numbers making a massive show
during the Kursk Bend battle. While the La-5 was equal to most of the
German front line fighters at low to medium altitudes, it still had a
comparatively poor climb rate. With the new 'Lavochkin' arrival this
gap was filled.

Externally the La-5FN differed from the late production

La-5 by the more articulated air intake on the top of the engine
cowling, providing more room (and more air) demanded by new ASh-
82FN supercharged engine with direct fuel injection. Farings on the
cooling/exhaust side louvers were removed. Slightly larger new VISh-
105V (3m diameter) propellers were installed.

But the 'hidden' changes were even more substantial. A

more powerful engine with better altitude performance was
supplemented by airframe improvements. These included new suction
operated leading edge slats and radically improved and balanced
controls (following the TsAGI expertise). As a result the La-5FN and
later aircraft of this line became the most lightly controlled fighters of
their time. In addition, large ailerons provided it with excellent roll
characteristics. Improvements in the wing structure allowed the use of
larger fuel tanks, but this opportunity was realized only on a few
aircraft. Commonly, the fuel tank's volume is the same or smaller than
on the La-5.

The La-5 pilot's complaints about excessive cockpit heat

were taken into account and the La-5FN provided sufficient comfort.
Spartan cockpit instrumentation was sufficient for a daylight prop
fighter.

In an effort to improve the high altitude performance of the

La-5FN a small number of La-5FN-TK were built. These fighters
were equipped with turbochargers designed by Treskin. Quite
commonly, marginal high altitude advantages were outweighed by
performance losses at low and medium altitudes - where 'Lavochkins'
were mostly used. However, a high altitude fighter on Eastern front
was not a pressing priority, and this project was abandoned.

Lavochkin La-5FN

PART 9

11A

12a

14a

20A

26A

26B

27A

27B

21a

16B

19A

B B

C D

19+19A

16B

16C

16A

WIRE

1 10

7a/b

23+wire

20A

18+I

21+II

13 12

11A

12a 14a

26A

26B/27A

27B

Document Outline