How It Works-Amazing Vehicles

Infl uenced in design by the British

Hawker P.1154 and Harrier Jump

Jet, the Yak-38 VTOL aircraf t

looked similar to its

contemporaries, but its radically

different internal confi guration

and general poor qualit y build

and systems turned out to be a

costly mistake. Contrary to the

Harrier’s single Pegasus engine,

where thrust was vectored

through four nozzles from a single

source, the Yak-38 featured only

t wo nozzles from the main

engine, relying on a pair of

separate, less-powerful engines

housed in the front portion of the

aircraft to be used in conjunction

for vertical take-off and landing.

Apart from being a less-refi ned

and underdeveloped system, the

Yak-38 was built en-masse;

however, soon it encountered

massive problems during sea

trials. In hot weather the separate

lift jets often failed to start (due to

oxygen starvation), leaving it

stranded on the fl ight deck and

while it was

initially deemed

capable of carrying heavy

payloads, the hot weather also

reduced its operational range to

such an extent that only extra fuel

tanks could be carried. Further,

the average engine life span of the

aircraft was a minuscule 22 hours

and many pilots encountered

serious engine problems in every

fl ight they undertook (over 20

Yak-38s crashed due to system/

engine failure), with it quickly

gaining a reputation as a killer.

Finally, it was horrendously

diffi cult to fl y and could only be

landed by remote telemetry/

telecommand link, rendering it

useless in land warfare.

Obv iously, the Yak-38 did not

live up to its conceptual ideal – a

multi-mission 980km/h combat

jet w ith VTOL capabilities, a

service ceiling of 40,000ft and an

operational range of 240km – and

after a fi nal deadly crash in June

1991 was retired out of ser v ice.

Yak-38

The Soviet Naval Aviation’s

fi rst and only foray into

VTOL multi-role combat

a i rc ra f t, t he Ya kovlev Ya k- 38

The pinnacle of tilt-rotor/wing VTOL

aircraft, the V-22 has been in development

for 30 years and offers the cargo carr y ing

capabilities of a heav y lift helicopter, with

the fl ight speed, altitude, endurance and

range of a fi xed-w ing cargo plane.

This fantastic hybrid of two distinct

forms of aircraft comes courtesy of its

revolutionar y tilt-rotor technolog y – t w in-

vectoring rotors that can be adjusted over

90 degrees by the pilot – which attached to

foldable fi xed-wings, allow for vertical

take-off and then conventional fl ight. Both

rotors are powered by A llison T406-AD400

tilt-rotor engines that – considering its

massive size and carr y ing capacit y (20,000

pounds internally) – develop 6,150hp each.

Interestingly, the V-22’s design,

despite being more accomplished at

short take-off and landing (STOL)

manoeuv res, loses out to tilt-w ing VTOL

aircraft – such as demonstrated in the

Vertol VZ-2 – in VTOL manoeuv res by

ten per cent in terms of vertical lift.

However, due to the lengthy periods of

time that the V-22 can maintain its rotors

over 45 degrees, longevity of the aircraft

is greatly improved.

Unfortunately, despite current safe and

successful operation in the Iraq and

Afghanistan confl icts, during testing

numerous accidents occurred involving

the V-22, resulting in over 30 deaths to

crew men and combat troops.

V-22 Osprey

The world’s fi rst tilt-rotor aircraft, the V-22 Osprey is

at the cutting edge of VTOL technology

1. Separate
   engines
   T wo small separate
   engines were used for
   VTOL manoeuvres.
   2. Main engine
   The Yak’s main engine
   powered only the t wo
   main nozzles.
   3. Pipes
   As with the
   Harrier, a series
   of pipes carried
   pressurised air.

Yak-38 take-

off system...

A Yak-38 on the deck of a

Soviet aircraft carrier

Chirnilevsky© George

A retired variant

of the Yak-38 with one

of its vector nozzles

clearly visible

© Tosaka

The V-22 broke new ground

for VTOL aircraft

V-22 Osprey

Crew: 4

Length: 17.5m

Wingspan: 14m

Height: 6.73m

Weight: 33,140lb

Engine: 2x Rolls-Royce Allison

T406/AE 1107C-Liberty

Turboshaft

The statistics...

Yok-38

Crew: 1

Length: 16.37m

Wingspan: 7. 32 m

Height: 4.25m

Weight: 16,281lb

Engine: 1x Tumansky R-28

V-300 Turbojet

The statistics...

DID YOU KNOW? The Yak-38 used a hands-free landing system, utilising a telemetry/telecommand link to land