Aeroplane – June 2018

TECHNICAL DETAILS FAIREY ROTODYNE

94 http://www.aeroplanemonthly.com AEROPLANE JULY 2018

the hydraulic clutch drive.

However, these modifications

interfered very little with the

Eland’s basic design so that

from the third stage of the

turbine the Rotodyne

installation was basically

standard. The engines drove

13ft (4m) Rotol propellers.

The Fairey-designed, fully

retracting, wide-track main

undercarriage comprised a

single oleo-pneumatic shock

absorber strut carrying twin

wheels on a common axle. The

legs retracted forwards into the

engine nacelles and were

designed to cope with landings

up to 69mph (110km/h). The

twin nosewheel unit, mounted

aft of the pilots’ cabin,

retracted forwards.

The aircraft’s main hydraulic

system featured dual pumps,

one for each engine, with a

duplicated system having an

independent source of supply

using a pump driven by the

rotor head. The two systems

worked continuously in parallel

to ensure control could be

maintained even if there was a

double engine failure.

Although the prototype

never featured its full

complement of passenger

seating, it was assumed that in

service the Rotodyne would

have offered a comfortable,

well-appointed environment.

Seats would have been

arranged in pairs with

appropriate toilet and in-flight

catering facilities. There would

have been 10 well-spaced

elliptical windows which would

have given the Rotodyne’s

passengers a generous view

outside. Entry to the cabin

would have been via an airstair

door at the front.

The Rotodyne Y’s fight deck

featured side-by-seating for

two pilots. Flying controls

followed normal helicopter

practice with cyclic controls

and collective levers. A

generous level of cabin glazing

was provided to give the crew

a good view of the ground

directly under the aircraft,

especially for landing.

Even though it was

constructed as a prototype, the

Y was still capable of meeting

the one-engine-out safety

requirement specified for

production Rotodynes. “A

great deal of thought has gone

into the handling control

problems in this case”, Hislop

said in a Flight interview

published a fortnight after the

first flight. “This approach has

perhaps tended to lengthen

our task in designing and

building the prototype, since

for a purely research aircraft it

would have been possible to

have omitted certain of these

design features. In my view this

would have been quite wrong.”

ROTODYNE Z

The Z, later designated FA1 by

Westland when it assumed

responsibility for the

programme, differed

significantly from the prototype

in many respects. For one thing

it was considerably bigger, with

a fuselage that would have

been around 6ft (1.82m) longer

and 2ft (0.62m) deeper.

Another major difference was

that the Z’s Rolls-Royce Tyne

turboprop engines would have

provided power for forward

motion only. The additional

power demands meant that a

pair of Rolls-Royce RB176 gas

generators located in the rear

of each engine nacelle would

have been required to maintain

the air supply to the tip-jets.

This supply would have been

to diametrically opposite pairs

of rotor blades to maintain a

level of single-engine

capability.

The main rotor blades

represented a complete

redesign and featured stainless

steel main spars containing the

single steel extrusion duct

carrying air to the tip-jets.

These single-duct blades

would have been constructed

in two halves comprising

machined stainless-steel

forgings bolted together in

low-stress regions with integral

root and tip joints. Electrical

de-icing heater mats

represented new technology

for the 1960s.

The hub would have

comprised a single forging. As

the aircraft would have had

200mph potential, reducing

frontal area would have been a

factor. The main swash plate

would have been located

below the hub and inside the

rotor pylon, while the hub

would have been fully faired

with a lightweight casing

extending along the inner

spars. The taper roller bearings

were intended to be lighter

than those of the Y.

The Z’s wing was 60 per cent

bigger than the Y’s, but it

differed in other ways from the

prototype’s because it tapered

in section from root to tip and

featured swept-back leading

edges on the outer sections.

The passenger cabin would

have featured seating

arranged in a two-plus-three

configuration. Two layouts

were proposed: 57 seats with

34in pitch and 70 seats with

32in pitch. Fairey envisaged a

development programme

involving four aircraft — the

original Eland-powered

prototype, the Tyne prototype

and the first two production

machines. They would be used

for the certification

programme and be sold once

that had been completed.

In the event the production-

variant aircraft got no further

than the mock-up stage. A

representation of the

Rotodyne Z’s fuselage

complete with fully equipped

flight deck, cabin and rear

loading ramp with beaver-tail

doors — was assembled at

Hayes. It was fashioned from

wood with marine ply skinning.

A 1:19-scale model of the

complete aircraft was made for

wind tunnel testing: it was the

largest size that could be

accommodated by the Hayes

tunnel. A considerable amount

of this testing had been

completed by the time the

Rotodyne project was

cancelled.

FAIREY ROTODYNE: SPECIFICATIONS

ROTODYNE Y ROTODYNE Z (FA1)

POWERPLANTS Two Napier Eland NEL3 turboprops Two Rolls-Royce Tyne 562

each generating 2,800shp with turboprops each generating

auxiliary compressors providing air 4,955shp and two Rolls-Royce

for four Fairey pressure jet units RB176 gas generators

FUSELAGE LENGTH 58ft 8in (17.88m) 64 ft 6in (19.7m)

WING SPAN 46ft 5in (14.17m) 75 ft (22.86m)

OVERALL HEIGHT 22 ft 2in (6.75m) 27 ft 3in (8.31m)

ROTOR DIAMETER 90 ft (27.43m) 10 9ft (33.22m)

GROSS WEIGHT 33 ,000lb (14,969kg) 60 ,800lb (27,578kg)

CRUISING SPEED 15 0-170mph (240-270km/h) 23 0mph (368km/h)

ACCOMMODATION Up to 40 passengers Up to 70 passengers, 62 troops

or 40 stretchers and two medical

orderlies

The Rotodyne Z differed significantly from the

prototype in many respects. For one thing it was

considerably bigger

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