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SEPTEMBER 2OTH,

1945

FLIGHT

  • ROLLS-

ROYCE GRIFFON (65)

Review of the Latest ^Rolls-Royce Piston Engine : Classic Orthodoxy of Design Powers Yet Achieved

Highest Specific

W HEN confronted with the Rolls-Royce Griffon for the first time, the facile result of an initial rapid appraisal is that the engine is nothing much more than a scaled-np Merlin, and, although there is doubtless a

certain amount of justification

accurate.

In

actual

fact,

as

for this view, it is not wholly one's investigations progress,

the impression is steadily merely a scale-up of an

strengthened that, far from existing engine, the Griffon

being is an

entirely new engine in its own right. probably be pretty accurate to hazard

It would, however, the assumption that

the Griffon eliminating

was born of all the snags

a desire and, at

to redesign the Merlin, the same time, increase

the capacity to meet the imminent demand engine whilst retaining the smallest overall possible.

for a larger dimensions

How well the men of Derby have succeeded in doing what they set out to do may be appreciated in part by a comparison of overall dimensions as between Griffon and Merlin, together with the respective swept volumes and

29.5m., and Merlin 2y.825in.

It would seem well-nigh

impossible, ,011 the overall dimensions

face of

it, that

in two

engines

with such similarity of of the same basic type,

the swept volume of one should be 35.9 per cent,

than

that

of

the

other.

Such,

however,

is

the

case.

larger Piston

area of the Griffon is 23 per cent, greater than Merlin, this having been achieved by increasing bore to 6oin. : a figure which is just about the optimum limit.

that of the the cylinder verging on

In view of this one is led to wonder what form the Griffon's successor will take; the useful limit of piston diameter halving been reached, one is forced to the conclu- sion that any largar capacity piston engine that Rolls have in m^nd to follow the Griffon will, of necessity, have more cylinders. It is an interesting speculation which naturally, and on precedent, takes it for granted that Derby do intend to produce a new and bigger orthodox engine.

Influence of the Racing '' Buzzard ''

piston areas. In three inches longer

overall length than the 78m.

the Griffon 65 is 8iin., of the equivalent Merlin,

the 66; Merlin,

overall heights are respectively, Griffon, 45111., and 43.675111., whilst the overall widths are: Griffon

Before going on to deal with the Griffon, a word should be said on the prevalent and somewhat erroneous assump- tion that the engine is a counterpart of the famous " R "

special

Buzzard racing engine which secured the Schneider

BEARING VENT PIPE

Trophy for England in 1929 and 1931, and

established a World's Speed Record. Certainly, the bore and stroke size are the same and so is the fundamental layout of the engine—but there

the similarity ends.

It

that have

the lessons learned had their influence

can truthfully be said on the " R " engine on all the subsequent

Rolls gained ments

engines,

but equally,

the knowledge

in the Merlin has resulted in which distinguish the Griffon.

the refine- The one

particular directly to amount of

feature

which

the feriffon owes

the " R " is the crankshaft, development put into this

for the member

on the racing engine virtually towards making the Griffon the very beginning of its life.

paved theway a success from

7

Induction throat to impellers show- ing turbulence spider with fuel nozzles.

It is not, perhaps, gener-

ally

known

that

the

Griffon was" originally de- veloped primarily to meet the Fleet Air Arm's specific- needs—low-altitude power,

ease etc.

of service, reliability, In the early days of

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