Pilot – June 2018

pilotweb.aero | Pilot June 2018 | 35

Tech Log: Rotax 915iS

I

t would be fair to say that
since the Rotax 912 exploded
onto the general aviation
scene a scant 29 years ago
in 1989 the ‘nine-series’ of
Rotax engines has transformed
GA. With hindsight, it seems
incredible that none of the other
major aero engine manufacturers
had the foresight to predict the
need for a relatively lightweight
yet powerful engine. With its
innovative combination of
air-cooled cylinders but liquid-
cooled heads, relatively small
cylinder capacity and mechanical
reduction gearbox, the Rotax
was a world away from the air-
cooled Lycoming and Continental
engines that most of us grew
up with. With its good power-
to-weight ratio and low fuel
consumption the design rapidly
gained acceptance, even if the
way it started and stopped made
most of us wince!
It was the emergence of the
Light Sport Aircraft class in
the USA, with its strict 600kg
maximum all-up weight (MAUW)
limit that really secured the nine-
series Rotax’s place as the engine
of choice for most light aircraft

designers. The original 80hp 912

was soon joined by the 100hp

912S and then the turbocharged

115hp 914, while the 100hp

model was subsequently

marketed in both carburetted and

injected versions, either certified

or, for LSA, ASTM-compliant.

However, you can never have

too much power, especially for

four-seaters, and after this year’s

AERO at Friedrichshafen aviation

journalists were invited to visit

the Rotax factory at Gunskirchen

in Austria to hear more about the

latest engine−the 141hp 915−

see how it is made and sample it

in flight.

Before going flying, our

party enjoyed a visit to Rotax’s

ultramodern factory. It’s quite an

easy place to find as it’s based on

Rotaxstraße, while if you’re flying

in to the lovely local airport of

Wels you can’t miss it, as ‘Rotax’

is writ large in red letters on the

factory roof. Rotax make many

engines of different types−

around 300,000 a year in fact,

although only around one per

cent of these are aero engines.

The rest are used in a bewildering

variety of applications, from

skidoos and seadoos to ATVs,

SSVs and even as stationary

engines. (I got to sample some of

the other applications in various

off-road vehicles at a sporty little

test track. This was so much fun

that I hoped the Editor, who’d

had to stay at home, manning the

office, wouldn’t find out!)

Indeed, at a glance you might

think that building aero engines

is almost a hobby for Rotax.

However, quite apart from the

significant contribution the aero

engine division makes to parent

company BRP’s bottom line it’s

also important from a branding

perspective. It’s a given that

aero engines must be reliable, so

when a prospective customer is

considering their next purchase

The name is not just proudly spelled out on the roof, but the factory is located in a street called Rotax – Rotaxstraße!

Another Rotax-engined machine...