60 AUGUST 2018 ÇPlane&Pilot
and rate of climb were, as you’d expect,
not as good as the SW’s. However, it
did seem signiicantly better than the
100-hp Aquila that I tested back in
2014, although unlike the Bristell the
increase in horsepower meant that a
LOT more right rudder was required to
keep the slip ball centered in the climb.
As with the Bristell, I climbed rapidly
up to 7,000 feet, set 5,500 rpm and 37
inches of manifold pressure, trimmed
forward and let the aircraft accelerate.
Again, the turbo worked as advertised,
manifold pressure was maintained and
the IAS inally settled on 131 kts for a
TAS of 148 with a fuel low of 9 gph. he
engine had seemed extremely smooth
in the Bristell, and in the Aquila it felt
even smoother. his may be due to the
dissimilar propellers or even a product
of the diferent materials used in the
manufacture of the two airframes (the
Aquila is predominantly of compos-
ite construction, while the Bristell is
mostly made of metal). From a quan-
titative perspective, I’m reasonablyconident about the veracity of the data
gathered, as both aircraft were itted
with a Stock Flight Systems Engine
Monitoring Unit. Sometimes referred
to as a Stock Box, this fully integrated
digital EMU was developed by German
engineer Michael Stock in conjunc-
tion with Rotax and can display (and
record) a wide range of parameters in
a variety of diferent units. We inished
a fun day’s lying with a ine meal at a
traditional Austrian restaurant, hosted
by BRP-Rotax GmbH & Co. KG General
Manager homas Uhr. homas proved
to be a most convivial host, and over
some excellent schnapps (I can recom-
mend the zirbenschnaps, which are
made with pinecones), he indulged us
with a Q&A session. Bearing in mind
both test aircraft were itted with C/S
props and that the 915 was speciically
designed with C/S props in mind, an
obvious question was “would ixed
pitch propellers be an option?” He
replied that we should “have a look
at all of our other products—thereare none where we have let our ixed-
pitch customers down. But oicial
announcements are only possible if a
product is available. So: no comment.”
He wouldn’t be drawn on the launch
customer for the 915, conirmed that he
keeps a close eye on electric and hybrid
developments, and, when asked about
the possibility of developing an aero-
batic nine series engine, replied “How
many thousands will you order? From
an engineering point, we would love to
do so, but we don’t see the market yet.”
He was then asked—bearing in
mind parent company BRP makes
several vehicles (such as Sea-Doos, Ski-
Doos and Can-Am ATVs and SSVs)—
has Rotax ever considered building an
aircraft? “Well,” he smilingly replied,
“we obviously have some of the skills,
tools and resources to build an aircraft
on an industrial basis—but we have a
high level of respect for our custom-
ers’ ingenuity, and, simply framed,
why should we [upset] 267 of our best
customers?” PPRotax engines are well known today by pilots and aviation enthusiasts and have been around the United States since the 1980s. But Rotax builds engines for
a large number of applications, including snow machines and watercraft.