Engine makers: 4. Rolls-Royce

From:         Andrew Chuang <chuanga@iia.org>
Date:         11 Aug 94 02:18:16 
References:   1
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Rolls-Royce
===========

Rolls have been in the civil jet business for a long time.  After all,
turbojets were invented by the British.  The Comet, Trident, Caravelle,
BAC1-11, VC10 and B707-420 were all RR-powered aircraft.  They also build
the Tay engine for the Fokker F100 as well as some reengined B727s and 1-11s.
In addition, R-R is a major partner of IAE, and R-R is collaborating with BMW
to build the BR700 family for regional jets and the MD95.  The Berlin-based
Anglo-German joint venture is also mulling to build the BR500.  Nevertheless,
R-R's current bread and butter is the RB211/Trent which can be found on the
L1011, B747, B757, B767 (with British Air being the sole customer), B777, and
A330 (the first-ever R-R-powered Airbus).  Although, Some MD11s were to be
powered by the Trent 600, the engine program was eliminated with the demise
of Air Europe which was the only Trent-powered MD11 customer.

Similar to the PW4084, Trent is likewise a derivative engine.  It is most
impressive that R-R is able to provide thrusts ranging from 37,000lb to over
100,000lb with the RB211 family, while the American competitors need at
least two families to fulfill the same requirement.  (Just for reference,
the initial JT9D-3 generated 43,000 lb of thrust, while the largest JT9D,
the -7R4H1, generated 56,000 lb of thrust.)  Although R-R were the only
supplier for the L-1011 powerplant, and R-R are marginally dominating the
B757 market, R-R have the smallest overall market share among the three
engine firms.  Thus, it was not surprising that R-R had once agreed to
co-develop high-thrust engines with GE.  R-R subsequently retracted from the
deal and revived the RB211-524 program with Cathay Pacific Airways' B747-400
order.  In spite of the near cancellation, the RB211/Trent is still a
formidable competitor for both the PW4000 and CF6/GE90.  It's puzzling why
R-R cannot cash in on the commonalities of the RB211/Trent engines to gain a
larger share of the market.  Perhaps, they have an ineffective marketing
operation, or their engines are not as good as they claim.  Nonetheless, the
American manufacturers do have a notable cost advantage over R-R, and this is
probably the most important factor of all.

There are some significant differences between the RB211/Trent and the
American counterparts.  First of all, the RB211 was the first engine to
use wide-chord fan blades.  Although, the wide-chord fan blades are much
larger than the traditional fan blades, there is hardly any weight penalty
because the wide-chord blades are hollowed and the blade count is reduced
by a third.  Furthermore, they are aerodynamically more efficient and less
susceptible to vibration problems.  R-R wanted to use the technology back
when the L-1011 was first introduced, but it was not until the mid-80s (?)
were they able to put wide-chord fans into service with the newer RB211,
the -535E4 and -524G/H.  As a result of R-R's involvement in IAE, the V2500
is the only other in-service engine that uses wide-chord fan blades.
Nevertheless, both the PW4084 and GE90 will use wide-chord fan blades, too.
On top of that, GE will take one step further by using composite materials
for the GE90 fan blades.

Other visible RB211 differences are: 1) the engine rotates in the "wrong" :-)
direction (clockwise, forward looking aft), 2) the newer RB211s (-535E4 and
-524G/H) have "integrated exhaust nozzles", i.e., the bypass flow is mixed
with the hot jet flow from the core before it is exhausted.  The most visible
characteristic of integrated exhaust nozzles is that the cowling run through
the whole engine length.  The advantages of mixing the bypass and core flows
are improved thrust, reduced specific fuel consumption and reduced noise; but
there will be more drag, the engines will be heavier and more items are
needed to be maintained.  Other high-bypass turbofan engines that use the
same feature include the V2500 and the CFM56-5C on the A340.  However, the
Trent 800 does not seem to have the integrated nozzle.

In addition to the aforementioned differences, the biggest difference is in
the basic design: the RB211/Trent has three shafts that drive the low-
pressure (LP), intermediate-pressure (IP), and high-pressure (HP) stages,
while the traditional two-shaft configuration has the LP and HP stages, only.
The advantage of the three-spool design is that the IP stages operate at the
optimum speed instead of the lower fan/LP speed, but its mechanical
complexity makes it harder to maintain.  In fact, the RB211 is the smallest
and yet the heaviest engine because of its three-shaft and long-cowl
integrated-nozzle configuration.  However, Rolls boasted the Trent 800 as
the lightest B777 engine because the efficiency of the three-spool design
is now fully realized with the high-thrust applications.  As a result, Rolls
anticipated that the B777 with the Trent 800 would burn less fuel than with
competitors' engines on trips shorter than 4000 nm.  If all these claims are
true, then financial incentives must be more important than performance
figures.  Otherwise R-R should not have lost British Airways' B777 order to
GE!  (BA is the largest and most loyal R-R customer.  Other than the old
B747-100s and a few ex-BCal DC-10s, BA's widebody fleet as well as the B757
fleet are exclusively powered by the RB211.)

Significant customers: British, Cathay Pacific, Qantas, American (B757),
		       TWA (the first and only Trent customer in North
		       America)