Powertrain & Energy - July 25, 2012 - 9

advantages because it does not freeze and is more
benevolently controlled during load change situations.
During the technical briefing, the Behr expert
highlighted the benefits of ethanol but said that
“this decision will ultimately depend on an industrywide
discussion.”
Asked about how the recovered energy is best
fed back into the drivetrain, Pantow said that both
the direct mechanical use and the electrical storage
have advantages: “If we use the kinetic energy from
the expander directly as mechanical driving force,
the total system efficiency will be higher. However,
there are driving situations where there is no need
for the recovered energy. If the expander energy is
converted to electrical energy, it can be stored and
used freely, independent of the driving situation.
The downside of this thermo-electric process is the
amount of loss, which is caused by the conversion.”
During the oncoming further development work,
the supplier is optimistic that there is even more potential
to increase the WHR system’s efficiency: “For
one, we have not yet optimized the system design
details for individual working fluids. Secondly, we
have had some heat losses through the many sensor
accesses we integrated into the prototype.”
Joerg Christoffel
Engineers work off extra engine-blade weight
Changing from alloy to composite materials for engine
fan blades is an identified path to reducing
overall engine weight by a significant amount—typically
up to 1000 lb (454 kg).
Further weight reductions in nacelle structure in
turn enable pylon and wing weight reductions that
enhance aircraft performance and increase potential
profitability. The gains, when spread across large
airline fleets, could build into millions of dollars
saved each year.
But this switch to composite blades has been
tried before and failed initially as a result of insufficient
resilience when it came to bird strikes. The
technological knowledge about composite blade
manufacturing was at a relatively primitive stage.
However, over the years new methods involving
the laying up of the multiple crossed layers of composite
material sheets have given a far stronger
“woven” texture to the material that is far less likely
to shatter when hit by birds or other foreign objects.

When combined with titanium tip edges, the
composite blade benefits from the best of both
worlds, with outstanding lightness along with extreme
strength and the ability to resist damage.
The success of the GE90 from GE, currently the
only engine option offered on the hot-selling
Boeing 777-300ER, which features composite wide
SAE Powertrain & Energy
CTAL’s developmental composite blade
incorporates titanium-bonded leading and
trailing edges. (Rolls-Royce)
July 25, 2012
9
Powertrain & Energy - July 25, 2012

Table of Contents for the Digital Edition of Powertrain & Energy - July 25, 2012
