The
Intersection of Speed and Efficiency
by Klaus Savier
As
a result of the ever-increasing fuel
cost, I decided to demonstrate the
efficiency of the Delaminator, a highly
optimized Vari EZE, a grocery getter and
25-year-old “Technology
Demonstrator” for Light Speed
Engineering.
This
airplane is well known for winning all
kinds of races since 1984. From the CAFÉ efficiency races in the late 80’s to the
AirVenture Cup race in 2007, where it
won the 400 mile race from Dayton to
Oshkosh at an average speed of 254 mph.
In 1990, two closed course world
records were set in the C1-A weight
class for the 1,000km and 2,000km
distances at over 200 mph. They are
still standing.
The
Delaminator’s configuration for this
endurance flight was identical to that
used in the AirVenture Cup:
-
Same LSE Composite 64x86
Propeller,
-
Dual Plasma III CDI,
-
Our own Timed Sequential
High Pressure Electronic FI,
-
No extra tank- standard
29-gal Vari Eze fuel system,
-
About 25 pounds of
luggage: minimal tools, no spare parts.
On
Monday April 7th, just prior
to Sun ‘N Fun, the weather looked
great for a non-stop flight across the
country, coast to coast, 2000 miles.
I hopped in the Delaminator as
early as I could bear and set out for
Florida.
The tailwinds were good but not
quite as strong as predicted so I had to
slow down a little to increase my range.
It took 8 hrs and 58 min for the
total distance of 1985 statute miles,
SZP, CA to PFN, FL via ELP TX to avoid
the restricted area.
Total
fuel used was 25.8 gallons of the 29.2
carried in the standard tanks, leaving
more than an hour worth of fuel
remaining.
Average fuel flow for the entire
flight was 2.87 gph.
Average speed was 220.6 mph.
Tailwind average was around 30
mph at 17500 ft.
The density altitude was above
19000 ft.
Of course, I was on oxygen for
the entire flight.
Now
for the technical run-down on engine
configuration and the methods used to
achieve this level of efficiency.
In the Delaminator, the maximum
manifold pressure available at 17500 is
almost 16”. See picture 1 and note the
fuel flow of 4.2 gph at peak power
giving a true airspeed of 204kts,
resulting in 55.9 statute mpg.
As shown in picture 2 taken
during this cross-country flight, the
throttle was reduced by almost 1”.
While our custom FI automatically
adjusts the mixture for all engine
conditions, it can be biased just like
the Plasma CDI timing. The automatic
mixture adjustment was thus manually
leaned to almost 300 degrees past peak
EGT, where slight roughness occurs.
Manual increase of timing advance
returns some power lost under these
conditions and eliminates any lean
misfiring.
As a result of these settings and
lean burn, all temperatures are near the
low limits, oil pump outlet temp is
below 150 F and the cylinder head
temperatures are all below 300 F.
See picture.
While leaning this far on the
lean side of peak reduces power
significantly, it is slightly more
efficient to reduce power by leaning
rather than by closing the throttle
because the pumping losses of the engine
are lower.
The
best “no wind range” is normally
achieved at best glide speed.
For the Delaminator, this is
about 100mph when fully loaded.
Most of the trip was flown at 130
mph indicated at 17500 ft.
Prior testing has shown that the
airplane achieves well over 80mpg at
best glide speed.
Flying at 130 mph, the
Delaminator still achieves over 60 mpg.
The tailwind brought the mpg to
nearly 80 mpg.
While
I could think of a faster airplane with
a higher wing loading and a bigger
engine, such a configuration could not
come close to the efficiency
demonstrated here at high altitude.
It seems that this combination of
a highly optimized 0-200 engine and high
aspect ratio wings offers a combination
of efficiency and speed that simply
cannot be beat.
Klaus
Savier
4-08 |
™
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