Glad to hear that everyone had a good time, Laura & I were honored that
you all came that far to be here. Already looking forward to next
year!
Just have to comment on some test results that seem to be a "free
lunch" in the fuel economy area. Some of you may recall that I see
only a small reduction in fuel burn on the Renesis compared to the earlier
13B. The biggest change is at low throttle, like at idle and taxi power
settings where it really does not matter much (usually).
Yesterday on a mental health flight, I was slowly descending at a
power setting too low to maintain level flight (about 3100 rpm burning about 1.5
GPH) and was grinning at the MPG readout on the EM2 which was showing about 55
MPG. The best I can manage in level flight is around 30
MPG. VSI was showing 200 FPM down so it took 5 minutes to descend 1000
ft. I started thinking about the time it took to climb 1000 ft and
wondered about what the MPG was in climb since I don't usually pay much
attention to that. I setup a moderate climb power setting but instead of
setting up best power mixture I set it fairly lean to minimize fuel burn instead
of maximizing climb rate. At 9.5 GPH and 100 MPH I was climbing at
1500 fpm and getting 10.5 MPG. It took 40 seconds to climb 1000
feet. Hmmm, I thought, what is the average MPG if I get
10.5 MPG for 40 seconds and 55 MPG for the next 5 minutes? I think
the answer is around 48 MPG but that seems to be too good to be true.
Seems like some one would have used this technique long ago if it would give a
60% increase in fuel economy. The error in the EM2 fuel flow readout may
be higher at this low flow but nothing like 60%. Any math majors out there
see a flaw in my math or logic? Or maybe I was in a giant thermal at
the time? I repeated the test twice so I don't think so.
The only down side is that I had to fly relatively slow to get these
results (95 - 100 mph) but a 60% increase in fuel economy sure could
be handy in some situations. This test was at 1000 - 2000 feet so
I'll have to see if it holds true at higher altitudes.
Tracy
----- Original Message -----
Sent: Monday, October 31, 2005 10:26
PM
Subject: [FlyRotary] Shady Bend
As always, it was 'worth the drive'. Had an enjoyable trip down
with
Kelly, Monty & Ken on Thursday. As you can tell by seeing
Bill's
photos, the tour of Finn's 'incident site' was terrifying. The rest
of
the weekend was much more pleasant. All the forums were informative,
from Tracy de-mystifying engine controller programming to Monty starting
a research program into quieting the rotary's exhaust. In my
not-so-humble opinion, this could be a pivotal factor in the widespread
acceptance of the rotary.
The highlight of the weekend for me was
my ride in Tracy's rotary RV-4.
Acceleration & climb were obviously
more impressive than my Lyc powered
-4, but the exciting thing for me was
seeing a low altitude (~1500ft)
cruise power setting yielding 190-195 mph
true airspeed burning between
8.5 & 9 gph. My goal for my RV-7 project
is minimum 200 mph cruise at
max 10 gph. I've been a huge fan of the
rotary since my dad's purchase
of a new '74 model RX-4, but I've had
serious misgivings about whether
the rotary could achieve that fuel
burn/speed combination due to numbers
quoted by others already flying.
Tracy's plane proves those numbers are
achievable. Now, Mike Magee needs
to get back to work on that aluminum
accessory cover that will bolt up to
a standard Lyc mount. (Are you
listening, Mike?) Even though Mistral seems
to be making their parts
available, I really can't afford the exchange
rate & 'certified' prices.
The more I see of the Renesis, the more
pleased I become that I'm
running so far behind everyone else. :-) By the
time I'm ready for an
engine, it will be almost as cheap as a 2nd/3rd gen
engine & *much*
easier to convert for aviation use. No water pump mods
needed, dirt
simple & compact intake & exhaust manifolds, easier
to tame exhaust
pulses, equal or superior horsepower, available used
without being 'used
up', etc, etc.
Anyone who is installing or
planning a rotary installation can't help
gaining invaluable knowledge
while attending these events. Beyond that,
you just can't beat the great
people you meet & form friendships with.
My heartfelt thanks to
Tracy for sharing his wealth of knowledge & to
Laura for making these
events possible. I can't wait to see you guys at
Bill & Linda's in
February.
Charlie
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