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Dave (and Al),
Thanks for the data points. I havent done any
experimenting yet with lean of peak ops. My EGTs seem to be pretty well balanced
with only a 10 - 20 degree spread max at cruise settings. So I should be pretty
well set for LOP, just havent messed with it yet.
French Valley is outside my test area. So far I havent
really flown anywhere but Borrego and back, but I'm going to start
expanding that a little. The trip to Borrego is getting boring.
Mike
Sent: Thursday, January 07, 2010 9:07 AM
Subject: [FlyRotary] Re: first flight of the new
year
Again, my experience is very similar to Al's. I cruse between 6k' and
17k' depending on the winds. That gives quite a range of variables.
Interestingly though, regardless of altitude and RPM etc, about 8 gph seems
to hit the narrow sweet spot with my EGT's (actually TOT) below
900C (about 1600F) and yet the engine not running too rough (giving me
about 155KTAS). Yes, the RPM decreases quite noticeably when going to the
lean side of peak and the engine is not as smooth (I have grown used to it, but
I think Al really notices when he flies in my plane). In order to
help my turbo last longer, I avoid peak EGT pretty religiously (that seems to be
working so far, over 200 hrs on current turbo). At the lean setting, the
O2 sensor off the lean end of the scale.
Because of my turbo Manifold, I am unable to install individual EGT sensors
for each rotor, so my rotors are still slightly unbalanced (probably most of the
problem with roughness). Besides, even if you were able to get them
perfectly balanced at one RPM, it would change slightly at a different RPM/power
setting.
Without the turbo, you should be able to safely run closer to peak EGT or
best power without risk of damaging anything.
On Wed, Jan 6, 2010 at 10:19 PM, Al Gietzen <ALVentures@cox.net> wrote:
For cruise do you lean enough
that you notice any reduction in engine RPM? What sort of fuel flows, manifold
pressure, and cruise speeds are you getting and at what
altitude?
For it to run well
very lean the mixtures to the rotors need to be balanced – similar EGTs; so
you may want to do whatever mode that is. You can get a handle on good
lean cruise and max power by watching the EGT. I tend to run about 100
lean of peak for cruise. Although it will do fine leaner, it doesn’t
fell quite as smooth. You’ll have to add some throttle to maintain rpm. Max
power is somewhere about 150+ rich of peak IIRC from the dyno
runs.
I typically cruise
5400-5500 rpm, 9.5 – 10.5 Kft, maybe 9.7 gph on my 3-rotor; so you should get
the 2-rotor in the area of 6.5. That gives me 165+ KTAS in my 4-place
Velocity – not
bad. Could get better economy going slower, but unless I’m just
sight-seeing, I wanna get there.
Does your test area
extend to French
Valley?
Al
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