Subject:
[FlyRotary] Re: Engine run
Al, sorry to hear about your
trials and tribulations. But, this group should be able to help you
resolve them - by offering suggestions if nothing else.
I’d guess it’s
pretty normal. Just unexpected and too many issues at
once.
Could you refresh my poor memory
about your fuel set up. How many injectors, what type (Low high
impedance?) what size, where located? I really don't think the 550 are
the cause. I have run with them and the only problem was the
engine was not quite as smooth as with the 460cc/min it was really not
bad. Certainly functional and flyable and that with a 2 rotor.
See attached
photo. I have the stock 20B fuel rail at the primary. I had RC
Engineering clean and measure flow, and they were 570 cc/min. (I thought
they were 550’s). There are three MS injectors in the TWM TB that are 50
lbs/hr, which is about 525 cc/min. All saturation type. I don’t
think that’s the issue either; based on the dyno runs. We didn’t have
much issue at the stage point, although it was a bit tough to keep it steady
right at that point.
2000 rpm and 13" sounds low to me,
also, but then you have three rotor's "sucking" air out of the manifold rather
than two. So, I suppose it could hold the manifold pressure down a bit
better. I generally see somewhere around 15-17" at
2000.
For the same
power/rotor I’d guess the 2 and 3-rotors would have about the same MAP.
And I guess my 66” 3-blade should need something like the same power at
the same rpm. Based on what little dyno data I have at lower rpm, the
number seems too low; but can’t I believe the EM2 reading? It’s all I’ve
got.
I presume you EGT temps are
Celsius?
Wha-a?
No. I think around 1100F is OK at 2000 and low power.
No?
I have a heated borsch O2 sensor
as well and yes, it reads 0-1volt with 0 being lean and 1 being rich. I
presume its not one of those expensive so called "broad band" sensors that are
used on some autos today?? They generally run close to $200 or
more.
It’s a
three lead one that I picked out at the auto parts store for about $55.
I think it is used in the Miata, and in some
Fords.
So if you would bring me up to
speed on the induction system, I'll hopefully be able to offer some
suggestions
Thanks, ED.
If you are patient enough to read the other two responses to Dave and Rusty
ther may be some other relevant info there. One of the big concerns
right now is about oil flow to the redrive. I have no idea why it
wouldn’t be flowing, but why is the line not getting hot? I don’t want
to run further it there is no oil flow going to the drive. As I recall,
there is no restrictor in the RD-1B, and that the oil goes into a little
gallery in the rear bearing (or something like that). Also, I have about
1” gear play, measured at the tip of my 66” prop. Is that
normal?
Ed Anderson
RV-6A N494BW Rotary
Powered
Matthews, NC
----- Original Message -----
Sent:
Thursday, August 26,
2004 9:14
PM
Subject:
[FlyRotary] Engine run
I
guess I have now done what I’d consider the first serious runs of the engine
on the plane, and I have so many question marks in my head, it’s hard to
know what to address next.
The biggest issue
is; I cannot get smooth running up to about 2200 rpm; which is as far as I
went. At about 2000 I adjusted mixture from too lean to too rich, and
nowhere does it smooth out completely – some roughness, mild surging.
At lower rpm, 1000 – 1500 it is quite rough and unsteady, which is
disconcerting in itself, but worrisome when it goes through periods of
torsional vibration with the reduction gear backlash, which is noisy and
shakes the plane.
Of course it
brings back the recent discussions of you other guys with the 550 injectors
in the primary. I kind of glossed over that because I recalled smooth
running on the dyno. In hindsight now, I think the operator figured
out early-on that to keep it smooth he needed to keep some load on – just
turn the load knob a little and it was fine. And on the dyno when it
wasn’t running smooth, no big deal – no redrive to backlash, and the engine
is bolted down in the next room. You could just hear that it wasn’t
running smooth.
Still, I suspect
something is different now; and perhaps you’ll indulge my dumping, and pass
on a clue or two.
At 2000 I’m
seeing a 13.1 MAP reading. Seems low to me. Is it? That puts it
below the stage point, yet when I turned off the primary injectors, it
continued to run; just rougher. Same effect turning off the
secondaries. Hotest EGT was at about 1100, lowest about 980.
Bigger spread than I ever saw on the dyno runs, but the data we took
there was always under higher load.
Fuel pressure
reads 50 psi, TWM tells me it came to me preset at 43.5. When the
coolant temp read 125 when the pipes and rad tanks were just about too hot
to touch, which I guessed to be more like 140. I’m suspicious of just
about every readout. Later when the WT read 140, the CHT TC that measure
temps in and out of the rads were reading about 85. I believed backup
gauges were unnecessary.
Oh yeah; the
mixture bar reads just about full scale all the time, even when the engine
is about to die from being too lean. I have a different heated Bosch
sensor, which I assumed would have the same 0-1volt range. Maybe
not. Is the sensor output voltage low when lean or rich? With
the engine off and sensor heated I measured .052 volts. I tried to get
a reading with the engine running, but all I got was about .025 and I can’t
be certain I had contact with the lead – and with the prop spinning so close
by I didn’t spend too much time trying.
One other major
concern. With hot oil (150) at the filter block where the feed goes to
the redrive, the ¼” Al line to the redrive was hardly above ambient temp a
minute or two after shutdown; suggesting little or no flow was going
there. Oil pressure was in the 90’s. I’m not aware that there is
an orifice in there. This has me a bit baffled.
Oil pressure,
coolant pressure, Oil temp seem fine.
Maybe I should go
to a movie.
Al (not
ecstatic)