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)