|
Brian,
The popping and back-firing could signify either
a mixture problem (could relate to staging parameters not set
appropriately) and/or perhaps ignition timing mis-set.
Ed
Sent: Thursday, November 11, 2010 10:53 AM
Subject: [FlyRotary] Re: Improved performance of my new (2009)
intake manifold
I'm staging up pretty high- at fuel MAP station 90, I think
that's around 19 inches of manifold, but I am not absolutely sure because the
manifold sensor channel is not dead on in it's calibration. That's why I asked
about what others are using for a scale factor, low end offset, etc for their
manifold pressure. The EM2 reads and uses each manifold pressure as an
absolute value, but displays it according to whatever settings you have put in
for it. So, whatever value that corresponds to 90 on the MAP table is where
it stages. It stages smoothly on the ground, but in the air it starts doing all
sorts of backfiring and popping that gets all sorts of unwanted attention from
the ground. I can only imagine what observers on teh ground are thinking when
they hear the plane start backfiring.
My EC2 is on the left side panel in front of the throttle,
which is mounted on the side of the cockpit. I was wearing flight gloves and had
switched from A to B controller. The switches are so close together that hitting
one will hit the other and you will not feel that through a gloved finger or
thumb. I already installed a switch guard, and will also have a rubber band
holding it in the off postion. Not elegant, but effective, cheap, and
installation an removal is a snap( Ha! I make funny pun!)
Brian Trubee
-----Original
Message----- From: Bill Bradburry <bbradburry@bellsouth.net> To:
Rotary motors in aircraft <flyrotary@lancaironline.net> Sent: Thu, Nov
11, 2010 4:51 am Subject: [FlyRotary] Re: Improved performance of my new
(2009) intake manifold
That is the second
report I have seen of someone hitting the cold start switch while in
flight. The first time there was discussion about switch guards, etc.,
which I decided I didn’t need. My cold start switch is not located
anywhere on the panel where I should have my hands unless I am changing the
mixture. But now with two reports, I am beginning to wonder what I am
missing.
Where are your cold
start switches located and what were you doing when you accidentally hit
them?
I just moved my staging
point from 15 inches to 16 inches because 15 was right on top of 3800 rpm where
the EC-2 changes map tables.
Bill
B
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of bktrub@aol.com
Sent: Wednesday, November 10, 2010 9:52
PM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Improved performance of my new (2009) intake
manifold
Interesting manifold.
Are you still using the VDO fuel pressure sender? I had heard that it might not
be suitable for use with fuel, I am still using mine at present however.
I went up today for a
few laps at 3000 over Paine Field. The engine ran well below the staging point,
but started stumbling when above the staging point. It ran smoothly through the
staging transition on the ground, but when in the air I could not tell by the
mixture monitor if it was lean or rich. I tried leaning it out and richening it
up, but results were inconclusive so I stayed below the staging point for the
remainder of the flight. Temps were down around 130 degrees at 4800 RPM and 110
mph, MP was not noted.
I accidently hit the
cold start switch while on downwind with two other planes ahead of me, the tower
told me to go around on final, but the plane ahead turned off onto the taxiway
just in time so I told the tower that I would really like to land, so they
cleared me. The engine died as I turned off onto the taxiway and then I noticed
the cold start switch. The first order of business was making and installing a
switch guard for the cold start switch. I'm also going to pre-load the switch
with a rubber band so it stays in the off position unless I'm pushing it on, and
can just pull the rubber band off of it if I need to shut down a set of
injectors and run the remaining injectors on cold start.(limp home mode for
failed injector.)
The fuel self
transfering issue was resolved by installing manual valve on the transfer line
between the tanks.
As some of you know I
started flying my RV-7A with a cut - off Renesis intake manifold. In 2009
I installed an new intake designed to route pressure waves from the
closing of rotor #1's intake into rotor #2 just before rotor #2's intake
closed. After using the new intake for over a year I am still very
happy with it's performance.
I gained about 15 mph
TAS at the same altitude and manifold pressure
My static engine rpm
increased 300 to 350 rpm.
My takeoffs are faster
and shorter with noticeable increase in acceleration
My oil and water
cooling is more critical now because I make more HP.
But - I must confess I
don't believe the manifold can be reproduced economically. It's just too
complicated.
I also believe it
should have slightly shorter intake runners to increase the performance at
higher RPM. Decreasing the intake runner length probably would require
complete new geometry of the system.
I have another concept
for designing a Renesis intake that using a reflected wave from Rotor #1
returning to Rotor #1 .
I believe it would be
much easier to build and small enough to fit into the James rotorary cowl but
because my intake works well I am not moving ahead with completing the design
and building it.
|