Mark,
I am wondering if you have a feel about
the accuracy of the engine rpm vs the prop rpm? They seem to differ
somewhat when you report them together. For instance, it seems that you
were getting 1800 prop and 5500 engine. 1800 prop should give you 5130
engine and 5500 engine should give you 1930 prop.
If I understand how they both are
determined, they are both measured by counting the times a magnet passes the
pickup and therefore, should both be accurate? What is your take on this?
I am impressed beyond measure at the
planes performance! It is a rocket!
You said you could hit Vne with the old
motor. That is an indicated speed, you haven’t disclosed any
indicated speeds here?? What are you indicating here and what is the Vne?
That cowl flap should also be worth several knots of speed as well.
Lancair claims a 75% cruise of 225 mph true
at 8K ft with the 310 HP engine, but that is with a 19 GPH fuel flow. Your
fuel flow is way lower than that and you haven’t even got the tuning
completed or tried to lean it out!!
Keep spurring our discussions!!!
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mark Steitle
Sent: Saturday, July 17, 2010 9:05
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] P-port
Project Update
A Flight Report to Spur a little discussion...
For those that haven't been following my project's progress (or lack
thereof), I replaced my side-port 20B with a p-ported 20b in January of this
year. And have been fighting "issues" ever since. The
main problem was a persistent misfire at various rpm. That appears to
have been solved with a new CAS bracket and setting the gap to .025".
The rest seems to be tuning related. I have finally managed to get
it to run smoothly through the rpm range needed for safe flight.
So, after a thorough pre-flight, I flew my p-port 3-rotor on Friday.
OAT was about 90*F, but coolant stayed below 200 during climb and oil
temps were 185*F max, 165-170 in cruise. The p-port engine ran great,
except for a little mis-firing around 5700 rpm, which was corrected in flight
with auto-tune. Pre-takeoff run-up gave a brief excursion to 6900 rpm.
Takeoff run was 6500, running very well, but limited by prop setting.
It started to lightly misfire when I dialed the prop back for
cruise-climb, so I dialed it back up to 2000 (prop) and it ran smooth again.
Once at 3500 and leveled off, I entered auto-tune and brought the rpm
down to the 5700 range and let the EM-2 tune the EC-2, map addresses 90 - 92.
Afterwards, it ran great throughout the rpm range. (I had
"auto-tuned" much of the upper map range on the previous flight.)
At 3500 - 4500 MSL, the EFIS was indicating 172-174 TAS at 1800 rpm
prop setting, and 201-203 mph per the EM-2. This is consistent with a
previous test run I had recently done and represents a 12-14 knot improvement
over the side-port motor. The cool thing is that these speeds are in
"economy cruise" mode. EM-2 was indicating 12.1 gph, but has
not been calibrated since switching to the larger 60 lb./hr injectors.
Engine was just purring along at 5500 rpm. There should be a bit
more speed on the table as I realized after the flight that I had never closed
the cowl flap. Oh well, I guess I'll just have to go fly again real soon
to see how she performs with the cowl flap closed.
Later on, I plan to run it a bit harder, around 6500 rpm, and see how
she performs. I could hit VNE with the old motor if I ran it up to
6700-6800. But since the vast majority of my flights are in the 5200 -
5500 rpm range the 12-14 kt improvement is very good to see.