| are you planning on getting into a drag race with the space shuttle??!!
You never know! I could have gone with 80 lb/hr, but that might be a bit overkill. ;-)
I changed injectors because with the p-port motor I had to fabricate a new intake. To do that, I bought three of PL's weld-on injector blocks. These are bored for the smaller DEKA IV injector. So, I bought a set of 60# injectors.
The Seimens injectors are rated in lbs/hr rather than cc/min. Yes, I wish the industries would standardize on stuff like this. Drives people nuts, right Ed. Besides, 60 lb/hr seems to be very common size. The DEKA IV injectors are more controllable at the low end (or so I'm told), so I went with the slightly larger ones. I bought a set of 8, so I've got two extras. Like you said, we typically run our systems at lower pressure than the "standard". Mine is set to the mid 30's. The p-port 20b is capable of 350 hp, so running at slightly lower pressure should still give me a small margin of safety. And, it seems to be working. And lately, that's worth a lot.
Mark
On Sat, Jul 17, 2010 at 11:38 AM, Bill Bradburry <bbradburry@bellsouth.net> wrote:
Aren’t the size numbers on injectors
normally given in CCMs (Cubic Centimeters per Minute)? These static flow rate
statistics are given at a standard fuel pressure, which is usually 43.5
PSI. Most of us seem to run our fuel pressure lower than 43.5, so our
injectors would flow at a lower rate than their spec.
Mark, when you set your fuel pressure
regulator, do you remember what you set it at? I assume that you have 6
injectors? If they are all the same size (old were 550?), I wonder why
you increased them?
60 lbs/hr calculates to 630 CCM for the
new injectors. The old injectors, if fuel pressure was set at 43.5 PSI
and with a duty cycle of 80%, should have handled 76 HP each at a BFSC of .55.
That is a total HP of 456 for your engine. Using the new larger injectors
that HP capability would go up to 87 HP per injector at the above PSI and duty
cycle for a total HP of 522!
Mark are you planning on getting into a
drag race with the space shuttle??!!
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mark Steitle
Sent: Saturday, July 17, 2010
10:48 AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: P-port
Project Update
Kelly,
The flow hasn't been
recalibrated from the old 550's, but it was reading 12.1 gph. Didn't
specifically read the fuel pressure, but it was a couple of ticks above the
midpoint on the graph. Yes, I'm running Deka IV 60 lb/hr injectors in the
primaries and secondaries.
On Sat, Jul 17, 2010 at 8:53 AM, Kelly Troyer <keltro@att.net> wrote:
What was the gph flow rate of the
previous injectors and are you using 60 gph injectors
in both primary and secondary positions
??..................Also what fuel pressure are you
using ??................Has been very quiet
lately..............OshKosh
I presume.............
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
From: Mark Steitle
<msteitle@gmail.com>
To: Rotary
motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, July 17, 2010 8:04:58
AM
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.
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