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John,
I did have a fairly good flight one time, but only after adding an adjunct
to the scoop. Before that, the temps would climb up, what I think is too
high, especially the oil.
I've been flying only in the mornings when the temperature is <80. The last
flight the coolant was OK (about 200) but in just climbing to 1500' AGL the
oil was 220. That was at a 110-120 kt. Climb. After leveling off, and
powering back to about 4100 RPM's, the oil dropped to about 210. OAT for
that flight was right at 80 F.
At level flight, when I add power, the temperatures start climbing. I did
move the intake air back from the plenum to the scoop for the intercooler,
which did help the last time, but I haven't flown since then. Tomorrow the
OAT is suppose to hit 100F, so I won't be flying then either.
After adding the vortex generators the temperatures were definitely lower
oil 220 down from 240, and coolant 200 down from 210-215. So they did
definitely help.
I am curious about what your temperatures are running. What do you see in
climb ? and what do you see in cruise ?
I read the reports from the RV guys, and the norm there seems to be 180 (or
less) for the coolant, and about the same for the oil. I've been looking at
220 oil and 215 coolant as the redline. Maybe I'm wrong.
Steve
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of John Slade
Sent: Tuesday, July 13, 2004 7:29 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: New Scoop
Steve,
This is just my 2c, so take it or leave it but....I think you're going the
wrong way here.
We have almost identical engines on the same airplane. If anything, mine has
a little more power. I have no armpit scoops and am using only the plans
NACA for the air intake, yet my cooling is fine. Why the difference? First -
is there a difference? From the numbers you published it seemed that your
temps were just a little higher than mine, but if I recall correctly, you
were getting stable temperatures while flying once you added the belly
vortex generators. Are you certain that what you have/had is inadequate?
I approached this on the basis that, so long as I can taxi for a while, then
take off and climb at a reasonable rate on a hot day, I'm happy. I don't
mind backing off on the throttle a little until I get to height. There's
always going to be a compromise between drag and cooling. I get the
impression that you're leaning too far toward cooling at the ultimate
expense of your cruise performance.
Greg Richer came at the problem with lots of big ugly (sorry Greg) scoops,
and I think he hit a speed wall at around 160kts. He was planning to cut the
scoops back, then got the idea for a turbine instead. My approach was the
opposite - NACA scoop only, and every trick in the book to move the air. I
think the turbo heat shield and augmentation must be helping a lot. I'm not
sure about the fan, and am thinking about taking it out. The plenum
approach, with a BIG rad and two oil coolers is probably contributing as
well.
I know that adding more scoop is the easiest way to get airborne, but I'm
wondering if you'll regret it down the road.
Like I said - just my 2c.
Regards,
John Slade (anyone want their turbo tested?)
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On
Behalf Of Steve Brooks
Sent: Tuesday, July 13, 2004 4:28 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] New Scoop
Ed, and others -
Attached are some photos of the new scoop I'm building to replace
my old new
scoop. As you can see the new one actually has less intake area, but
extends further in order to get outside of the boundary layer.
I don't want the intake any larger than it has to be, but I want to make
sure also that it is sufficient to allow for enough air flow. My old new
scoop did improve cooling, but as I found out, it was only marginal.
The new scoop, which is patterned after a P51 style scoop, not only gets
outside of the boundary layer air, but also excludes it, with the dam that
you see at the bottom. Well, actually it will be at the top, once it is
mounted under the belly. It also gives me an expansion area once
inside the
scoop.
Using the program that Al sent me, the boundary area calculated
out to about
1.625-1.75 inches +/- depending on speed.
The scoop intake measures 10.75" inside at the top (narrowest)
and 14.75" at
the widest point average = 12.75"
Height of the inside of the scoop measures 4.25"
This should equal about 54.18 sq in of area.
The inside of the scoop sits exactly 2" from the bottom of the
fuselage, and
overall height to the outside of the scoop is about 6.6" again, measured
from the fuselage bottom.
I haven't glassed the scoop yet, other than on one side to help
with gluing
it together.
I am interested in any feedback concerning the size of the intake area.
Regards,
Steve Brooks
Cozy MKIV N75CZ
Turbo Rotary
Homepage: http://www.flyrotary.com/
Archive: http://lancaironline.net/lists/flyrotary/List.html
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