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Message
Good to hear that your cooling worked so well. I
would have guessed that the oil cooler getting the air first would work better,
but you must have LOTS of extra cooling capacity for it to work so well with the
air being heated by the radiator first.
Have you tested climb rate at lower speeds, where
drag is less important? Also, you could try reducing the size of the inlet to
the Radiator scoop to see if that reduces cooling drag, since you have excess
cooling available.
Please keep the data coming, we are all
learning.
Bill Schertz
----- Original Message -----
Sent: Saturday, September 13, 2003 9:01
PM
Subject: [FlyRotary] Good news, Bad
news
Greetings,
Well, the log
below pretty much says it all.
Decisions,
decisions...
Rusty
9-13-03 1
hour / 2.0 hours
total
Made 2 flights today. On the first, I noticed that it take
some work to get the oil temp up to 130 before takeoff. I guess this was my first sign that
the new cooler was working. The
second sign was during climb. The
oil and water both stayed right at 180 degrees during climb and cruise. During descent and landing, I noticed
that the oil drops pretty quickly to 130, which I can live with. The RPM at 30 inches MAP, and 100 mph
in climb was 5400. This is really
pretty much perfect, and I know that it will go to 6300 with 36 inches of
MAP. Sadly, the climb performance
just isn’t there. I tried
everything from 90 to 110 in climb.
If I try to get to 120, I’m basically flying level and not climbing at
all. Best climb was probably
around 95 mph, which is just way lower than it should be, and the rate was
only about 1000 fpm at best. Once
I leveled out, I ran at 30 inches of pressure, and 6000 rpm, with only a 130
mph speed to show for it. This is
horrible! Finished the flight
with a bouncy attempt at a wheel landing. At least they were gentle bounces, so
it’s an improvement.
Out of desperation, I set the prop back to
14 degrees (it was on 12). I
couldn’t rationalize how this would help, but it was worth a try. I also disabled the relief valve, to
see how much boost I could get at altitude. Well, this climb was even more dismal
than before, with an rpm of 4900 at 100 mph. Best climb rate was still in the 95
mph range. I only managed to get
up to 4000 ft, because it was just taking too long, and there were some clouds
around to complicate things. At
4000 ft, I advanced the throttle to see how much boost I would get. Knowing that I have run 3 psi on the
ground, I should be able to run 5 psi at 4000 feet, and have the same
MAP. The boost is very smoothly
controllable with throttle, which is the good news, but I got to 5 psi quite a
bit before I got to full throttle.
I stopped there, so as not to tread new engine territory in flight, but
I’d estimate that I would have gotten another couple psi out of it, for a
total of 7. This is with the
wastegate fully open. I need a
bigger wastegate, or some exhaust restriction. During descent from 4000 ft, I noticed
that the plane just doesn’t want to go over 130 mph, even downhill. I was descending at 2000 fpm, with 20
inches MAP, and still only 130 mph.
This sure ain’t how the RV-8 worked. The
one really good thing was that my landing was beautiful? A real
squeaker!!!
Unfortunately,
I’ve come to the conclusion that the current big ugly cowl is a much bigger
problem than I figured. I’ve got
a lot of decisions to make. Do I
keep the turbo- I like it, and it works, so I’d like to. Do I try to work on it at the hanger,
or do I just pull the wings off, and take it back home. This makes more sense, and wouldn’t be
that hard to do. It’s just
painful to think about.
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