Received: from [137.186.225.160] (helo=ms01-414.tor.istar.ca)
by mail2.toronto.istar.net with smtp (Exim 1.92 #2)
for
murphy-rebel@dcsol.com
id 109Kx2-00047l-00; Sat, 6 Feb 1999 22:32:04 -0500
X-Sender:
crs1188@inforamp.net
X-Mailer: Windows Eudora Light Version 1.5.2
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
To: <
murphy-rebel@dcsol.com> (Murphy Rebel)
From: Bob Patterson <
bob.patterson@canrem.com>
Subject: Re: N78MT Takes to the Air
Message-Id: <
E109Kx2-00047l-00@mail2.toronto.istar.net>
Date: Sat, 6 Feb 1999 22:32:04 -0500
CONGRATULATIONS Bill !!!
=========================
You may not have as much to worry about as you think - especially
if you used the "speed cowl"...
The vast majority of builders who use this cowl try not to cut it -
it NEEDS to have the bottom opened up CONSIDERABLY ! There should be
a LOT more space for air to exit than there is to enter - check the
measurements before you rush out for a cooler !!
Several builders here have enlarged the back opening, then added
a 'lip' at the bottom. This is just a strip of aluminum, maybe 3" wide,
wrapped at the front of the bottom outlet. It can be almost 90 degrees
to the air flow - the idea is to create a low pressure area to aid in
pulling the air through the cowl. This can drop the oil temp 30 or 40
degrees !!
Another bit of aluminum that will really help is a piece attached
to the front of the firewall, a couple of inches up, coming down and
wrapping over the lip made by the bottom skin, and fastening to the
belly skin. The standard setup makes a 'pocket' that really screws up
the airflow trying to exit the bottom of the cowling! Have a look at
any of Van's RV's - they all have this rounded cover at the bottom of
the firewall ...
Some have also added 'V' shaped louver openings on the bottom of
the cowl, in front of the lip, although this is extreme.
If you are breaking in a "new" engine, it is normal to have very
high oil & CHT's for about 10 - 12 hours, until the rings seat in. The
best thing is just to fly it, but don't keep the engine at a constant
speed - run it right up, then throttle back to 1800 rpm for 4 or 5 minutes,
then up to 2400 for 5 minutes, then 1600 for 5 minutes ..... The
acceleration of opening the throttle helps seat the rings, but keeping
the power up there can overheat....
You might want to check the prop pitch (should be 12 1/2 - 13 1/2
degrees - approx.). The worst thing is to have it too coarse initially
- it really lugs it !! You should see 2,600 or more on the climb. You
can always crank it up a bit after it's broken in ...
FWIW - O-235's LIKE to be run fast - they cruise best at 2450 rpm
- this should give you at least 110 mph (and you can pull TWO notches
of negative flap !)
I have the standard metal cowl on my O-235, with a large opening
and a lip - my oil temps are usually a little on the cool side - and
I'm pulling amphibs (and no oil cooler) ! The only time it got up to
near 240 was on a 95 degree day, dragging it through the Rockies ...
Hope all this encourages you to get out and fly it some more !!
They love to fly !!!
Good luck !!!
....bobp
--------------------------orig.---------------------------------
At 09:44 PM 2/5/99 -0500, you wrote:
It can be done. Following six years and 2000 construction hours N78MT,
Rebel 199, completed it's maiden flight. Rebel 199 has a O-235 L2C
Lycoming, weight 909 lb empty, had an excellent center of gravity (middle
of the new Murphy range, and 3 blade Warp drive prop.
The Airworthiness certificate was issued 1 December 1998 and due to a
series of scheduling problems and weather difficulties the first flight was
not made until today 5 Feb 1999. The flight was at Madison Indiana airpot
on runway 21. Wind was 5-10 mph at 170, ait temperture was 55F. Mr. Ralph
Rogers made the first flight. He is a vetern of over 25,000 flight hours.
Ralph said the plane left the ground smoothly and level. No control inputs
were needed for roll control. The rebuilt Lycoming did miss a few times
when he reached about 1000 feet agl. Application of carb heat alleviated
the miss and it did not reappear. The plane flew straight and level with
hands off. After about 20 minutes the engine oil temperature increased
above 240F and Ralph throttled back and decided it was time to land. While
he was at higher engine speeds he observed 105 mph at 2300 RPMs. Ralph said
the most difficult thing to do was get the Rebel back on the ground. It
just did not want to land.
Today the ground air temperature was 55F and the engine was overheating. I
believe that the baffling was adeqaute so I am planning to add an oil
cooler. It has been said that an remote oil filter will reduce temps 10-15F
but I need even more than that so the cooler is likely required. The plane
will need to wait a few weeks until the cooler is installed.
Keep those rivits going in.
Bill Brady
Rebel #199
N78MT
brady@bluegrass.net
Crestwood, KY USA
-----------------------------------------------------------------
List archives located at:
https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe:
rebel-builders-unsubscribe@dcsol.com
List administrator:
mike.davis@dcsol.com
-----------------------------------------------------------------
with ESMTP id VAA25512