Today's Message Index:
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1. 06:13 AM - Re: Engines-List Digest: 1 Msgs - 07/29/03 (FSmith9890@aol.com)
2. 07:23 AM - Re: Engines-List Digest: Re Prop Balancing (FSmith9890@aol.com)
3. 01:22 PM - Dual radiators... (Grant Corriveau)
4. 05:17 PM - Re: Dual radiators... (Ed Anderson)
Message 1
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| Subject: | Re: Engines-List Digest: 1 Msgs - 07/29/03 |
--> Engines-List message posted by: FSmith9890@aol.com
Message 2
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| Subject: | Re: Engines-List Digest: Re Prop Balancing |
--> Engines-List message posted by: FSmith9890@aol.com
Prop balancing with modern electronic equipment is accurate, fairly quick
and effective. Chadwick-Helmuth and some others make equipment that will
measure the vibration and tell you where to put the weights, and how much . This
is
a dynamic balance with the engine running normal cruise speed. It usually
takes three or four runs of one minute or so to get a reading, and then the
engine is shut down. Although the engine is uncowled, this does not damage the
engine, if temperatures are watched, and cooling is allowed between runs.
The vibration is measured at the extreme front and rear of the engine with two
sensors. The front sensor is the primary indicator for the prop, and the rear
sensor is to check to see if the reduction of vibration in the front also gives
a corresponding reduction in the rear, although 180 degrees out in phase. If
not, if there is an increase there is something wrong with the engine.
Vibration is measured in IPS(inches per second). An initial reading of more than
1.2 ips indicates a serious problem, and the prop should go to the shop for
examination, and a static balance. A reading of greater than 0.2 is unacceptable.
It is possible with a series of runs to get the final ips down to 0.05, or
lower. This magnitude of reduction will be immediately obvious to the pilot.
It will also reduce the maintenance required for the whole airframe, and
especially the engine accessories. It should be done on all airplanes in my
opinion.
I have been doing this as a hobby for several years, and never had a case
where no improvement was possible. The post was about a fixed pitch prop,
but the CS props are more likely candidates. A case in point, I recently had
a three bladed Mc Cauley on a 300 HP Cessna Stationair that had an initial
reading of 1.1ips, just below the limit. Final reading was 0.05 ips. The
owner had been fighting the vibration problem for some time with no success, and
in fact had sent the prop in for overhaul. He was very happy. This is an
extreme case.
Just one final note. Even with low final ips readings there will always
be some vibration in stock four cylinder aircraft engines that cannot be
eliminated. Maybe they have been able to do this in modern four cylinder
automobile engines, but our engines are not modern. FWIW Frank
Message 3
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| Subject: | Dual radiators... |
--> Engines-List message posted by: Grant Corriveau <grantc@ca.inter.net>
When using a dual radiator setup, is there a preference for series vs.
parallel connection? I'm thinking of putting a pair of motorcycle radiators
on my CAM100 (Honda conversion), either in each corner of the cowling, or
maybe one in each wing root. Series would be less plumbing ...
I'm moving my 'chin' mounted rad. It's been working fine wrt keeping engine
coolant within limits, but the dumping of hot air into the engine room has
led to other complications.
Thanks
--
Grant Corriveau
C-GHTF / Zodiac 601 HDS / CAM100
Message 4
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| Subject: | Re: Dual radiators... |
--> Engines-List message posted by: "Ed Anderson" <eanderson@carolina.rr.com>
Subject: Engines-List: Dual radiators...
> --> Engines-List message posted by: Grant Corriveau <grantc@ca.inter.net>
>
> When using a dual radiator setup, is there a preference for series vs.
> parallel connection? I'm thinking of putting a pair of motorcycle
radiators
> on my CAM100 (Honda conversion), either in each corner of the cowling, or
> maybe one in each wing root. Series would be less plumbing ...
>
> I'm moving my 'chin' mounted rad. It's been working fine wrt keeping
engine
> coolant within limits, but the dumping of hot air into the engine room has
> led to other complications.
>
> Thanks
>
> --
> Grant Corriveau
> C-GHTF / Zodiac 601 HDS / CAM100
Hello Grant,
You will undoubtedly get differences of opinion on your question (so
whats is new in this hobby {:>). I fly an RV-6A with a Rotary engine with
two radiators, one stuck on each side of the prop. Most of us (but, not
all) that do use two radiators hook them up in series. Technically, that is
not the most efficient use of the raditors as the coolant flowing to the
second radiator is cooler therefore with less difference in temperature
between the air flowing through the second radiator and the coolant
resulting in less heat given up.
However, the plumbing is simpler for the radiators in series. A few folks
who tried to "Y" their coolant flow to two radiators in parallel have found
that the flow can be unpredictable. Apparently, conditions can exist that
most of the flow might only go to one radiator at certain rpms. One
individual even put a valve in the "Y" to fine tune the intial flow - but,
found out that the flow condition at one rpm did not necessarily hold at a
different rpm. I have no personal experience with trying two radiator in
parallel. I went with two in series from the beginning and have plenty of
cooling even on hot days.
I only know one person who is flying a rotary powered aircraft (and they do
need good cooling) that has sucessfully gotten two radiators in parallel to
work, the rest of us fly with the flow in series.
Hope this helps
Ed Anderson
RV-6A N494BW 200+ Rotary Hours
Matthews, NC
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