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Hi Michael,
Good to hear from you again. Take some
photos and post them to the list of your project when you get a
chance.
Well, I must admit I'm a bit biased toward the
standard mechanical pump. However, I am also flying with my 13B rotated 90
Degs (Plugs Up) to move certain high profile items below the cowl line
(Initially, I really it was because I hated doing cowl fiberglass
work - now, I just don't like it {:>)).
So I believe there are times and conditions
that perhaps justify departing from the norm. I am certainly not against
electric pumps (I mean, I use three electric pumps for my fuel system -
certainly a critical system). I think there may be conditions and
constraints were an electric water pump is the answer.
But, as I mentioned, early on I was faced with
objects (alternators, water pump inlets, distributor, etc, sticking above my
cowl line. By rotating the engine 90 deg that solved that problem, made
the exhaust outlet easier and provide much more room on the side for
experimenting with induction systems. Also it position my injectors so
they were no longer "above" the hot exhaust manifold - so fuel leaks were not as
likely to hit it. Despite some few individuals who mandated that the
engine just would not operate in that orientation, its worked fine for over 400
hours and 10 years.
However, they are three major
downsides (none of a technical nature) of the "Plugs Up" approach, which why I
would not normally recommend it.
1. I would no longer have a unique "Plugs
Up" installation {:>)
2. You will need to build a oil sump to
accommodate the new orientation of the oil system - certainly not difficult, but
something you would have to do.
3. Most of the products produced by vendors
for the flying rotary are made for the automobile orientation of the engine
.
I had to modify the motor mounts of the RWS
gear box to fit it. Again not a major problem but one that would have to
be addressed.
People have addressed the high profile items in
other ways, such as moving the alternator mounting to a different location,
machining down and welding on a adapter water pump inlet. using the Crank
Angle Sensor (very much lower than the distributor) - but, which then requires
an ignition computer. (Might as well get the EC2 from RWS and have both
your ignition and injector computer).
So as you know, its all doable - its been done
before by various folks in different ways, some may pop up and offer their
solutions.
Best Regards
Ed
----- Original Message -----
Sent: Sunday, April 27, 2008 11:56
AM
Subject: [FlyRotary] Re: Electric Water
pumps - Interesting
Ed:
I have been thinking about a similar set up as
those electric water pumps but more on order of a remote mechanical water
pump in order to get rid of the original heavy cast iron cartridge and the
tall housing. I have been unable to locate a water pump that would be like
those electric stand alone units but minus the electric motor. My thought
would be mounting it as one perhaps would mount an alternator. In my case I
seem to have a god bit of room on the lower back end of the engine. An other
thought on installation was a direct drive with a coupling of the back pulley.
My natural apprehension is messing with a system that we know works. So I may
wind up with a bump or two on my cowl to accommodate it as well as the
distributor.
Michael in Maine
Falconar F-12 progressing at glacial
pace.
----- Original Message -----
Sent: Sunday, April 27, 2008 9:31
AM
Subject: [FlyRotary] Electric Water
pumps - Interesting
I was just thumbing through a recent catalog
from Summit Racing and came across a couple of pages on electric water
pumps. There has always been a degree of interest (and some
debate {:>)) regarding the use of electric water pumps in aircraft.
It was interesting to read some of the descriptions, but basically the
current consumed ranged from 4 - 9 amps and the quoted flow rate
(presumably without back pressure) was from 16-35 gpm.
So if you take 9 amps at say 14 volts = 126
watts = 0.167 HP to get that flow. However, some of them indicate you
can save 15 - 20 engine HP at HIGH rpm. So why the
difference?
Apparently (my best guess) is that
they are advertising their product to best advantage (surprise?). I
would suspect that the flow rates shown are without back pressure and that
when attached to a real engine coolant system that :
1. The flow rates would decrease
2. The current requirements would
increase.
However, not to the point the electric
pump would be required to make 10HP or more to provide the required
flow. I suspect there are considerable losses (such as pump cavitation
and pressure drops through the cooling galleys)with mechanical pumps
at high pump rpm as driven by a high revving engine which accounts for
the high power requirements. Whereas the electric driven pumps may
operate at lower and more efficient rpm without the majority of those
losses.
That said, the pumps cost range from around
$200 - $400 and while no weights were given, basic on the
photographs showing the heavy electric motors and additional plumbing
would not appear to offer any significant weight savings over the
proven, reliable mechanical pumps most of us are using.
So while certainly interesting and
perhaps of value in some aircraft installations(how would you like to gain
an additional 10 HP on takeoff?), I remain confident in my old 86 13B water
pump housing and cartridge which is still going strong after 10 years.
I have moved it from my first 86 N/A engine to my current 91 turbo block, so
it has performed for over 10 years in two different engines without any
problem.
Interestingly, of the 11
electrical water pumps advertised, only one was specified for drag race use
only - and it had the lowest current drain - 3.5 amps.
Ed
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