----- Original Message -----
Sent: Sunday, April 27, 2008 10:26
AM
Subject: [FlyRotary] Re: Electric Water
pumps - Interesting
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