----- 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