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Yea Al,
I luv youse too!
You are most correct that Theory MUST go hand in
hand with Experiment. BTW, I would never EVER try to go to the moon
by trial and error (or any other means!). Have no desire whatsoever.
I'll leave that to the "Men from ACRE / LSTIRS"!! Boy do they know how to
"run the numbers"!! Intergalacitic Rocket Science is more their bag than
mine!! (}:>)
However, what really concerns me is when
people come out with outlandish statements, based on ALL Theory and NO
Experimentation or Observation. One of these daze, I'll write a
dissertation on Dr Karl Popper's methodology of Falsification. But
briefly, if you come up with an hypothesis, then you shouldn't try
to prove it correct, you should design an experiment to try to falsify
it. More later ....
Electric Water Pumps are one of the major points of
contention. You, my good friend Al, might NEVER say an
EWP wouldn't work in an airplane. However, I have
literally dozens and dozens of ACRE emails full of Lamar's abusive
invective and derrisive drivel, mathematically proving conclusively beyond
all reasonable doubt that EWPs can't work, don't work, &
won't ever work, and also stating categorically that the guy that makes
them, Richard Davies, of Davies Craig here in Melbourne Australia is
a fraud, a cad, a bounder, and a scam artist! Boy,
is he lucky Richard is such a nice guy!!
Unfortunately, there are now possibly 1000
odd people who, (including Jerry Hey), believe this. And it's all
lies!! Coz Todd Bartrim demonstrated conclusively that they do
perform, even in aircraft, as advertised. (Thereby falsifying the
hypothesis that they don't work). But you will never hear or see a
retraction or an apology to correct what was a blatant error of
assumptions, false premises and dubious mathematics.
I first became
a believer in EWPs when I saw my dyno man using one to cool a big
block
V8. In fact, the two dyno guys I know both use EWPs for
cooling.
The EWPs are set up permanently on the dyno to pump the coolant from
the
main water cooling resevoir tank to a heat exchanger. Beats a
Jabsco with belt and mains electric motor any day.
See attached
pix. Unfortunately, the pix don't show the EWPs as they are over on
the wall. These were just "happy snaps".
The particular
engine in the pix has its own mechanical pump to take cool water from
the
heat exchanger. Often however, a second EWP is often used to
circulate the
engine coolant, especially if the engine is a marine
engine. On big block
V8s (454s and up), one EWP is often used per
head, especially if the motor
is supercharged as are a lot of these ski
boat engines.
I can also state that there are literally
hundreds of people here in Oz (me included) and elsewhere in the
world (including the USA) who happily use EWPs in race cars and ski
boats etc, which EWPs perform as advertised without any problems.
The most punishing use is on the cooling systems of dynamometers, but they
also cop a fair pizzling in race cars as well. Most race cars run WOT
greater than 80% of the time on the track.
OTOH, most aircraft only run WOT 5% of the
time, and the vast majority of the time is spent at 65%-75% throttle
at cruise and also some considerable time during descent is spent with the
engine effectively idling. A lot less arduous than a race car! So
why wouldn't they work in aircraft?? Let's see if we can falsify the
hypothesis. O.K., let's stick 'em in an aircraft. Todd &
Rusty did. Do they work?? I don't want you to believe me, just
ask Todd or Rusty!!
As for the heat exchangers in the sump, Paul
Lamar MIGHT have proposed it (from a theoretical point of view - he's
really good at that!!), but I DID it back in the mid '70s. I
didn't have the mathematical sophistication (still don't!) to work out the
exact size I needed. I just eyeballed a stock Mazda air/oil cooler,
then eyeballed some transmission coolers, and said: "yeah, that's PLENTY
big enough if it uses cold water instead of air!!".
Turned out it was TOO big, and I had to
throttle the water supply, especially on cold daze, which was
kewl!! However, always better to over-engineer than
under-engineer. It was in a hydroplane, and we were running
straight cold sea/lake water through the engine at the time (NOT the really
smart thing to do!!). Had REAL trouble getting the engine up to proper
operating temp. Especially dangerous if the oil isn't HOT
enough. Really easy to spin a bearing!
So we got more sophisticated later and ran a
stainless water/water heat exchanger to avoid running salt water through the
engine. That meant we could run a thermostat (the motor then made more
power), and we could use glycol coolant /corrosion inhibitor in the engine
cooling system. Rotaries don't like being fed salt water in their cooling
system. Didn't matter for how long the engine was flushed with fresh
water, it still corroded internally - and FAST!!
Anyway, that's my little chamois bag full of
uncut Glen Innes saphires for today.
Cheers,
Leon
----- Original Message -----
Sent: Sunday, January 16, 2005 3:19
AM
Subject: [FlyRotary] Re: Experiement vs
Theory take 2 was Re: [FlyRotary] Re: water cooled matrix in oil pan
I've been studing the development
of the rotary for 30+ years. I also had the dubious priviledge of
working on NSU Ro80s in the early '70s. Nothing that ever came out
of the NSU Factory ever worked (for long). MTBF of the engines was
around 15,000 - 17,000 miles!!! All good German Engineering Theory
that didn't EVER work (for long) in practice.
Leon; I love you, man;
BUT, I think you miss my point. It is:
THEORY AND
EXPERIMENT!
Without the theory
there would not have been the rotary that would go the 15,000 miles. You
do the theory; you do the experiment; you do some more theory; experiment
etc. It wasn’t the experimenter who did the metallurgy; the heat
balance, etc; all the stuff needed to get in the ballpark. Nor could the
theory advance without the tests of what worked and didn’t work, and trying
new ideas. Theory is born out of observation; which then models and
leap-frogs to what the next observation should be.
Try going to moon
by trial and error.
I would never say
that putting a oil/water heat exchanger in the oil pan wouldn’t work.
Why; Paul Lamar proposed that years ago. But is it the best way? The
most reliable? For example; you can try a half dozen fin/tube heat
exchangers in the oil pan trying to find the optimum configuration; and maybe
get close; or you can combine it with some analysis and maybe get there in
two.
I would never say
an EWP wouldn’t work in an airplane. But, for other than configuration
reasons, is it a more efficient and reliable way to go. No one has
proven that yet. But it’s true for most of us here; we do things by
experience and experiment – we don’t usually have access to sophisticated
analytical tools.
Anyway; enough of
this – I need to get out in the garage and try out some things and see if they
work.
All the
best,
Al
For sure, the NSU Ro80
chassis itself was a magnificent road car (thanks to Audi knowhow),
but the powerplant and drivetrain was a mobile (more often than not IM-mobile)
mechanical disaster from day 1. They were NEVER able to satisfactorily
fix it. Many a divorce and many a heart attack was caused by these
infernal contraptions.
It also took Mazda several
years to get it right. By 1974, with the intro of 3mm steel
seals, different alloy in the rotor housings, and proper
teflon/silicone water seals, most of the problems were
fixed. But it was mainly by trial and error, and
observation, and sheer dogged perseverence. The exercise nearly sent
Mazda broke too. In the end, it was what worked in practice that
mattered. Bugger the theory!!
By 1974, Mazda had fixed
most of the basic intractable sealing problems. Looked after, the
engines would go well over 250,000 miles between overhauls. Now,
with the REW powered RX7s, the motors are so reliable that Mazda
don't even have an engine reconditioning facility in Oz any
more. However, I still get ignorant people coming up to me
telling me that rotary engines are no good because the "seals blow". (But that
is another issue) .. I do digress ....
SUMP MOUNTED HEAT
EXCHANGERS
Back to the matter at hand.
Personally, I can't see what oil flow rate has to do with convective
flow/heat transfer, at least in the application I'm proposing.
Maybe I'm like the bumble bee that is too ignorant of physics to know what
can't work?? As it happens, the flow I've used is a kinematic
inversion of a normal oil/water heat
exchanger !!!
The coolant is INSIDE the tubes)
of the heat exchanger, and is at normal block pressure (15-22
PSI). The hot oil is passing over the EXTERNAL fins of the heat
exchanger, so it will experience TURBULENT flow. Really good
for convective heat transfer, or so they tell
me!!
The HOT oil actually enters from
the top and flows (drizzles - depending on engine RPM) down to the
bottom of the pan over the fins and is continually removed by the
pick-up, which is below the heat exchanger. Bulk oil flow
rate will depend on engine RPM. As Mike Wynn said, if the
oil dwells on the fins a little, so much the better. There's
(relatively) cold water running through the tube(s), taken from the cold
side of the rad, so it is just going to cool the oil a bit more ...
The flow of cooling water can be
controlled either by a thermostat, a manual heater tap, or an
electronically controlled EBP. (Electronic Booster Pump - shock horror
Batman!) In cold climates, you want to be able to warm the oil
quickly, and keep it at near water temp when running
hard.
As I mentioned in a previous
post, the best heat exchanger unit I've found is something like a Hayden
auto tranny oil cooler. See attached pic. The one on the right is
about the G_O. Also see:
Different sizes are
available, and depending on the heat rejection capacity
required, (and available space), often it is better to run 2
or 3 small ones in parallel rather than one giant one.
So to summarise, COLD water
passes through the tube(s), and the oil flows over the outside
fins. NOT expensive, NOT heavy, and really easy to
engineer, and a lot more compact than an oil/air heat exchanger,
AND no high pressure oil hoses to spew hot oil at 70+ PSI all over your
pristine engine bay and canopy!!
----- Original Message -----
Sent:
Saturday, January 15,
2005 1:44
PM
Subject:
[FlyRotary] Re: water cooled matrix in oil pan
And BTW, folks.
A good balance of theory and experiment is where it’s at. Let’ not
forget that without the theory and engineering; there wouldn’t be a rotary
engine.
Al
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