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Like my wife always says, "Dave, you are a lousy communicator."
My apologies.
Jim says/asks: "My original question was "... what will a coolant level
indicator, if/when finally
implemented, buy us that we don't already have... " I still haven't heard
an answer. "
Here's what a coolant level indicator seems to give - in a high mounted
pressurized tank, not some plug in thing in the block or the water pump
housing, which were the "other" suggestions I was trying to be careful to
differentiate from :
--- It will show "loss of coolant" before (seconds to minutes depending on
flow out of leak) there is any air in the engine block or at pump's
impeller, and, in slow leaks, maybe before you see any changes in pressure.
For sure, before you see any change in temperature.
--- If I understand the "pressure only" concept (no coolant level
indication): The coolant leaks out, unknown to the pilot, until the level
in the engine cooling passages is low enough to start exposing "hot" metal
and start getting localized boiling and therefore bubbles of steam, and
therefore slight (2psi?) fluctuations in pressure. Or, if not climbing or
racing, just cruising along or loafing, there may not be any significant
boiling, just steady loss of coolant until the pump's impeller unports.
THEN, only after the pump no longer has any coolant it can move, the water
temp sensor would go up and you'd say, "Hey, I have a problem." Why wait
that long to know you have a leak?
- - - - - - - - - - - - - - - - - - - - - - -
--- Regardless of having a level indicator or not, in all but a "minor &
insignificant leak - VERY slow leak" you aren't going to have much time to
retard power and get on the ground before you cook seals and need an
overhaul. So, it is likely that in faster leaks, NO warning system is going
to prevent engine seal damage.
- - - - - - - - - - - - - - - - - - - - - - -
Beyond Jim's question about "what will a coolant level indicator....buy us
that we don't already have...", there are other advantages of the "ideal
system" (high mounted pressurized coolant tank) I was throwing out for "peer
review":
1. Filling the system with less potential for trapped air - reduces the
complexity of filling, reduces the amount of short engine runs to "burp" the
system to elim air and get system 100% full of liquid. You just pour
coolant into the expansion tank. Kind of simple.
2. Filling the system with less work: With the air vent from top of
engine, and an air vent from top of radiator, you don't have to remove
radiator hoses and/or plugs in top of engine to let air out and get liquid
in. Again, just pour coolant into the expansion tank. Kind of simple.
....... I will still pay attention to Lynn Hannover's caution to assure that
the area around the thermostat doesn't have trapped air - that it is full of
liquid. I don't know enough about that area to comment further.
3. Eliminate the unpressurized "old style auto" expansion tanks that
collect expanded coolant but don't give it back until after engine shutdown
and cooldown.
4. Purge/eliminate air (shouldn't be any) and steam during flight - without
burping coolant out of the closed system.
..... Provides "steam vent/collection" - in event your early flight testing
isn't providing adequate cooling and you boil the system. The vent at top
of engine and vent at top of rads both allow steam, like air, to go up into
the pressurized expansion tank - and wind up on top of the coolant in that
tank, with coolant ready and available to flow back down into the engine-rad
system when you throttle back - nothing gets burped overboard and lost, to
require replacement after you land. Closed system stays 100% full.
- - - - - - - - - - - - - - - -
........I don't worry to much about mild localized nucleate boiling - would
need to be watching for pressure fluctuations during climb or when racing
and throttle back a bit or increase climb speed a bit to increase cooling.
At least, after throttling back and/or increasing speed, I'd have assurance
that my "closed system" was still 100% full of liquid; as long as the
expansion tank's "low" indication is not lit up, I have a 100% full system.
Seems like good results/characteristics to design for. I don't think it is
"more complex".
From peer review comments: I'll add a "high level" indicator for detecting
"blowby of combustion gasses forcing too much coolant into expansion tank.
David
----- Original Message -----
From: "Jim Sower" <canarder@frontiernet.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, March 08, 2004 12:40 AM
Subject: [FlyRotary] Re: Ideal Cooling System Plumbing (was Re:[FlyRotary]
Re: overflow connections
> You're bound and determined to design and install a coolant level
> indicator/alarm.
> I'm confident you'll come up with a successful design and installation. I
wish
> you well. I personally see no point in it. I've read a couple of
thousand
> words of deathless prose to the effect that some of us don't understand
your
> scheme (and would get on board if we did?) and how air and coolant and
foam
> behave in the system and how you can overcome all the obstacles to
implementing
> a reliable system. What I haven't heard is how, when the smoke clears and
the
> dust settles, your scheme is going to improve on the simple, reliable,
proven,
> inexpensive pressure and temperature indications already in use. My
original
> question was "... what will a coolant level indicator, if/when finally
> implemented, buy us that we don't already have... " I still haven't heard
an
> answer. This whole thread is IMO an exercise in P.V.O.R.T (Pole Vaulting
Over
> Rat Turds) aka "... chasing foul balls ...".
> More complex, needs development, adds no discernible value .... Jim S.
>
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