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Hi Dave,
Really appreciate you taking the time out of your
undoubtedly busy schedule to give us your perspective on use of the NPG in the
rotary. I did want to stir up the nest a bit on the topic - and it appears
I did {:>). Humm, I thought I had stuck to comparing the 50/50 and NPG+
although I did mention pure water being the "best". I'll have to be
more careful.
Clearly, folks have use NPG in an airborne rotary
(ken and you at a minim) and apparently found it satisfactory - except perhaps
for is availability on trips. I agree that is more environmentally
friendly (non-toxic) compared to Ethylene. Theoretical analysis is fun
and interesting - but, nothing proves(or disproves) it like the real
world.
Perhaps because I have never experienced any boil-over or
other inflight cooling problem in 8 years of flying, I have found no
deficiency with the glycol/water mixture approach. I am still not
certain what to make of your assessment that the use of a 7 psi cap may have
contributed to your loss of coolant. My understanding was that was one of
the benefits of NPG - a non-pressurized coolant system. I suppose that the
high altitude and low PSI cap could have played a factor in your situation - but
then that's where we operate our engines.
I decided to see if I could find an authoritative source
on the flammability of Propylene Glycol on the web. This is what I
found:
Propylene glycol is colourless, odourless and viscous liquid
(hygroscopic).
Boiling point 187.4
to 189 OC
Half-life in air <10.012 hrs ( Interesting fact - wonder what it means?)
Flammability Slight
Explosive Properties Containers may explode in heat or
flame
So it appears that as long as you don't carry a can of it
near your exhaust, looks like you don't have to worry about flamability of
it.
There are two cases I am aware of where the rotary engine
loss cooling capability - one was the loss of coolant and the other was a belt
failure that stopped the water pump. In both case, the aircraft continued
to produce power long enough to get the aircraft to a runway. In one case
I am most familiar with, it was 10 plus minutes without
cooling, including a go-around (due to conflicting traffic), don't know how
long the other guy flew before landing. All the rubber seals was cooked in
the one case (10 minutes) and the pilot stated that when poured coolant into the
engine it leaked like a sieve.
In any case, hope you find the time to get to the engine
before you leave - can't imagine sitting over there for several months
without knowing the cause {:>).
Thanks again Dave.
Ed A
----- Original Message -----
Sent: Thursday, February 02, 2006 3:04
PM
Subject: [FlyRotary] Re: Suitability of
NPG for Rotary Engine use
The HP is the easy part. Get the cooling right first.
Lynn E. Hanover
Very true. Will the "right" cooling system please stand up!
My cooling system is too small for the power I wanted to be able to
use. I could still outrun any 160 hp RV-6 and outperform those with 180
hp and fixed pitch props.
But I was out-climbed by the guys with 180hp and c/s props and outrun by
the 200 h.p. crowd.
This should have been good enough. Flying n.a. there were no
cooling issues at all.
But I am starting to think that cooling is like money. No
matter how much you have, its never quite enough.
My current plan it to go from a 2" rad to a 3" rad of the same or
larger surface area. I will also add some fresh intake
ducting, a cowl flap, and spray system.
That should allow me to easily beat the 200h.p. guys.... but then
there is always the tri-aviathon...
Any suggestions? :-)
--
Dave Leonard
Turbo
Rotary RV-6 N4VY
http://members.aol.com/_ht_a/rotaryroster/index.html
http://members.aol.com/_ht_a/vp4skydoc/index.html
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