|
I think we all understand that being rather "smart" ,we
all pride ourselves on our analytical and decision making ability (however
occasionally good/bad it may be). So when we encounter a
circumstance we consider options (pure water does indeed help the cooling -
considerably) I've done it myself in early flights trying to get a temp
decrease.
But, like Dave said, there would have been no
problem had he 1. Not flown into the cold temps or 2. Put adequate
anti-freeze prior to doing so. So this does not sound like a marginal
cooling system - to me, just one that was operated outside of the
environmental parameters the pilot expected. I don't care how big the
radiator would have been, the lack of sufficient anti-freeze would have likely
had the same results. So at least in this case, the "marginality" of the
cooling system does not appear to be a factor.
Now I have seen marginal cooling systems, one
individual who is thankfully back to a Lycoming would come flying in and upon
shut down would have smoke curling out of his intakes. When this was
pointed out to him, his response was "It always does that". True this
individual did cook at least 2 engines before he even got to a marginal
system. Since his radiator hose burst and resulted in a force landing -
That also might be another indication of a "marginal" system.
But, the two instances that I am aware of that
resulted in truly "cooked" engines had again had nothing to do with how
"marginal" their cooling system was. In one case, a loose radiator hose
clamp led to loss of coolant and a cooked engine, in the second a freak incident
in which both water pump belts popped off the pulley and resulted in no coolant
flow. Fortunately, the robust rotary got both aircraft back to a safe
landing.
This is not to make small of Al's points. He is
certainly correct that a cooling system that results in degraded operation or
excessive temperature excursions is not desirable and can lead to serious
problems. On the other hand, accepting temporary limited excursions for
limited periods have been done by just about everybody I know flying a rotary
and I've yet to see any evidence that this detrimental.
Certainly as someone mentioned all WWII fighters had
some regime of flight where cooling was less than adequate (generally on the
ground or take off) - on the other hand, the designers knew that if they
gave them enough cooling capacity to handle a normally time -limited situation
then the fighter would never have achieved satisfactory
combat performance. Not that we are in the same league {:>),
but nice to pretend.
So the point I attempted to make and others seem to think
the same, is that it would be difficult to pick and agree on the parameters and
values that we could use as a criteria. Al indicated that the
"marginal" point was a spot on a curve - does any one know what this curve's
parameters are? I would at least like to be aware of them.
Ed
|