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[FlyRotary] Re: Performance coatings- bearing damage?
Hi
Dave;
I considered this as well at one point, as a way to provide
cooling and as possible way to prevent icing by having warmer fuel. I quickly
dismissed this as first I'd rather just avoid icing at all costs and second this
wouldn't have a constant effect as the tanks are drained. As you near to empty
you would have much less volume of fuel to absorb the heat and it would be in
contact with much less area of the wing skin to dissipate that heat to the air.
I suspect that vapour lock would occur quickly.
About the only time I could see any possibility for
this is if you have a valve arrangement where you could select or bypass this
cooling option. That would allow you to use that cooling during initial climbout
when you have full tanks, but once at cruise altitude where you won't need the
additional cooling you could bypass it, avoiding the possibility of vapour lock.
This adds extra complexity and pilot workload and more possibilities for
failure. Another slim possible failure mode would be coolant leaking into the
fuel. Not likely in a well made heat exchanger, but it sure would ruin your
day.
I had a couple of vapour lock incidents that stopped the
fan, two of which I was at high altitude and was able to restart, but one was in
the circuit and resulted in a deadstick landing. I had all kinds of bypass
valves and header vents, etc. back when I used a header tank, that I
didn't think were too complex, but it sure was a pain to deal with when you're
under pressure. I'm glad to be rid of them and all possibilities of vapour
lock.
If you're just looking to join the Deadstick Club so you
can drink beer with us, I'm sure we can count your busted turbo, smoking oil,
low power semi-emergency landing as admission to the club. Heck, I believe you
had your wife on board when that happened? That's gotta add a whole new
dimension of stress! :-)
I think what George was referring to about the fuel cooling
the rotors was the (new/old?) German Wankel which uses a charge air approach
much like a 2-stroke engine where the incoming air/fuel mixture is drawn into
the crankcase first to provide cooling & lubrication to the crankcase and
gets precompressed by the piston down stroke as the port opens allowing the
mixture to pass into the combustion chamber. This works well in that
application, as the air/fuel mixture is already in a state of vapour and has no
worries about vapour lock issues that stop fuel flow in fuel delivery
systems.
Those
are my thoughts anyways...
Todd
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