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Message
Rusty, did you get my note regarding measuring the total
pressure with pitot style probe?
Bernie
Hi Bernie,
I got it, but I didn't
really "get it". I just read it a couple more times, and think I
might finally understand what you're saying!
It sounds like you're
saying that a pitot probe will give a better reading of the
actual (total) pressure of air in the runner. You mentioned that the
pitot reading in the plenum will be the same as the reading in the runner,
minus frictional losses.
This makes sense from
what I've seen so far. About the only thing I'm
sure about intakes is that smooth transitions are really
important. Now I see that smoothing the flow is reducing
the losses, and allowing more of the original energy to be retained as
useful air volume that makes it into the rotor housing when the port
opens.
So, if you had a perfect
intake, you would measure the same pitot pressure inside the runner, as you
would read ambient static pressure at the inlet to the TB. Since the
TWM TB apparently has an excellent "static" style port, I'm only seeing
part of the picture, which makes it look like my intake is
lousy.
From all this, it would
seem like the real test would be to put a static style port in the runner, and
see what it measures compared to ambient. If this is near ambient, at WOT,
then the intake is not causing a significant restriction in power. If
the pressure drop is still significant, then it proves I've got too much
restriction.
Would you agree with
that test? If so, I can pull one of the plugs out of
an injector port on the TWM, and install a pitot tube that
reaches down into the air stream temporarily for testing. That
would end up about the same location as the stock MAP port on the
TB.
I can't help but laugh at myself for all
this effort to increase the MAP. It all came to a head again when I
wasn't making the RPM's I expected to make with the new engine and prop
changes. I bet if I spent the same amount of time flying, as I have
thinking about the intake "problem", the engine would have broken in well enough
to get all the RPM I originally expected.
Thanks for making me go
look at your message again.
Rusty (in need of therapy)
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