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Hi Dale,
I have flow approx 160 hours
with a stripped down stock RX-7 NA throttle body. Yes, you can ditch
everything detachable from the throttle body as well as take out the "secondary"
secondary butterfly plates - the first set. Depending on whether you want
to use both the secondary and Primary bores you can mill quite a bit off.
However, I did not do that as it was just too convent to attached the air inlet
ducting with the stock bolts.
If you check I think you will find that even when
the primary butterfly is fully open, the secondaries have a bit of "lag" and are
not 100% open. I redid that linkage to force the secondary to 100% anytime
the primary was 100%. I also reworked the springs so that should the
throttle cable fail, the butterflys got to full open (WOT) rather than close as
on an automobile.
I think Tracy would agree that power does not seem
to suffer from using the "smaller" stock throttle body compared to some of the
"Monster" single throat throttle bodies. I have used both and I agree with
Tracy. I have found no advantage other than saving a small amount of
weight using the larger throttle bodies (that stock TB IS heavy). I
also do not like the momentary "Bog" that occurs when you quickly open a large
throttle body.
FWIW
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
Sent: Monday, April 05, 2004 11:57
PM
Subject: [FlyRotary] Mazda TB (was: idle
speeds)
Hi All,
Is anyone on the list using the
stock throttle body with the
EC2? I've been stripping mine down to
repair the fire damage,
and it looks like there's a lot on it that isn't
needed for
aviation operation. In fact, it looks like I could mill
away
the top 50% of the TB and not impair function at all - except
making the intake ducting a little more complex.
One thing I'm working on is a simplified version of the
EdDIE
manifold, with the secondary bores feeding only the secondary
ports - rather than just increasing the airflow to a common
plenum. Perhaps, it will be easier to get a low speed idle that
way. I'm also sticking with the original 6 port manifold base;
it's just too tempting to use the secondary power port valve
actuator
holes for the secondary injectors.
What I'm looking for is
more information about the upper
butterfly assembly in the secondary
path. It appears to be
a delay mechanism to keep the secondaries
from effectively
opening during low speed WOT conditions. Can I
safety remove
it? It seems as though it's not buying me anything in
an
aviation environment.
Thanks,
Dale R.
COZY MkIV-R
#1254
(It is now 20:20 AZ time (23:20 EDT)
Subject:
[FlyRotary] Re: idle speeds (prop stopped flight)
I had
a cruise prop (80 inch pitch) sensenich metal prop on the 6A. When I was doing
engine off glide testing, some thought I would do better with engine stopped
rather than turning. Really had to slow way down to get prop to stop. Could
not measure the difference in glide engine stopped or windmilling. Really had
to go fast, over a hundred to get it going again!
Bernie Kerr,
painting the 9A waiting to get rotary back from Bruce T at
SnF
A stopped prop is
in a complete stall condition, and would be expected to provide less drag
than one that is turning at an RPM of incipient stall. There will be
some RPM for a given pitch and touchdown speed that will provide the most
drag. We just have to figure out what that is.
Landing speed in
Kts times 100 gives you ft/min. Pitch divided by 12 gives you ft/min
per revolution of the prop for neutral thrust (approx.). So my 85
pitch prop at 70 kt landing speed is neutral at 1000 RPM. So
maybe the max drag point is somewhere around 650 RPM (mas o menos 100).
Just a guess. Someone less propeller-design challenged than I
may have a better answer.
Al
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