smokey_bear_40220(at)yaho
Guest
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 Posted: Sat Jun 03, 2006 11:52 pm Post subject: Performance (Was Wood Prop Advice) |
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Hi John,
I found my best ROC speed to be very critical at 59
knots. My ROC dropped 9% just 2 knots faster and 22%
just 2 knots slower. That steep curve was the biggest
surprise of my testing. I thought I could get good
enough at best ROC within +/-5 knots, but not true.
If I really need to clear something, I have to hawk
the speed.
I suspect it is due to a steep drag curve that will
improve when I add more fairings, and I wonder how
this compares to the rest of you? How critical is
your climb speed?
Another thing I need to test is flappeon angle.
Reflexed a little might help a lot. Those who use it
for trim say it makes a big difference.
Those things you could consider too.
Combining this with your prop pitch change figures and
what you wrote before, I'm not quite sure what limits
you reach first.
If you are using 5000 rpm as your upper limit, I would
set pitch to fall just short of this RPM limit in
level full power flight and see how it performs there
for climb. If you want more climb than that gives,
you have to watch your RPM yourself. It will not be
self limiting with less pitch.
If you want more cruise, you can always add more pitch
until climb suffers too much to suit you.
With your observed boost drop below 4300 rpm, you
probably don't want to set pitch to give below this
for static full power rpm.
For me, I would set pitch to give me say 4900 at max
speed and throttle and make sure I get more than 4400
static. Start from there and tweek more pitch for the
biggest  at 4000 cruise, as long as climb is good.
This is fun!
Kurt S.
--- John Anderson <janderson412(at)hotmail.com> wrote:
| Quote: | Yes Kurt, I tend to climb faster too but for the
test result I've put it
through the paces. 5000max, 4600 (at)55kts BRC speed
1500'pm (just one up of
course) and 4300 97kts level. Ive settled at 4000
for cruise as runs
smoothest there and 90. I notice quite a boost drop
from 4300 down to 4000.
I've very pleased with how well it has turned out...
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