I swapped props on the 2180cc VW Friday (both Sterbas)....adding 2 more
inches of pitch (54x50 -> 54x52). In back-to-back tests, the added
pitch gained me 7 mph (TAS) at WOT at 9500' while dropping 90 rpm. At
7500' and my favorite 2180cc VW rpm of 3150, I gained a whopping 14 mph
TAS at the same rpm. My point is that propeller choice matters! If
you're not happy with your KR performance, check the "KR Performance
Info" spreadsheet at http://www.krnet.org/kr-info.html to see if you're
in the ballpark, and if you're not, ask around...somebody may have a
prop for sale that you could try out. There are a lot of KRs flying
that I have no info on, so please send me your data and I'll add it to
the spreadsheet so others can benefit from your experience. Keep in
mind that not all prop makers' pitch numbers correlate to others.
Sterba numbers seem to be slightly higher than comparable props with
similar performance, for example.
Somebody asked about CHTs with the new Revmaster heads, and for the 160
mph WOT @ 7500' run with OAT 56F, CHT was 338F. On climbout I never saw
over 365F, so on a hot summer day, it should be under 400F as long as I
keep the climbout down to the usual 1
I also had a productive Saturday...I finally got my Stratux ($125
home-brew) ADS-b working again with the iFly 720 and Android...I just
needed to reimage the ADS-b with the latest image, which apparently
fixed something that iFly software now requires. So now I have airport
weather, Nexrad radar imagery, winds aloft, aircraft traffic, etc.
again. I'm using a "previously owned" $100 ebay Nexus 7 tablet
(2013..second generation), which is brighter, clearer (higher screen
resolution), and about 20 times faster than the iFly720 is, not to
mention it zooms by pinching, pans instantly, and all that kind of
stuff, and runs the Stratux status/diagnostic app in the background,
along with whatever else I would like to run. And the Nexus 7 has a
built in battery (good for hours) so it doesn't go dead and take three
minutes to reboot when power is cycled!
I also reinstalled my transponder, which had blown a fuse and is now
fixed, so I can fly over controlled airspace again. I also eliminated
some microphone feedback from caused by the iEFIS audio which fed into
the headset jack...I disconnected that wire, and now it works perfectly!
And if that's not enough, I flew to the Swift Museum and checked out
five awesome Swifts...including the prototype, the first production
Swift built, and the last Swift built (which is still 100% original).
Got 2.5 hours on the Hobbs, and it was another great flying day!
Ready for OSH, Terry's BBQ, and the Gathering now...
Mark Langford
m...@n56ml.com
http://www.n56ml.com
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