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12-03-2019, 04:09 PM
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Join Date: Oct 2019
Location: SoCal
Posts: 318
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Facebook:
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Ed
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12-03-2019, 05:17 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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Quote:
Originally Posted by partner14
. Flying with half throttle, 2,230rpm, climbing at 200fpm, at 15,480',
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I have to ask: Why would one fly at half throttle, at 15K??
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12-03-2019, 05:23 PM
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Join Date: Apr 2018
Location: louisiana
Posts: 140
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I was happy with my 200kts ground speed in my 6 this week. I was down at 7k and I had to make the return trip in the afternoon. As awesome as 200kts was going, 120 on the way back SUCKED.
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12-03-2019, 07:33 PM
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Join Date: Feb 2008
Location: Pecan Plantation Granbury TX
Posts: 20
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As far as flying at half throttle.... My engine (IO540) has higher compression and cold air induction, so I pay really close attention to CHT's. Sometimes the temps are fine at WOT, but a higher percentage of the time they're not. You can see the numbers, they're almost perfect.... they wouldn't be if I was WOT. Can't totally tell you why, but after 1,100 hours I have a pretty good handle on what my engine wants and needs. Also I fly by mpg. So even at lower altitudes, if I run several inches less, ususally the mileage is greater. Most pilots don't even mess with the settings, I do. If I gave it those extra 2 inches, sure let's say I pick up from 160kts to 165kts (3% increase), but my fuel burn went from 9.5 to 10.2gph (7.4% increase).
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12-04-2019, 02:44 AM
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Join Date: Feb 2017
Location: Australia
Posts: 615
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Guys please have a read of the article " Flying high and fast" by Ken Krueger, (Google it) makes for some sobering thoughts as a lot of pilots don't understand that VNE at Altitude is NOT based on IAS but TAS.
The Vans designs are very capable of exceeding VNE under certain conditions with fluttering.
Stay safe out there, learn something new everyday -)
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12-04-2019, 07:56 AM
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Join Date: Oct 2009
Location: Victoria, BC, Canada
Posts: 3,932
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Quote:
Originally Posted by Latech15
I was happy with my 200kts ground speed in my 6 this week. I was down at 7k and I had to make the return trip in the afternoon. As awesome as 200kts was going, 120 on the way back SUCKED.
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Just think how badly it would suck in a Cessna...
__________________
Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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12-04-2019, 08:21 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Quote:
Originally Posted by partner14
As far as flying at half throttle.... My engine (IO540) has higher compression and cold air induction, so I pay really close attention to CHT's. Sometimes the temps are fine at WOT, but a higher percentage of the time they're not. You can see the numbers, they're almost perfect.... they wouldn't be if I was WOT. Can't totally tell you why, but after 1,100 hours I have a pretty good handle on what my engine wants and needs. Also I fly by mpg. So even at lower altitudes, if I run several inches less, ususally the mileage is greater. Most pilots don't even mess with the settings, I do. If I gave it those extra 2 inches, sure let's say I pick up from 160kts to 165kts (3% increase), but my fuel burn went from 9.5 to 10.2gph (7.4% increase).
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Throttling an engine with the butterfly in the servo results in higher pumping loss than if the engine is free to breath unrestricted. In your example above, why wouldn't you shove the throttle in and grab those two inches of MP, but simply lean back to your 9.5 GPH? All else equal, the engine should produce a bit more power (with less pumping loss), and your CHTs will come down too.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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12-04-2019, 09:28 AM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Quote:
Originally Posted by Capt
Guys please have a read of the article " Flying high and fast" by Ken Krueger, (Google it) makes for some sobering thoughts as a lot of pilots don't understand that VNE at Altitude is NOT based on IAS but TAS.
The Vans designs are very capable of exceeding VNE under certain conditions with fluttering.
Stay safe out there, learn something new everyday -)
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His TAS was well below his Vne, so no issues. Notice he listed both IAS and TAS.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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12-04-2019, 09:58 AM
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Join Date: Jun 2008
Location: San Diego, CA
Posts: 206
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You might be interested in reading my buddy Jerry Jackson's account of his round trip transcontinental record setting trip in his RV6A.
https://www.amazon.com/Flight-Feral-.../dp/1453574166
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12-04-2019, 02:07 PM
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Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,574
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To the OP - thanks for sharing in a later post what engine you have. Your initial post made my heart stop. Sure, the ground speed is great because of the wind, but your IAS and TAS would be unheard-of for a normally aspirated 4 cyl Lyc. at "half throttle and 2230 RPM".
And I agree with Toobuilder - as long as you can run smoothly LOP, you should be able to open the throttle and lean the mixture to the same fuel flow, and get the same CHT, and probably go a little bit faster.
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 625
LS6-15/18W sailplane SOLD
bought my old LS6-A back!! 
VAF donation Jan 2020
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