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05-15-2014, 06:26 PM
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Join Date: May 2009
Location: Colorado
Posts: 302
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Quote:
Originally Posted by Kahuna
Couple of things next.
1. You said "Are you able to go from very rich to lean and do all cylinders react accordingly? No!" Please tell us what it does please. This will be a clue.
2. Timing. Id like to know if the timing was checked per the manufactures requirements.
3. If 2 is yes, Id pull a mag off and view the gear timing on all accessory gears per lycoming requirements.
4. Do you have an inductive timing light and do you know how to use it?
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Please don't take this the wrong way, but it would be difficult to impossible to check the internal gear timing from crank to cam by removing a mag. The simple check for this is to accomplish the test in post#22.
If the internal timing is off your mag can still be properly timed creating more confusion.
Ryan
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05-15-2014, 07:07 PM
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Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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Please check my math & specs for the engine.
This a/c full throttle sea level fuel flow is quoted as 53 liters/hr is ~14 gallons/hr.
180HP (sea level full throttle 2700 rpm, full power) should use
(180*.55 pounds)/6=16.5 gallons per hour, minimum.
In this a/c, full rich, 14gph/16.5gph= 84.8% power.
Can this a/c match Van's sea level climb rate at full power setting? (Full power climb rate should minimize aerodynamic drag influences to judge whether the engine is making full rated power.)
75% power on a 180 hp Lyc should be ~10 gallons (37.8 Liters)per hour, using 135*.45 lbs per hp per hr.
Quote from previous post:
At 8000ft and 75% Van's indicate 172Kts, there is 42kts of more, perhaps 15kts for fairings, I lose 27kts!
Unquote.
Van's numbers for 75% power at 8000 ft altitude assume wide open throttle and 2700 rpm, leaned for best power. (Fuel flow should be ~10gph; perhaps slightly less if the ignition advances for reduced manifold pressure.) What's the speed under those conditions?
Charlie
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05-15-2014, 07:41 PM
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Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,218
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The original poster indicated his airplane doesn't have the wheel pants installed. Are the gear leg and intersection fairings installed?
I would verify engine RPM. Get a digital tachometer and verify that the panel mounted tachometer is accurate.
__________________
Kyle Boatright
Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
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05-15-2014, 07:59 PM
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Join Date: Oct 2005
Posts: 1,516
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From the OP's first post:
Quote:
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I have flyed with fairings, it doesn't change anything.
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I find that hard to believe
I know of no RV that has not gained at least 10 to 15 MPH when fairings are installed.
__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 600 plus hours
Running on E10 mogas
Don't believe everything you know.
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05-15-2014, 08:00 PM
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Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
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Quote:
Originally Posted by 131RB
Please don't take this the wrong way, but it would be difficult to impossible to check the internal gear timing from crank to cam by removing a mag. The simple check for this is to accomplish the test in post#22.
If the internal timing is off your mag can still be properly timed creating more confusion.
Ryan
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Yes post 22 works fine. But a mirror, light, or any of our cheap cameras or bore scopes gets us the actual marks aligned without having to try and measure degrees moving a prop. That is not very accurate for the inexperienced.
__________________
Kahuna
6A, S8 ,
Gold Hill, NC25
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05-15-2014, 10:30 PM
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Join Date: Dec 2011
Location: North Carolina
Posts: 94
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Quote:
Originally Posted by N427EF
From the OP's first post:
I find that hard to believe
I know of no RV that has not gained at least 10 to 15 MPH when fairings are installed.
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10-15mph sounds like alot. just thinking outloud.
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05-16-2014, 05:08 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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Our 6A gained 16 MPH on a 4 leg course at 7500' and WOT, turning 2750RPM on a three-blade Catto, optimized for cruise speed, from 184MPH to 201MPH after all the fairings, including upper and lower intersection fairings (from fairingsetc). That's not at all unusual.
Best,
__________________
Pierre Smith
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!
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05-16-2014, 08:32 AM
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Join Date: May 2005
Location: X35 - Ocala, FL
Posts: 3,679
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Quote:
Originally Posted by pierre smith
Our 6A gained 16 MPH on a 4 leg course at 7500' and WOT, turning 2750RPM on a three-blade Catto, optimized for cruise speed, from 184MPH to 201MPH after all the fairings, including upper and lower intersection fairings (from fairingsetc). That's not at all unusual.
Best,
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In en-10's we consistently gain 17kts when we add fairings (assuming the fairing brackets are on the mains without the fairings initially).
__________________
Jesse Saint
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05-16-2014, 08:54 AM
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Join Date: Nov 2010
Location: ____
Posts: 829
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Confirm your GPS is accurate
There can be quite a variation between GPS velocity indications in the same vehicle. Hard to believe until you see it. My ipad is about 10 kts slow compared to my Garmin. I don't trust any of them until you test them for time over a known distance .
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05-16-2014, 09:31 AM
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Join Date: May 2014
Location: Sarrebruck
Posts: 13
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Quote:
Originally Posted by Low Pass
Are you absolutely certain the engine (ignition) is timed properly? Have seen a situation with a new plane I test flew once that had a retarded timing condition that resulted in slightly reduced power/speed. The A&P/IA multi-builder was certain the first time or two I asked him as well. It was retarded.
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It's probably the problem, I have an appointement with a specialist equiped with contr?ler T300 for check timing with precision. Thank
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