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  #11  
Old 07-07-2018, 04:09 PM
rv7charlie rv7charlie is offline
 
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Location: Pocahontas MS
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At altitude (7500' +), if you're happy with the cruise speed/fuel burn, then that's great. A lot of guys never seem to go above 2400 in cruise. I rarely do these days, if I'm just up boring holes. But you're leaving a lot of performance on the table for cross country work. Try to find an operations manual for the engine. With normally aspirated engines, operating up in the 7500-8500 foot altitude range, you don't get to 75% power unless you've got wide open throttle and turning 2700 rpm. At that altitude, full throttle and 2700 rpm, you should be burning almost exactly 10 gallons an hour, unless you have electronic ignition. That *might* buy you 1/2 to 1 gph at 75% power. (Many claim bigger savings, but they are typically running much less than 75% power.)

edit: Here are Van's numbers for the -7, which are very close to a -6:
http://www.vansaircraft.com/public/rv7perf.htm
Those 8000' numbers are at full throttle, 2700 rpm.

Yes, it might last a bit longer at 60% than 75%, but it's designed to run at 75%+ all day long & go 2000 hours. The ones that don't make TBO usually fall short because they weren't flown regularly; not because of running at 75%. There is somewhat of an exponential curve in fuel burn as you get past 60%, though... :-)

Manifold pressure with a carb'd engine will be just slightly under atmospheric, at full throttle. Standard pressure chart:
https://www.avs.org/AVS/files/c7/c7e...de54f87b9e.pdf

The most efficient way to operate, once you're at a reasonable cruise altitude, is at wide open throttle with the prop dialed back to limit RPM, if you're lower than ~8000'. This is a gross oversimplification, so get the operating manual & a book on piston engine operation. As others mentioned, there are 'yellow arcs' in rpm where you can't linger with metal props, and a couple of other cautions.

Charlie

Last edited by rv7charlie : 07-07-2018 at 04:13 PM.
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  #12  
Old 07-07-2018, 04:21 PM
Chkaharyer99 Chkaharyer99 is offline
 
Join Date: Oct 2011
Location: Pilot Hill, CA
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Not sure what model Hartzell you have.

This link may be of interest to you if you have this prop commonly used on RV's: https://www.vansaircraft.com/pdf/Hartzell_c2yr.pdf


New Hartzell "Blended Airfoil" HC-C2YR-1BF/F7496 Prop RecommendedFor Lycoming 360's With Electronic Ignition / FADEC Systems

Propeller vibration characteristics and stress amplitudes on a reciprocating engine installation are primarily mechanically generated by the engine. Any modification to the standard engine configuration to include high compression pistons, electronic ignition, FADEC, tuned induction and exhaust, and turbocharging or turbonormalizing have the potential to adversely effect the propeller vibration characteristics and stress amplitudes. Hartzell Propeller, therefore, does not endorse any such engine modification unless the specific engine and propeller configurations have been tested and found to be vibrationally acceptable according to FAR 23.907.

Such flight testing of a new “blended airfoil” propeller has been accomplished in accordance to FAR 23.907 to ensure compatibility with Lycoming O-360 engines and various ignition systems. As a result of this testing, Hartzell’s new blended airfoil propeller, model HC-C2YR-1BF/F7496 is approved for use as described below and is the recommended propeller for use on Lycoming O360 engines equipped with electronic ignition systems and FADEC. This propeller essentially eliminates the “no continuous operation” zone of the original HC-C2YK-1BF/F7666A -2 , -4 propeller, when operated in conjunction with the Lycoming O-360-A1A (undamped 180hp) engine. The specific approvals are indicated below:


Hartzell Propeller Model HC-C2YR-1BF/F7496 is vibrationally approved when mounted on Lycoming model O-360-A1A rated at 180 HP at 2700 RPM and equipped with magneto ignition and/or Lightspeed Plasma II or Unison LASAR electronic ignition installed in Van’s Model RV-8 and similar single engine tractor aircraft with the following operating restrictions:

1. Do not operate above 22” manifold pressure below 2350 RPM.

2. Operation above 2600 RPM is limited to takeoff. As soon as practical after takeoff the RPM should be reduced to 2600 RPM or less.

3. The propeller diameter limits are 74” to 72”.

Hartzell Propeller Model HC-C2YR-1BF/F7496 is vibrationally approved when mounted on Lycoming model IOF-360-A1A rated at 180 HP at 2700 RPM and equipped with Aerosance FADEC engine control installed in Van’s Aircraft Model RV-8 and similar single engine tractor aircraft with the following operating restrictions.

1. Do not operate above 22” manifold pressure below 2350 RPM.

2. Maximum engine RPM must be limited to 2650 RPM.

3. The propeller diameter limits are 74” to 72”.

Note:

No testing has been done, at this time, on the IO-360-A1A, AIB6 (200 hp) or other derivatives of that engine.

The HC-C2YK-1BF/F7666A-2, -4 propeller will continue to be available for those aircraft where its use has been tested and is approved.
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  #13  
Old 07-07-2018, 04:27 PM
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Toobuilder Toobuilder is offline
 
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Keith-

Not that this matters at all, but I have more than 27 years on the U-2/ER-2 program both as a GI and Engineer, and the RV-8 I fly is owned by a former Deuce pilot. We probably know a lot of the same people. Gimme a shout via PM and I'll give you my contact info. I'm very familiar with the mission profile of the Lady and can talk to you in terms you are familiar with. Easier to talk through this on the phone than message boards.
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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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RV-8 - Flying
1940 Taylorcraft BL-65 -flying

Last edited by Toobuilder : 07-07-2018 at 04:30 PM.
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  #14  
Old 07-07-2018, 04:56 PM
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azrv6 azrv6 is offline
 
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Default O360-A1A power settings

Power settings for 55%, 65% and 75% power at varying altitudes, versus RPM and MP. I don't remember where I originally got this, but found it this afternoon on a backup of a long gone computer. Also have easier to read tables in my RV6 (O360A1A, Hartzell CS) which I have been flying for 22 years. Could get them next time at the hangar and bring them home and scan and post if desired.

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  #15  
Old 07-07-2018, 06:11 PM
rv7charlie rv7charlie is offline
 
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Here's a Lyc document.
https://www.lycoming.com/sites/defau...2060297-12.pdf
You might not find your exact model listed, but all the parallel valve 360s for fixed wing a/c will look pretty similar.

Try page 3-41, a HP/altitude nomograph for an IO-360 M1A. Raw 8k' 2700 rpm is 135 HP. There is also a set of MP correction lines, and the 22" line indicates close to 140 HP. I'd assume that this is a correction for slightly improved efficiency due to lower backpressure on pistons with higher altitude; note that the graph on the left shows a straight 135 HP at 22"/2700 rpm. Corrected HP at 8k'/2400 rpm appears to be 126 HP.
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  #16  
Old 07-08-2018, 10:42 AM
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flion flion is offline
 
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Quote:
Originally Posted by MountainU2 View Post
Great. Ideally I take off at full throttle (of course) and just leave it there until descent, assuming a cruise alt over 5000ft. It’s those other two squirrelly knobs that are so mysterious.

So do you lean in the climb? How about the prop? Say you’re climbing to 7500ft... When do the blue and red thingys become active? In what order? I feel like I know what to do when I get to cruise altitude (mostly), but how about on the way to it? Is this a lot of questions? If I have to ask, don’t I already know?!
It seems no one exactly answered your question about the prop control. After cycling in runup, my prop is full for taxi and takeoff. After takeoff, when I am at about 500' AGL, I reduce the prop to cruise (my field is at 7K'. If I'm taking off near sea level, I blow through 500' before the rush of the RV takeoff has passed, so I may be somewhat higher). I usually go with 2400 but 2200 also works (2350 is the restricted rpm on my prop). I stay at that rpm until I am on downwind and/or my speed is at pattern speed, when it goes back to full. There's not much reason to fiddle with the prop in normal flight operations.

By the way, I seldom bother with MP since we don't get full power anyway at my field elevation, not to mention variations in density altitude. I find my injected engine does about 10-11 gph at full throttle and I set my cruise throttle at about 7-8 gph to get an indicated 135 knots in level cruise at around 8500'. These are probably not the most efficient settings but they are comfortable for me.
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  #17  
Old 07-08-2018, 12:54 PM
Tracer 10 Tracer 10 is offline
 
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Default Climb/Cruise Power settings.

TAKE OFF AT SEA LEVEL:
Mixture full forward = Rich.
Prop full forward = Low Pitch, High RPM.
Power = Full forward.

CLIMB FROM SEA LEVEL:
Mixture full forward = Rich.
Prop = pull back slowly to 2,500 RPM
Power = pull back slowly to achieve 25” of manifold pressure.

As you gain altitude increase power with throttle to maintain 25” of manifold pressure; as you gain altitude start leaning mixture while monitoring cylinder head temperatures, and oil temperature; (—leaning starts, generally above 5,000’)
As your altitude increases your manifold pressure will slowly drop & even at full power you won’t be able to maintain 25”. This is normal unless engine is turbocharged.

LEVEL CRUISE FLIGHT:
Bring prop back to 2,300–2,400 RPM.
Bring power back to 21-24” of Manifold Pressure.
Bring mixture back as you previously described.
Lower manifold pressures will result in less fuel burned & less cruise airspeed.
As you descend from cruise altitude don’t forget to ease the mixture forward.
***ALL THAT SAID:: I SUGGEST SOME DUAL INSTRUCTION FROM AN EXPERIENCED RV PILOT WHO IS FAMILIAR WITH YOUR TYPE AIRCRAFT & ENGINE***
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  #18  
Old 07-08-2018, 02:22 PM
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Toobuilder Toobuilder is offline
 
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I see some differences in operation from my own. Not saying it's the only way to do it but I typically fly the throttle as the OP is used to in the Deuce... WOT from takeoff to descent. I'll pull the prop back a little (2500) for cruise climb, then set RPM for cruise (2250 for the Rocket or 2350 for the -8); the mixture at target EGT for the climb, then as desired for cruise (peak for the Rocket or 30 LOP for the -8).
__________________
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
______________
Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying
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  #19  
Old 07-08-2018, 06:05 PM
Boyd Birchler Boyd Birchler is offline
 
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My plane had your carbureted engine with a fixed Sensenich prop when I bought it.

On take off,full throttle, I got 2300 RPM during climb.

I have since changed the engine over to fuel injection and a C/S prop. I now take off ,full throttle,2700RPM and after clearing obstacles reduce the RPM to 2500 or 2600 leaving the throttle full in. Remember with the fixed pitch I only got 2300 to 2350.... My highly instrumented engine has lower CHT's in climb if I DO NOT reduce MP with the RPM reduction.

I agree EGT's are not important in value but are used to determine PEAK. Your 1250 EGT may be different if your probes were placed closer to the exhaust port or further away. Comparing one cylinder to another may help trouble shoot a problem (cold cylinder,intake leak ect).

Your method of leaning is likely to be LOP (lean of peak): lean to roughness then richen until somewhat smooth. LOP gives a reduction in CHT over the same percentage of power ROP (rich of peak). I have operated LOP for many hundreds of hours, in Mooney's,Bonanzas and My RV7.
My speeds at 8500 are similar 132 to 140 KTS indicated on 7.4 GPH for a TAS of 155 to 165 KTS...
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  #20  
Old 07-08-2018, 07:18 PM
MConner MConner is offline
 
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Location: Snead Island, Florida
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Quote:
Originally Posted by azrv6 View Post
Power settings for 55%, 65% and 75% power at varying altitudes, versus RPM and MP. I don't remember where I originally got this, but found it this afternoon on a backup of a long gone computer. Also have easier to read tables in my RV6 (O360A1A, Hartzell CS) which I have been flying for 22 years. Could get them next time at the hangar and bring them home and scan and post if desired.

Where can I get these numbers for my O-540 ?

Mark
Rv-10
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