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  #41  
Old 12-12-2013, 10:01 PM
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RV10inOz RV10inOz is offline
 
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We lean from 663', flowing 25.6 gph, to our usual cruise altitude of 12,500' at a takeoff EGT of 1250F, 2700 RPM. Once at cruise, RPM to 2200-2450, WOT, pull mixture to get me close noting normal FF of 9.5-10.5 gph(yes, I am always below 75%), then slowly lean using GRT to 30-40F LOP. Typically cruise at 150-158 KTAS.

How many hours on the engine? 125 since Dec 1, 2011 thanks to our great economy.
What plugs do you use?massive on top and fine wire on bottom
How long since they were gapped? 25
How many hours on them? 125 on massive/25 on fine wire

Can you send me a EMS data file?No
I will try to deal with each part separately. Your takeoff fuel flow and EGT are spot on, and the use of Target EGT is excellent, that is great, and you are pretty close to best power or slightly richer doing that once you get above say 9000', so the climb rate is maximised and everything is great.

The RPM selection is fine but where I am sure the problem kicks in is best answered by reading my post to Kevin Horton http://www.vansairforce.com/communit...0&postcount=23 in that you are going a long way LOP, and if you are doing what you think is 30-40dF LOP at that altitude, and you are running smooth, I would say your GAMI spread is pretty darned good. For better BSFC I would encourage about 10dF LOP at that height and you will get more like 160TAS than low 150's. But I am impressed your F/A ratio's are so good untuned.

Spark plugs sound good??the economy, well I have been doing my best to inject cash into it of recent times.
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  #42  
Old 12-13-2013, 07:15 AM
Wayne Gillispie Wayne Gillispie is offline
 
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Originally Posted by RV10inOz View Post
I will try to deal with each part separately. Your takeoff fuel flow and EGT are spot on, and the use of Target EGT is excellent, that is great, and you are pretty close to best power or slightly richer doing that once you get above say 9000', so the climb rate is maximised and everything is great.

The RPM selection is fine but where I am sure the problem kicks in is best answered by reading my post to Kevin Horton http://www.vansairforce.com/communit...0&postcount=23 in that you are going a long way LOP, and if you are doing what you think is 30-40dF LOP at that altitude, and you are running smooth, I would say your GAMI spread is pretty darned good. For better BSFC I would encourage about 10dF LOP at that height and you will get more like 160TAS than low 150's. But I am impressed your F/A ratio's are so good untuned.

Spark plugs sound good??the economy, well I have been doing my best to inject cash into it of recent times.
GAMI spread, balance injectors and running a little richer is on my to do list. Thank you for your advice.
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  #43  
Old 12-13-2013, 11:27 AM
rvator10 rvator10 is offline
 
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I had a similar event and accounted it to ice gulp?
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  #44  
Old 12-13-2013, 01:50 PM
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RV10inOz RV10inOz is offline
 
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GAMI spread, balance injectors and running a little richer is on my to do list. Thank you for your advice.
Hi Wayne, I suspect your injectors may well be fine as they are, you could be one of the lucky ones. If it is 0.5 or better, happy days!

Let me know how you go.

Best regards
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  #45  
Old 12-13-2013, 01:51 PM
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I had a similar event and accounted it to ice gulp?
Is your engine carby or IO? If IO not likely and the rest of the thread is a good read.
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  #46  
Old 12-13-2013, 02:30 PM
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DanH DanH is offline
 
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Originally Posted by RV10inOz View Post
The first Data block I have noted is at peak or just lean of peak, in an attempt to keep the HP the same rather than the reduced power and obviously even lower PSI's. The second is full rich.
1. MP=31" RPM=2400 BMEP 133.9 BHP=219 ICP's ranged 600-620PSI
2. MP=31" RPM=2395 BMEP 136.6 BHP=223 ICP's ranged 750-780PSI
Now we're getting somewhere. The subject is break-in (post 33, paragraph 4), meaning the goal is to generate ring pressure. When quantified, we see there is no significant difference between knob twiddling on climb out and just leaving the knobs alone and flying the new airplane...except for the much-maligned ICP, the source of combustion ring pressure.

Quote:
I think if you had done any of this even doing it slowly on either the FAA's or GAMI's test cell you would not be so scared and willing to believe the BS Lycoming have printed.
You the same guy who detonated your 540 and blamed it on a too-short mixture cable?

http://www.vansairforce.com/communit...9&postcount=15

Quote:
I suggest you email the editor of the AOPA's Australian magazine and ask her about her first BMP done overwater at 1500' and see how she responds. So all the smarter tougher and more macho test pilots should be able to cope.
Ahh...even girls do it. Good argument.

I'm going to stick with suggesting that rusty pilots flying their new RV's just leave the knobs alone, fly the airplane, and stay eyes out until well clear of the airport area. LOP is good; learn it in cruise first, and progress to more advanced management later, after sorting out the airplane.

The stats say early test flights are the deadly ones. Let's not make it more complicated.
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  #47  
Old 12-13-2013, 09:11 PM
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RV10inOz RV10inOz is offline
 
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Dan,

You are getting somewhere but missed the point.
Quote:
Now we're getting somewhere. The subject is break-in (post 33, paragraph 4), meaning the goal is to generate ring pressure. When quantified, we see there is no significant difference between knob twiddling on climb out and just leaving the knobs alone and flying the new airplane...except for the much-maligned ICP, the source of combustion ring pressure.
During break in you want less of the peak and more of a broad area under the curve to give you better break in. The graph below is generated from real data and plotted nicely for classroom use. Take a look at which has a lower peak ICP but a broader and wider range of average pressure. So tell me which is better Dan, a higher MEAN effective pressure or, higher peak pressure? Higher CHT or lower CHT? Cleaner or dirtier combustion chamber and oil? One operation as all the good things and less of the bad. (NB: 80dF LOP would be better, this graphic is produced to show the traditional thinking 50LOP/50ROP comparison. It applies here full rich Vs even 50dF LOP.)


As I said before, either do it full rich or 80dF LOP.

Quote:
You the same guy who detonated your 540 and blamed it on a too-short mixture cable?
Glad you remember that, that incident/s happened with very high inlet temps, and rapidly rising CHT on a few (not all) cylinders and only started with a takeoff with already hot cylinders. Looked all the world like either preignition (i.e. maybe a cracked ceramic) but it was not, or the very mild edge of light detonation. Even to the point we wondered if there was fuel contamination. The data at the time looked like it. As you rightly remembered we found the flex in the bracket from engine thrust and too short a cable was the cause.

I subsequently looked into this with George Braly and we concluded it was not detonation in the true sense as defined by the FAA. It may well have been close and enough to register on the Lycoming test method, but I doubt it. But the CHT rise per second looked almost like it. So today, I would write that post differently.

Ouch!!
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Ahh...even girls do it. Good argument.
Proves the point, but she is a pretty sharp operator I guess, so how about an old retired airline guy, took him flying today, got him to do a BMP, never done one before, and exactly like Kreisha Ballantyne he landed bang on target at the appropriate number of degrees LOP. I mean bang on with huh accuracy, and so did Kreisha and everyone else I have asked to do it. Close your eyes and pull back, under two seconds, eyes open.

And here you are complaining about eyes down in the cockpit. Please, the BMP means NO FIDDLING, and maximum eyes outside. In a busy terminal area this is what we teach, no fiddling just a BMP and park the engine in a safe place. Works for turbo or NA guys. Zero downsides. Maximum SA.

Quote:
I'm going to stick with suggesting that rusty pilots flying their new RV's just leave the knobs alone, fly the airplane, and stay eyes out until well clear of the airport area. LOP is good; learn it in cruise first, and progress to more advanced management later, after sorting out the airplane.
Stick with what you like, but I am going to challenge you that RUSTY pilots should not be test flying their new RV's. I am on the board of the SAAA (Australian EAA) and was a founding participant in http://www.rvflightsafety.org ( I even named it ) and one of the biggest things we push is recency and experience for test flying any new plane. We are having a big push here at the moment with CASA over transition training in a formalised sense, and I know this is one of the issues in the USA as well, and Van himself is very strong on these matters.

If the pilot is incapable of doing a BMP on his second or third flight which will be longer duration typically, then fine, leave it full rich as that is where it belongs, unless you are comfortable with a simple BMP to a high power LOP breaking. It is a non event. Clearly you have not done any. I have done many.

Quote:
and progress to more advanced management later, after sorting out the airplane.
I have to agree 100% On your first flight there are priorities, but for the majority who have done a good job, the first flight should uncover nothing of any significant nature, and the second or third flight there is far more capacity for a two second BMP while you move onto other things. If the first flight yields major issues, fuel or oil leaks etc, then back on the deck, fix it and then you basically have another first flight again. I firmly believe if the first flight did not prove the plane was capable of a 4 hour flight next, then the next flight after rectification is a first flight repeated.

Quote:
The stats say early test flights are the deadly ones. Let's not make it more complicated.
Agree again. I have sat down and poured through 10 years of NTSB accident reports and 10 years of ATSB reports, looking at those stats. Plus the special focus on ABE that the FAA and ATSB have done. Even provided some corrections to ATSB. So I agree 100%.

So tell me on the second or third flight what achieves the most eyes down and complication?
A: flying around and constantly worry about the high CHT's. (Eyes down a lot, and that is what happens) Refer all the threads on VAF as statistical data.
B: flying to 1500-2000' levelling off, accelerating and cooling the engine and doing a BMP that requires absolutely no eyes down, (most folk need to close their eyes the first couple of times-perhaps in transition training) and then parking the engine safely and not worrying about CHT's as much. Then sitting in the lounge at home later looking at data.

You might prefer A, but I prefer B.

You do not have to agree with me, the readers can make up their own mind, but when you rock up to Ada in March, print this out and go ask Deakin or Atkinson during a lunch break what they think is the better way to go for engine breakin and safety of eyes outside. I would love to hear their comments.

Anyway, enjoy your RV8, and thanks for all the good posts on airflow under cowls and all that good stuff!
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  #48  
Old 12-14-2013, 04:36 AM
MGS767 MGS767 is offline
 
Join Date: Sep 2012
Location: Perth Western Australia
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Default Same experience

I witness the same shudder for approximate one second a couple of weeks ago.
Aircraft type RV-10 with 550 hours on the engine. After flying the aircraft for 45 minutes to our destination the aircraft sat on the ground for approximate one hour. The shudder occurred on climb out passing through 3000 feet AGL, approximate 6 minutes after take off.
We have a light speed electronic ignition running the top plugs W27EMR-C, magneto operating the bottom plugs Champion REM 38 E.
At the time fuel boost pump was off, mixture full rich. OAT was approximate 27c quite warm.
I tried to download the engine data, from the Advance AF-2500 EMS, had an issue with my laptop not having a serial port. I have ordered a USB to Serial converter hopping this will allow me to download the EMS data.

David once I download the data would you mind taking a look please?

Mike
Western Australia
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  #49  
Old 12-14-2013, 04:58 AM
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DanH DanH is offline
 
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Originally Posted by RV10inOz View Post
During break in you want less of the peak and more of a broad area under the curve to give you better break in.
In the context of desired ring pressure, tell me why.
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  #50  
Old 12-14-2013, 05:44 PM
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AlexPeterson AlexPeterson is offline
 
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Originally Posted by DanH View Post
In the context of desired ring pressure, tell me why.
I'll add some more to this question - I have heard about pressure being needed during break-in to "seat the rings" better. Exactly what forces does the cylinder pressure apply to the rings? I can see the pressure forcing the rings towards the crankshaft within the piston grooves, but I do not see anything forcing the rings radially outward. If anything, the pressure in the cylinder will "find" the outer diameters of the rings through the oil film and apply radial force inward on the rings. There will, of course, be some pressure which finds its way over the top and behind the rings, but that is a more tortuous path than through the oil film on the OD of the rings. ??
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