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James plenum question

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Lenny Iszak

Joined: 23 Mar 2008
Posts: 270

Posted: Sun Sep 27, 2009 5:14 pm Post subject: James plenum question

Those of you who installed the James plenum (Deems, Robin?), how did you get air to the left side heat muff?



Thanks,

Lenny

recapen(at)earthlink.net
Guest

Posted: Sun Sep 27, 2009 5:59 pm Post subject: James plenum question

Here's how I did the ones on my 6A.....



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robin1(at)mrmoisture.com
Guest

Posted: Sun Sep 27, 2009 6:46 pm Post subject: James plenum question

Lenny,  

            Because of high temp issues early on we upgraded and relocated the oil cooler to accept RAM air from the front of the cowl. We sealed the rear hole leaving all the cowl/plenum air for cooling the cylinders. While I hope temps will not be an issue with your build I suspect you will experience similar thermal challenges. Assuming I were using the James Cowl/Plenum again (highly doubtful) I would consider side louvers as the under cowl louvers were beneficial but still not sufficient to keep temps in an acceptable range. I have even toyed with the idea of converting the Plenum back to standard baffles but there are too many unknowns to go that route at this point in time.   

            I hate to sound like an RV-List whiner dealing with the Garmin issues and the James Cowl/Plenum cooling but these are real life challenges and I sure hate to have people see my beautiful front end and think it's all rainbows and unicorns. That being said I did display the -10 at SBP Airport Day last Saturday sitting across from a fleet of Cirrus and a bunch of other experimental & certified aircraft and we can be pretty proud of the decision we made to build these airplanes. Once you have a flying -10 there are some planes you no longer have the need to envy.  

   

Robin  

   

Note: Ram Oil Cooler inlet just below Pilots Side Inlet   

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Lenny Iszak

Joined: 23 Mar 2008
Posts: 270

Posted: Mon Sep 28, 2009 6:04 am Post subject: Re: James plenum question

Robin,



Thanks for you input. That's a brave idea to cut into the lower cowling and move the oil cooler. How did it work out? By the way, do you have some before and after numbers for oil temps?



I have the stock engine, so I hope I'm not going to have too high temps but everyone reassures me that I will so life is good, i'm assured to have a "hot" airplane 



Were your CHTs ok? Did closing off the oil cooler hole in the back help your CHTs at all?



Lenny

robin1(at)mrmoisture.com
Guest

Posted: Mon Sep 28, 2009 8:52 am Post subject: James plenum question

Lenny,

	I no longer have any specific numbers but here is a thumbnail of

our development.

	First we worked closely with Airflow Performance who loaned us a

Manometer to test differential pressure (DP) in many different areas on

our set up. We probably relocated and tested DP's in 20+ different

areas. It was immediately obvious that the DP over the oil cooler was

very poor. And in the case of the oil cooler wedge the DP was small and

not evenly distributed meaning that the upper portion of the cooler was

receiving most of the minimal airflow while the lower 1/3 had almost no

airflow so 1/3rd of the cooler was just along for the ride. In rough

numbers we were getting DP's of between 0.7 to 1.5 "W/C. We tried a

bunch of different configurations with the oil cooler temperately

supported in different areas. We also tested DP from the top of the

engine to the bottom and near the outlet area. The DP was just not that

significant in our set up to drive the air through the cylinders and out

the bottom of the cowl. If our thinking was correct and we were not

seeing a large DP over the cylinders than most likely much of the

cooling air was reversing out the inlet holes causing two issues,

minimal cooling and disturbed aerodynamic as the airflow is pouring out

the front of the cowl instead of down & out the underside.. Once we knew

that we first worked on opening up the bottom of the cowl by trimming

back & adding first one set of AFP louvers then a second set of louvers.

This helped substantially but still not enough to drive out CHTs' under

400. 

	After exhausting all other likely options we decided that the

CHT/EGT issue was one in the same and that we were not going to get the

CHT's lower till we got the oil temps inline. We seem to always have

CHT's two times Oil Temps (215/430, 212/425...).  We decided that

pulling hot air off the engine and running it through the largest oil

cooler AFP makes was not enough so we chose to seal up the back end of

the plenum providing more cooling air to the cylinders and cutting a RAM

air inlet for a high volume of cooler air direct to the oil cooler. The

DP results were immediate. We went from 0.7-1.2  "W/C (depending on the

phase of flight) to 7.0-9.0 "W/C. That is a HUGE change over the cooler.

This made the plane flyable and brought our oil temps to about 220-230

in climb and 210 in cruise. CHT's were now 410-420 in cruise. Please

keep in mind this was a brand new engine that tends to run hot for up to

150 hours. I am now at 85 hours and am seeing further settling down of

both CHT's & oil tempts. Again the oil temps are coming down slightly

because the CHT's are a bit lower. Unfortunately they are both still

higher than I would like and probably higher than optimal.

	So the major improvements came when we opened  up the bottom of

the cowl and when we plumbed RAM air to the oil cooler. Still none of

these numbers are great or even good in my opinion but I can now fly the

plane consistently with numbers that are not detrimental to the engine.

My plan is to get past 150 hours TT and see where the engine settles in

temp wise. Additionally I am working on optimizing for LOP which should

really help the temps all the way around.

	I have to say I am a bit surprised that most standard build

-10's still using the wedge and original oil cooler do not have greater

temp problems. I do live in CA with high OAT's but still our numbers are

still too high to be acceptable.

	The one option we did not try was to place a louver on the side

of the lower cowl and orient the back side of the oil cooler towards

that louver. Some have added these side louvers (one or both sides) with

some success (I believe). We did not want to ruin the appearance of the

nose area but in retrospect anything that improves functions is probably

better looking than Yellow or Red warning indications on your PFD.  

	To those that are to follow us down the path of alternate

cowl/plenum I can only say good luck. This mod has cost us significantly

more time & money to develop than we ever thought it could. Add the

potential costs of an engine not going to TBO and the stock Vans cowl is

looking better & better all the time. That Van is a smart guy. Finally

the hassle of having to remove the plenum every time you want to take a

look at something quadruples (or worse) the amount of time it takes to

remove the lid. I can take my top cowl off in 90 seconds. The plenum is

another story even with our simple attachment mechanism It's 5-7 minutes

off and 10 minutes on plus wear & tear.

	I have to say that so many of my original ideas in aviation were

wrong. I always thought I wanted retract aircraft till I owned several

of them. I then discovered the retracts can be a pain in the rear by

adding complexity, weight & maintenance costs, plus increase insurance

rates. I hope to never own a retract again (Pilatus excluded). Same goes

for the beauty of the round inlet cowls that have ZERO engineering

behind them. Don't fool yourself, these cowls are originally crafted for

looks. No one did 3D modeling, computer simulations, critical airflow

analysis, probably not even a slide rule or an abacus to generate this

design. Just another pretty face. And hot too! But the wrong type of hot

unfortunately. Throw in the pressure issues trying to run LOP vs. the

standard cowl and you may have more R&D than you were planning to

perform once you plane is past Phase 1.  



Again off to the airport for my regular commute.



Robin

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Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Mon Sep 28, 2009 12:06 pm Post subject: James plenum question

Here's a link to some pictures that might help.



http://deemsrv10.com/album/Sec%20FF6%20Exhaust%20System/index.html



However, it should be noted that I have since removed the heat muff on 

the left side, in a semi-successful attempt to clean-up the airflow in 

this area and to improve cooling.

(Cabin heat is NOT an issue for me currently)



Deems Davis

N519PJ



Lenny Iszak wrote:

 	  Quote: 	
		   



 Those of you who installed the James plenum (Deems, Robin?), how did you get air to the left side heat muff?



 Thanks,

 Lenny





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 65254#265254

Lenny Iszak

Joined: 23 Mar 2008
Posts: 270

Posted: Mon Sep 28, 2009 3:05 pm Post subject: Re: James plenum question

Thanks Deems! That's what I was looking for. Where did you get that Y splitter from?



Lenny

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Mon Sep 28, 2009 3:48 pm Post subject: James plenum question

I believe I got it from Aircraft Spruce. 

http://www.aircraftspruce.com/menus/ep/engineaccessories_connectors.html



Deems



Lenny Iszak wrote:

 	  Quote: 	
		   



 Thanks Deems! That's what I was looking for. Where did you get that Y splitter from?



 Lenny





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 65415#265415

Lenny Iszak

Joined: 23 Mar 2008
Posts: 270

Posted: Mon Sep 28, 2009 4:01 pm Post subject: Re: James plenum question

Duh... should have checked first. Thanks!



Lenny

 	  Deems Davis wrote: 	
		  I believe I got it from Aircraft Spruce. 

http://www.aircraftspruce.com/menus/ep/engineaccessories_connectors.html



Deems



Lenny Iszak wrote:

 	  Quote: 	
		   



 Thanks Deems! That's what I was looking for. Where did you get that Y splitter from?



 Lenny





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 65415#265415

rene(at)felker.com
Guest

Posted: Mon Sep 28, 2009 4:13 pm Post subject: James plenum question

Vans sells the y also.



Rene' Felker

RV-10 N423CF Flying

801-721-6080

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