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  #1  
Old 08-10-2018, 10:35 AM
F1R F1R is offline
 
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Default Post your Plenum Photos

I recently found a cracked injector line that I am very lucky did not torch me and the aircraft.

The aluminum plenum takes me a couple hours - or longer to remove. a real detriment to frequent inspections.

I am considering fabricating a new carbon fibre or fibreglass plenum that allows rapid removal / install with good sealing.

Any ideas and help is appreciated so please post a photo or two of your plenum.
If anybody knows who has "THE BRILLIANT DESIGN" please volunteer their name so we can save some time.

Thanks in advance!

Last edited by F1R : 08-10-2018 at 10:49 AM.
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  #2  
Old 08-10-2018, 08:45 PM
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Steve Melton Steve Melton is offline
 
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what about a couple of plenum inspection access covers? inspect with mirror or borescope.
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  #3  
Old 08-10-2018, 09:12 PM
F1R F1R is offline
 
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Well, I have a large inner door that mirrors the outer cowl oil door.

While bore scopes and or mirror would be better than nothing,the inspections would be tedious and you could not pull spark plugs.

I really like tool builders piano hinge version- as seen in the Rocket section.
I also like Kevin Eldrige's various plenums on his 540 and 720 installs on his NXT,


The above screen grab shows Kevins IO 720 plenum cut down to fit on a straight valve IO 540 for a recovery flight in 2013 after a thrown rod allowed him to demonstrate his excellent forced landing skills for a textbook perfect gear up soft field landing. The inlet transitions resemble my AL plenum.

Tool Builders corner joints with piano hinge and wires will likely be the fastest arrangement to remove and put back in place. Now if I can adopt the piano wires to my own top section....

I am sure there are lots of great ideas out there.

Last edited by F1R : 08-11-2018 at 10:35 AM.
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  #4  
Old 08-11-2018, 08:06 AM
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olyolson olyolson is offline
 
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Default Plenum

F1R,

I used to have a plenum on my IO-360 under a Sam James Cowl. Like you I always disliked doing the annual beacause it took forever to remove the bizillion screws on the plenum. And I’m not even sure it even helped cause I always seemed to have high oil temps. I got fed up one year and ditched the plenum and ordered a new baffle kit from Van’s.

So starting from scratch the baffles were installed, trimmed, removed and powdercoated. Reinstalled with the seal material that came with the kit. I made sure any air leaks were sealed took a lot of time to make sure there wasn’t any gaps. Since the baffle install there have been no more oil temp issues. CHTs are always 325-350 depending on OAT and the oil temp is usually 190-200 with a max of 210 on a really hot day during a climb.

And I don’t dread the annual anymore either- since there is no plenum the top plugs & the fuel spider are right on top with easy acess. Lots of discussion about why plenums work but in the cramped Sam James cowl it didn’t seem to be the hot setup. 80 trouble free hours since the baffling and no heat issues.
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  #5  
Old 08-11-2018, 08:17 AM
dwranda dwranda is offline
 
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Quote:
Originally Posted by olyolson View Post
F1R,

I used to have a plenum on my IO-360 under a Sam James Cowl. Like you I always disliked doing the annual beacause it took forever to remove the bizillion screws on the plenum. And Iím not even sure it even helped cause I always seemed to have high oil temps. I got fed up one year and ditched the plenum and ordered a new baffle kit from Vanís.

So starting from scratch the baffles were installed, trimmed, removed and powdercoated. Reinstalled with the seal material that came with the kit. I made sure any air leaks were sealed took a lot of time to make sure there wasnít any gaps. Since the baffle install there have been no more oil temp issues. CHTs are always 325-350 depending on OAT and the oil temp is usually 190-200 with a max of 210 on a really hot day during a climb.

And I donít dread the annual anymore either- since there is no plenum the top plugs & the fuel spider are right on top with easy acess. Lots of discussion about why plenums work but in the cramped Sam James cowl it didnít seem to be the hot setup. 80 trouble free hours since the baffling and no heat issues.
This is the first I have heard of using the regular baffle material with a sam james cowl. I have just ordered my cowl and baffling but didn't order a plenum because of the nightmares everyone has with the James plenums. Can you please post some pics of your install?
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  #6  
Old 08-11-2018, 09:01 AM
F1R F1R is offline
 
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Quote:
Originally Posted by olyolson View Post
F1R,

I used to have a plenum on my IO-360 under a Sam James Cowl. Like you I always disliked doing the annual beacause it took forever to remove the bizillion screws on the plenum. And I’m not even sure it even helped cause I always seemed to have high oil temps. I got fed up one year and ditched the plenum and ordered a new baffle kit from Van’s.

So starting from scratch the baffles were installed, trimmed, removed and powdercoated. Reinstalled with the seal material that came with the kit. I made sure any air leaks were sealed took a lot of time to make sure there wasn’t any gaps. Since the baffle install there have been no more oil temp issues. CHTs are always 325-350 depending on OAT and the oil temp is usually 190-200 with a max of 210 on a really hot day during a climb.

And I don’t dread the annual anymore either- since there is no plenum the top plugs & the fuel spider are right on top with easy acess. Lots of discussion about why plenums work but in the cramped Sam James cowl it didn’t seem to be the hot setup. 80 trouble free hours since the baffling and no heat issues.
In my case the plenum works very well cooling wise. Oil temps never go over 180 to 185. The inlet transitions and sealing at the cowl inlets was nicely done. But all those screws... I have considered the conventional setup as you describe. I look at all the sloped surface on the underside pushing upward from 250 kts, and then think about adding the cooling air pressure pushing upward on the top cowl and so I have kept the plenum. I know there have been many great photos posted over the years, but I am looking to collect some of the best ideas in one place. So far Michael Robinson's piano hinge arrangement looks like the most serviceable setup.

I will be following how he does the inlet transitions closely.

Here is a screen grab of Kevin Eldrige's inlet seals and transitions on a 720


But I appreciate that a good job of conventional baffle and seals to the top cowl does work well for a lot of aircraft and builders.

Last edited by F1R : 08-11-2018 at 10:31 AM.
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  #7  
Old 08-11-2018, 09:30 AM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by F1R View Post
...So far Michael Robinson's piano hinge arrangement looks like the most serviceable setup.

I will be following how he does the inlet transitions closely...
Great- now I'm on the spot!

I'd hoped to keep the plenum and some of the other radical cooling ideas secret until I'd actually flown them and could declare victory. The "transitions" seem low risk however. I have one coming out of the mold today so cant show the final integration, but in the meantime I can throw out a brief description. The cowl inlets are low Vi/Vo, so there is no real aerodynamic magic going on except a positive seal. To that end, the transitions are in essence large volume "plenum extensions" which bring the primary plenum volume forward to the cowl inlets. Since pressure recovery occurs external to the inlets, the ducts are not critical aerodynamically - they just cant restrict. Easy. Making them translate in the X,Y and Z axis and still seal is the trick. To that end, my plenum "front wall" is just that. It looks like the back wall we are all familiar with, but the extension ducts need to articulate and seal. My plan is to create a flange on the composite ducts which would easily bolt solidly to the front wall, but instead, the hole in the front wall will be oversized compared to the flange OD. The "filler" will be a membrane of silicone sheet - like a diaphragm. This membrane will be completely sealed and permanent, but will allow the rigid duct to articulate. The front of the duct will be trapped between the upper and lower cowl and sealed with rubber or an O-ring allowing some angular articulation there.

Hard to describe, but until I have pictures (and a success story), this will have to do.
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  #8  
Old 08-11-2018, 01:37 PM
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olyolson olyolson is offline
 
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Default Sam James Cowl & Standard baffles

Pictures requested by dwranda, below shots of the standard Vans baffle kit in a Sam James Cowl- no issues, normal temps all around.









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  #9  
Old 08-12-2018, 07:00 AM
KatanaPilot KatanaPilot is offline
 
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Default Bill Lane Plenum

BL plenum on an RV-7A IO-360 (Titan Lycoming clone).

Takes about 15 minutes to remove for inspection of the engine. Oil temps have not gone above 182 despite 95 degree Georgia heat. CHT's have been a little high on #3 and 4 (I've seen 410 on occasion during climb) - probably due to too much air supply to remote oil cooler, too small dam on #1 and lack of baffle mods to #3.

Down side is limited application of this plenum and availability.

Sorry, still don't know how to easily post pictures to VAF, hence the Dropbox link instead.

https://www.dropbox.com/sh/9n5i1bpvh..._bbHSSRxa?dl=0
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  #10  
Old 08-12-2018, 08:43 AM
dwranda dwranda is offline
 
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Great pics Oly thanks! Looks like you did a very nice job with the baffles. Am I to assume that the round inlets of the cowl just feed into the squarish(is that even a word?) inlets with no real seal between the 2?
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