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Cowling Door installed

N363RV

Well Known Member
I bought the cowling door from the antisplat folks and installed it a few weeks ago (Back in august). It was pretty easy to install. I had it painted by GloCustom over at 52F.

I had some occasional hot oil that annoyed me. Always a summer time problem and mostly experienced up on the front range of colorado or other high altitude airports (field elevations > 6000 Ft with density altitude > 9000 ft)... when I would take off at greater than 90F full full, passenger and bags.

At lower altitudes(texas, ok, missouri) we would see high oil temps too but it took longer to get hot. So during the climb we would have to stop at an intermediate altitude and cool off.

I have performed several tests since I installed the door and it I am now able to make it all the way up to 13k without stopping. Whats even better is that when we level off, it only takes a few minutes(less than 10) to cool down from 210 to 190F or lower (oil). It has improved our hot oil situation and we are happy with the results. I'm sure these numbers will be different for you. Take em with a grain of salt and good luck.


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Thanks Steve

Cool beans. I can't see the photos but I believe you. Your engine will thank you.

I had some trouble with the pictures. I think I got it them working. Maybe somebody else can let me know. I can see them on a different computer than the one I did the post...so I think they are visible now.
 
CHTs

Did the door change the CHTs?

Gill...In the climb, the CHTs are more manageable too. In the past the CHTs would rise quickly as well, particuarly up in colorado on a hot day. When I tested the other day, my hottest CHT was 410 when I leveled off at 13K.

I feel much better about making a continuous climb to altitude now. :)
 
2

Thanks for the report.
Nice pictures too.
Any thoughts on installing two, one on each side?
If one is good, two might be better?
 
Probably not.

Thanks for the report.
Nice pictures too.
Any thoughts on installing two, one on each side?
If one is good, two might be better?

Hi Bob! Probably not. I'm having good enough results that I don't feel I need it. In addition to that I'm not convinced you get more airflow with 2 holes as opposed to 1. Dan Horton has covered the issue of airflow thru the cowling in some other post. You might search on "shrinking exit" or something like that.


I think that there are diminishing returns for 2 cowling doors as opposed to one with a standard vans inlet size... and even less for a sam james.
As I understand it, if you want more flow you gotta have big holes on both ends. I'm sure somebody will raise their hand and tell you all about. :)
I think these guys with io540s could probably use more flow...sometimes. I just have a plain vanilla O360. A stock vans cowling.

Brantel went with 2 of them. I think he likes 2 but i don't know if he tried it with one or not. I really like the product, but it is a little expensive for me to sling out the bucks for 2 right out of the shoot. Now that I have tried it I am satisfied.

What really sealed it for me was the last test I did. My wife and I took off with a bunch of water in the cargo hold to simulate our bags on a normal trip. It was 96F around 3pm. We flew for about 20 minutes and landed. Filled up on Fuel. So with full Fuel, the two of us, and our simulated bags we took off. We were heat soaked as you would expect. Field elevation is about 700'. We climbed out between 500 and 800 feet per minute up to 10,500. I didn't take any pictures on this flight... but IIRC, the oil was about 205 and highs CHT was 410. The good news is that after we leveled off it cooled right off. Then I shut the door. Funny as the oil temp dropped a little more after I shut the door.

Hopefully this link works... it is an album of pictures I took. There aren't very many and it certainly is not scientific. It was mostly meant for me to look at so I would not lie to myself about the results. I was alone in all the photos you see in this album, but I usually conducted continuous climbs of between 800 1100 feet per minute. Enjoy. Let me know if the link doesn't work.

When you clickon the pictures, there is a little info button on the right side. Click this then go thru the pictures and you can sorta see the time line as I took them.

https://photos.google.com/share/AF1...?key=ZHV2ZHlfbkVCUExwRm5wZlpKMlpaakFjWkNvdlFB
 
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Great

John,
Thanks for the informative post!!
The link to pictures worked great, very nice.
I am a student of "Dans"...shrinking exit thoughts as well as many other fiberglass lessons.
Thanks for the reminder of Brantel's dual set-up.
Can I assume you chose the left side location because it was directly under the oil cooler?
 
I think that there are diminishing returns for 2 cowling doors as opposed to one with a standard vans inlet size... and even less for a sam james.
As I understand it, if you want more flow you gotta have big holes on both ends. I'm sure somebody will raise their hand and tell you all about. :)

Yeah, just might...

Forget about the size of the holes for a moment. Think about pressure instead. Mass flow through the fins is driven by differential pressure. To get more mass flow, you either raise the pressure in the upper cowl, or reduce the pressure in the lower cowl.

Here are measured static pressures from two different airplanes:



Airplane Blue and Airplane Red exhibit approximately the same differential pressure, so assuming they are equipped with the same baffle wraps and oil cooler, they will have the same mass flow, i.e. equal cooling. Either can increase deltaP (and thus mass flow and thus cooling) by further reducing lower cowl pressure. Neither is currently at zero, so adding more exit area would do it. Obviously Blue can effect a greater change.

So two points.

One, an aircraft with better pressure recovery can vary mass flow a lot with variable exit area, while poor pressure recovery limits the effectiveness of additional exit area.

Two, all that's necessary to determine if an additional cowl door would be beneficial is a simple pressure measurement. One leg of a manometer connects to a piccolo tube in the lower cowl, and the other connects to airframe static. If that deltaP is already quite low with one door open, a second door won't have much effect. If there is pressure remaining, a second door will increase mass flow.
 
Yes

John,
Thanks for the informative post!!
The link to pictures worked great, very nice.
I am a student of "Dans"...shrinking exit thoughts as well as many other fiberglass lessons.
Thanks for the reminder of Brantel's dual set-up.
Can I assume you chose the left side location because it was directly under the oil cooler?

Yes. I put it on that side because my oil cooler is on the back of the baffling on that side.
 
I had similar results after installing one on my 9A, definitely helps the oil temps on hard climbs, especially when it's warm outside.
 
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