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Oil temperatures too LOW


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Hi Cozyflyers and builders,


I've a COZY with the good old Lycoming O-235-C2A...


I seem to have absolutely no problem with OIL TEMPS, in the colder climates my engine in running a bit on the "cold" side, cruising at FL100 (10000ft PA for you US guys..., my Oil temps stabilize around 150 to 155°F. That is with an OAT of about 0°C or 32°F. I would rather see them in the neighbourhood of 170 to 180°F.


My Cozy has a NACA Oil cooler scoop installed on the right side which is connected to a 2 1/4 inch SCAT duct.


I'm wondering if anybody ever had the same problem and if it would be possible to install kind of a valve in the SCAT duct to reduce the cooling airflow over the Oil cooler. I'm thinking of a valve which maybe can be manually adjusted for cold and hot weather operations...


If this is a good solution...., which valve would you use? Looked in the Aircraft Spruce Cat. and couldn't find any...



Hope this is clear enough, anyway I include a couple of pictures to make it more clear if needed.



Thanks for your usual help,


Enjoy the summer flying and/or building....






Flying was my first love and it will be my last one!

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Very interesting, BJORN.


Less power = less heat, so an O-235 would be expected to run cooler than the 0-360 that most are using. Those scoops look good, and fairly easy to do. I'm thinking that I might need something similar, so I'm interested to hear that it works well. What sort of cruise speeds do you get?


As for closing the scoops, it might be easier to close off the exit from the oil cooler. If you close the exit, the air will "bounce off" the input.

I can be reached on the "other" forum http://canardaviationforum.dmt.net

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Hi John,


Yes the OIL cooling seems to work too good actually... With the European summer now, it's fine, but in a couple of months it will run again on the cold side.


The scoop was made by the builder (not myself) before the aircraft first flew, so hard to compare Performance with or without.


At 8000ft wide open throttle (2800RPM) I get a TAS of 150KTS or 173MPH.


At 12000ft wide open throttle (RPM 2680) I get 146KTS or 168MPH.


I guess I loose quite a bit of cruise performance with the VG's installed on the GU Canard. I think it's reducing top speed with about 10MPH. But on the other hand it lowers the approach speed by about 10MPH as well. My approach speed (average weight) is 70KTS, to touchdown around 62KTS or so.



John, how would you close of the exit of the Oil cooler...? My installing some ALU behind it or so...?

Wouldn't it be easier to put kind of a air-blocking valve in the SCAT tube?


Just wondering if somebody on this forum has ever done a similar job...



All comment more than welcome....






Flying was my first love and it will be my last one!

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Thanks for the speed info, Björn

Yes. A butterfly valve in the inlet would probably be the easiest. The adjustable NACA floor would be better for drag. I did this with my cockpit cooling NACAs, but it looks as though your NACAs are on a curved surface that wouldnt close off easily.

I can be reached on the "other" forum http://canardaviationforum.dmt.net

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Yes mplafleur..., that's what I was thinking as well.


Any idea where to look for a butterfly valve that would fit...?

Can't find it with Spruce...




Would you place it in the SCAT tube or before that by blocking the inlet itself...?



Thanks for your comment,






Flying was my first love and it will be my last one!

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I'd go to an auto salvage yard and get one off a carb.


Well, there are probably pros and cons to each. One of course is ease of installation and routing of the cable. Would placing one in the entry be a candidate for icing or corrosion? Putting one at the exit will be in a warmer and possbly more frendly environment and easier to install.

Mike LaFLeur - Cozy MkIV #1155

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if you don't take all of the air the naca scoop pulls in you will create a preasure wave at the scoop. I think making an adjustable scoop floor would be quite easy, especially if you don't make it adjustable from the pilot seat.


Just cover the bottom and sides of the scoop with plastic tape and wax it. Lay up 5 layers of bid and you have a perfect floor.


Hinge it at the front and figure out how to change the floor position, maybe just a simple wedge under it that slides to put the floor at diferent positions.


A winter and a summer position might work.


Enjoy the build

maker wood dust and shavings - foam and fiberglass dust and one day a cozy will pop out, enjoying the build


i can be reached at



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You might want to talk with Vance Atkinson and hear from him all the pros and cons with installing a variable NACA scoop. He has a variable door on his scoop. It required a much stronger actuator than one might think. His was not a trivial solution. His experiences and his plans are well-documented in the Central States Newsletters. Contact Terry Schubert to join and to obtain the back issues.




Wayne Hicks

Wayne Hicks

Cozy IV Plans #678


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Thansk Wayne and Dust for your advice.


I'm subscribed to the CSA newsletters. Have them since JAN99, issue 53.

Any idea in what newsletter Vance his set up was explained? I searched but can't find it....




Thanks guys,



:) Björn

Flying was my first love and it will be my last one!

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  • 4 weeks later...

After consulting some Northern European canardiens, I will initially just try to remove the SCAT duct going to the Oil Cooler and leave the Naca scoop open...


This should make the air go more around it, without cooling too much.


Will do it somewhere next OCT, when the temps come down.


Keep you informed,









Flying was my first love and it will be my last one!

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