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-   -   Oil filler door/Cowl Flap (http://www.vansairforce.com/community/showthread.php?t=171987)

crabandy 05-30-2019 09:28 PM

Oil filler door/Cowl Flap
 
I've been contemplating using the existing oil filler door in my upper cowling as a cowl flap. The hole is already there and my main goal is cooling on the ground with very little pressure differential between the upper and lower cowling. Extra cooling on climb out is another benefit.

Previous issues described in this post:
http://www.vansairforce.com/communit...=161338&page=6

I've spent a little time mocking up templates with cardboard but have narrowed things down a bit and time to "start making scrap." I rolled some scrap .063 since it's faster to make than glass.



It fits the cowling contour pretty good with a little extra manipulation.





I'm down to 2 possible door styles. #1 is a one piece slider door that works like a sliding glass door sliding down using a track and linear actuator. It has to slide down because not enough room forward or aft. The bottom of the door must also slide in toward the centerline of the cowling because of the increased curve of the cowling.







#2 idea is a 2 piece door design hinged on the upper and lower portions, excuse my errrr uh I mean my 3 year old boys drawings.



#1 issues making a curved track inside of the existing upper cowling radius and required linkage that can also make the door flush with the upper cowling.

#2 is much easier to make flush with the upper cowling, but what kind of linkage to use to make it work. Or do I use 2 linear actuators.

I'ld appreciate any thoughts to move me along!

Walt 05-31-2019 08:35 AM

The simple chore of checking the oil could prove to be a bit of a problem?

crabandy 05-31-2019 09:27 AM

Quote:

Originally Posted by Walt (Post 1349941)
The simple chore of checking the oil could prove to be a bit of a problem?

Walt,
Cowl flap/oil door open on pre-landing checklist as I’m going for ground cooling so it would be normally open on the ground. I would have to have external screw/screws on the door to gain access in case of electrical/linkage or servo failure.
It is making the simple door more complicated, but it’s been a while since I’ve tinkered on the airplane. I need more cooling on the ground, 90* and a quick turn starts cooking my EarthX battery as noted by the over temp alarm. I was surprised how the lower cowling temps started increasing below 120 knots even though CHT’s and oil temp drop significantly. Preliminary testing without the oil door shows temps drop slightly throughout landing phase.

Paddy 05-31-2019 09:48 AM

Cooling
 
Andy, wouldn't an opening in the top cowl just let cooling air out without passing over the cooling fins of the engine? It would seem that this might make things worse from a cooling perspective. What am i missing here?

rv8ch 05-31-2019 12:06 PM

low pressure zone
 
Quote:

Originally Posted by Paddy (Post 1349963)
Andy, wouldn't an opening in the top cowl just let cooling air out without passing over the cooling fins of the engine? It would seem that this might make things worse from a cooling perspective. What am i missing here?

Depending on the engine, the oil door is on the low pressure side of the engine cooling, so all the air that would exit should have already been pushed through the engine cooling fins.

rocketman1988 05-31-2019 12:16 PM

Umm...
 
The air on the upper side of the cylinders is typically high pressure, moving down through the fins to the low pressure side and out of the cowling exit...

Typically, the dipstick/fill tube is on the top side of the engine, in an area of high pressure...

Bicyclops 05-31-2019 12:43 PM

Quote:

Originally Posted by rocketman1988 (Post 1350000)
The air on the upper side of the cylinders is typically high pressure, moving down through the fins to the low pressure side and out of the cowling exit...

Typically, the dipstick/fill tube is on the top side of the engine, in an area of high pressure...

On a four cylinder engine, the dipstick is behind the baffle. The six has the dipstick tube in the upper plenum area ahead of the baffle. Rocketman has a 10 and is used to seeing it in that position.

Ed Holyoke

crabandy 05-31-2019 03:43 PM

Quote:

Originally Posted by Paddy (Post 1349963)
Andy, wouldn't an opening in the top cowl just let cooling air out without passing over the cooling fins of the engine? It would seem that this might make things worse from a cooling perspective. What am i missing here?

Paddy, on your 6 cylinder you are correct. On the 4 cylinders the oil dipstick is behind the baffles and part of the lower cowling volume.
Oops sorry it was already covered previously

BobTurner 05-31-2019 04:15 PM

I think this idea has some merit for increasing the battery cooling, via convection, when on the ground. I'm not so sure about in-flight. If the area above the new opening has a higher pressure than the exit area from the cowl (between the exhausts), then you will get some cool air over the battery - but at the expense of higher pressure at the exit, which may mean reduced cylinder cooling/higher CHTs. OTOH if the new opening area has a lower pressure than the normal exit area, then you will get additional flow up and out, helping cylinder cooling - but at the cost of running warm air over the battery. I don't know how to find out without actually testing in flight.

rocketman1988 05-31-2019 10:08 PM

Ah...
 
Thanks for the clarification. Yes, I am used to looking at the -10ís six cylinder...


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