What Is This?

[radfordc]

Ooh...great minds think alike!

[Sonerai13]

Joe, I think there is something else to be said for the top mounted cooler. Without the air flow into the bottom of the cowl you should get better engine cooling due to higher pressure differential. Did you notice anything like this?

I think I commented on this in another thread, but I'll mention it here too. The two airplanes I use most for the T-Flight program are the Waiex and the original prototype tri-gear Sonex, which is also the original Sport Trainer. When we put the new cowl (and the top-mount cooler) on the Waiex we installed a new cowling. It does not have the little "mouth" below the prop. the Sport Trainer was converted from the bottom-mount oil cooler to top-mount without changing the cowl, so it has the little "mouth" that used to feed the oil cooler. It also has the pan baffle that the old oil cooler used to mount to, which now simply ducts air along the bottom of the oil sump and then out the bottom.

I have found that the Sport Trainer (with the mouth and pan baffle) runs about 5 degrees cooler on oil temp as compared to the Waiex, which I attribute to the extra air moving along the bottom of the oil sump. CHT runs pretty close to the same on both airplanes, with the Sport Trainer generally running just slightly higher. But the two planes do not have identical instruments in them, and of course don't necessarily have identical AeroInjector settings either, so I am not surprised by some variation in CHT.

Certainly not a scientific comparison, but you might find it interesting.

Cheers!

[gammaxy]

Joe,

I have a top mounted cooler and have been working on the cowl. I believe the plans still say to cut the "mouth" in the cowl even if you have the top cooler, but had been considering leaving it off. Without the mouth, does it still use the fiberglass flap and southco fastener to securely fasten below the prop hub? Do you just have a small notch for the piano hinge where the "mouth" would normally be?

Hoping to make it up to Wisconsin when it starts warming up for some transition training.

[MichaelFarley56]

I have a top mounted cooler and have been working on the cowl. I believe the plans still say to cut the "mouth" in the cowl even if you have the top cooler, but had been considering leaving it off. Without the mouth, does it still use the fiberglass flap and southco fastener to securely fasten below the prop hub? Do you just have a small notch for the piano hinge where the "mouth" would normally be?

I'll let Joe answer this for a final answer, but personally, I'd say that you can either keep the fiberglass flap and southco, or another option would be to extend the piano hinge all the way to the top of the cowling halves but underneath the prop area. (right underneath where the fiberglass tab would be). If it were me, I'd run the piano hinge up to the top of where the fiberglass tab would go, then determine a way to insert the hinge pin from the bottom up (you'll need to determine a way to secure the pin at the bottom). This would give you a clean look with no hinge pin visible.

I'll jump in here as well on the discussion...

Last summer I rebuilt my engine and converted my oil cooler from the bottom style to the Onex style, top mounted cooler. For all the reasons Joe talked about already, I much prefer the top mounted style setup. My plan was to fiberglass the bottom opening hole closed, but as a test I taped the opening over and flew the airplane a little bit. I think it's an unfair measurement but I found my oil temps rose a considerable amount; on the same conditions, I would see a jump from 170 up to just under 200 degrees. I have no doubt that cold air blowing on the bottom of the oil temperature sensor probably lowered my indicated temperature more than what it really was, but I finally just decided to leave the cooler opening hole in the cowling and not worry about it. I didn't really notice any change in my CHT temps between that opening being taped over or not.

Have fun!

[Sonerai13]

I have a top mounted cooler and have been working on the cowl. I believe the plans still say to cut the "mouth" in the cowl even if you have the top cooler, but had been considering leaving it off. Without the mouth, does it still use the fiberglass flap and southco fastener to securely fasten below the prop hub? Do you just have a small notch for the piano hinge where the "mouth" would normally be?

Chris,

On our Waiex we still have the fastener below the prop, above where the piano hinge starts. We inserted our pin for the piano hinge from the top, so there's just a little slot where the pin goes in. Of course you are the manufacturer of your individual airplane so you can do it any way you want. If I were doing one for myself I might consider bringing the hinge pin up from the bottom to eliminate the little slot in the front of the cowl. Not sure if I would eliminate the fastener below the prop or not. I'd have to see how it works without it, and how easy it is to get that long a hinge pin in and out. I know the cowl on ours is super easy to get on and off, so I can't complain about the setup we have.

Hoping to make it up to Wisconsin when it starts warming up for some transition training.

I look forward to flying with you. Hopefully the weather will warm up sometime so that we can get some flying done!!

Cheers!