Cooling System

[Area 51%]

I know that I need to move more air through my cowling BUT wish to keep the openings to the minimum required. In my mind this means locating them in a relativly low pressure zone, hence my interest in your reasoning for placing the louvers on the underside of the cowling.

My only reasoning behind the location was the recommendation on the instruction sheet. I totally get your point of looking for a low pressure area to enhance the flow, but compared to the stagnation point of the front of the cowl, everything is a low pressure area. Some are just better than others.

I have a whole wastebasket full of updraft cooling ideas. Given the "lifting body" design of the fuselage, it would seem the logical choice. But.......... I run an Aerovee, and the added weight of a windshield wiper to keep the oil out of my line-of-sight is prohibitive.

[Skippydiesel]

Without a wind tunnel/smoke machine/video equipment - Locating/sizing air vents seem to be a black art. I was hoping that someone with a similar problem, (Ebay temps to high) that they have solved, may respond, removing the need for me to disembowel a chicken or ten.

[Murray Parr]

Very pleased with the ground testing so far!

I have only been able to test at 25 Celsius (77 F) but I ran the engine for 30 minutes while parked into the wind and did some full power run ups. Highest engine coolant temp it got to was 75 Celsius (167 F) and oil temp of 68 Celsius (154 F)

At full power, the ducting nozzle flap closed under the pressure of the prop blast. I did the last 10 minutes of testing with this flap fully closed and still got no increase in temps.

IMG_7025.jpg (216.4 KiB) Viewed 332 times

IMG_7027.jpg (195.6 KiB) Viewed 332 times

The image below shows the fully closed position which still cools just the same as fully opened. Maybe I can find a way of closing it further.

IMG_7035.jpg (61.24 KiB) Viewed 332 times

As you can see, it is already a fairly thin profile and I was worried the inlet might be too small, however, I think I could have gone much smaller and benefit from even more reduced cooling drag. I should be able to test at 30 Celsius (86 F) tomorrow or 33 on Wednesday (91 F) to hopefully confirm this. If it is marginal at those temps, I could have an option next Saturday of 35 Celsius (95 F )

[Skippydiesel]

Dont forget your undercowl EBay temperatures.
My oil/coolant is sitting just where I want it, however my EBay is far too hot - got to over 40C with OAT 22C @ 2500ft, two days ago and regularly hit 60 C immediately after engine shut down - can't be god for electronics & fuel vaporisation/vapour block.
Have increased the size of my exit air and am in the process of refitting a cowl flap.

[Murray Parr]

Dont forget your undercowl EBay temperatures.
My oil/coolant is sitting just where I want it, however my EBay is far too hot - got to over 40C with OAT 22C @ 2500ft, two days ago and regularly hit 60 C immediately after engine shut down - can't be god for electronics & fuel vaporisation/vapour block.
Have increased the size of my exit air and am in the process of refitting a cowl flap.

This cooling duct is a straight through system and isn't connected in any way to under cowl airflow. This will likely improve the under-cowl temps as the wasted heat from oil and coolant radiators will be ejected outside the cowl, not like previously. Most of the under-cowl heat with this new configuration will be coming from the engine mass and the cylinder cooling fins, I will need to measure the cylinder temps as per Rotax guidance and play with the cowl inlets from there (Yes, I have studied the Robyn Austin Sonerai with interest and would be stoked if I could have an aircraft half as slick as he built).

The 2 small outlets where the exhaust comes through will be assisted by the exhaust ejector nozzles and I will be making the nose inlets smaller, I am really focusing on reducing cooling drag and will sometime in the future provide cold ram air to the carbs, my electrics under cowl have temperature monitoring strips and so far haven't exceeded 60 Celsius which is most likely the after shutdown temps (I don't always remember to open my oil door to release after shutdown heat), the limit is 80 so I will continue to monitor temps and see what the max eventually gets to.

Skippy, I think you have done well to get yours down to 40 Celsius

[Kai]

Guys- you may be familiar with this installation?

When for the first time you put your hand on the cowling top of a recently run MCR 01 Ban Bi made by Dyn Aero in France, you will immediately pull it back because you reason something must be on fire in there: it is piping hot! Take off the top and you are presented with the view shown below: the muffler is sitting on top of the engine, just above the spot where the ignition modules should be. Should you have a feverish wish to permanently cook your engine electronics, this must surely be the way to go.

However, to keep the engine happy, the manufacturer has put in some remarkable development work: the engine must be supplied with cool ambient air (NOT from the cooking engine room!), which is drawn from outside the cowling through the white squarish inlet box shown on top in the picture. The ignition modules have been removed from their original position, supplied with extension wiring, and are now sitting low down on the firewall where of course it is much cooler. Finally, every (!) fuel line in the engine room has been fire sleeved.

The free space under the engine created by relocating the exhaust system is now occupied by coolant- and oil cooler, which by the way are installed in series.

It works- hundreds of these planes have been flying all over the place for years.

[Skippydiesel]

Hi Kai,
I have seen photos of the Ban Bi engine installation before and marveled at the different approach to exhaust management.

The tuned header pipes are a fantastic - I wonder what hp improvements they claim?

I can't see how they have allowed for engine movement and expansion contraction of the exhaust system.

Nor can I see any fuel lines , other than the IN/Out from the engine driven pump. - they must be coming from under the engine to the carburettors.

[Murray Parr]

Guys- you may be familiar with this installation?

When for the first time you put your hand on the cowling top of a recently run MCR 01 Ban Bi made by Dyn Aero in France, you will immediately pull it back because you reason something must be on fire in there: it is piping hot! Take off the top and you are presented with the view shown below: the muffler is sitting on top of the engine, just above the spot where the ignition modules should be. Should you have a feverish wish to permanently cook your engine electronics, this must surely be the way to go.

However, to keep the engine happy, the manufacturer has put in some remarkable development work: the engine must be supplied with cool ambient air (NOT from the cooking engine room!), which is drawn from outside the cowling through the white squarish inlet box shown on top in the picture. The ignition modules have been removed from their original position, supplied with extension wiring, and are now sitting low down on the firewall where of course it is much cooler. Finally, every (!) fuel line in the engine room has been fire sleeved.

The free space under the engine created by relocating the exhaust system is now occupied by coolant- and oil cooler, which by the way are installed in series.

It works- hundreds of these planes have been flying all over the place for years.

Yeh nah, I won't be doing any of that lol. Looks way too heavy/bulky and if you managed to get to that point in a tight cowl Sonex, where do you route the tail pipe! In all seriousness, I admire the different approach