Cabin Heat Air Supply

[majuro15]

Due to my air conditioning, I cannot have the stock cabin heat air supply on the left inlet area. I currently have the supply on the right side rear baffle split to the front and rear heat ducts, but it is not enough airflow to adequately heat the cabin.

I'm considering adding a NACA duct on the cowl and splitting the air to each heat muff then the heat ducts.

My concern is when not using the heat, the air coming in on the low pressure side of the baffles will have to exit the cowl just as the engine cooling airflow. Will this influx of air decrease the effectiveness of engine cooling air? Essentially, will it pressurize the low side of the cowl (enough) to cause issues?

I'd like a few opinions before I cut a big hole in my cowling. Thoughts?

Thanks!

[Electrogunner]

Can you run a 3" then split it into the 2 diverters? I would try something like that or find another location to pull from before I cut a NACA into the cowl with possible negative affects on something else.

[Dustyone]

Hi Tim,

The only way you will know for sure is with a dual digital manometer to measure the pressure differential between the top and bottom of the cowl .
(lots of cheap sensors that plug into a standard multi-meter are available on-line)

RV-10's have excessive cooling in standard configuration with lots of opportunity to reduce cooling drag left on the table I can only imagine that where you live you would not need the cooling reserve like we do in Australia.
(The coldest I have flown in is -10 Celsius ) so your Naca duct would have an effect, but maybe only minimal.

The only way you will know is with data.

[Electrogunner]

I meant to say 3 in off of the baffles then split it to the two heat muffs not the diverters.

[Zuldarin]

Just a thought but do you have enough room on the air outlet of your oil cooler to install a duct to pull air from? No new holes in the baffle required for this scenario and since its air already in the lower cowl you don't change the cooling dynamics.

[midwest rv-10]

Tim,
I have A/C from Bill Genevero @ Flightline and didn't have to modify the heat air supply, I just wrapped the supply hose in ceramic blanket and SS foil to keep heat off of it as it runs close to the exhaust. I have 1,200 hrs and still the original hose and my AC still works great btw. Not sure which AC vendor you are using but just sharing my experience.

[majuro15]

I just don’t have any room between the compressor and the first cylinder for the scat flange.

I’m considering adding a second flange near the other one above #6. Another builder has and likes the results. Avoids putting a naca duct in.

[lr172]

I put both inlet flanges next to one another on the rear baffling behind #5. Scat run was about the same as for the plans location. Works fine. I definately wouldn't put a naca duct in. If that spot is good for one heat muff, why not the other?

Larry

[majuro15]

Copy, I think I'll do that. Les did that too and seems to be better than a naca duct.

Thanks!