Cutting hole in bottom skin for AC heat exhaust

[bjohnson1234]

I have a small battery powered electric AC unit (zero breeze) and I currently have the inlet and outlet for cooling the condenser (cool cabin air has a separate inlet/outlet) vented through the baggage bulkhead, but I think due negative pressure in the tail it still heats up and cooling capacity drops, sometimes even causing the AC to shutdown temporarily. I’m considering cutting a hole and adding a 2.5” flange on the bottom of the tail section to vent hot air directly out of the plane. It’s fan driven so I don’t think there should be any issues with moving the hot air out so I think the main concerns are any structural integrity issues or exhaust getting drawn in when the unit is not running. For the latter it seems like there are already a lot of potential entry points back there already and I’m also considering some kind of reverse scoop over the hole to help draw the air out and prevent anything from getting drawn in. The ac outlet will be connected directly to the flags with a hose. I’m still waiting for a response from Vans and thought I’d check here as well to see if anyone had any thoughts or concerns about it

 

[bjohnson1234]

I know there are also potential concerns with holes in the baggage bulkhead that have been addressed in other threads. I kept them to a minimum and reinforced around them with angle. I bought another bulkhead from vans to make a piece to cover the openings during the winter when I don’t need the AC and also cut a piece as a doubler plate around the holes.

 

[bjohnson1234]

This is in an rv6 and using flange from acs https://www.aircraftspruce.com/catalog/pnpages/10350-10.php

 

[brad walton]

In my RV8, air flows from the tail to the cockpit. It seems intuitively that it would flow out the rear of the aircraft, but that is not the case.

 

[Bdflies]

Zero Breeze

I have a small battery powered electric AC unit (zero breeze) and I currently have the inlet and outlet for cooling the condenser (cool cabin air has a separate inlet/outlet) vented through the baggage bulkhead, but I think due negative pressure in the tail it still heats up and cooling capacity drops, sometimes even causing the AC to shutdown temporarily. I’m considering cutting a hole and adding a 2.5” flange on the bottom of the tail section to vent hot air directly out of the plane. It’s fan driven so I don’t think there should be any issues with moving the hot air out so I think the main concerns are any structural integrity issues or exhaust getting drawn in when the unit is not running. For the latter it seems like there are already a lot of potential entry points back there already and I’m also considering some kind of reverse scoop over the hole to help draw the air out and prevent anything from getting drawn in. The ac outlet will be connected directly to the flags with a hose. I’m still waiting for a response from Vans and thought I’d check here as well to see if anyone had any thoughts or concerns about it

I’ve considered trying a Zero Breeze myself, but held out for someone to report their experiences. Hey, I’m cheap…
Please let us know how you solve the condenser airflow issue and let us know what you think about the A/C unit!

 

[bjohnson1234]

I’ve considered trying a Zero Breeze myself, but held out for someone to report their experiences. Hey, I’m cheap…
Please let us know how you solve the condenser airflow issue and let us know what you think about the A/C unit!

I’m using it in some pretty extreme conditions in the AZ summer. It was actually working quite nicely until it started getting over 100.

 

[cxb003]

Does anybody have photos of their installation layout. I have an RV-9 and I'm thinking I could set the unit in the back baggage area, and simply cut two holes in the back bulkhead aluminum panel (the corrugated metal panel), which would pull/push the air into the empennage/tail area. The only thing I would then need to address is some way to store/collect any condensation the unit may produce.

 

[bjdecker]

Does anybody have photos of their installation layout. I have an RV-9 and I'm thinking I could set the unit in the back baggage area, and simply cut two holes in the back bulkhead aluminum panel (the corrugated metal panel), which would pull/push the air into the empennage/tail area. The only thing I would then need to address is some way to store/collect any condensation the unit may produce.

For the condensation drain, do something similar to Van's fuel vent in the -7/9 (attached). Just need to point the opening aft.