Poor Man A/C Idea

I live is South Texas where summers can be VERY hot. Thought long and hard about adding A/C, but just didn't want to be saddled with the weight penalty or add another system to maintain.

So, I'm trying something out and thought I'd share the idea in case others are faced with same decision point in their build (A/C vs. No A/C).

The plan is to use an "ice chest cooler" but plumb the air to come through the overhead vents via the Aerosport cabin tunnel. This way, I can have chilled air when needed on very hot days, but don't lose the useful loads for times with it's not needed, or when I need more weight capacity. Here's a link to my cooler choice. It uses a cooling coil, circulating water and fan for chilled air. Was highly rated by Aviation Consumer. https://www.b-kool.net/

Here's the steps for doing so:

1. Only plumb for one rear fresh air NACA vent. I put mine on the left side. My Mooney only has one NACA vent for overhead fresh air, and it's PLENTY.

2. Create a 2" passthrough hole in rear bulkhead to plumb chilled air from cooler (in baggage compartment) to Aerosport air vent controller.

3. Re-clock Aerosport air vent controller so that when one valve is open (fresh air) the other is closed (chilled air). When I want chilled air, controller will be turned for chilled air and the cooler fan will feed the overhead vents. When I want fresh air, turn valves other way. If I want no air, simply turn the controller for chilled air, but don't hook anything up. At this point, no air flow because no fan is on.

Here are pics of "work in progress" for others who may want more detail...

Here's pic showing fresh air NACA, rear bulk-head passthrough location and controller.



Here's pic of controller with valves "re-clocked" so when one is open, the other is closed.



Here's image of passthrough location in rear bulkhead. Wanted it to be in spot to easily connect chilled air hose, but out of way of other luggage. So, chose spot just inside baggage door towards top of opening. I plan to make a fiberglass "cap" to cover hole when not in use.


Won't know how well this will work till flying, which as you can see, is a long way off. But, it's seems like it can take some of the heat factor out and make taxi and run-up at least bearable.

I like your idea, and I am also deciding against A/C because of the weight and added complexity on my first build. Although I want it bad, I just can't justify the cost.

Are you concerned about condensation/moisture buildup inside the overhead console?

I scratched my head long and hard (and filled several napkins with sketches) about how to do this, complete with re-clocking the AeroSport valve. Couldn't figure a way to make it work. Looks like you may have cracked the code

I think part of my mental block was my insistence on two NACA vents in the back. Whatever, I couldn't make it work on paper in a way I was happy with.

Currently I have the valve wired as originally intended, and plan to make my air conditioner injection hole in the rear portion of the overhead itself (inside the cabin, though), rather than in the baggage bulkhead as you have so cleverly done. Unit will blow chilled air into the overhead while the AeroSport servo valve blocks off outside air. This technique has even more need for a hole cover when not in use than your scheme does. I may go back and plumb it your way. All it would take is hours of lying on my back in the tailcone now that the rear skin is on

iwannarv said:

Are you concerned about condensation/moisture buildup inside the overhead console?

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Good question. I assumed that what can create condensation/moisture will be the temp differential of the cold air in the tunnel against hotter ambient air on outside of tunnel. I see that risk being no greater than a true A/C system (both create a temperature differential). Since the chilled air from the cooler is not blowing directly over ice, but rather over a cooling coil circulating chilled water, my thought was that it won't be pumping much moisture directly into the tunnel.

But, as I said, not flying yet. If I find condensation to be a problem, I'll simply plug the hole in bulkhead and fly as any other plane without chilled air would fly.

I had/have the EXACT same idea, except I'm intending to use my Icy Breeze unit instead of what you show. The only hang up I've having now is: I really don't want the weight/cost of the overhead console either. What I've heard is that the RV-10 offers plenty of air from its intakes, but that people don't like how the front ones are directed at your crotch. If there's a way to relocate the front eyeballs a bit higher in the panel, that takes care of that problem. As far as the ice cooler AC thing goes, it's been my experience that it's mostly for use on the ground. Well my Icy Breeze pumps out the air quite well, when it's on high. It also has the ability to direct that air, somewhat, to a desired location using it's vents and an optional vent extension I bought. My thinking is "do I really need the overhead console?" For now at least, I'm thinking no, but this depends on the day..

ppilotmike said:

My thinking is "do I really need the overhead console?" For now at least, I'm thinking no, but this depends on the day..

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The beauty of experimentals is that we get to build what WE want, not what someone else wants. My main reason for wanting overhead air is due to my Mooney. The overhead air does a great job of keeping me cool during flight.
I'm bald, and the cool air at cruise altitude directly on top of my bald head keeps me cool and comfortable. Even if I could relocate front air vents to blow air "higher up than the crotch", I don't like air blowing directly onto my face (even in my car). It tends to dry my eyes out making me feel "tired". With air blowing on top of head, instead of face, it keeps me cool and doesn't dry my eyes out.

A few years back I was flying from Austin back to Oklahoma with wife and two of my kids in tow. Took our time getting up, took a bit too long at lunch and the next thing you it about 1 pm on a hot summer day.

Preflight, taxiing and run up were extremely unpleasant and I found myself rushing through things just to try and get in the air. At that point I decide to put AC on my build. It turned from being a comfort issue to a safety issue.

If I didn?t do the AC the next best option might be rear NACA vents with a blower, just to get some air blowing on you to try to cool off a bit. Personally I would be a bit concerned with humidity using the ice/water system.

I will tell you through with 25 hours or so in my friends RV-10, it is a bit like a green house. Even flying today when it was 68 out I got a bit hot while landing.

rvanstory said:

Good question. I assumed that what can create condensation/moisture will be the temp differential of the cold air in the tunnel against hotter ambient air on outside of tunnel. I see that risk being no greater than a true A/C system (both create a temperature differential). Since the chilled air from the cooler is not blowing directly over ice, but rather over a cooling coil circulating chilled water, my thought was that it won't be pumping much moisture directly into the tunnel.

But, as I said, not flying yet. If I find condensation to be a problem, I'll simply plug the hole in bulkhead and fly as any other plane without chilled air would fly.

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Think of your AC at home or in the car. All of the condensation forms on cold coils as the warm air passes over it. Downstream of the coil, the air is actually drier than when it started and it won't further condense unless it reaches something cooler than that air's dew point (now lower courtesy of the condensation at the coil). Same way that your AC at home keeps the air dry - Much of the moisture was pulled out at the coil.

You should see all of your condensation in your little AC contraption and none in the console, except when it runs out of ice and pumps warm air into the now cool console.

Moisture will only condense out of air if that air reaches it's saturation level or it comes in contact with something that cools it to it's dew point.

Larry

My experiences with the "poor man's" AC

AviatorJ said:

Personally I would be a bit concerned with humidity using the ice/water system.

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Not a problem with the IcyBreeze, or any other ice box cooler that circulates the cold water through a coil that the air is pumped through. The condensation occurs inside the cooler and drips back onto the ice. The air that comes out is dry and cool. The main drawback to using the ice cooler AC is that it's limited to the BTUs that the ice can remove from the air. Once the ice all melts, it's done. However, from my testing, it seems it's not too bad of a system, and it's a LOT cheaper and more flexible than a hard-installed AC system. AC in an aircraft would certainly be nice, but I value the mission flexibility more than flick of the button comfort. Below is my experience putting my ice box system to the test.

For my first test, I left my IcyBreeze (full of ice) running full blast in the back of my car, while it was parked, turned off and left out in the sun on a hot summer day (95 deg F+ outside). Then I went inside to the gym for an hour. When I came out, the inside of my car was just a little below the outdoor temps. Noticeable, but certainly not nice and cool like I was hoping. There was still ice water left in the cooler and the air coming out was nice and dry, just not adequate to remove all the heat that was being added to the car.

For my second test, I left my IcyBreeze (full of ice) running in the back seat of my car while I drove around on the same hot summer day. I had the IcyBreeze blowing on me the whole time and did not turn on the car's AC at all. It actually did a better job of cooling the car down the second time. I would imagine it's because the car was moving and not simply sitting there baking in the sun.

My general conclusion is that the IcyBreeze will take the edge off during taxi and should do a decent job of cooling the cabin in flight (to combat the greenhouse effect). Therefore I elected not to use a "real AC" system in my build. That being said, Arctic Air sells a portable (removable) "real AC" system that could be hooked up later, if I determine I simply cannot live with just the IcyBreeze in back. If that happens, I'll just continue to use the IcyBreeze for our camping trips. It's great to have it in a tent, when it's hot. Afternoon "tent naps" in the summer can finally be comfortable! YMMV.

I'm curious how much the cooler weighs when loaded. Plus the idea of concentrating the weight in one area of the cabin.

The airflow system in my RV10 weighs in around 45 lbs. The weight of the A/C is distributed evenly on the fuselage - Compressor in front, Condensor on the bottom middle and the evaporator is in the back. Once you charge the system, there is no other maintenance needed.

A friend of mine had the ice cooler in his 182 and was only able to get about 45 minutes of cool air. He then had to lift the ice cooler out of the airplane and refill it.

When I flew my RV8 at altitude in the nice cool air, you could actually feel the temperature rise up as you descended. If there is moisture outside (drizzle, fog) with out the A/C, my windows would fog up on the inside.

I agree, even on a cool day the cabin can get very uncomfortable and blowing warm/hot air from the outside vents in a greenhouse cabin.

Just something for you to think about.

greghale said:

I'm curious how much the cooler weighs when loaded. Plus the idea of concentrating the weight in one area of the cabin.

The airflow system in my RV10 weighs in around 45 lbs. The weight of the A/C is distributed evenly on the fuselage - Compressor in front, Condensor on the bottom middle and the evaporator is in the back. Once you charge the system, there is no other maintenance needed.

A friend of mine had the ice cooler in his 182 and was only able to get about 45 minutes of cool air. He then had to lift the ice cooler out of the airplane and refill it.

When I flew my RV8 at altitude in the nice cool air, you could actually feel the temperature rise up as you descended. If there is moisture outside (drizzle, fog) with out the A/C, my windows would fog up on the inside.

I agree, even on a cool day the cabin can get very uncomfortable and blowing warm/hot air from the outside vents in a greenhouse cabin.

Just something for you to think about.

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My IcyBreeze dry weight is 16 lbs and it holds about 30 lbs of "bagged" ice. If I fill it with hard glycol ice packs and enough water to submerge them, it all weighs about 50 lbs. It will fit in the baggage compartment of the 10, but will also limit the amount of baggage you can put in there with it (limit is 100 lbs in the baggage compartment). If I run it on High, I get an hour of cooling or maybe a little more, depending on the temps. For dumping the water, my plan is to carry a small length of tubing that I will attach to the recirculation side of the system, so that instead of recirculating the water, it pumps it overboard, through the baggage compartment door.

A/C vs useful load

I also use an icebox cooler with gel packs for A/C. It weighs about the same as a real A/C system but it doesn't work as well. It's enough to take the edge off on a hot day, does quite well at dehumidification and lasts only long enough to turn it on for taxi, climb and descent. That said, a real A/C system weighs 40-50lbs all the time, whether it's needed or not, winter or summer.

The icebox takes up a lot of room in the baggage area, so I don't use it on family trips fully loaded. By the same measure, a real A/C eats into useful load and places a considerable portion of that weight in the rear, moving the effective C/G back, further compounding the effect - and you can't take it out.

I built my -10 to carry 4 people, all their bags and full fuel on a regular basis. I couldn't do this with built-in A/C. Those who want to be super comfy without concern for the weight penalty would probably be happier with a real A/C system vs a portable cooler.

The picture below was taken after our family trip to see the solar eclipse last year. You can't fill all the seats and still bring this much stuff with you if you have A/C in your plane...

Paddy..

..it sounds as though you and I think alike. Did you guys install an overhead console, or leave it out to keep it light and simple?

iwannarv said:

I like your idea, and I am also deciding against A/C because of the weight and added complexity on my first build. Although I want it bad, I just can't justify the cost.

Are you concerned about condensation/moisture buildup inside the overhead console?

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Here is a video on building one. It should take the moisture out of the air just like a conventional AC unit.

https://www.youtube.com/watch?v=JWeyuB_dUKU

Overhead Console

ppilotmike said:

Did you guys install an overhead console, or leave it out to keep it light and simple?

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We did install the overhead console from Aerosport. Although expensive, it's a nice piece and weighs very little. We painted the inside of the cabin top rather than install a head liner to save a little weight.

Overall, the approach was to build a comfortable family cruiser. We tried to balance comfort with utility and redundancy. We did install a full aerosport interior, heated seats, center console and rosen sun visors. However, we opted for portable oxygen (for now), portable DVD players for the kids and of course portable icebox cooler, so we could leave those behind when we need to maximize useful load.

Another aspect that received a lot of attention was systems redundancy. Not only am I flying my family around in this thing, mostly IFR, but it was built with a transatlantic trip in mind from day one. To satisfy that level of redundancy, it has a dual bus/dual battery/dual alternator electrical system, as well as dual AHARS. To offset this additional weight, we went with LiFePo batteries and ditched a 28lb chunk of lead from the tail section.

So, with all this in mind, the installation of a permanent real A/C system just didn't fit our particular mission. Not everyone's mission is the same of course, if my kids were grown and I didn't want to cross the ocean, I think a real A/C system would be very nice to have.

Alright, so I have been looking at doing this: Run permanent plumbing (power, hot air exhaust, condensation drain) for an Arctic Air "real a/c" system so we can use real a/c when the weather and mission require it, or remove the 42 pound a/c unit from the plane when it is not needed or wanted. This allows for real a/c without the marriage to the weight penalty yet still stays away from ice chest type systems. Not sure what amperage the alternator makes a low power settings (during taxi when you really want the cold air blowing). Might be necessary to use additional battery capacity to piggyback the Arctic Air so if the low RPM power generation was not up to the task the system would still run. You may be able to use your duct to the overhead console and use the real a/c system in place of the ice chest.

http://www.arcticaircooler.com/product-p/rac-200-1-12d.htm

Just a quick note:

If you want electric air conditioning like the Arctic Air "Real AC", you'll probably really want to consider installing a 24V electrical system. The larger Real AC is 24V only and I think you'd find the smaller one disappointing at only 7,000 BTU.

digidocs said:

Just a quick note:

If you want electric air conditioning like the Arctic Air "Real AC", you'll probably really want to consider installing a 24V electrical system. The larger Real AC is 24V only and I think you'd find the smaller one disappointing at only 7,000 BTU.

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Question: Would it be possible to have the Arctic Air 24V "Real AC" run solely off of battery power, with an alternator charging said battery. In other words, the battery would be being "depleted" while the AC is on High, on the ground, but then would be recharged after the A/C/ gets turned off/down, once off the ground? If so, I would think you could set up a 24V circuit using two 12V batteries (primary and backup). Any electrical whizzes out there that could suggest a solution so as not to need a large 100Amp alternator to drive an electric A/C unit?

Randy how did this end up?

Randy I was curious how you cooler AC system through the overhead ended up working out. Does it work well? Do you use it?

Great question! If I had to do it over again, I wouldn't. Here's why:

The volume of air coming through overhead vents is low. After reducing hose from 4" down to 2", it really takes a toll on air volume. It does work to cool down cabin well before flight (if letting it cool down while doing pre-flight), but would get the same result if just putting cooler in and letting it blow from baggage area.

I also had some straps made that allow me to "crack" the doors open (about 1.5") with prop running. This allows a significant amount of prop wash to come in to cool cabin, adn me. MUCH MORE volume of air than cooler. This is so easy, that I don't even bother with the cooler anymore.

Randy, would you mind sharing a photo of the strap set up to hold door open, I’ve been thinking of a way to do this, any help appreciated. Thx Pete

I’m happy to. I’ll be at hangar tomorrow and will take pics to share.

Does this cooler driven climate control not add a lot of moisture inside the airframe?

No. It pumps chilled water (ice water) through a coil and the fan blows air over the coils for the chilled air. No moisture issues at all.

Kiwi flyer said:

Randy, would you mind sharing a photo of the strap set up to hold door open, I’ve been thinking of a way to do this, any help appreciated. Thx Pete

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Here's some pics. 1st of off another RV-10. Last pics are of mine. Before I had these made, I used paracord from Home Depot to make a pair of straps. Worked fine, didn't look as "fancy".

Thanks! That is super helpful. Might have saved me a lot of time!

Thinking more about the Ice Chest AC going through the overhead console, it seems you would need to modify it a much stronger fan to handle the diameter reduction. Some of the cooling would also be lost in all the duct work.

-Craig

Thanks Randy.

PIREP on a similar system:

I run a cooler in the back (with bilge pump and heater core in the lid) that holds about 30lbs of ice. *Two* 4" ducts connect the cooler to the rear bulkhead and then a aft fuselage mounted blower pushes the cooled air through a high flow DIY overhead console. (There is no fan in the cooler.)

This system works pretty well and IMO the keys to success are:
- Lots of airflow / big ducts and vents (two 4" hoses and 250 CFM actual flow through all the ducts and the cooler)
- Pointing the air at your face and chest (through overhead vents)
- Burning lots of ice quickly
- Quick disconnects - look for ones designed for clothes dryers
- Using a cooler with wheels

If you want to be cool, don't think about how long the ice lasts. Instead focus on how quickly you can use up your ice. More ice melted=more cooling. I go through between 0.75-1lb of ice per minute depending on the the fan speed. That translates to 7500-9000 BTU/hr. My typical profile is 10-15 min start/taxi, 7-10 min climb, and 5-10 min descent/taxi cooling. The system is off in cruise to save the ice for descent. One nice feature is that the system can run off the battery prior to engine start. Often I'll turn it on while passengers are loading so they're not sweating during close out and start up.

Here are some specific part numbers that can serve as a baseline:
Blower - Spal 007-B42-32D (24V)
Cooler - Igloo Profile 30qt (fits great and holds ~30lbs)
QDs - Deflecto Dryer Easy Dock (use two hoses in parallel)
Pump - Rule 25DA
Heater core - Spectra Premium 99265

The system weighs about 40lbs and leaves room in the baggage area for two carry-on size bags. If I don't need the bag space, I sometimes pack two coolers---one for there and one for back. Real AC would in many ways be better, but you'll have to decide if the tradeoffs are worth it or not.