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  #1  
Old 10-29-2018, 10:23 AM
rvanstory's Avatar
rvanstory rvanstory is offline
 
Join Date: Dec 2016
Location: New Braunfels
Posts: 139
Default 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.
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  #2  
Old 10-29-2018, 10:59 AM
iwannarv iwannarv is offline
 
Join Date: Aug 2005
Location: Stafford, KS
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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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  #3  
Old 10-29-2018, 12:17 PM
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Bill Boyd Bill Boyd is offline
 
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Location: Landing field "12VA"
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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
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  #4  
Old 10-29-2018, 02:19 PM
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rvanstory rvanstory is offline
 
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Location: New Braunfels
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Quote:
Originally Posted by iwannarv View Post
Are you concerned about condensation/moisture buildup inside the overhead console?
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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Building RV10
N783V - Reserved
Flying Mooney M20J
Emp Kit Completed, Section 29 done, Tail Cone Attached, QB Wings delivered and stored for now.
Dues Happily Paid 2018

Last edited by rvanstory : 10-29-2018 at 02:23 PM. Reason: typo
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  #5  
Old 10-29-2018, 02:21 PM
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ppilotmike ppilotmike is offline
 
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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..
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  #6  
Old 10-29-2018, 08:39 PM
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rvanstory rvanstory is offline
 
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Quote:
Originally Posted by ppilotmike View Post
My thinking is "do I really need the overhead console?" For now at least, I'm thinking no, but this depends on the day..
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.
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  #7  
Old 10-29-2018, 10:23 PM
AviatorJ AviatorJ is offline
 
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Location: Oklahoma City
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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 didnít 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.
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  #8  
Old 10-29-2018, 10:51 PM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by rvanstory View Post
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.
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
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Last edited by lr172 : 10-29-2018 at 10:59 PM.
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  #9  
Old 10-30-2018, 10:14 AM
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ppilotmike ppilotmike is offline
 
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Location: Denver, CO
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Default My experiences with the "poor man's" AC

Quote:
Originally Posted by AviatorJ View Post
Personally I would be a bit concerned with humidity using the ice/water system.
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.
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VAF Dues Current: as of 01/15/18
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  #10  
Old 10-30-2018, 05:59 PM
greghale greghale is offline
 
Join Date: Jan 2006
Location: TULSA, OK
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Default Poor Man A/C Idea

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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