Using modelling clay I fabricated ducts to feed the air to my Jaguar XJS adjustable air vents in the panel. On the forward end of these ducts I added inlets for the internal air. Note: I originally added the inlets on the sides, until I realized that the pipes would interfer with the radio stack. The wire connected to my closable scoop goes through a small hole in the duct and hooks onto an aluminum lever which is turned by a knob on the panel next to the vent. I painted the ducts with gold engine enamel which seems to work well on cured epoxy and makes the result look vaguely professional.
One day in November '02 I set out with my toolbox to hunt down the parts. I went to a local U-Pick breakers yard. On the way in I asked how much an AC evaporator would be. The guy said "about $40 - $50". I found a '90 Mazda 323 which seemed in good condition apart from accident damageand it looked like I could get at all the AC stuff, including the pipes. It took me about 4 hours to remove the compressor, condensor and evaporator along with all the pipes and attached gizmos. I also got the heater core. It's fun working on a scrap car because you dont have to remember how everything goes together, you dont have to keep all the nuts, bolts and screws, and it doesnt matter if you accidentally damage something else along the way. Most of the stuff came off easily. The real trick was the heater box which took me a couple of hours. I tried to remove it nicely, but in the end I simply demolished it with a hacksaw blade and a pair of pliers until all that was left was the two cores. No-one ever buys a used heater box anyway - right?
I put the pile of parts on a trolley and wheeled it to the exit. When the "pricing" guy asked what I had, I responded "Air conditioning for my airplane". "Really", he says. "I'm a pilot too. What are you building?" A half hour later, after we'd swapped hanger tales and discussed the 13B in detail I asked - "so what's this lot going to cost me?". My new buddy Gerry sniffed at the trolley and said "$75 sound fair?". "Very fair", I said, and happily loaded the stuff into my trunk. I caught hell when I got home. I had cuts and scratches all over my hands and dried blood on some of the parts. I hadnt noticed the cuts while I was working.
Condensor 5 lb Evaporator 9 lb Fan 1 lb Compressor 18 lb
For heater control I'll install a push pull cable and a valve in the engine compartment to adjust or shut off the hot water supply to the heater core. I'm not sure how to adjust the AC yet. I guess it involves switching the clutch on the compressor. There was a temperature probe embedded in the evaporator core. I put it the freezer and tested the solenoid. Sure enough it goes off when cold and comes on when warm (that's as accurate as I got). OK. This baby will connect in series with my switch and send power to the compressor clutch. I can easily wire this circuit in series with a full power microswitch, but I think I'll set it up manually via a check list for now. Obviously the first few flights will be done with AC off. Later, one of the flight tests will be to see how much power I loose with the AC on and how that impacts take off. I should have at least a 50 HP edge over an IO-360 powered Cozy. If I give up 5 or 10 HP to the AC I should still be well ahead of the game. Maybe "AC off for take-off" will only be required on a short field, or a very hot day at high elevation. We'll see. At least the first stage is done. The AC unit is installed and the blower is wired up. Now all I need is a few pipes....
Once I'd got two 5/8 pipes inserted I cut oval holes in the sides of the heat duct under the front seats, pulled the pipes through until they lined up with the holes and deftly snagged them into the cabin. With Char pushing from the firewall, and me pulling from the cabin we gradually persuaded the pipes to curve gently into the area under the seat where I could add connections. Since one goes to the pilot side, and one to the passenger side, these pipes will be the AC return to the compressor, and the heater feed.
A word of advice for those working on Chaper 8 who plan on using a water cooled engine.... Install you're pipes now, while you're building the heat duct. Once the pipes are in you can fill the whole thing with pour foam for insulation before closing it up.
I'd bought some automotive heater hose, but decided that 5/8 3003 AL pipe would be better if I could get enough of it down the heat duct. I had two pipes installed, and it looked to me that I could get the other two in as well. I ordered some more. In the meantime I worked on the connections at the front. The heater core had two hose connectors coming straight out of the side. I had set this up to point downwards, so I needed to install 90 degree angles and some sort of screw up fitting. I used 1/2 inch copper 90's with a short piece of 1/2 copper pipe into a male compression union. I soldered the joints the same way I'd done when installing copper lines for my home air conditioning. If it worked there, then it should work here. Right?
The last large pipe was interesting. This was for the vacuum. With a certain amount of gentle persuasion I was able to insert the pipe into the heat duct through the nose well. I got it all the way back to the gear well, bent it around the gear and inserted it in the "back passage" a couple of inches. There seemed no way to budge it from here. I pulled, twisted, pushed and wiggled it to no avail. Admitedly the heat duct entry in the firewall was getting a bit full of pipes by now, but it looked like there was room. I hit on a plan. I drilled two holes across the end of the pipe and inserted some steel rudder cable. I hooked this up to my "comealong" which I attached to a stansion holding the patio roof. No. I didnt pull the roof down, but I did pull the plane backwards. OK. I have a parking brake! I set the parking brake and pulled again. The plane skidded on the tires. OK. I got a 2 * 4 and braced the engine mount against the bottom of the stantion to form a triangle. Now the pipe began to move. In no time I pulled the pipe through the hole and out a foot or so behind the firewall. i was quite pleased with myself until I inspected the pipe. It was flat on one side. There was no possible way to get a fitting on there. I folled the pipe forwards until the flat side dissappeared as the pipe went over the gear. Of course. I'd been pulling soft aluminum against hard fiberglass. The aluminum had flattened. Duh. I cut the pipe off where it entered the gear well and pulled, wiggled and pushed some more. I "adjusted" the hole into the firewall a bit with the dremel and eventually got the fourth pipe into the engine compartment without damaging it on the way. The forward end of the pipe ends just in front of the panel. I attached a right angle fitting there to connect to the vacuum hose, filled the gap with pour foam, sanded it flat, then sealed off the gear well with a fiberglass patch.
A little later I realized that my right angle fitting was pointing towards the pilots feet, so the vacuum hose would have to run across the floor. Damn. That doesnt make sense when all I had to do was run it vertically up behind the panel. I cut away my nice fiberglass patch, dug out the foam and rotated the vacuum fitting 90 degrees. I lowered the vacuum hose down behind the middle of the panel and screwed it into the fitting with teflon tape. More pour foam and another fiberglass patch finished the job. The vacuum hose now sticks up a few inches above the gear well cover where I attached a T fitting to split it between the attitutde indicator and the DG. I'll need a plastic right angle fitting to feed the air from the filter to the DG, and a straight one for the AI. Why straight? because it's impossible to screw right angle fittings into both holes on the AI - one hits the other and can't turn. Seems like a simple problem, but it means I have to wait for some more fittings from Wicks before the vacuum system is done. Then, of course, there's the engine end.....
All I had left was the 1/4 al 3003 pipe for the AC freon feed. The four 5/8 pipes made a square, so my theory was that the 1/4 pipe would fit in the hole down the middle of the square. The theory worked until I got to the rear cabin where the pipes went down below the rear seat belt attach point. I didnt want to damage the structure around this area, so rather than force the issue I ran the remaining pipe along the top of the heatduct, through the seatback, then down under the co-pilot seat to condenser.
This was another of those times where the plan evolved. Once the pour foam was cured, cleaned up and carved into a "pleasing shape" I decided that it needed covering to stop the gritty foam getting damaged and spreading around. Once that stuff gets loose it gets everywhere - I know - our bed has been full of it on numerous occasions. So, 1 ply BID covered the foam nicely. I made bumps Where the freon feed went down the right side, and a bundle of wires went down the left side of the center console.
At last all my connections were done - in the front. All I have to do now is connect the other ends to things in the engine compartment.
I was dreading the job, but eventually I had to tackle it. I cut the pipes off where they entered the landing gear box and removed one side of the rear heat duct so I could bend them out enough to put fittings on the ends. Removing the pour foam was a pain, but eventually I got the pipes out. While I was at it, I revised the fuel pipes as well. They used to run over the landing gear box to the filters behind the back seats, then on through the firewall. I'd recently had a conversation with another builder who had had a fuel vent pressurize and dump a couple of gallons of gasoline into the back seat area. Scary. I decided it might be better if the fuel pipes headed out of the back seat area as quickly as possible. Now all the heater and AC pipes were out of the way I could run the fuel pipes into the LG box and mount the filters centered above the gear with plenty of clearance. Much better. I floxed nutplated to the top of the gear well and used those rubberized clamps to hold the filters in place.
The next job was to reorganize the metal pipes. I got some more pipe and -10 bulkhead fittings and proceeded to make connecting pipes with 5/8 6061 aluminum. After a day trying I decided that I needed flexible hose for these connections. The Aeroquip hose I had is good to 250 PSI, but it doesn't support freon, so I used aluminum for the AC return. I got the AN push on barb type fittings for the hose. The price of all these fittings has numbed me to the point that I don't even ask anymore. Rather than worry about it I've taken the attitude that it's like gasoline. I have to have it, and I'm not going to buy less because of the price. Just show me where to sign, and give me the stuff I need.
I installed the Aeroquip hose in no time. Much better. Tom, who's building a Glasair a couple of hangars down the row, stopped by and noticed the seven bulkhead fittings sticking through my firewall. "What's all these?" he asks. "Well, there's two for water, two for freon, two for fuel and one for vacuum", says I. "Hmmm. I only have one for the fuel pipe", he says. Maybe there's something in this KISS thing after all.
When the connections were all tight I persuaded the pipes to go back where they belong and got ready to repair the heat duct. I cut a piece of scrap fiberglassed foam to shape and floxed it in place. It was late evening, and the light in my hangar is one of those opinionated type that gets overheated and shuts itself off to cool down. I wish I could do that. No problem, though, since I have my handy inspection light hooked over the turtleback so I'm getting lots of light. I'm busy with the second of six plys of BID when the overhead light decides to take some time off. At that point I knocked the inspection light off it's hook. Darkness.
Oh. This is great. Here I am with gloves on, crouched in the back of the plane. I have precut BID, flox, brush, heat gun, plastic and epoxy at the ready and I'm half way through stippling my second ply. Pitch black. Can't see a thing - not even to put stuff down and get out of the plane. I wait the prescribed minute or two while the lazy damned light took a break, and then there was light. Whew. I stippled, added another couple of plys, reached out for the epoxy cup. Darkness. This is getting to be very annoying. Eventually I completed the layup in spurts intersperced (can you say that quickly) with periods of total darkness. I went home, with a reminder to myself to bring spare bulbs, hoping the layup came out ok.
<<< Back | Index | Next >>>