An easier/cheaper/apparently more efficient option?
As it happens, EAA Chapter 193's el Presidente, Elvis Golden, brought in his 'Mark II' air conditioner to the monthly meeting just two days ago. The basic concept was the same ('ice in a box') but for those who want an 'easy' choice, Elvis' design might be worth considering. It will be posted on the chapter website...but meanwhile, here's the basics:
-- medium size (plastic) cooler
-- smallest available 12V bilge pump (from West Marine, Defender et al.)
-- small heat exchanger, off the shelf from a local car parts store, mounted on the underside of the cooler lid
-- light tubing, running the coolant (chilled water) from bilge pump to heat exchanger and returning water to bottom of cooler
-- 200 CFM 12V muffin fan, mounted (at an angle suitable for the cooler's location in the cockpit) in the cooler lid (chilled output air)
-- several small grills in the top of the cooler lid (supply air into the box)
-- on/off switch (the Mk III model will feature a rheostat) and 12V power cord to 12V supply on the panel
-- 1.5 qts. of water (inside the cooler)
-- 8# bag of ice, plopped into the cooler just before departure
Testing done in/around Jacksonville FL - ambient temps: 95F
Cost: $100
How long chilled air lasts: Over one hour, including two airport stops along the way on c/c test
Amp Draw: 2A @ 12V
Time to cool down cabin (4-place Cherokee 180): 5 mins (!)
Other options: use Blue Ice vs. bag of ice - lasts a bit longer; larger cooler - longer endurance, especially with rheostat; chilled/near frozen sodas plus ice - cold drinks on a longer flight
Most surprising test to me was the report of one fellow who borrowed this unit while doing pattern work at CRG (read: hot, humid 95F mid-day flight). By third landing, the cabin windows started to fog up. One member at the meeting then asked, given the reduced viz, if he'd filed...
Jack