Craig,

 

We’ve designed and built a case for the condenser and compressor that doubles as a big air duct.  It sits behind the co-pilot’s seat on two reinforced holes in the belly to get to the outside air.  The case and holes are carefully sealed to ensure the outside air, with some engine exhaust fumes in it (CO), do not get into the cabin.  A fan on the condenser pulls the air through the case.  The compressor sits in the downstream air which is still plenty cool enough to handle the compressor and its electronics heat rejection needs.  The evaporator and blower assembly sits behind the pilot’s seat.  There are air ducts that run along the fuselage sides.  Each side has three eyeball air vents.  I’ll send a few photos in a couple weeks.

 

The good thing about going with this system is that it is easily installed, does not have any equipment under the cowling or behind the instrument panel and it’s easily removed when you don’t need or want it in the airplane.  The down side is that you need to have the electrical capacity for it and need to be running a 28V electrical power system voltage.  I made a mistake in the steady state current demand I stated in my reply to the power supply question – the steady state demand is more like 50A and can be as high as 60A depending on temperatures.  So, you need a good size alternator.  Ours is 100A. 

 

We’re going to offer this kit for sale when finished.  I’m not sure it will fit in a 320, though. 

 

Thanks,

 

Valin

 

Legacy in work

Steamy Houston, Texas

 

http://www.starflight.aero/legacy

 

 

Hi Valin,

 

Can you post some pictures showing how that AC went in?  I would like to see if I could get something like that going for my 320.  I really like the idea of taking it out when not needed. 

 

Thank you,

Craig

Lancair N73S

 

 

Thank you all for your helpful advice on and off the list.  The LML people are a great resource.

 

Our Legacy is still under construction.  We want to be able to do system testing before the engine is installed and without the engine running after it is.  Our desire for a power supply sized around 50A is because we’re about to begin testing of an all electric air conditioning system we’re developing for the Legacy in partnership with an aircraft A/C company.  The whole system sits behind the seats, there is no P-51 air scoop, and we get the cold air in front of the pilots.  Oh, and for the winter or if you want to off-load 40 lbs, it can be removed in less than 5 minutes.  Anyway, I digress…J  The A/C system running at steady state pulls about 30A between the compressor, condenser fan, and evaporator blower. 

 

We’d also like to eventually do simple EMI testing.  With all the avionics on we’ll cycle other components like gear, lights, and A/C looking for interference.  We’re planning on a Garmin G900X integrated avionics system and it pulls about 15A max intermittent (for 28V system). 

 

The cheapest approach is a good size battery with a serious charger to get power for brief periods of time.  We want to do some long duration testing so we’ve decided to get a StartPac Portable Power Supply Model 53050 which can provide 50A continuously at 28.5 VDC, with over voltage and over current protection.  ACS price is $896. 

We’re planning to add two Odyssey batteries to the set up to provide more surge capacity and ensure good power quality.  We’re assuming we can work a setup where the StartPac power supply just looks like the power coming from the alternator and the batteries (2 Odyssey 12V in series) with a voltage regulator in there somewhere…  We still have some homework to do and welcome more advice from the DC power distribution gurus out there on the best way to set this up.

 

Thanks,

 

Valin

 

Legacy in work

Hot & Humid Houston, Texas

 

http://www.starflight.aero/legacy

 

 

Hello LML gang,

 

Could I get some advice on the best way to get a 28 VDC 50 Amp power supply set up in our hangar?  On the web I’ve seen $5000 ground power units that can be plugged into our hangar’s AC power outlets to solve the problem…  Surely there’s a cheaper way to do this.  Anyone know of a more affordable source?  Maybe a couple of 12V car batteries ganged together with a battery charger in there somewhere. 

 

Suggestions?

 

Thanks,

 

Valin Thorn

Legacy

Texas

 

http://www.starflight.aero/legacy