For all the touted utility of so-called TAAs-technically advanced airplanes-the great equalizer remains in-flight icing. When you find yourself slogging through a layer of mixed rime, it doesnt matter if youre in a 20-year-old Archer or a just-out-of-the-factory Cirrus. But the TAA manufacturers have risen to the challenge, with Cirrus and Mooney offering the fluid-based TKS de-ice system as an option and Lancair striking out on its own with something really technologically edgy: Electric de-icing.
Electric de-icing has always been a sensible idea that hovered just out of reach, chiefly because light airplanes cant generate enough power per square-inch of wing area to make it work. Electric pads have found selective use on transport aircraft, but no one has tried to thaw an entire airplane with volts instead of boots or fluid.
Now comes Lancair stepping up with a system called ThermaWing developed in conjunction with NASA research by an Ohio company called Northcoast Technologies. We heard about Northcoasts research about five years ago and lodged the information in our over-the-horizon file. But Lancair has test flown ThermaWing in natural icing and is confident enough in its performance to begin offering it as an option later this year. Lancairs chief engineer, Tom Bowen, told us this system is intended as an inadvertent de-ice solution to provide a safe escape, not a known-ice system for launching into winters worst.
Northcoasts breakthrough technology is a paper-thin, energy-efficient flexible graphite heating film thats bonded to the leading edge of the wing. The heating element-total thickness 12-mil-is sandwiched in layers a tough plastic called Tedlar
On the Columbia, the wing and horizontal stabilizer are protected by ThermaWing but the vertical fin isnt. The prop is protected with conventional electric de-ice but not the windshield. Bowen told us that flight tests revealed little need for heat on the vertical stabilizer and the Columbias side windows remain free enough of ice to make forward visibility possible if not easy.
Because electrical de-icing requires so much power to operate it, power is applied selectively to zones or segments rather than all the elements at once. On the Columbia, Bowen told us, the wings two outer upper wings are heated together, then the lower wings, then the inner wings and so forth.Each element heats for about 7 seconds and the entire system requires about 90 seconds to cycle. Energy management is done through a digital controller; the pilots only option is to switch the system on or off, as conditions warrant.
Obviously, electric de-icing requires the kind of power heretofore found only on jets and transports. Northcoasts solution to that is an enormous 70-volt, 7500-watt belt-driven alternator on a mount normally reserved for air conditioning. (If you have an air conditioned Columbia, Lancair envisions an electrically driven compressor powered by the de-ice system alternator. Presumably, youd never need de-ice and AC at the same time.)
Bowen told us electric de-ice systems have been of two types, evaporative and run wet. The former generates enough heat to melt ice and evaporate the water while the latter melts only the molecular layer adhering the ice to the airframe, allowing the relative wind to do the work of removing it.
The Northcoast system is a run-wet design and has a -inch wide continuously heated strip-called a parting strip-at the stagnation point of the leading edge, where the air splits to flow over the top and bottom of the wing. The parting prevents the ice from capping the leading edge and by melting the build-up continuously, it gives the airflow purchase on the ice, so it can be blown off the surface. The heating elements extend back to about 15 percent of chord and are actively heated to 8 percent of chord.
Total system weight is 36 pounds and Bowen told us the heating elements are thin enough to exact no performance penalty. If damaged, theyre easily replaced, bonded on with the same adhesive used for pneumatic boots. Lancair told us the Northcoast system will be a $00,000 option on a new airplane and can be retrofitted to any Columbia 350 or 400.
What we find most intriguing is the likelihood of ThermaWing retrofits for other, older aircraft. Northcoasts Bob Rutherford told us the company see the retrofit market as larger than the OEM field and will eventually pursue STCs for other aircraft, something we look forward to. Cost would be in the $22,000 range. The only potential show stopper might be finding a pad or drive source for the alternator. Well examine this system in greater detail in a future issue.
Contact – Northcoast, www.aircraftdeice.com.