Question: Is it enough to wrap the blanket around the cowl and plug in
the Tanis even though the plane is sitting outside with the cold wind?

Sure. We do it all the time.

Last year I parked our plane in Wisconsin on the coldest weekend of the
year. The temperatures were below zero, and the wind was howling.

My oil temps were above 35 degrees at start-up -- considerably lower than
the 80 - 90 that the pan and cylinder heaters usually achieve in my hangar,
but certainly plenty warm compared to the ambient temperature. Here are
some pix from that trip: http://alexisparkinn.com/frigid_january.htm .

The blanket is the key. Without a form-fitting, well secured blanket, all
of your heat will just blow away. (And don't underestimate the wind. It
WILL remove your blanket unless it's velcro'd on securely.)

How often do airports offer this?

Most Midwestern airports have outside outlets -- but you can't always count
on having a long enough extension cord. We carry a 100 foot extension cord
whenever we fly in the winter.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"