Carl Orton wrote:
I live in TX, so I frequently see temps in the 20's , but not much colder.

For me, I got a ceramic cube heater from WalMart ($20), and a 6" flanged
duct adaptor from Home Depot ($6), and an 8' length of aluminum 6" dryer
vent (~$8). I go out to the plane the night before I want to fly, stick the
duct up the cowl, set a standard lamp timer to come on about 3-4 AM, and I'm
ready to go.

I did the same, but had two of the cube heaters, so made two
preheaters. I used an "offset adapter" as a source of flanges, and
used 4" dryer vent hose (half of an 8' length for each side). I put the
heaters on the ground and insert a hose in each cowl flap opening. I
made hooks from safety wire to hold the hoses in place (attach to the
cowl flap actuator rod). My plane is outside, so I don't have the
option of leaving this setup in place when I'm not around.

Conclusion? They do work, and make the plane much easier to start with
an hour or so application. I think there is room for improvement - I
note a significant temperature drop over the length of the dryer hose.
Perhaps supporting the heaters close to the cowl flap openings (and
using shorter hoses) will help - or switching to some sort of insulated
hose (if I can find any). Another thought (untested) would be to use a
couple of cheap hair dryers - one inserted in each cowl flap. Comments?

David Johnson