A cheap voltage converter is likely to be very noisy in the RF
spectrum.Â* I tried one for charging a pda and it continually broke
squelch on my radio.

And, as to the original topic of circulating cockpit air, I don't think
that would be of much use and the air in the cockpit is cold. You feel
warm due to infrared heating from the sun.Â* I've felt quite warm in the
sunlight, seen my breath condense in front of me, and been very cold the
instant I flew under a lennie.

Dan

On 12/28/2018 6:45 PM, wrote:
On Thursday, December 27, 2018 at 7:10:25 PM UTC-5, AS wrote:
On Wednesday, December 26, 2018 at 5:16:20 PM UTC+1, wrote:
On Tuesday, December 25, 2018 at 11:53:19 PM UTC-6, wrote:
As we know, flying in wave with the sun shining, much of the cockpit stays reasonably warm, but the feet, down in the shade, get cold. So, as I'm here at home on a cold night with a fan helping distribute the heat from the wood stove to another room, it occurred to me that something like that may be possible in the cockpit? A small fan (using a fraction of the electric power that the typical instrument panel uses), perhaps with a short duct, could move sun-warmed air towards the feet. Has that been tried? Does it help? Would it use more electrical power than electrically heated insoles?

Back when I flew an HP-14 which had a canopy that extended forward over the rudder pedals, my feet were much warmer in cold but sunny weather than they are in my current glider. As long as I was pointed towards the sun, that is - typically pointed into a West wind in the afternoon. As soon as I turned around to the East the cockpit temperature plunged.
Have been flying now for 5 years with these Gerbing insoles and the recommended temp controller, also from Gerbing.
https://www.revzilla.com/motorcycle/...caAvYwEALw_wcB
I run them on a dedicated 12V LiFePo4 battery. After 2 hours at altitude when the feet get cold I turn the unit on and dial the controller back to a setting that I tested prior to keep my feet toasty but not hot. I know of at least 4 pilots who also use these with no issues.
Herb
An alternative to these insoles are heated socks. I bought a pair years ago from a hunting supply catalog. The advantage is that they warm your feet all around up to your ankles rather than grilling just the bottom of your feet. They run on 4.5VDC. I built a 12V-to-4.5V converter using a fast switching power supply with a simple on-off rocker switch for temperature control. Worked well and did not drain the battery too badly.

Uli
'AS'
Uli: if those socks are designed to work with 3 alkaline cells, nominally 4.5V, they probably would be quite happy with 5V too (like fresh alkalines). (Or you can put a regular silicon diode into the supply line to reduce the 5V to about 4.3.) So you can use a cheap 12V to 5V converter (designed for USB jack charging).

--
Dan, 5J