REFLECTOR: Cold Weather Flying

[John Dibble]

Larry,

Previously, my sensor was installed in the 1/8" fitting you mention.  It 
always measured OAT.  You pointed out that my probe may not be in the 
fuel spray pattern.  It is quite short.  So I moved it to the top of the 
carb in the MP fitting.  It's out of the mixture flow, but I have 
insulation around it.  Maybe I need more insulation.  Is there a spray 
foam insulation I can try?

John

On 12/21/2012 11:18 AM, Laurence Coen wrote:
> John,
>
> The carburetor has a 1/8" pipe thread fitting for the mounting of a 
> temperature probe.  It places the probe in the throat of the 
> carburetor where ice tends to form.  That is where mine is and it 
> works fine.  One of the things that I thought of trying were 
> temperature sensing linear actuators that are used to open and close 
> vent windows on greenhouses.  If they were used to operate dampers in 
> the plenum plumbing you'd have automatic thermostatic control.  After 
> 10 years of tinkering I decided to go flying instead.
>
> Larry Coen
> N136LC
>
> --------------------------------------------------
> From: "John Dibble" <aminetech at bluefrog.com>
> Sent: Friday, December 21, 2012 10:04 AM
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Subject: REFLECTOR: Cold Weather Flying
>
>> Had a good flight from MS to NY on Wednesday.  Stopped at DKX Knoxville
>> for fuel.  That's a hard airport to find hidden in the hills.  A while
>> back I reported that my temps were too low in cold weather and not
>> enought cabin heat.  I decided to go after the source of the heat and
>> reduce the engine cooling air, see pic.  I thought this would be over
>> kill and I would have to trim it a bit, but it turns out that this just
>> gets the engine temps to the bottom of the desired range (250-300F) with
>> an OAT of 40 F.  At 30F CHTs are 240-245F.  Still, the oil temp ran at
>> 275F with the diverter flap fully deployed and that gave too much cabin
>> heat.  During descent for landing, temps got very low and I had no cabin
>> heat.  I would like to have a way to adjust engine cooling air from the
>> cabin, so I can have max cooling for T/O and reduce cooing air at cruise
>> and reduce it further for descent.  Has anyone done this?
>> When the OAT got down to 30F, I decided it would be a good idea to add
>> some carb heat even though my manifold pressure was holding steady.  I
>> did not see an expected increase in the carb temp gauge, but the MP did
>> decrease by a few tenths indicating that the carb heat was working.
>> Guess I need to work more on the the carb temp sensor placement.  I had
>> moved it to the fitting where the manifold pressure line connects (carb
>> outlet).  It seemed to be giving sensible readings at higher OATs, but
>> not at 30 F where it counts. Looking forward to returning to warmer
>> weather after the holidays.
>>
>> John
>>
>>
>>
>
>
>
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