REFLECTOR: Cold Weather Flying

[John Dibble]

On 12/21/2012 11:34 AM, Scott Derrick wrote:
> I was amused to see "oat down to 30f"!  30f?  really?  Not to belittle your experiance, but when I'm trying to get heat at -10f oat,  30 just seemed on the trivial side...


If my CHTs were as high as yours, I think 30F would be trivial for me as 
well.....

John
>
> I have an operable flap on my front oil cooler exit, which does help in controlling oil temps, full open for takeoff and hot summer cruise.  I close it in the winter once I transition to cruise climb.
>
> I also have a rear lower engine cowl flap, that needs to be operable.  Right now its fixed open, which works well in summer but is too much air in winter.
>
> Scott
>
> Laurence Coen <lwcoen at hotmail.com> 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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