Winter flying ops

[Viperdoc]

It is now a balmy 3 degrees here in Wisconsin, and I was thinking about
trying to find the winter fronts and putting on my Baron.

The question that comes up every year is whether to open the cowl flaps for
start, taxi, and take off, knowing the ambient temperature is so low.

It's hard enough to get the oil to the right operating range, and in the
winter the CHT's never go above 350, even with high power settings, so why
cool the engine even further by opening the cowl flaps?

I know some "experts" will say: "follow the POH", but why do this blindly if
the purpose is to get and keep the engine in an optimal operating range,
rather than too cold or too hot?

Any other reasons to keep the cowl flaps open on such cold days?

[Denny]

If you have CHT on all cylinders so that you can watch for overheating
during take off and climb out I would leave the cowl closed at 3
degrees and modulate it as needed...

Denny

[zatatime]

On Thu, 23 Dec 2004 06:29:00 -0600, "Viperdoc"
> wrote:

>It is now a balmy 3 degrees here in Wisconsin, and I was thinking about
>trying to find the winter fronts and putting on my Baron.
>
>The question that comes up every year is whether to open the cowl flaps for
>start, taxi, and take off, knowing the ambient temperature is so low.
>
>It's hard enough to get the oil to the right operating range, and in the
>winter the CHT's never go above 350, even with high power settings, so why
>cool the engine even further by opening the cowl flaps?
Exactly.

>
>I know some "experts" will say: "follow the POH", but why do this blindly if
>the purpose is to get and keep the engine in an optimal operating range,
>rather than too cold or too hot?
I don't know. I'm a believer in doing what's required, when required.
If the outside temps require closed cowl flaps to keep in the heat,
then by all means do so. Just make sure you monitor the temps
closely.

>
>Any other reasons to keep the cowl flaps open on such cold days?
>
Because you like to look cool moving the handle back and forth? <g>

z

[[email protected]]

Viperdoc wrote:
> The question that comes up every year is whether to open the cowl
flaps for
> start, taxi, and take off, knowing the ambient temperature is so low.
[stuff snipped]
>
> Any other reasons to keep the cowl flaps open on such cold days?

I know of a very experienced skiplane pilot that is concerned with
overheating during long ski taxiis. (In soft snow, the power settings
are higher than taxiing on a hard surface.)

I think you need to realize that cooling on the ground while
taxiing is a whole different ballgame than when at flying speed.

I've flown with the above mentioned individual in a C185 when it
was minus 25 C and the cowl flaps were open for startup, taxi and
takeoff. He then went to half open during climb out (he knew from
experience that worked about right). For descents he slowed the
airplane into the white arc and then descended with full flap and
a fair amount of power, staying in the white arc.

So, I don't have any magic answer, but keep ground ops and flying
separate. There's no comparison between a 140knot breeze flowing
past the cowling and propwash on the ground, IMHO.
Have a good holiday, rick

[Viperdoc]

I have a multiprobe engine analyzer, and at normal taxi power the CHT's are
in the low 200's on a normal day, let alone when it's around zero outside.

Even though the plane's in a heated hangar, I still may use the Tanis
heaters on very cold days to help heat the oil, but I was looking for other
possible reasons to open the cowl flaps other than responding to a knee jerk
reaction or simply a matter of routine.