Really cold weather operation

[Shadrach]

I do not have a relocated cooler or lower cowl closure. What "low pressure" area are you describing? There certainly areas of low pressure within the cowl, but it does not strike me as likely that air is flowing from the lower cowl out the of the front of the cooler.

[Shadrach]

Ross, my oil cooler is relocated so the air through it comes across the top of the port cylinders. I suppose blocking air in this case is less important. For one thing, diverting air from the oil cooler moves more air thru the post cylinders perhaps cooling those cylinders more than the starboard side which is typically hotter already.

I am dubious about the notion that blocking your relocated cooler would provide any additional cooling to the pilot side cyls. What it will do is allow more heat to remain in the oil that is flowing through the cooler.

[Bob_Belville]

That air goes somewhere. Getting all the baffle seals tight and shimming #3 1/8" off the back baffle makes a significant difference. This seems like a greater change than those... 

[Shadrach]

That air goes somewhere. Getting all the baffle seals tight and shimming #3 1/8" off the back baffle makes a significant difference. This seems like a greater change than those...

Yup, it typically spills back out of the front of the cowl!

[Bob_Belville]

I'm dubious. If there is not a positive pressure on the top of the engine how does any air flow though the cooler? (I have 201 style cowl. Baffles direct inlet air to the top of the engine.)

[BorealOne]

Here's a shot of the oil cooler with cover in place on my Ovation. You want to cover the entire cooler in cold temps.

 

 

[triple8s]

Boreal One........how cold is cold? My better half is from up north and her and I have different definitions of "cold". Was ice fishing once and I called it quits because -18df and wind is too much for me, she said I was a wuss!

[Ned Gravel]

How cold is cold?  

 

Well, we are used to being outside in the winter at temperatures colder than that.  It is all about how you dress and prepare.  

 

We can do things for ourselves that we cannot do for our aircraft in those temps.

[BorealOne]

Ask a Canadian, eh? If you listen to those thin-blooded Texans down in Kerrville who write the manuals, anything below 30 df is cold enough to install the cooler plate blocking the airflow through the cooler entirely. (At 30 df, I'm not even wearing a jacket :-)

I find it works well enough to keep oil temps above 170df at OATs down to -40df. Your mileage may vary.


Sent from my iPhone using Tapatalk

[yvesg]

I do not put anything in front of the oil cooler myself. On my return flight two days ago the outside air temperature was minus 20 Celcius. The oil temp was always in the green, so was the cyl head temp. i did fly one day many years ago at minus 30 Celcius which is my personal limit. When I took off, some dials were erratic but settled a few minutes later.

The oil I use in winter is 15W50. This seems to be the way to go to prevent oil circulation issues at cold temps. Boreal one, what oil do you use?

Yves

[BorealOne]

Hey Yves -

 

20w50 year round.

 

- Larry

[yvesg]

Larry, assuming you are using Phillips, the 20W50 pour point is -33 degrees C. The Aeroshell that I use has -36. Just a 3 degrees difference. Both are good Canadian winter oils however we can see that cooling those oils below -30 C will make them thick as molasse.

I am wondering what type of oil Aaron is using? He mentioned issues with his oil coiling on his return trip.

Yves

[aaronk25]

20w-50w Phillips with camguard. And your pour points seem right because all was good until I hit -36 to -38c.

[jlunseth]

Just as a rule of thumb, preheat if it is below 40 dF and use a cooler block below 20 dF. No cowl flaps open below 20 unless you see a reason on the panel.

[Super Dave]

Just as a rule of thumb, preheat if it is below 40 dF and use a cooler block below 20 dF. No cowl flaps open below 20 unless you see a reason on the panel.

I don't think it's ever a good idea to run with cowl flaps closed on the ground, even in arctic conditions.

[Shadrach]

I agree with Dave,

Cowl flaps stay open for ground ops. Maybe my thinking would "evolve" on this matter if i were operating in sub zero temps, but for temps that i fly in here in MD (12df was my coldest flying day this year), the engine warms up just fine and with the flaps open it does so evenly.... On landing I usually open them when I drop the gear just so I don't forget.

[aviatoreb]

I don't think it's ever a good idea to run with cowl flaps closed on the ground, even in arctic conditions.

 

Why not?

[jlunseth]

Sorry, but actual experience has for me shown just the opposite.  I agree that 20 is a little conservative (on the high side), but when it gets down to somewhere between 10 and 15 dF there are real consequences.  The most interesting was when my air/oil separator froze, which has the effect of causing pressure to build up in the crankcase which in turn blows oil out any available orifice, and can blow the front seal.  Short of that, I have seen oil temp drop and pressure fluctuate on takeoff several times.  If you have not built up significant temps in the engine compartment, and don't keep the cowl flaps shut to retain them, you will have problems the minute the airspeed picks up and the cold dense low level air hits the engine.  The problem in temps below 20 is retaining heat, not cooling, you will have plenty of cooling.  And notice I am talking about temps at low level.  Temps in the flight levels are routinely in the -25 dF range in the summer, but they do not have the same effect because the air is thin. 

 

The most vulnerable parts of the engine systems are not the engine itself, they are the oil cooler and air/oil separator that are on the firewall away from the engine, and for that matter any oil line that is distant from the engine.  You need all the engine compartment heat you can get to protect these.

 

That said, I have not flown an F and I understand they run hotter.  And by all means, if you find the temps rising above your comfort level open the cowl flaps.  I have just found that cowl flaps should stay shut during cold weather ops, in the air, on takeoff and on the ground.  The engine does not need help cooling itself.

[N201MKTurbo]

It got down to 40 last night. It is too cold to go outside. I might have to put socks on.

[jlunseth]

Yes, well write us again in July!  I spent a summer between high school and college on the desert west of Albuquerque staking mineral claims for a mining company.  We would run all day with a load of 2x2's on our shoulder.  107 F is not fun even if it is "dry heat."

 

I think the Mooney POH would have read differently about cowl flaps if it had been written by people in MN rather than the boys down in Kerrville.

[N201MKTurbo]

Funny thing, I've been an active member of road bike and inline speed skating clubs for the last 15 years. More people will show up for practice when it is 115 then when it is 40.

[jlunseth]

I usually put about 2000 miles on a bike in the summer.  You make your own wind.  We don't get 115, but we do get 98 dF and 98% humidity, and it is not uncomfortable on the bike.

 

I have found, however, that as I age (I am 64) and my max heart rate slowly falls, I need to not exert myself too much on the bike when it is hot.  My heart rate runs 10-15 bpms higher in those temps, and I just do not have as much room between normal operating heart rate and max rate anymore.  It was not a big deal until I turned 60.

[yvesg]

It got down to 40 last night. It is too cold to go outside. I might have to put socks on.

Arizona! This is where I want to move. N201MKTurbo, would you be able to help me find a job in AZ?

I will move!

Yves

[Marauder]

I usually put about 2000 miles on a bike in the summer. You make your own wind. We don't get 115, but we do get 98 dF and 98% humidity, and it is not uncomfortable on the bike.

I have found, however, that as I age (I am 64) and my max heart rate slowly falls, I need to not exert myself too much on the bike when it is hot. My heart rate runs 10-15 bpms higher in those temps, and I just do not have as much room between normal operating heart rate and max rate anymore. It was not a big deal until I turned 60.

Another cyclist! I ride in the winter even though I occasionally end up with ice cream headaches going downhill. Funny story, I rode on January 1st a few years back. It was 25 degrees out and I came upon a couple of cyclists. There were separated by a couple of hundred feet. I rode up on the back rider and said "Hi!" to him. I noticed he was a bit older and had a good 6 inch snot thread hanging off his nose. He said he was doing okay.

I then rode up to the front rider, an older woman. She asked me how he was doing back there. I said he looked a little tired but okay. She then said, "he was the one that wanted to ride today". She also told me he was 84 and she was 80! From that day on, I never, ever complain about bike riding or riding in the cold.

And I also hold out hope that I too can do what they are doing!

[N201MKTurbo]

We usually get the 110+ days in late June and Early July. The dew points are quite low that time of year down in the 30 and 40. It truly is a dry heat.

 

I would take a dry 115 over 98 deg and 98%RH any day. I did a marathon skate race in Tahiti once (2002). It was 90+ and almost 100% RH. That was the hottest I have ever been. My skin suit was stiflingly hot. One of the top finishers (Eddie Metzger) was wearing a speedo and a straw hat.

 

I hope everybody is enjoying all the talk about extreme heat!