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Cold weather and flying

LettersFromFlyoverCountry

Well Known Member
We had a discussion at the hangar about this and while we both had heard various no-go temperatures, neither of us knew exactly why. So I'll put it out there this way: What's the temperature, below which you will not fly?
 
Ours are almost entirely pilot limitations. We've gotten to the airplane and looked at each other on a beautiful clear day and said "what were we thinking", and gone back home. I know it is funny, but this is supposed to be fun.
 
0F to 5F once in the air with a good heater you don't know the difference, I have vetterman mufflers with heat muff, it amazing how much heat you get.
Tim
 
Bob,

I agree with Scott that it is a personal limitation more than anything.

There is almost nothing better than flying in cold Minnesota on a clear day. Aircraft performance is amazing in the dense cold air and there is almost no turbulance. I really enjoy it.

However, when the temperature reaches about -10 to -15 degrees F, for me, the pain outweighs the gain.

So my personal limit for enjoyable flying is -15 degrees F.
 
Try a J-3 on skis in subzero temps (out of Anoka County) ... but I was a lot younger then!

I really don't have any firm temp limits in terms of flying - so long as the airplane comes out of a warmed hangar if the temps are below freezing. Preflighting and getting ready to go in the cockpit when everything is frozen is just plain work!

Paul
 
As I get older my cold weather limit is rising. Currently -10F is plenty cool enough- and that's coming from a Canadian.
Realistically, with a properly prepped aircraft -25F is doable, if not comfortable. But if you are up for winter flying (fantastic by the way) be sure to personally prep with winter survival gear aboard too.
 
Cold cold cold

Here in the mountains of Colorado it is common to fly at temps in the minus 5 to minus 10 if the sun is shining but then I installed two heat muffs, one on each bank. With the sun shining in the cockpit it stays quite nice, but heaven help you if you fly under a cloud. One interesting thing happens quite often is to have way below zero on the ground and temps as much as 30 drgrees warmer a couple of thousand feet in the air.....
 
0 to 10 on clear days. Only if preheat was on.
15 to 20 on cloudy days.

Flew regularly down to -10 or -20 in my younger days in Minnesota. Never really thought twice about it as the Tomahawk actually felt peppy (if you got it started).

All temps in F
 
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Try a J-3 on skis in subzero temps (out of Anoka County) ... but I was a lot younger then!

Paul

I agree with Paul. I flew a Taylorcraft for 18 years and when I was younger 20 degree days were doable. I think more wind came in the cabin than went over the wings.

Now, I'm a Florida wimp (and I have real heat in the RV) and I don't fly if it's below 50 :D
 
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The company I work for says -30c (-22f) for pistons and -40c (-40f) for turbines. As I had it explained to me, the -40 cutoff is because that's where the steel axels and other metal parts get too brittle. It also takes noticably more power to taxi because the wheel grease is so thick.

My answer to lower tempuratures is buy warmer clothes. :D
 
Wind chill is the thing for me. Cold, clear, and no wind is one thing, blustery just makes preflight too painful. Back in a former life, I flew my Phantom ultralight as cold as minus 5 and loved to land on frozen lakes. Snowmobile suit and I was ready to go! Now, since I have to go out and preheat, about 10 is my limit in my unheated hangar.

Respect the cold! On a long flight in the u/l at around 45 degrees, I didn't think it necessary to dress all that warmly. An hour into the flight, I went into hypothermia at about 2500 feet that day, and it was the scariest flight of my life. I was shaking so badly I couldn't hold onto the stick and my vision was a little blurry. At about 200' the shaking subsided enough to land. Like anything else in flying, preparation is everything.

I will say the RV-12 with its run-you-out heater will probably make this winter more of a fun experience. I will bypass my 9A if I am just going out for fun. That heater rocks!

Bob
 
The coldest day I have taken off in was ~ -18F. The coldest in flight temp I've seen was about -28F. Flying in the cold air is generally pretty nice, especially out here in Colorado where it makes the DA go down to 3900 feet. :cool:

Coming back from St. Joseph last week it was 12F on takeoff, but as soon as I got a thousand feet in the air, temps went up to above 30F. By the time I got to KFTG they were above 50F (I had put on thermal undies expecting colder temps and I was roasting). Inversion type weather/temps seem to be pretty common out here.

The biggest problem I have with the cold is how it affects metal...:( On those days when the temp gets colder at altitude and stays there everything starts to get stiff. Stepping on the rudder makes you think it is jammed. :eek: The stick gets harder to push around etc. Stopping for breakfast when it's in the minus numbers means the engine and parts stiffen back up really quick. Not sure just how detrimental that is to the plane/engine.


KSTJ St. Joseph, MO closed for snow removal last week.

stjoe.jpg



So this is what Kansas looks like with snow...

kansaswithsnow.jpg


Regards,
 
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Being in Florida I have never even considered a low limit. Every day is flyable. Well except maybe hurricane days.
 
The coldest day I have taken off in was ~ -20F. The coldest in flight temp I've seen was about -28F. Flying in the cold air is generally pretty nice, especially out here in Colorado where it makes the DA go down to 3900 feet. :cool:

On those days when the temp gets colder at altitude and stays there everything starts to get stiff. Stepping on the rudder makes you think it is jammed. :eek: The stick gets harder to push around etc. Stopping for breakfast when it's in the minus numbers means the engine and parts stiffen back up really quick. Not sure just how detrimental that is to the plane/engine.

I don't think I've seen -28F while flying but it has been darn cold at times. I know one Christmas heading to KOCH my wife and I almost froze to death with OAT -15F and a malfunctioning heater. Fixed it at the fuel stop and all was well.

When temps fall to the single digits the controls start to get real stiff. Makes you wonder if something is wrong.
 
So what about your engine? Without preheat, what is the coldest you are prepared to start your engine? Do you use any different techniques.

I'm planning to install a sump heater, but for now I don't start below 3 deg. C
Don't know exactly why I picked that number. I use 15W50.
 
5*F in this pic during a lunch stop in Bozeman(BZN) during phase 1 testing
frozenRV-7.jpg


I recall 2700fpm climbing out, so on the way home I think it was -5f at 6500' so I tested the straight and level, WOT, 2620rpm....194Kts TAS WooHoo!

I normally don't like to open the hangar door if temp is <10F. Actually I worry mostly about cracking my canopy, going from heated at 50F to 0 or whatever. I broke a headset at -5 in the club 172 picking it off a cold glareshield one day.
 
My limits used to be based on how cold I could tolerate it when pre-flighting the plane outside (usually in the wind). Now I can preflight in the shelter of the hangar, and I have very good preheat for the engine, but I have kept my limits at about -20C or about -5F. It's not that it's too uncomfortable either preflighting or flying; it's survivability if I had to put the airplane down off-airport and wait for help. I never really thought about that for years, but started taking it into consideration when my son starting flying Harvard II's (T6's) at the training base here. Their temperature limits are based purely on survivability after an ejection, which started to make sense to me. Plus I'm getting to be a wuss as I get older;)

Having said that, there is absolutely nothing like flying on a clear, cold, windless day on the Canadian prairies; it can be magic-carpet smooth with takeoff and climb performance to burn. The other thing that people rarely mention is how easy that dense air makes landing; your ground speed for a given TAS is so much lower at these low temps and the dense air gives such a beautiful cushion in ground effect. Everything seems to happen in slow motion and you just settle sweetly onto the runway after flaring.

Jeez; I'm looking out the window at a gorgeous sunny, cold day and this is really making me want to go flying. I really need my medical back....:(
 
Steering

So I'm leaving LA (Lower Alabama) tomorrow for a trip to KIOW in Iowa to visit family for a few days. I talked to the FBO and they said there is "patchy" ice on the runway and braking is "fair". (5000' runway) How concerned should I be about steering on that runway/taxiway? I've never had the RV on any snowpack. The old PA-28 was a different story with nose wheel steering, though NO WHERE nearly as much fun!!!!

I opted out of my first choice of airports to stay at due to it being 100% snow and ice packed.
 
The "A" models steer just fine using rudder only. Braking is the issue. On snow packed surfaces I have had no problems. On ice you need to be really careful.
 
As a rule of thumb I generally don't fly when the temperature is less than my age. Started flying at 15 and now at 53 I can say that it works out about right :)

V/R

Jim
 
about 65 F. why do you think I live in southwest florida. :D

every time I move I go farther south. key west is looking real nice.

bob burns
N82RB

RV-4
 
0

I used to think I wouldn't fly if the temp were much below freezing. But, in the last few days I've logged about five hours cruising around central Minnesota at about 5 degrees F. It has been the most enjoyable flying I've ever done. Smooth air with tons of power and lift. I've had the heater and defrost on the warrior set at about half, and only need to wear a sweatshirt. :)
 
cold!

Flying in the cold can be dangerous. I have experienced hyporthermia in my Super Cub,
Several RV8 owners have had cracked canopys because of cole temps.

My limits are,,,, is it nice enough to go for a walk in a light jacket? If yes, flying will be comfortable too.
 
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As I had it explained to me, the -40 cutoff is because that's where the steel axels and other metal parts get too brittle. It also takes noticably more power to taxi because the wheel grease is so thick.
:D

Used to fly into the Alaska North Slope where I've seen less than-65F. The cutoff for turbine aircraft wasn't the outside temp, but what happens inside. At altitude the standard temp is -57C and the gear etc gets that cold every flight.

Jet A starts to jell at -40C and engines are limited to -40C on the oil temp for starting because it does the same thing. While there on site visits we used Jet B (-50C) and ran the engines every half hour so we didn't get stuck there until spring thaw. :eek:
 
20V @30 below

A newly purchased RV 4 was pulled out of a heated hanger on a 30degree below zero morning, he was on his first cross country and taking the 4 home back east, when the canopy cracked in about 5 different places.... They spent about two hours stop drilling, safety wiring and duct taping then he was off. I had just spent my life savings on ordering my own 4 kit so it was a good lesson on the care and feeding of these airplanes....
 
Temp limits

My personal limit (because I think you should have one) is zero F. The reason for 0 and not -5 is it is easy to remember. My rationale is simply that if I had an off field landing I felt I could survive longer in zero on the ground than -5 F on the ground.
 
Does anyone have bad experiences with cracked canopies?

Yup - I can cite several cracked canopies on RV-8's that correlate with cold weather - at least two of them on the same bird (sorry "Doll"....). The Val's canopy cracked after a cold night at Big Bear, followed by hitting some significant bumps in turbulence shooting down to LA.

Speculation is that this is more common with the -8's because of the long canopy....but that is, of course, anecdotal. I have yet to hear of it happening on other models.

Paul
 
49clipper

How about temps for the oil in cold weather? I fly all winter, but not normally below about 15f due to comfort, but I can't keep my oil over 150f even at 30f oat. I bypassed my cooler (since it did no good to block it off completely), checked the sensor (and found it to 14 degrees low), and even only put in six quarts of oil and the change, and I can only get 150f on the oil. I am down to trying to block off the exit area in order to warm it up. CHTs are all from 160-225 at 30f outside. Lycoming says no less than 165f on the oil, but I can't get there.
Any ideas?
Jim
RV-6 O-320-D1A carbed.
 
Flying in cold weather

Up here in Northern Ontario, Can. We fly down to 0 degrees F or about -20 C. Hoping it we rise during the day while out Ice fishing.... Just plane fun. Sorry for the pun.
Working Wings of a RV- 4:)
 
cracked canopies

Back when I was building I was curious about the effect of cold on plexiglass. I did some experiments with small samples that I made by riveting together two squares of plexi with the aluminum pop rivets used to hold the canopy to the frame. The squares where assembled with their edges slightly offset, so that I could put stress the rivet holes by clamping the assembly edge-wise in a vice.

The assemblies then went into the freezer overnight. I put them in the vice immediately after they came out, and squeezed. The net result of several such tests was that I was repeatedly able to shear the pop rivets, but never did manage to induce a crack in the plexi! From this I drew two conclusions: 1. plexi is strong stuff, and 2. moderate cold, by itself, does not necessarily make it crack.

I'm not sure what this means in the real world, but I suspect that cold helps existing cracks to propagate but doesn't actually cause them. Since doing the tests I've flown my RV-8 through 7 northern winters, commonly in 0?F temps and below. My canopy skirt does show some evidence of movement of the aluminum rivets (paint cracks above the heads in the aft skirt), but no there are no cracks in the canopy (yet).
 
How about temps for the oil in cold weather? I fly all winter, but not normally below about 15f due to comfort, but I can't keep my oil over 150f even at 30f oat. I bypassed my cooler (since it did no good to block it off completely), checked the sensor (and found it to 14 degrees low), and even only put in six quarts of oil and the change, and I can only get 150f on the oil. I am down to trying to block off the exit area in order to warm it up. CHTs are all from 160-225 at 30f outside. Lycoming says no less than 165f on the oil, but I can't get there.
Any ideas?
Jim
RV-6 O-320-D1A carbed.

Jim,

That is way too cold. You need to block off your air inlet more to raise the CHT temps. If you can't get over 225 CHT then I doubt you will get the oil temp you want. If it where me I would built aluminum block off plates, and drill some holes in them until it was letting about half the air though, then a short flight to see where I'm at and add more holes if needed.

Remember, this is an air cooled engine which means that the cyl expands when it gets hot. The piston/bore clearance is set to work at operating temp, which is why you want your engine well warmed up before takeoff. In your case, it never gets to operating temp which is dangerous.

Another issue is that your oil isn't getting hot enough to burn off the moisture, which can cause corrosion issues.

As for my limits, I live in Alaska and winter flying is great and if you have skis safer in my opinion since you have 5 times more options for a forced landing than in the summer, however I won't operate in less than 10f for fun flying, but I may go down to 0 if I really need to go somewhere.

The issue isn't the airplane since everyone up here has block off plates or cowl flaps and uses a red dragon to preheat, the issue for me is the survivability. At 0 or below if the crash doesn't kill you, the cold will, unless your very prepared.

As far as cold starting go, personally, I've started my airplane in 35f without worrying about it. The oil isn't that much thicker than at 50f. Anything less than that and ill preheat at least a little.

I should note this is with a multigrade oil which tends to not stick to engine parts as well so you need to use the airplane frequently, but it does really work better for cold starts.

I think that straight 50 weight oil protects the engine better overall if you have a hanger and preheat every time, but in Alaska this isn't very practical for most pilots.

Schu
 
In my earlier post I noted the coldest temperatures I have ever flown in. Those were the extremes that I've seen. To answer (The Original) "Bob Collins" question I don't normally fly in anything below Zero, it's just too cold. Flying in the cold is comparable to night skiing. I love to do both, but you need to be prepped and ready for it. :D

I am fortunate that my engine really seems to like the cold temps. On that coldest day, I seem to remember oil temps of around 150 or so. I see 170 to 180 when the OAT's are in the 10F to 60F temps. Above that, it just climbs proportionately to the OAT....:( (bigger oil cooler needed?) CHT's will run from 300 to 380 depending on OAT.

That said I am less inclined to go flying when it's Hot out. Once it gets above 90F the "Fun" factor starts to go way down for me. Coming back from OSH in 2007 was the worst. Siesmo and I couldn't get out of the 100 plus temps at altitude. My oil was 230 and it was too stinkin hot in the plane. :mad:

I guess that makes my flying range from 0F to 90F. :cool:

Regards,
 
49clipper

Schu,
I have since blocked off of 45% of my cowl exit area. Have not have the opportunity to fly since. In years past, with my Luscombe, I did the same thing you suggested and blocked off my inlets with plates and drilled one inch holes in them until I got my oil temps up (which it did), but had no way to no what the cylinders were doing at that time. I am reluctant to do that with the RV since it has such small inlets anyway. I would rather restrict the outlet so i do not screw up the airflow inside the cowl area above the cylinders. I did call Lycoming and they were pretty stumped. They want to see pictures of my oil cooler, hoses, and baffles, which I have already sent. They say, don't worry about the cyl temps till they get below 150f. But, the oil is another story of course. I also have removed a quart of oil (to five qts) which I know should bring the temp up some. The minimum on these lycs is 2 qts but recommended no less than four for normal use, so that will not hurt it. I have found that with less oil, the temps go up about 5-10f for each quart low which of course makes perfect sense to me.
I am an AP/IA and work on lots of aircraft, but have never run across this problem before (except J-3 cubs). Normally its a challenge to get them cool.
 
-65 C OAT

Our limit is -65 C for fuel gelling issues- strangely enough the coldest weather isn't over the pole but closer to the siberia area. If fuel gelling is observed, its funny they mention the ram air heating effect and obviously descending to find warmer air. I would hate to bail out over pretty much any of the places we fly over, even with all the survival equipment on board. I haven't ever quantified a limit for the -8, but I have deduced an equation: if desire to fly is greater than the deterence of the agony of chilling cold then I go fly. Otherwise no. Always giving consideration to cold effects and 'dress to egress.'

Out of curiousity, who does cold wx baro corrections for approaches in their RVs?
 
Went flyin' last night, temp at the airport, 7F. Nice full moon, no wind, temp at 3,500 MSL was 18F or so. I have 2 heat muffs, each feeding an "RV-4" style wedge airbox. Plenty of heat, even at night without help from the sun. I am in a 45F heated hangar so starts are not a problem. My limit is 0 degrees F or so. Up here we fly in the cold because we would not fly otherwise. You just need to follow the "rules" or it can more dangerous to you and your airplane than it has to be.
 
Speaking of cracked canopies, I had my plane on the ramp for a 2 nights at Angel Fire, NM, with the intent of bringing it in the hangar a night before I was to leave. I was pushing it in the hangar today and what do I find? I nice 4 inch crack straight up from the canopy locking handle that wasn't there when I parked her. Now, what to do. I am definitely not a builder, but I am assuming I can stop drill it and fly it home, maybe put some tape over it? How hard is it to replace a canopy, or have one replaced? Having never built I'm more inclined to either keep it as is, with a stop drill, or have someone replace it at next cond. inspection in July (I'll be deployed for a while so I don't mind the out of commission time...). Safe to fly until then? I'm wondering if there is a stress from the canopy handle that is the root of the problem? Thoughts? Thanks!
 
I flew my canopy stop drilled for about 6 mo. One day my buddy and I decided to 'G it up' in a long descending spiral at about 5G's for a few thousand feet and the crack connected with another stop drilled crack on the opposite side of the canopy- effectively seperating the canopy into 2 pieces. I worked with my A&P buddy and we 'sewed' the pieces together by drilling every inch on either side of the crack and running .005 safety wire through the holes to mend the break. It has since flown for another 6 mo until I can afford another canopy. Still seems very airworthy in my opinion. Good luck
 
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