NEVER start a recip with the oil temperature below about 40°F.

[steve181]

(which is 4.4°C) according to John Deakin's Pelican's Perch prop article (http://www.avweb.com/news/pelican/182082-1.html)

What kind of OAT would give you an oil temperature of 4.4°C? Wouldn't it be something like -15°C? If that's the case I was wondering why John would mention it when it wouldn't apply to most pilots?

Thanks

[Joker 10]

Any cold soaked engine in the higher latitudes of Canada, US,Russia,Scandanavia to name a few would be below 4.4 degrees celcius core tempreture, easily achieved just outside in winter for 24 hours +

[steve181]

Oh ok, thanks for that Joker. The winter isn't too harsh where I live, maybe -5°C max during the night so it wasn't really up there on the priority list of things taught to me when I learnt to fly I guess.

Just out of interest in those particular cold parts of the world how do they go about warming the oil before they start the engine? Do they sit a warm hose over the engine for a while?

[djpil]

Heated hangar or sump heaters for aeroplanes.

We had an insulated garage and as long as we drove the cars every day they'd be OK otherwise a sump heater was needed too.

Typical max temp in January was -10C. My thermometer only went down to -30C and was usually off the scale below that in the mornings.

[ForkTailedDrKiller]

What kind of OAT would give you an oil temperature of 4.4°C?


OAT = 4.4oC :E

Dr :8

[Mach E Avelli]

The good Doctor is right. Oil will eventually reach ambient.
In days gone by on the big radials, flying in the Arctic we diluted oil with fuel prior to shutdown. We had a table in the cockpit which told us how long we had to run the diluter pumps, according to temperature and the anticipated time we would be shut down. Raw fuel was mixed with the oil to thin it.
On start up, we had another table to give us the 'boil-off' time. With the engines running at a fast idle, time was allowed for temperatures to come up and boil off excess fuel, to allow the oil to return to something approximating the viscosity needed to properly lubricate. On real long shutdowns, there was nothing for it but to either pre-heat, or go into a heated hangar for the night.

[Aerozepplin]

What do you use to heat the oil/sump if you don't have a hangar? I've got images of electric blankets around a big Wright radial that I can't shake.

[Red Jet]

Herman Nelson heaters are used widely in the colder climates. Basically a propane driven heater with a long insulated hose that gets hooked up to the underside of the engine cowls, with a gaggle of pilots and engineers hangin around to try to "steal" some of the heat for themselves as well! Looks like a big ghost busting machine, but the glorious heat they radiate on a -30C morning is absolutely glorious. Electric blankets are also used for engine cowls and props if operating near civilization.

[compressor stall]

Yup and turbines use them too: Herman Nelsons or equivalent to keep the engine bay warm. Also Tanus heaters (or block heaters) for the sump. Also Electric blankets for the battery to keep it warm.

And people wonder why preflights take so long....:rolleyes:

And black wings help. No, not that sort either :=

[Aerozepplin]

:eek: Those heaters do look pretty crazy.

Are there any other engine operating differences for extreme cold? Just curious mainly, would enjoy working somewhere chilly one day. I've worked various vintage machinery since I was a wee fellow and apart from my old 60's car (I think I've actually died of hypothermia while driving her once) it was always special running things on a cold morning. Maybe the extra care you had to put into the equipment made you appreciate it more.

[sms777]

In northern America including Canada most automotive engines equipped with a engine block warming device that simply replaces your expansion plug most commonly known as Welsh plug in the side of your engine block. It simply warms up your coolant with the ignition turned on while you are having a cuppa in the comfort of your lounge room.
I know it is a bit more difficult in your air cooled aircraft engine but it is an advantage if you have water cooling.

[MakeItHappenCaptain]

Just out of interest in those particular cold parts of the world how do they go about warming the oil before they start the engine?

If anyone from RQAC flies VH-AFR (C172S) check inside the pilot's side cowl intake. There is suspiciously what looks like a hard wired American domestic power plug.
Further investigation with LAMEs and the conclusion was for plugging in an extension lead.(?)

Guido's Sea Fury apparently used to have its oil pumped through an external heating unit prior to startup for cold temps.

[compressor stall]

http://i663.photobucket.com/albums/uu353/stallie001/aviation/_DAN0627.jpg

[VH-XXX]

If this interests you you need to download and watch Ice Pilots NWT, details in the other thread. They operate radials to -40.

[steve181]

It's all very interesting, thanks for the posts.

Thanks for pointing that out Dr re: Oil temp = ambient temperature. :ok:. Just to clear up my confusion; if oil freezes at lower temperatures than 0°C at 0°C oil will have a temperature of 0°C but because of it's properties it will remain in liquid form?

When I was learning to fly I'm sure I started an engine with an OAT of 4.4°C or less & the instructor never mentioned anything? Maybe it's something I should talk to the CFI about because I've never been told of a before start procedure on very cold mornings. Maybe they just have the attitude that most starts here are above 4.4°C so the odd start under that temperature isn't going to bust the bank?