[imsofuture]

I know that for piston engine aircraft, it is critical that the engine be properly warmed up before takeoff. Otherwise, the engine would likely stall shortly after liftoff, leading inevitably to a crash. This is a common cause of accidents.

This is not true. Engine start to takeoff is usually at least a few minutes, but there is no critical temperature factor for the engine (barring extreme heat or cold).

It's a lot like a car, you don't want to overly stress by flooring it when cold, before oil is circulating comfortable -- but running for 10s of seconds is plenty to get going.

[WalterBright]

My source is my father, who flew 23 different types of aircraft, single engine, multi engine, piston and jet. He spent some years as a flight instructor, and a crash investigator for the Air Force.

He said not properly warming up the piston engine meant that there was cold oil still in the reservoir, and sucking that into the engine would cause it to stall, usually right after takeoff, causing many accidents.

I've read about it in the paper myself a couple times, the report goes like the engine stalled right after takeoff and the airplane crashed. Didn't warm the engine up.

I can see this in my car. If the engine isn't warmed up, pulling into traffic often meant it would stall right in the middle of the lane I'm trying to cross, leaving me vulnerable to being rammed.

Now, if you're in an airplane overloaded with gas and bombs (and combat missions are always overloading the airplanes), you're going to make darn sure the engines are all at normal operating temperature before you start the roll. And you're going to fly right through the smoke of the previous guy whose engine hiccuped after he was committed.

I've flown in a Cessna a few times, and the pilot will always trundle out to the runway, set the brakes, and run it at full power making sure it's warmed up and both magnetos are working. I'd get out if he didn't :-)

[yason]

I can see this in my car. If the engine isn't warmed up, pulling into traffic often meant it would stall right in the middle of the lane I'm trying to cross, leaving me vulnerable to being rammed.

Sounds like your car is broken if that really happens.

A functioning car engine won't stall when pulling into traffic because of cold oil. Surely it will just wear out horribly and its lifespan will shorten to a fraction if you do that regularly but today's oils still work pretty good when cold and there will be some circulation to prevent pistons from grinding themselves stuck or bearings from mushing themselves into powder.

I could imagine you could get your engine stuck for real in very cold weather if you cold-start the car and floor it right away before there really is any practical oil circulation at all. Even if you really try this it's still more likely you'll wear out bearings first and get served a knocking engine rather than a stall or stuck pistons.

But your wording by "often meant" suggests that this stall would happen regularly if you did it with a cold engine so unless you live right next to a highway on-ramp your car probably had something else broken, causing it to stall.

[ncmncm]

Cold oil lubricates better.

It has higher viscosity, meaning it takes more energy to move it out of the way. As it warms up, its lubricating power decreases, but not too much, and its viscosity decreases, enabling better engine efficency. A cold engine is less efficient, but only for a short time, until it heats up.

Oil too thick to pump rarely happens in normal life. In arctic and subarctic conditions people use electric heaters to keep the oil thin enough to pump.

[chrisseaton]

> Cold oil lubricates better.

By this logic a solid would be the best lubrication, which it clearly isn’t.

[ncmncm]

If you had solid oil -- i.e., wax -- between your moving parts, metal would not be touching metal, so no wear, but the force needed to move the parts would be large. With cold but not solid oil, the effect is similar, but less.

[WalterBright]

> Sounds like your car is broken if that really happens.

Yeah, it happens with every carburetor car I've ever had, less so with fuel injected ones. It takes about a half mile of driving to where it won't happen.

[Symbiote]

I remember this (reported in mainstream news as well as this eco-blog), with pollution at London Heathrow reduced by taxiing with only one engine running.

I don't know if it was implemented generally.

https://www.treehugger.com/aviation/airports-can-cut-noise-p...

[bluGill]

Takeoff is when an airplane engine needs to be at full power. Thus the time when you need the engine warmed up the most is right after startup.