What's the difference of air plane engine cooler?

Question

I don't know much about air plane engine, but yesterday I saw something about liquid cooler engine.

Any other cooler is available and what's the difference?

At the high altitude the temperature is cold, why cooler is still needed for air plane engine?

Answer 1

Air and water (glycol) are your choices.  Air is lighter, and has less moving parts/things to break -- radiator, water pumps, etc.

Rolls-Royce built several famous water-cooled engines; Merlin, Griffon, etc.

Answer 2

Small aircraft have air cooled engines because they are lighter and less complex then water cooled engines. There is however a diesel engine that is on the market that does have water cooling. Not sure why it is water cooled other then its makes for better engine temperature control.

The most engine cooling required is at low altitudes and high power setting when taking off and climbing to altitude so the cold of high altitudes is not available for cooling.

Answer 3

To answer you question correctly you have to understand aircraft engines and automotive engines are totally different.

First automotive engine are designed to operate at below 212-degree temperature and are not designed to operate at full rated horsepower rating.

On the other hand aircraft piston engines operate up to a max temperature in most case of 245 degrees.  The reason is the tolerance is larger for aircraft engines because of the heat expansion of metal parts.  It’s important to know aircraft engines are designed to run at full power setting with no problems (don’t try this with an automotive engine).

Aircraft and automotive engines are both 4-cycle and work on the same principles.  Aircraft engine burn a much higher octane fuel to prevent vapor lock and denotation (knocking), which will severely damage your engine.

The cooling part is for the oil.  In aircraft the abound of fuel and  oil is used to control temperature and lubrication.  Some engine will have an oil cooler install to provide addition cooling in very hot environments.  The oil cooler will by-pass the oil if its temperature is to low kind of like a radiator in you car.

The reason aircraft use air-cooled engines is simple weight to power rating.  Having a water-cooled engine requires a lot of plumbing, storage, pumps and so on, which is excess weight.  Air-cooled engine don’t need the additional equipment and are less complicated because of this fact.

Aircraft engines are warmed up to an operating temperature for a couple of reasons.  One is the cylinders are taper bore, which means the top of the cylinder is narrower than the bottom.  At operating temperature the top expands to make the cylinder wall straight up and down to put it in simple terms.  The engine case half are made of aluminum and the crankshaft bearing is steel different expansion rates and at operating temperature there is an exact space between the parts for the oil.  Again oil removes heat between this parts and lubricants them.

Not all aircraft require an oil cooler.  Many high power aircraft will have an oil cooler or if you live in the desert areas where ground temperatures are very high.  It is very possible to over heat an aircraft engine on the ground because of low air flow over the cylinder.  An oil cooler will help removing the heat from the engine and passing it out through the oil cooler.

You can find addition information on this subject in for free on the FAA web site at http://www.faa.gov look under AC’s and look up AC 65-12.

Answer 4

Actually in smaller air planes the fuel itself is used as a cooler. Although  at high altitude air is cooler, the heat from the engine needs to be dissipated faster, since a hotter engine has less efficiency.

Answer 5

Rotax and Hirth make small two aircraft stroke engines that are water cooled. These little uncertified aircraft engines are between 65 and 100 HP and are generally put on ultralites and light sport aircraft. Rotax also makes a certified (and uncertified version)100 HP 4-stroke engine that has water cooled cylinder heads with air cooled cylinders. It is called the Rotax 912.

They are pretty much jet-ski and snowmobile engines that have been optimized for aircraft usage.