Here is an excert from one of our engine manual thanks to Roger Lee (Australia).

"Basic laws of physics
1. Air expands when heated. Volume of hot air is greater than the volume of equal mass of cold air.
2. Volume is an inverse function of density. Increased air volume reduces the air density.
3. Increased air velocity leads to increased air volume over a constant flow area.
4. Air will flow down the path of least resistance.
5. By the law of thermodynamics, because the temperature of air is always lower than the cylinder head of a running engine, heat will be transferred from hotter cylinder head to the cooler air.

Efficient Engine Cooling
Efficient cooling aims at transferring the largest amount of heat from the cylinder head to the largest amount of cold air surrounding it. The most effective method is called Baffling. Baffling is the technique to channel / direct all intake air over the cylinder head, thus forcing air to flow across the engine rather than bypassing it. This is a very effective cooling method on air cooled engines.

To ensure constant flow of cold air around the cylinder, and to reduce the air pressure build-up inside the engine cowl, the hot air exhaust exit must have a much larger cross section area than the cold air intake. As a rule of thumb, allow 4 times the area for exhaust air than intake air, this may be achieved by reducing the intake area (as in a radial type cowl) and expanding the exhaust area. Air entering the smaller cowl opening will expand and cool existing at a lower velocity, further aiding cooling of the engine

Cooling for Various Engine Configurations
Type 1 – Scale model of planes powered by radial engine. E.g., Corsair F-4, FW-190 (see pic)
Type 2 – Scale model of planes powered by liquid cooled engines. E.g., Mustang, Spitfire. (this is what Shadow has)
Hint: use a baffled intake below the huge spinner to redirect airflow on to and around the cylinder head. Note that the host engine exhaust gas exits below the cooling air. This cooling configuration gives sufficient cooling to the engine. It also helps to keep the model clean during flight. The optional scale exhaust not only gives a scale look, it also functions as additional exits for warm air inside the engine cowl.


Peace,
Steven Chao,
CERMARK