CG (Center of Gravity)

CG ("Center of Gravity"): For modeling purposes, this is usually considered -- the point at which the airplane balances fore to aft. This point is critical in regards to how the airplane reacts in the air. A tail-heavy plane will be very snappy but generally very unstable and susceptible to more frequent stalls. If the airplane is nose heavy, it will tend to track better and be less sensitive to control inputs, but, will generally drop its nose when the throttle is reduced to idle. This makes the plane more difficult to land since it takes more effort to hold the nose up. A nose heavy airplane will have to come in faster to land safely.

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Carburetor

The part of the engine which controls the speed or throttle setting and lean/rich mixture via setting of the needle valve.

Wiki:

A carburetor (American and Canadian spelling), carburator, carburettor, or carburetter (Commonwealth spelling) is a device that blends air and fuel for an internal combustion engine. It is sometimes, but not always, shortened to carb in North America and the United Kingdom.

Slide Carburetors

A slide carburetor has a throttle valve that slides out the side. This reduces air restriction, for better performance, and requires the servo to move less to open it fully, for better throttle response. They also require a more precise alignment of the carburetor and throttle servo to prevent binding, which can result in dangerous stuck throttle conditions, which can often only be resolved by killing the engine after the vehicle is stopped by a large immobile object like a tree. Slide carbs are used on all big block nitro engines, and on many small block nitro engines. They are fairly prone to sticking because of dirt, and on land vehicles, an air filter is always used.

Rotary Carburetors

Rotary carburetors have a barrel with a hole in it that rotates. This takes more servo movement to completely open, and reduces throttle resopnse. They also have more restriction, which can reduce overall power. Some people feel that these are better for offroad use, because they have more throttle range. They aren't used on big block engines. They are as prone to dirt as a slide carb.

Butterfly Carburetors

Butterfly carburetors are common on gasoline RC engines and small 2 stroke engines designed for other purposes but used on RCs. They have a butterfly, or a thin piece of metal that rotates to open the throttle. They don't stick when they get dirty, but the dirt can still cause engine damage and poor performance. These carburetors are also used in alot of full scale applications, like cars and lawnmowers. They often have a second butterfly as a choke valve, to reduce air flow, temporarily richening the mixture for easier starting. These carburetors have more restriction then other carburetors, but the engines they are used on are larger, and the performance doesn't matter as much.

Nitro Rc Engine Diagram

• Cylinder Head
• Glow Plug
• Pullstart
• Combustion Chamber
• Piston
• Exhaust port
• Carburetor
• Mixture needle
• Idle screw
• Throttle linkage
• Crankcase
• Crankshaft

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