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Guide to Remote Control RC Model Helicopters: What Are 2, 3, 3.5, 4, and 6 Channel Helis? What Is a Gyro?

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A visual comparison of all the different sizes of RC helicopters available, from the biggest to the smallest (yes, they do vary by that much, from 8 inches to child-sized!)

A visual comparison of all the different sizes of RC helicopters available, from the biggest to the smallest (yes, they do vary by that much, from 8 inches to child-sized!)

Introduction

With the advent of lightweight lithium polymer batteries and powerful yet tiny motors, the genre of mini remote-control model helicopters is available for a cheap price (as low as $25 in the US). They can be found in mall kiosks, Best Buy, and similar electronics stores, as well as toy stores and many other outlets. However, the cheapest stuff may not be suitable for you. This guide will explain all the buzzwords, and what to look for when it comes to buying such RC helicopters.

Pro-hobby RC Heli Sizes

Pro-hobby RC helicopters generally are classified by either blade length or engine size.

For example, for a pro-hobby electric RC helicopter, you will often see the word "500 class". That means the rotor blade is roughly 500 millimeters (mm) in length though it can include blades that are shorter. The actual main blade size can vary slightly due to different blade tip designs.

For the pro-hobby grade helicopters with glow (i.e. nitro) engines (see "Classify by Engine") the size class is based on the engine displacement (i.e. how big are the cylinders). These engines are tiny. For example, a "class 30" nitro engine would have a displacement of 0.3 CI (cubic inches). Nitro engines can go up to 90 (0.9 cubic inches). They do not correspond directly to rotor blade size, but here's a rough translation table (it can and often do vary).

Rough equivalency table of RC heli nitro engine class, displacement, size, and equivalent electric RC heli size class

Nitro ClassNitro SizeRotor SizeElectric Class

30

0.3 CI

500-550 mm

500

50

0.5 CI

600-650 mm

600

60

0.6 CI

650-700 mm

650

90

0.9 CI

700 mm

700

Here's the WLToys V922 next to a can of 12 oz Pepsi... Yes, it's that small, and yes, it's a full 6 CH bird.

Here's the WLToys V922 next to a can of 12 oz Pepsi... Yes, it's that small, and yes, it's a full 6 CH bird.

Types of RC Helicopters

There are three ways to classify RC helicopters: engine, size, and sophistication.