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RC helicopter sizes explained
By Paul Walsh Last reviewed
RC helicopter sizes are described in "classes", such as a 450 or a 700. The naming is a bit loose, but the idea is simple: the number roughly matches the main blade length in millimetres. A 700 class helicopter uses blades about 700mm long.
The size classes
Figures are typical examples, mostly from current Align and other UK dealer listings (Model Helicopters UK).
| Class | Typical rotor diameter | Typical battery | Where to fly | Examples |
|---|---|---|---|---|
| Micro (under 150) | 150 to 300mm | 1S | Indoors | Blade Nano S3, RC ERA small scale |
| 150 to 250 | 300 to 450mm | 2S to 3S | Halls, calm outdoors | Goosky S1, OMPHobby M1, Blade 150 S |
| 200 to 300 | 450 to 550mm | 3S | Outdoors, light wind | Blade Revolution 235 CP, T-REX 300X |
| 380 to 420 | 700 to 900mm | 6S | Club field | Goblin 380, OMPHobby M4 |
| 450 / 470 | 700 to 850mm | 3S (classic) to 6S | Club field | T-REX 450, 470LP |
| 500 to 550 | 1050 to 1250mm | 6S | Club field | T-REX 500X, 550X |
| 600 to 650 | 1350 to 1450mm | 6S to 12S | Club field | T-REX 600, 650X |
| 700 | about 1580mm | 12S | Club field | T-REX 700X, Goblin 700 |
| 800 | about 1.8m | 12S to 14S | Club field | Mikado Logo 800 |
How size changes the helicopter
Stability. Bigger rotors carry more inertia, so large helicopters feel smoother and less twitchy, and cope better with wind.
Visibility. A 700 class helicopter is easy to see at a distance; a micro disappears quickly outdoors.
Cost. Everything scales up: batteries, blades, servos and crash damage. A crash on a 700 can cost more than a whole micro helicopter.
Safety. A 700 class rotor is about 1.6m across and spins very fast. Large helicopters belong at club fields with proper separation from people. The UK rules for RC models explain distance requirements.
Transport. Larger helicopters need a big car boot or a carry case.
Which size for a first helicopter?
- Indoors: micro.
- First outdoor collective pitch: 200 to 300 size, stabilised. Crashes are affordable and the helicopter is steady enough to learn on.
- Second helicopter: 380 to 500 size, usually at a club.
Size is only one decision; the type matters more. See coaxial vs fixed pitch vs collective pitch, then the RC helicopter buyer's guide. Typical running costs by size are in how much does an RC helicopter cost, and every guide is on the RC helicopters hub.
Frequently asked questions
What size RC helicopter is best for a beginner?
A micro for indoors, or a 200 to 300-size stabilised model for a first outdoor collective pitch helicopter. Bigger helicopters fly more smoothly but cost much more when you crash.
Are bigger RC helicopters easier to fly?
They're more stable and easier to see, so in some ways yes. But they're heavier, more dangerous and far more expensive to crash.
What does 450 class mean?
It refers to the classic Align T-REX 450 size, with main blades of roughly 325 to 360mm and a rotor of about 700 to 800mm.
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