| |
Ferrite "Can" |
Ferrite Car |
Cobalt/Neo |
Brushless |
| Cost |
Low cost - $10..$30 |
Medium cost - $20..$50 |
High cost - $125..$600 |
Very high cost $400 + |
| Quality |
- Low quality
- Brass bushings
- Carbon brushes on leaf springs
- Cheap ferrite magnets
- Large armature-magnet gap |
- Medium quality
- Bushings or ball bearings
- Copper or silver brushes
- Brush holders and separate springs
- Better ferrite magnets
- Some have adjustable timing |
- High quality
- Ball bearings
- Thicker output shafts
- Large brushes (usually silver)
- Brush holders and separate springs
- Powerful cobalt or neodym magnets
- Adjustable timing |
- High quality
- Ball bearings
- Thick output shafts
- No brushes
- Powerful cobalt or neodym magnets
- Adjustable or self-adjusting timing |
| Weight |
Heavy (~2.3lb/HP) |
Heavy (~2.3lb/HP) |
Light (~1.5lb/HP) |
Very light (~0.5 to 1.2lb/HP) |
| Efficiency |
- Narrow efficiency curve
- Maximum efficiency about 70%
- Typically about 60% |
- Narrow efficiency curve
- Maximum efficiency about 75%
- Typically about 65% |
- Wide efficiency curve
- Maximum efficiency about 80%
- Typically about 70% |
- Wide efficiency curve
- Maximum efficiency about 85%
- Typically about 75% |
| Power |
- Maximum power at about 50% efficiency
- About 140W out for a 7oz motor |
- Maximum power at about 55% efficiency
- About 140W out for a 7oz motor |
- Maximum power at about 60% efficiency
- About 220W out for a 7oz motor |
- Maximum power at about 65% efficiency
- About 280W out for a 7oz motor |
| Advantages |
- Cheap!
- Readily available
- Can often be found surplus
- Wide range of sizes
- Low cost is great for multi-motor models |
- Fairly inexpensive
- Readily available
- Brushes replaceable
- Some have ball bearings
- More efficient than "cans" |
- Brushes replaceable
- Ball bearings for long life
- More efficient than car motors
- Low maintenance
- Wide voltage and current range |
- Zero maintenance
- Ball bearings for long life
- More efficient than brushed motors
- Very wide voltage and current range |
| Disadvantages |
- Difficult to maintain
- Brushes not replaceable
- Loses power at high temperatures |
- Difficult to find specifications
- Limited selection of sizes |
- Fairly expensive
- Harder to get
|
- Very expensive
- Requires special speed control
- Not usually in stores |
| Examples |
- Graupner Speed 400, 600, 700
- Great Planes Goldfire and Thrustmaster
- Master Airscrew
|
- Kyosho Magnetic Mayhem
- Trinity Speed Gems (Ruby, etc.)
- Leisure Model Electronics |
- Astro Cobalt
- Cermark Cobalt
- Graupner Ultra Neodym
|
- Astro Brushless 020 and 05
- Aveox
- MaxCim
- Kontronik
|
Effect on Power
- Sailplane with 12x8 prop and 7x2000 cells, geared for 4 minute run |
- Graupner #1793 Speed 600 7.2V
- 2.65:1 gearbox
- 25A input
- 123W output |
- Kyosho Magnetic Mayhem
- 2.7:1 gearbox
-25A input
- 128W output |
- Astro #605 Cobalt 05 Sport
- 2.5:1 gearbox
- 25A input
- 146W output |
- Aveox 1406/3Y
- 2.4:1 gearbox
- 25A input
- 159W output
|
- Effect on Run Time
- Sailplane with 12x8 prop and 7x2000 cells, geared to give 138W output |
- Graupner #1793 Speed 600 7.2V
- 2.2:1 gearbox
- 32A input
- 138W output
- 3:12 run time
|
- Kyosho Magnetic Mayhem
- 2.3:1 gearbox
- 31A input
- 138W output
- 3:19 run time |
- Astro #605 Cobalt 05 Sport
- 2.6:1 gearbox
- 23A input
- 138W output
- 4:24 run time |
- Aveox 1406/3Y
- 2.55:1 gearbox
- 22A input
- 138W output
- 4:44 run time
|
