ACTUATORS
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ARTICLE
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PHOTO
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COMMENT
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PRICE
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magnet servo
kit
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S1 the pair:
S2 the pair:
S3 the pair:
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20€
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magnet servos mounted
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3 sizes: small, medium, powerfull
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30€
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drilled magnets
grade 45
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grade 45 magnet diametraly magnetized 0.5mm diameter hole 25% more powerfull than a traditionnal grade 36 magnet
4 sizes: 4x1.5 mm 0.15g
4x2.0 mm 0.20g
5x2.0 mm 0.28g
5x3.0 mm 0.42g
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sold with the kit
2€
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accessories for magnet servos
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machine drilled bellcrancks, horns, hinges, 0.3mm carbon rods for hinges, 0.3 metal rod for Z (to be glued on the pushrod), and micro silicone balloons for trim system + detailed short article
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sold with the kit
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Pic magnet servo controler
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80 mg pic microcontroler for magnet servo control from a receiver signal
For coil >= 130 ohms
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8€
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Depending of the plane you are building, the mounting of a magnet servo differs.
For a scaled model, you prefer to see the less things possible and have hidden servos.
For an ultralight model, the consumption is important as the cell can't supply too much current.
For these reasons, the concept of a magnet servo kit, modular and adaptable to all the situations has the following advantages:
- you can choose the coil for high power or low consumption.
- you can choose the magnet for an optimal weight for the torque needed.
- you can choose the confoguration to hide or not the servo and always have the bellcrancks in front of rudder and elevator horns so that the pushroads can work in a direct line to minimize frictions.
- a pre build servo minimize dramatically the price.
We use a Mac Donald's paws 6.85mm as the coil and axis support.
The grade 45 magnets (25% more force in relation to classicals grade 38) are diametrally magnetized so that they can turn around their 0.5mm center hole.
Four sizes for the magnets:
A1: 5x3mm 0.4g
A2: 5x2mm 0.3g
A3: 4x2mm 0.2g
A4: 4x1.5mm 0.15g
Three types for the coils:
B1: 55 ohms 7/100 wire 0.40g
B2: 130 ohms 5/100 wire 0.28g
B3: 65 ohms 5/100 wire 0.14g
Their inner diameter = 7mm. They slip on the paw.
This gives 3 main configurations for a remote magnet servo:
S1: A1 + B1 (fixed axis, mobile magnet)
S2: A2 + B2 (fixed axis, mobile magnet)
S3: A2 + 2B3 (mobile axis, fixed magnet)
Others configurations possible.
S3 configuration is good for scaled models, but there is a price to pay: separation of the coils with the axis between gives around 20% torque penalty compared to an unique coil.
The distance between the 2 axis is 22mm. The 2 magnest influence each other. This helps to maintais rudder and elevator at the neutral.
Accessories enveloppe is sold with the kit and contains machine drilled bellcrancks, horns, hinges, 0.3mm carbon rods for hinges, 0.3 metal rod for Z (to be glued on the pushrod), and micro silicone balloons for trim system.
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S1 type servo:
high torque (4.2g with 5mm arm at 3.6V)
but higher consumption (60 ma)
and more weight: 2 servos on balsa sheet = 1.8g
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S3 type servo:
external axis is very convenient for scaled models
2x65 = 130 ohms coil
lower consumption for light models
smaller torque
light: 1.3g for 2 servso on the balsa sheet
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Configuration
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weight
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torque (5mm arm)
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consumption (3.8V)
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S1 (A1 + B1)
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0.8g
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4.2g
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60 mA
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S2 (A2 + B2)
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0.6g
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1.6g
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27 mA
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S3 (A2 + 2B3)
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0.6g
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1.3g
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27 mA
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S4 (A1 + 2B3)
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0.7g
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2.1g
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27 mA
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S5 (A1 + B2)
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0.7g
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2.6g
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27 mA
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Agrade38 + 2B3
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0.6g
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1.1g
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27 mA
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