CanSat Rover 2526

Mechanics

Folding

1. Rover

Tires and motors

https://www.vcalc.com/wiki/vcalc/rpms-to-linear-velocity

Diameter 4 cm

RPM	Speed (cm/s)
15	6
30	3.1
Example	Example
68	14.2
381	79.796
Example	Example

Designs

File:Version1.zip

2. Boat / Snowmobile

Idea

Aerosled

With tutorials etc https://www.thingiverse.com/thing:4496127

• XXD HW30A 30A Brushless Motor ESC For Airplane Quadcopter.
  • Weight: 25g
  • Dimensions: 45 x 24 x 11mm
  • Price: 6€
• Racerstar BR2212 2450KV 2-3S Brushless Motor For RC Models
  • Weight: 52g

Power Arduino/ ESP32 from a powerbank. ESP32

• 2.2V to 3.6V input voltage. 3.3V is optimal. Cells around 3.7V (Li-ion) provide ideal voltage. V_in(max) = 12...16V?? The voltage regulator is AMS1117: may run hot if too much voltage.
• 10 mA - 500 mA
• ESP32 incorporates a regulator that steps down higher voltage supplies to a steady 3.3V output. The common AMS1117 regulator can deliver up to 800 mA, sufficient for most applications.

Powering the sensors and external components separately is highly recommended.

Motor options

• BetaFPV 19000KV Motor (7x16mm), 2.95g, 3.7V

Thrust

The thrust coefficient, $C_{T}$ measures how much thrust a propeller makes compared to the air pressure it faces. $Thrust=C_{T}\times \rho \times A\times (\omega \times r)^{2}$

Example

Header text	Header text	Header text
$C_{T}$	0.12
$\rho$	1.225	kg/m³
Propeller area $A$	0.0314	m²
Angular Velocity (ω)	314	rad/s
Propeller Radius (r)	0.1	m

Pushing force. The mass of the cansat should be 300–350 g.

1. RPM. More RPM => more thrust.
   1. KV: How fast the motor spins per volt.
   2. Voltage
2. Propeller
3. Diameter $d$
4. Pitch
5. Motor efficiency

Thrust (in grams): $=4.92x(PropellerDiameterininches)^{2}x(PropellerPitchininches)x(MotorKV)^{2}x(BatteryVoltage)^{2}/1,000$

Waterproofing the axle (driveshaft)

Underwater sealing. A rotary shaft seal. Sealed bearing. Stuffing tube. Water channeling. Stuffing box.

The axle passes through an arrangement called a "gland".

• a wide tube filled with discs of material and grease
• a standard lip seal

• magnetic coupling

Marine grease

• https://robotics.stackexchange.com/questions/150/preventing-leaks-in-motor-shafts-for-underwater-bots
• http://www.building-model-boats.com/model-boat-propeller-shaft.html
• https://seaperch.org/resources/library/#build
• https://www.mechanicalseals.net/
• https://ntrs.nasa.gov/api/citations/19670006352/downloads/19670006352.pdf

for submarines and 3d prints, check Making 3D prints actually waterproof https://www.youtube.com/watch?v=Q8x-mjjT8j4

Turning the motor

Use a servo to turn the motor. Eg

• https://www.thingiverse.com/thing:737588
• https://www.thingiverse.com/thing:2877306