Mech Mentor Meeting Notes

Questions:

• Suggested general size of motors (closer to MultiStar or KDE Direct)

• Good number of batteries?

• Ways we could simulate/measure stuff ourselves (for an excel sheet)

Jeremy says:

• popular supplier Tmotor

  • fairly afforadable

  • decent quality

• pick a supplier, and they will tell you power, voltage, current, thrust for diff combos of props and motors

  • under each motor type, they will tell you the thrust at different currents for different props

• lots of hobbyist suppliers don’t usually do this

• told him: 4kg max takeoff weight inc. batteries → 15 min flight time

  • 2kg takeoff weight → 30 min flight time

  • and $1200 budget for mech + motors

  • 40amps for max current

• cruising/nominal current?

  • typically target 50% current for steady hover

  • agile → higher resting current

  • needs to hover → lower resting current

• quadcopter might be suited to 4kg better

  • generally, hexacopters may be suited for 6kg more

  • higher diameter prop → higher efficiency

  • 15 in props good

  • blade theory for calculating thrust is not great

• Just use what the supplier is giving

  • don’t try to do your own analysis

• Batteries:

• Generally:

  • larger prop diameter is better

  • pick prop size → target 50% current draw for steady hover

  • figure out flight time

  • pick battery within voltage range of motors used, c-rating of battery must be suitable (continuous discharge)

  • then figure out total capacity for battery → size battery accordingly

  • might be nice to get one large li-po battery or two over four, but it depends on what we define for the battery

  • 50% current of motor + flight time → capacity for battery, assuming you are only discharging your batteries 30-40% DO NOT DISCHARGE BATTERIES COMPLETELY