profi-mot-prop-finder
Profi-Finder-Help

1. Getting started

The screenshot below shows the filter parameters.
Each filter may be enabled or disabled by the checkboxes.
The filter parameters are RANGES (from ... to). E.g. if you search for a drive with 2 ... 3 cells, just enter "2" and "3" and check the corresponding checkbox accordingly.
Once you have set up all filters, press the run button to start Profi-Finder.



Follow the steps below:
  1. Set the THRUST filter. If your airplane requires a thrust of let's say about 250 g, you should enter e.g. a range of 200 ... 300.
  2. Set the POWER-FLIGHT SPEED filter. If the estimated power-flight speed of your airplane is about 85 km/h, you should enter a range of about 80 ... 90.
  3. You may now already start the Profi-Finder with the run button and watch the results. If too many were found, you should set the remaining filters step by step.
  4. Set NUMBER OF LI-CELLS, PROPELLER TYPE, MOTOR DIAMETER and PROPELLER DIAMETER filters step by step accordingly.
  5. If there are too less or none hits, you should either set wider filter ranges or disable some filters.
  6. You may now analyze and compare the result.
The screenshot below shows the result. All paramters are explained under "2. Definitions".



To use the graphic function, just click on the red drive numbers in the result box and the graphic window below will open:



It shows the efficiency of the motor vs. the motor current.
The postion of maximum efficiency and the position of maximum motor current are marked by a blue resp. red dot, the position of the drive is marked by a green line.
The graphic window allows easy judging of the drive: The closer the green line is to the red dot the closer the motor works on its limit, the closer the green line is to the blue dot the higher is the efficiency of the motor.

2. Definitions

Filter parameter:
  • Thrust [g]: Thrust which the airplane requires.
  • Power-flight speed [km/h]: Typical speed of the airplane, best efficiency of propeller.
  • Number of Li-cells: Number of Li-cells.
  • Propeller type: Either folder or non-folder type.
  • Motor diameter [mm]: Diameter of the motor. Typical motor diameters are 18 ... 80.
  • Propeller diameter [Zoll]: Diameter of propeller.
Result parameter:
  • Status: Statusline to show various messages.
  • Hit number: Number of found drive combinations.
  • Motor: Motor name and type (diameter, length, windings).
  • Order number: robbe order number of motor.
  • Rotation constant [RPM/V]: Rotation speed per Volt of the motor .
  • Voltage [V]: Supply voltage.
  • Number of Li-cells: Corresponds to Voltage, average voltage of 3.5 V/cell.
  • No-load rotation speed [RPM]: Rotation speed of motor only under no-load condition.
  • Max. motor current [A]: Max. motor current.
  • Maximum electric input power [W]: Maximum electric input power of motor.
  • Motor weight [g]: Weight of motor.
  • Max. motor efficiency: Maximum efficiency of motor only.
  • Current @ max. efficiency [A]: Current at maximum efficiency of motor.
  • Rotation speed @ max. efficiency [RPM]: Rotation speed @ max. efficiency of motor.
  • Shaft power @ max. efficiency [W]: Shaft power @ max. efficiency of motor.
  • Propeller: Name of propeller.
  • Propeller diameter [Zoll]: Diameter of propeller.
  • Propeller pitch [Zoll]: Pitch of propeller.
  • Propeller type: Either folder or non-folder type.
  • Drive rotation speed [RPM]: Rotation speed of motor and propeller.
  • Drive current [A]: Current of motor and propeller.
  • Drive shaft power [W]: Shaft power of motor and propeller.
  • Drive efficiency of motor: Efficiency of motor only but with propeller.
  • Thrust [g]: Thrust of motor and propeller.
  • Power-flight speed [km/h]: Typical speed of airplane, best efficiency of propeller.

3. Safety notes

All guidelines, recommendations and calculations are basing upon an average voltage level of 3.5V/Li-cell and horizontal power-flight of the airplane.
The average voltage level depends on current consumption, C-rate and quality of the Li-batteries and can exceed the level of 3.5V/Li-cell. This will cause a higher rotation speed and current consumption than calculated.
It is recommended to test the combination of battery, motor and propeller to ensure that the specifications of battery , motor and propeller (maximum rotation speed, maximum torque, etc.) won't be exceeded.
Besides, it should be considered that the maximum rotation speed might be higher than the calculated one when the airplane is leaving horizontal flight into nose-dive.
Although all guidelines, recommendations and calculations are to the best of one's knowledge, it is not possible to consider all practical details.

Therefore no responsibility is taken for the correctness of these recommendations and calculations.