Hints &
Tips
Running en electric Motor below his optimal efficiency current
results in a faster increase of wast power than running it over this
point. If the Pitch is higher than 66% of its diameter (e.g. Prop
18"x13") the airflow will stall at the propellerblade.
This results in decreasing static thrust (see Prop Stall Thrust) and
decreasing max. current. For fast planes (e.g. Pylon) we have to
live with this. Prop. Const: The Propeller Constant
indicates its degree of the power absorbed by the prop due
aerodnamic resistant. In general the thinner a prop blade is the
lower the Prop Const gets. A typical Prop Const is between min. 1.00
and max. 2.00. Determine the relevant parameters:
Easy - low power and a very low wing loading.
Trainer - moderate power and a low wing loading.
Sport - moderately high power, and a moderate wing loading.
Pylon - moderately high power, high wing loading, high pitch speed.
Aerobatic - high power, moderately high wing loading
(~250W/kg)
3D Aerobatic - very high power, very low wing loading, very high static thrust, low pitch
speed (+400W/kg)
Sailplane - moderately high power, very low wing loading, low pitch speed.
Hotliner - very high power, moderately high wing loading, high static thrust
|
|
Auslegehilfen
Der Betrieb eines Elektromotors unter seinem optimalen
Wirkungsgrad führt zu einer überproportionalen Zunahme der
Verlustleistung.
Weist Ihr Propeller eine Steigung auf, welche grösser als 66%
dessen Durchmessers (z.B. Prop 18"x13") ist, wird die
Luftströmung am Propellerblatt abreissen. Dadurch ist nur noch
dieser reduzierte Standschub bei Abriss verfügbar. Der max.
Motorenstrom wird ebenfalls nicht erreicht.
Prop. Konst.: Die Propeller Konstante ist ein Mass für
die Leistungsabsorbtion des Propellers durch seinen aerodynamischen
Widerstand. Allgemein gesagt: Je dünner ein Propellerblatt ist je
kleiner fällt seine Konstante aus. Prop Konst liegt zwischen min.
1.00 und max. 2.00.
Richtwerte für unterschiedliche Modelle:
Gemütlich - low power and a very low wing loading.
Trainer - moderate power and a low wing loading.
Sport - moderately high power, and a moderate wing loading.
Pylon - moderately high power, high wing loading, high pitch speed.
Aerobatic - high power, moderately high wing loading
(~250W/kg)
3D Aerobatic - very high power, very low wing loading, very high static thrust, low pitch
speed (+400W/kg)
eSegler - moderately high power, very low wing loading, low pitch speed.
Hotliner - very high power, moderately high wing loading, high static thrust
|