Scale constant speed 4-blade prop for 60size RC airplane
This short video shows testing the final version of Scale constant speed 4-blade prop for 60size RC airplane. Stock Brushless Turnigy motor (TR50-55B-600) has been modified by replacing the shaft with the hollow 8mm model helicopter rotor shaft from TRex 500. Turnigy 6s 5000mAh LiPo battery runs the motor via Turnigy plush 80A/26V ESC delivering over 1kW. Four blade 10.5 inch diameter variable pitch prop can change in-flight pitch from negative 4 inch to positive 10 inch. The entire mechanism have been designed at home and made using mini late and mini mill. All carbon fiber prop blades were molded also at home.
To achieve constant speed the governor function in Turnigy ESC is used and one mixer in Futaba 8US radio has been programmed. In the radio CH3 (throttle stick) is setup for pitch control from zero (lowest stick position) to positive 10inch (highest stick position), the CH8 knob for prop rpm change (from zero to 10k rpm). Trainer switch is programmed to engage reverse thrust by changing the the pitch to negative 4 inch.
The video shows simulated all phases of the flight:
1. Taxi at 6k rpm. With zero thrust (lowest throttle stick position) the system takes about 75W. Half throttle (should be the maximum power used during the taxi) it takes about 170W and at maximum pitch which is not really efficient takes up to 450W. Breaking (reverse thrust) takes about 140W.
2. Take off at 10k rpm. With zero thrust (lowest throttle stick position) the system takes about 290W. Half throttle which should be used during take off roll takes about 700W and at maximum pitch which should be used to achieve maximum airspeed the power goes over 1kW.
3. Normal economic cruse performed at 7500rpm takes up to 550W with maximum pitch. When flying slow approach speed (half throttle) motor takes about 370W and 130W when throttle stick is in the lowest position (zero pitch for slowing down the plane).
4. For landing the maximum rpm should be used and throttle should be managed manipulating the throttle stick in the in the region of lower half. After landing the maximum breaking power will be achieved by applying reverse thrust by flipping the trainer switch. Such breaking takes about 600W.
I designed and built that power system for the model I'm designing now: 18% scale of Polish military trainer PZL-130 Orlik. For now here is the video of the scale constant speed 4-blade prop.
Click on the black box below to play the video.