Homework 1
Important of consideration THRUST IN DRONES�performance
NUR ALIA BINTI ABDUL NASIR
Title: Measurement of torque and efficiency produced by propellers
WHAT IS THRUST?
Thrust is the amount of upward force your drone can produce when generated by the propulsion system of the aircraft
-For example, Thrust of propeller 9443 which gives 706 gram thrust on 100% throttle the other hand 1045 gives 737grm thrust at full throttle 1045 which gives 31grm more thrust with same motor configuration.
SOURCE: Thrust Efficiency Of Drones (Quad Copter) With Different Propellers And There Payload Capacity, Volume 4 – No.2, April 2017
-Choose smaller propeller size or reduce the voltage on rotor
For example, The rigidity of plastic-based frame with a weight of 560 (gram) has a maximum displacement of 3.3 (mm) for 52 (N) thrust on the wing frame part. With the rotor specification stated in this research, 560 (mm) distance between rotor and 406x127 (mm) propeller, the maximum angular velocity that can be used is 7680 (rpm) which generated 21 (N) thrust.
SOURCE: Quadcopter Body Frame Model And Analysis, Issue #1, May 2016
-Consider speed of flight as the small speed change will have larger effect on thrust force
For example, In the lower corner of the flight envelope with stalling speed Vs = 105 km/h at full power at sea level the cumulative stabilizing effect of propeller thrust force is 1.511 per cent (0.01511) of mean aerodynamic chord. For the aircraft with more powerful engines, this derivative will rarely produce stabilizing or destabilizing effects greater than a few per cent of mean aerodynamic chord.
SOURCE: Miodrag Milenković-Babić, (2018) "Propeller thrust force contribution to airplane longitudinal stability", Aircraft Engineering and Aerospace Technology
Homework 2
How To Optimize A Propeller Design
NUR ALIA BINTI ABDUL NASIR
Title: Measurement of torque and efficiency produced by propellers
The Number of Blades
Increasing the number of blades can help to reduce the efficiency of the propeller but with a higher number of blades there is a better distribution of thrust helping to keep the propeller balanced.�More powerful engines require more propeller .
SOURCE: Volume 16, 2011, Pages 278-283
The Diameter
Larger propellers can create more power and thrust. If diameter is too small, the propeller will spin at the desired RPM but provide a reduced forward motion, increasing engine wear and impacting fuel economy.
SOURCE: 2010, 22(5), supplement 1:7-16
Pitch To Diameter
The lower pitch makes the engine reach maximum rpm at slower speeds. Conversely, a higher pitch will deliver greater top speeds, but slower acceleration. The most efficient designs are those which maintain a pitch to diameter ratio of 1:1.
SOURCE: https://www.simscale.com/blog/2019/06/how-to-optimize-propeller-design/
Homework 3��EFFICIENCY & TORQUE
NUR ALIA BINTI ABDUL NASIR
Title: Measurement of torque and efficiency produced by propellers
The purpose of a propeller is to convert power which is delivered by a rotating shaft into thrust by accelerating a large mass of air to a higher velocity. The effectiveness of a propeller performs this conversion is known as efficiency.
The propeller’s efficiency calculated using the following formula:
Propeller Efficiency
Mechanical power (Watts) = Torque (Nm) x Rotational Speed (rad/s)
The ratio of mechanical power delivered by the motor (output) to the electrical power supplied to the motor (input).
The motor efficiency calculated using the following formula:
Motor Efficiency
Mechanical power (Watts) = Torque (Nm) x Rotational Speed (rad/s)
Electrical power (Watts) =Current x voltage
System Efficiency
The overall performance of the system depends on a well balanced combination of motor and propeller. System will be very inefficient if these two parts don’t match together.
System efficiency expressed by the following formula:
System efficiency (g/Watts) = Propeller efficiency (g/Watts) * Motor Efficiency
Torque In Propeller
Since motor and propeller are linked, torque is important to measure as only torque and speed that will deliver to obtain mechanical power.
The prop torque can be measure by torque sensor.
Measure its electrical power input, the voltage and the current in the power line driving the motor ad torque is directly proportional to the current and can be derived from it by knowing shaft speed and motor efficiency.
𝑇𝑜𝑟𝑞𝑢𝑒 = 𝐾𝑡 X 𝐶𝑢𝑟𝑟𝑒𝑛𝑡
THANK YOU