Design and Development of Propeller for NAL-Micro Air Vehicle, Part II: Performance Evaluation of Indigenous Propellers (NAL-MAV-PR01)

Prathapanayaka, R and Vinodkumar, N and Mohan Kumar, K and Krishnamurthy, SJ (2010) Design and Development of Propeller for NAL-Micro Air Vehicle, Part II: Performance Evaluation of Indigenous Propellers (NAL-MAV-PR01). Technical Report. NAL, Bangalore.

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National Aerospace Laboratories is having major program to develop Micro Air Vehicles (MAV) for defence use. The present configuration of NAL MAV propulsion system is battery driven miniature motor and propellers. From the basic configuration for smooth hand launch, it is defined that the maximum weight of NAL micro air vehicle would be limited to 300gms with a minimum thrust requirement of 120gms and thrust to weight ratio would being 0.40. Indigenous design and development of miniature propeller for NAL MAV program is carried out and to be evaluated for its performance which includes Structural analysis using ANSYS11 and fabrication of propeller using CFRP. Commercially available propellers and motors also have minimum information (often with no information) which makes it difficult to select the efficient combinations of propeller and motor. A test setup designed and built for the purpose at propulsion division is used to evaluate the static performance of motor propeller combinations at different operating and at uninstalled conditions. The same test setup is also used in low speed wind tunnel for evaluating overall performance propeller-motor combinations. Else where like University of Illinois has set up a test rig for evaluating the static performance of micro propellers where in thrust, torque and rotational speeds are measured. The test setup has beam type load cell having capacity up to 600gms for measuring thrust and brushless electric motors for powering the propellers. Thrust, power, rotational speeds, weight of the propeller as well motors are measured. In the present test set up direct torque measurement is not envisaged. Propellers static thrust is evaluated using 4 electrical brushless motors combinations for optimizing the power consumption. Based on minimum thrust requirement, highest power consumed by the motor and its weight are used to eliminate and select relatively better motor propeller combinations. Finally selected propeller-motor combinations are used for evaluation in the low speed wind tunnel. Literature survey indicates that fabrication of propeller using Eppler-193; using metal thorough CNC and other methods have limited success due to its thin section. Successfully made one with using acrylic material. Fabrication of propeller using CFRP material and mould was tried and abandoned due to problem faced during machining of mould. We are able to design, fabricate one using CFRP and test it successfully. Propellers of pitch to diameter ratio closer to 0.5 found to give more static thrust. This report gives the details of propeller-motor selection procedures, experimental test setup, instrumentation, motor specification, propeller specification, evaluation methods and static test data of propeller motor combinations. Wind tunnel testing has been carried out at different wind speeds for evaluating the performance of the propeller-motor combinations selected under uninstalled condition. Wind tunnel results show that the NAL designed propellers meets the specific mission requirements of NAL micro air vehicle BLACK KITE.

Item Type: Monograph (Technical Report)
Subjects: AERONAUTICS > Aircraft Propulsion and Power
Depositing User: Mr R Prathapanayaka
Date Deposited: 22 Jul 2010 10:13
Last Modified: 14 Aug 2015 08:18

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