The propeller model and a model of the electric system, together with various optimization schemes, are used to design optimal propulsion systems for a mini unmanned aerial vehicle for various goals and under various constraints. Important design trends are presented, discussed, and explained. Although the first part of the investigation is based on typical characteristics of the electric system, the second part includes a sensitivity study of the influence of variations of these characteristics on the optimal system design.

Optimizing Electric Propulsion Systems for Unmanned Aerial Vehicles

Propeller design is a complex task that involves a variety of disciplines such as: aerodynamics, structural analysis, and acoustics. A new method of designing an optimal propeller which is based on a MDO (Multidisciplinary Design Optimization) approach is presented. By combining various analysis tools with an optimization tool, a powerful and flexible design method is obtained. During the design process three different optimization schemes are used, leading the design to its optimal goal. This new method is applied for the design of a propeller for an Ultralight aircraft. Several optional designs for different design goals are presented. The results of the new method are compared with results of the classical design method, based on Betz's condition, which considers only the aerodynamic performance of the propeller. The importance of addressing the characteristics of the entire air-vehicle, its aerodynamic characteristics and its propulsion system (engine, gear box, etc.), rather than only the isolated propeller, is emphasized.

Optimization of Propeller Based Propulsion System

The recent increase in the development of UAV’s and MAV’s has created a strong demand for small propeller performance data. Propeller performance is critical to the success of these aircraft and guaranteed performance demands accurate experimental data. These propellers operate at low Reynolds numbers (between 30,000 and 300,000), rendering performance scaling from larger counterparts inaccurate. An Integrated Propulsion Test System has been designed, developed and validated at Wichita State University to accurately and reliably measure performance of small propellers. Performance of a large number of propellers has been charted and a database of performance data has been created. This thesis discusses the salient features of this measurement system and data for a few of the, over 30 propellers, charted.

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Propeller performance measurement for low reynolds number unmanned aerial vehicle applications

This work focuses on the current civil engine design practice of increasing overall pressure
ratio, turbine entry temperature and bypass ratio, and on the technologies required in
order to sustain it. In this context, this thesis contributes towards clarifying the following
gray aspects of future civil engine development:
 the connection between an aircraft application, the engine thermodynamic cycle and
the advanced technologies of variable area fan nozzle and fan drive gearbox.
 the connection between the engine thermodynamic cycle and the fuel consumption
penalties of extracting bleed or power in order to satisfy the aircraft needs.
 the scaling of propeller maps in order to enable extensive open-rotor studies similar
to the ones carried out for turbofan engines.
The rst two objectives are tackled by implementing a preliminary design framework,
which comprises models that calculate the engine uninstalled performance, dimensions,
weight, drag and installed performance. The framework produces designs that are in
good agreement with current and near future civil engines. The need for a variable area
fan nozzle is related to the fan surge margin at take-o , while the transition to a geared
architecture is identi ed by tracking the variation of the low pressure turbine number of
stages. The results show that the above enabling technologies will be prioritised for long
range engines, due to their higher overall pressure ratio, higher bypass ratio and lower
speci c thrust. The analysis also shows that future lower speci c thrust engines will su er
from higher secondary power extraction penalties.
A propeller modelling and optimisation method is created in order to accomplish the
open-rotor aspect of this work. The propeller model follows the lifting-line approach and
is found to perform well against experimental data available for the SR3 prop-fan. The
model is used in order to predict the performance of propellers with the same distribution
of airfoils and sweep, but with di erent design point power coe cient and advance ratio.
The results demonstrate that all the investigated propellers can be modelled by a common
map, which separately determines the ideal and viscous losses.

Design space exploration and performance modelling of advanced turbofan and open-rotor engines

Propeller performance is traditionally represented by a performance map that gives propeller efficiency as a function of the flight Mach number, the power coefficient CP, and the advance ratio J. This work aims to demonstrate how this map changes when the design CP and J change and to propose a novel map format that is able to capture the performance of different propeller designs. For this purpose, the propeller performance is simulated using a propeller lifting-line method validated for the SR3 propfan. Subsequently, the propeller model is used within a sequential quadratic programming framework to optimize the blade twist and chord distribution for different sets of design CP and J. A complete propeller performance map is then generated for each one of the optimized designs. The results demonstrate that all the investigated propellers can be modeled by a common map, which determines separately the ideal efficiency and the viscous losses. The ideal efficiency is given in the traditional format of ηi=f(C...

Toward a Scalable Propeller Performance Map

: The technology needed for the design and installation of propellers is presented and summarized in three volumes. Volume 3 (Hub, Actuator, and Control Design) contains material on the design of the hub and actuator systems. The theories of propeller controls are presented with the details of the types used with conventional and V/STOL airplanes. A brief discussion of past and future propeller installations is given along with recommendations for future work. Design criteria, airfoil data, and a computer program are given.

Edward Sand

Papers

Summary of Propeller Design Procedures and Data. Volume 3. Hub, Actuator, and Control Designs