HELICOPTER ROTOR AERODYNAMICS AND MODELING 1 Helicopter .
HELICOPTER ROTOR AERODYNAMICS AND MODELING1Helicopter Rotor Aerodynamics and ModelingCourse Development, Part IIAntonette T. CummingsPurdue UniversityENE506 Content, Assessment, and Pedagogy15 April 2014
HELICOPTER ROTOR AERODYNAMICS AND MODELING2Table of ContentsList of Figures . 4List of Tables . 4I.Introduction . 5A.Setting. 5B.Motivation for this Curriculum . 6II.Content . 8A.Enduring Understandings . 9B.Important-to-Know. 11C.Good-to-Be-Familiar-With. 13D.Concept Map . 15E.Difficult Concepts and Misconceptions . 18F. Progression to Expertise . 20G.Cognitive Theory of Learning . 21III.Assessment . 22A.Learning Objectives for the Entire Course. 22B.Mapping the Learning Objectives to Bloom’s Taxonomy . 23C.Assessment Triangles . 241.Enduring Understanding 1 – Learning Objectives 1, 2, 3, 4 . 252.Enduring Understanding 2 – Learning Objectives 8 and 9 . 26
HELICOPTER ROTOR AERODYNAMICS AND MODELING33.D.E.Enduring Understanding 3 – Learning Objectives 10 and 11 . 28Assessment Worksheets . 291.Enduring Understanding 1 – Learning Objectives 1, 2, 3, 4 . 292.Enduring Understanding 2 – Learning Objectives 8 and 9 . 303.Enduring Understanding 3 – Learning Objectives 10 and 11 . 31Authentic Tasks . 32F. Rubric. 33IV.V.Pedagogy . 35A.Syllabus . 36B.Lesson Plan . 41C.General Synthesis of Overall Alignment of Content, Assessment, and Pedagogy . 46References . 47
HELICOPTER ROTOR AERODYNAMICS AND MODELING4List of FiguresFigure 1. Simple concept map for Enduring Understandings and Important-to-Know items. . 16Figure 2. Detailed concept map for rotor, blades, hub, and controls. . 17Figure 3. Detailed concept map of rotor with Good-to-be-Familiar-With Conservation of AngularMomentum and Control Loads. . 17Figure 4. Detailed concept map for Enduring Understandings of Modeling the Rotor andcalculating Total Performance for a mission. . 18Figure 5. Sequence of content for 15 week helicopter aerodynamics course. . 40List of TablesTable 1. Conceptually difficult knowledge for helicopters. . 18Table 2. Learning Objectives mapped to the revised Bloom's Taxonomy. . 24Table 3. Rubric for Enduring Understanding 3: design configuration for a given mission. 34Table 4. Perkins' Making Learning Whole principles incorporated into this course. . 35Table 5. Lesson plan for Enduring Understanding 1. . 42Table 6. Lesson plan for Important-to-Know forces in hover, forward flight; wake structure. . 42Table 7. Lesson plan for Enduring Understanding 2. . 43Table 8. Lesson plan for Enduring Understanding 3, Good-to-be-Familiar-With flight test. . 44
HELICOPTER ROTOR AERODYNAMICS AND MODELING5I.IntroductionThis document describes an introductory helicopter aerodynamics and design engineeringcourse for undergraduates in aeronautical or aerospace engineering. The three major sections ofthis document are Content, Assessment, and Pedagogy. These sections have been developedaccording to Engineering Education research principles and findings, such that the three sectionsare aligned with one another. The course’s foundation is to provide authentic practice formeaningful learning.The course emphasizes understanding of pilot controls of the hardware of a rotor,mathematical modeling of theoretical performance models, and design of a rotor to meet adefined mission. The assessment strategies are based on the types of learning in this course,where project-based learning and design thinking employ higher levels of thinking and thereforeneed the matched assessment strategy of a rubric. Pedagogy is primarily based on Perkins’Making Learning Whole, where certain elements for the student are emphasized: distributed,deliberate practice; intrinsic motivation and choice; working on the hard parts with feedback andassessment; participation in a community of practice; and metacognition.A.SettingI expect that the institutional setting will be an ABET-accredited engineering college thatoffers aerospace engineering at the bachelors level. ASEE reports 67 schools that awardbachelors aerospace engineering degrees, paling in comparison to the 283 schools that awardmechanical engineering degrees and to the 256 that award electrical engineering degrees(American Society for Engineering Education, 2011). For example, the rotorcraft centers ofexcellence are Georgia Tech, University of Maryland, and Penn State (Schweitzer, 2014).Kansas University offers a professional short course for helicopters. Purdue University and
HELICOPTER ROTOR AERODYNAMICS AND MODELING6Arizona State seem to have offered a helicopter course as recently as 2012. These institutionshave developed plans of study to support a complex subject such as helicopter aerodynamics.I assume that the students who would pursue this course have an eager interest inhelicopters as it seems to be a rare topic even among aerospace schools. I may encounterstudents who are airplane pilots, as the minimum age for a private pilot is 16. The knowledgebase of private pilots is correct but incomplete because the emphasis for a pilot is on operationinstead of on design. I will expect to compare new information to prior airplane knowledge. In ararer case of having a helicopter pilot as a student, I expect such a person to be older than typicalbachelor’s level students, as helicopter training is expensive enough to be a skill usually acquiredin the military.I expect to offer the course to undergraduates who have fulfilled key mechanical andaerospace prerequisites. The prerequisites include: introduction to kinematics, machineelements, introduction to dynamic systems and controls, introduction to fluid mechanics, andintroduction to aerodynamics. These prerequisites have their own prerequisites, such as physics,calculus, and mechanics of solids. These subjects will have introduced the concepts: a rotationalaxis system, aerodynamic forces and moments in the translational axis system, time-dependencyof forces and moments, and functions of common helicopter parts. These prerequisites arenecessary for design.B.Motivation for this CurriculumNothing about helicopters is easy and that is why it is satisfying to demonstrate masteryof the subject. I spent seven years in the helicopter business, in the aerodynamics departmentspecifically, working on military and civilian tiltrotors. I had the opportunity to participate inKU’s short course designed for professionals to understand helicopter aerodynamics and
HELICOPTER ROTOR AERODYNAMICS AND MODELING7handling qualities; it was a 40 hour lecture. There does not exist a civilian tiltrotor pilot license,so I pursued both fixed wing (airplane) and rotary wing (helicopter) pilot licenses in order to gaina more comprehensive understanding of the pilots, the rules, the machines, and the emergencies.I logged 62 hours (@ 150/hour) of airplane training and 46 hours (@ 325/hour) of helicoptertraining, numbers large enough to qualify but miniscule compared to career pilots. Because ofexorbitant cost of flight training, this marvel of technology is becoming more difficult to accessfor mere mortals either as a career or as a hobby. My hope is to bring the subject back toforefront of attainability for undergraduates in engineering, with a renewed emphasis on makingthe technology more affordable through sound engineering design.
HELICOPTER ROTOR AERODYNAMICS AND MODELING8II.ContentThe content of this course is arranged according to the principles of Backward Design(Wiggins & McTighe, 2005). The concepts are arranged according to enduring understandingsor Enduring Understandings, items that are Important-to-Know, and items that are Good-to-beFamiliar-With. I show here existing helicopter course descriptions from other prominentuniversities for comparison to my proposed content and assessment. I describe in the nextsection the concepts that fit into these three categories. In the Concept Map section below, Idescribe how I converged upon these categories for these concepts.I considered what other universities might offer as described in course descriptions,syllabi, and required texts. Three stand apart as helicopter centers of excellence: GeorgiaInstitute of Technology, Pennsylvania State University, and University of Maryland CollegePark. A fourth institution that deserves mention is the University of Kansas because of thetextbook author, Ray Prouty, who joined the American Helicopter Society in 1952 (AmericanHelicopter Society, 2014), a mere eight years after the Bell 47 was the first helicopter certifiedfor civilian use (Bell Helicopter Textron Inc, 2014). Georgia Tech and Arizona State providesenior level courses and Georgia Tech offers two semesters of specialization. Penn State offersundergraduate and graduate level courses. The University of Maryland, Purdue, and KU onlyprovide masters level courses, but my original goal is undergraduate level.Georgia Tech’s course AE4358 uses Prouty’s text and have five course objectives:“Identify and explain the purpose of key elements of a rotorcraft configuration; Utilize actuatordisk theory to analyze rotor system performance; Utilize rotor blade element theory to analyzerotor system performance; Predict rotorcraft performance such as maximum speed, maximumrate of climb, endurance, etc; Use the Rf design process to size a rotorcraft configuration against
HELICOPTER ROTOR AERODYNAMICS AND MODELING9a given mission” (Costello, 2014). I assume the Rf design process refers to a balance betweenwhat is required and what is feasible; this is not mentioned in helicopter textbooks. These fivecourse objectives are very similar to my Enduring Understandings and my learning objectiveslisted in the next sections.Arizona State offers a Rotary Wing Aerodynamics and Performance class, which isdescribed as “Introduces helicopter and propeller analysis techniques. Momentum and bladeelement, helicopter trim. Hover and forward flight. Ground effect, autorotation andcompressibility effects” (Arizona State Universiy, 2014). The required textbook is Principles ofHelicopter Aerodynamics by Gordon Leishman of the University of Maryland. The coursedescription is thin here I cannot infer much about the alignment of assessment or emphasis of thecontent.One interesting thing to note from these descriptions of other universities’ classes is thatthe undergraduate level courses (GIT and ASU) draw from textbooks written by individualswhose schools only offer graduate level courses (KU and UMD). I wonder why the graduatelevel-only universities have arranged their plans of study this way. Another interesting thing tonote is how few authoritative sources there are, such that different universities frequentlyreference each other’s work; this gives the impression of a tight-knit community.A.Enduring UnderstandingsHelicopters are unique because of the rotor at the top that does most of the work, secondto that of the pilot. How the pilot interacts with the helicopter is of paramount importance indesign. The rotor is typically made of many moving parts, the largest and most noticeable ofwhich are the blades, the hub, and the swashplate, all of which operate in rotation as a functionof time. The pilot commands the forces generated by the rotor through the controls in order to
HELICOPTER ROTOR AERODYNAMICS AND MODELING10accomplish a mission, whether it be hover, forward flight, or some combination of both.Therefore, Enduring Understanding 1 is: The student will be able to describe the rotor and blademotions in a rotational reference axis system and the student will be able to identify rotor designsand the allowable controls between the pilot and the rotor. This is shown best in Figure 2 andFigure 3 for the pilot controls to the main rotor.A rotor designer is different from a pilot in that a designer can make a prediction of rotorperformance, given a particular shape or configuration, whereas a pilot plans a mission aroundknown performance capabilities. (Performance has multiple definitions in helicopters;performance of the rotor considers thrust generated and power required; performance of the totalaircraft considers maximum attainable altitude, speed, gross weight, and range on a tank of fuel.)There are four common theoretical models of increasing fidelity to the physical geometry of therotor, and therefore increasing mathematical complexity. The student will be able to constructmathematical representations of different theoretical models that predict rotor lift, drag, thrust,and power required. Therefore, Enduring Understanding 2 is: The student will be able tocalculate performance using theoretical mathematical models of a rotor, and list the assumptionsand limitations of each of the theoretical models. This is shown best in Figure 4Error!Reference source not found.A rotor designer is also different from a pilot in that a designer can design an optimumconfiguration to satisfy a given mission. The engineering student should practice substantiatingand defending all their claims and decisions with sound engineering data. Therefore, EnduringUnderstanding 3 is: The student will draw upon a broad knowledge base of mission maneuvers,performance prediction tools, and rotor designs to create and select an optimum configuration tomeet or exceed a defined mission. This is shown best in Figure 4.
HELICOPTER ROTOR AERODYNAMICS AND MODELING11Expressing the differences between design engineers and pilots highlights the fact thatengineers think in a particular way and behave accordingly. One mode of behavior amongengineers is to distribute cognition among specialists, which necessitates particular vocabularyfor efficient communication. Another aspect of engineering thinking is to test large prototypesby first applying calculations where possible and by devising a rigorous test through carefulplanning. Therefore, Enduring Understanding 4 is: To develop design engineering thinking andtechnical communication. I note, however, that this Understanding is really an Outcome, is moredifficult to measure, and is beyond the scope of this course for assessing. These will bepracticed, however, in the various assignments of the course.B.Important-to-KnowOverlapping micro-concepts that are Important-to-Know are shown in blue in Figure 1.There are six clusters of micro-concepts, starting from bottom left of Figure 1 and movingclockwise. Lift distribution from four effects on the rotor in forward flight. Motions of the blade from three possible hinges. Motions are a result of aerodynamicforces. Hub configurations based on which motions are allowed and constrained by the hinges atthe hub. Because the blades are subject to large aerodynamic forces, the bladesthemselves may still flap (out-of-plane), feather (twist in-plane), or experience lead-lag(translation in-plane). Angular effects of RPM, rotor coning, and the Coriolis effect. Four controls available to the pilot. Collective and cyclic (longitudinal and lateral)control the main rotor. Anti-torque pedals control the tail rotor (a tail rotor can be
HELICOPTER ROTOR AERODYNAMICS AND MODELING12designed just as the main rotor at the top of the helicopter is designed; if the studentknows the main rotor, the instructor assumes that the student can design the tail rotor). Four common mathematical models of the rotor. It is possible to combine the momentumtheory and blade element theory models. There also exists vortex theory. Momentumtheory, blade element theory, and vortex theory are completely abandoned if the designeruses computational fluid dynamics (CFD).There are macro-concepts built from the above micro-concepts. These are shown in Figure 1in blue, closer to the purple Enduring Understandings. Descriptions below start from the centerleft of the Figure. Forward flight. One of the main interests in this class is the performance of the rotor inforward flight. However, for total mission performance, the student must know lift, drag,and pitching moment of the fuselage, which knowledge may have been gained in aprerequisite course. Hover, which is the main virtue of helicopters and merits the most study. When a rotor isattached to a fuselage, the fuselage may experience pendular action, which is of interestto a pilot for the purpose of controlling it. The rotor wake, as a consequence of the blade shape. The wake structure will change as afunction of aircraft velocity. The wake can also be affected by its proximity to theground (ground effect). Rotor blades, which will be the primary focus of optimizing performance for a mission. Hub, which has historical and manufacturer-specific significance. Understanding thisinvites a student into the helicopter community of practice.
HELICOPTER ROTOR AERODYNAMICS AND MODELING13 Mission, which is the de
described as “Introduces helicopter and propeller analysis techniques. Momentum and blade-element, helicopter trim. Hover and forward flight. Ground effect, autorotation and compressibility effects” (Arizona State Universiy, 2014). The required textbook is Principles of Helicopter Aerodynamics by Gordon Leishman of the University of Maryland.
6.13 Human-Powered Helicopter 331 6.14 Hovering Micro Air Vehicles 334 6.15 Chapter Review 338 6.16 Questions 338 Bibliography 340 7 Aerodynamics of Rotor Airfoils 347 7.1 Introduction 347 7.2 Helicopter Rotor Airfoil Requirements 348 7.3 Reynolds Number and Mach Number Effects 350 7.3.1 Re
Helicopter Aerodynamics - 2 - Concepts . A helicopter flies for the same basic reason that any conventional aircraft flies, because aerodynamic forces necessary to keep it aloft are produced when air passes about the rotor blades. The rotor blade, or
helicopter main rotor or rotor system is the combination of several rotary wings (rotor blades) and a control system that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight.
Aerodynamics is the study of the dynamics of gases, or the interaction between moving object and atmosphere causing an airflow around a body. As first a movement of a body (ship) in a water was studies, it is not a surprise that some aviation terms are the same as naval ones rudder, water line, –File Size: 942KBPage Count: 16Explore furtherIntroduction to Aerodynamics - Aerospace Lectures for .www.aerospacelectures.comBeginner's Guide to Aerodynamicswww.grc.nasa.govA basic introduction to aerodynamics - SlideSharewww.slideshare.netBASIC AERODYNAMICS - MilitaryNewbie.comwww.militarynewbie.comBasic aerodynamics - [PPT Powerpoint] - VDOCUMENTSvdocuments.netRecommended to you b
A Manufacturer name and helicopter model B Maximum takeoff weight in pounds. C Overall length in feet. (Rotors at their maximum extension.) D Overall height in feet. (Usually at tail rotor.) E Rotor diameter in feet. F Rotor plane clearance in feet. G Distance from rotor hub to tip of tail rotor
CHAPTER 1 HELICOPTER AERODYNAMICS WORKBOOK 1-2 THE ATMOSPHERE THE ATMOSPHERE ATMOSPHERIC PROPERTIES Helicopter aerodynamics is the branch of physics dealing with the forces and pressures exerted by air in motion. The atmosphere, the mass of air, which completely envelops the earth, is composed of varying and nonvarying constituents.
flapping trimmed to near zero. The new RTA rotor balance provides increased accuracy in measuring rotor hub loads. This five- component rotor balance measures rotor lift, drag and side forces, together with the rotor pitching and rolling moments. Also incorporated was an instrumented flex coupling to measure rotor torque.
development teams. In Agile Product Management with Scrum, you’ll see how a product owner differs from a traditional product manager having a greater level of responsibility for the success of the product. The book clearly outlines and contrasts the different behav-iors between the traditional and the agile role.
