flutter analysis of the polen special ii emphasizing addition of a wet wing and ailerons to flutter...
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Flutter Analysis of the Polen Special IIFlutter Analysis of the Polen Special IIEmphasizing Addition of a Wet Wing and Emphasizing Addition of a Wet Wing and
Ailerons to Flutter ModelAilerons to Flutter Model
Structural EngineersStructural EngineersErich Gross, Masayuki WakamatsuErich Gross, Masayuki Wakamatsu
Advisor: Marcus KrugerAdvisor: Marcus Kruger
ASE463Q [Fall2002]
Final Presentation
Presentation Outline
Polen Special II Background and SpecsPolen Special II Background and Specs Project Motivation and ObjectivesProject Motivation and Objectives Past Polen Group WorkPast Polen Group Work Flutter TheoryFlutter Theory AMAFALAAMAFALA Objectives Completed (Results)Objectives Completed (Results) Conclusions Conclusions
Polen Special II Background
Designed by Dennis PolenDesigned by Dennis Polen
Aluminum body, cantilevered low-wing, conventional Aluminum body, cantilevered low-wing, conventional
gear monoplane gear monoplane
Designed to achieve high speed (300mph+)Designed to achieve high speed (300mph+)
Development began in 1967Development began in 1967
First flew in 1972First flew in 1972
Currently owned by Dick KeytCurrently owned by Dick Keyt Ex-Air Force, current American Airlines PilotEx-Air Force, current American Airlines Pilot
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Polen Special II Background
Designed as a racing airplaneDesigned as a racing airplane Mr. Keyt participates in various competitionsMr. Keyt participates in various competitions A longer range would be desirableA longer range would be desirable Wings are the only practical place to store Wings are the only practical place to store
additional fueladditional fuel Addition of wing fuel tanks was one of the Addition of wing fuel tanks was one of the
primary project objectivesprimary project objectives
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Polen Special II Specifications
Polen Polen Special II (Specifications courtesy of the EAA)Special II (Specifications courtesy of the EAA) Model Year: 1967Model Year: 1967 Engine: Lycoming TSIO-360Engine: Lycoming TSIO-360 Horsepower: 180 hp normally aspirated, 200 hp turbochargedHorsepower: 180 hp normally aspirated, 200 hp turbocharged Number of Seats: 1Number of Seats: 1 Length: 19'6“Length: 19'6“ Height: 4'10“Height: 4'10“ Wing Span: 21'5“Wing Span: 21'5“ Gross Weight: 1,500 lbs.Gross Weight: 1,500 lbs. Max Speed: 345 mphMax Speed: 345 mph Cruise Speed: 325 mphCruise Speed: 325 mph Service Ceiling: 28,000 feetService Ceiling: 28,000 feet
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Critical Problem and Project Motivation: Insufficient Flutter Analysis
Rudder DamageRudder Damage
High frequency rudder flutter occurred during a low-pass fly-by
Fortunately, Mr. Keyt landed safely
Mr. Keyt requested a flutter analysis from the ASE department at UT Austin
Project has been developed since Fall 2000
Courtesy of Spring 2001 463Q group
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Past Polen Groups’ Works
Fall 2000 & Spring 2001 (Not Accessible)Fall 2000 & Spring 2001 (Not Accessible) GVT, Modal Studies GVT, Modal Studies
Summer 2001Summer 2001 AMAFALA user manual & initial input filesAMAFALA user manual & initial input files
Fall 2001Fall 2001 Revision of input files & wing tip EI and GJRevision of input files & wing tip EI and GJ
Spring 2002Spring 2002 Completed general Polen ModelsCompleted general Polen Models
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclustion
Project Objectives
Research flutter and analyze past dataResearch flutter and analyze past data Learn AMAFALALearn AMAFALA
Add components to the Polen modelAdd components to the Polen model Ailerons (Case 1)Ailerons (Case 1) Fuel Tanks [Wet Wing]Fuel Tanks [Wet Wing]
(Case 2, Case 3)(Case 2, Case 3)
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Team Organization
Dr. Ronald StearmanConsultant
Department of Aerospace Engineering and Engineering Mechanics
The University of Texas at Austin
Marcus KrugerAdviser
Masayuki Wakamatsu
Theoretical ResearchPast Group Data Analysis
AMFAFALA Editing
Erich GrossTeam Leader
Team OrganizationPast Group Data Analysis
AMAFALA Editing
Javier Fuentealba
AMAFALA Consultant
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Phenomena of Flutter (Flutter Theory)
Definition: a self excited vibration of a flexible Definition: a self excited vibration of a flexible body [ASE355 notes]body [ASE355 notes]
Imagine a ball in these conditionsImagine a ball in these conditions
a) Stable b) Neutral c) Unstable
Flutter speed is defined as a minimum (neutral Flutter speed is defined as a minimum (neutral condition) speed at flutter occurscondition) speed at flutter occurs
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Flutter Video!
Courtesy of www.airspacemag.com
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Causes of Flutter (Flutter Theory)
Inability of an airframe to dissipate energy Inability of an airframe to dissipate energy to the airstreams to the airstreams Airframe—elastic; deflects due to Airframe—elastic; deflects due to
bending and torsionbending and torsion New geometry - new aerodynamic forceNew geometry - new aerodynamic force And so on…And so on…
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
To find the Flutter Speed
Eigenvalue problemsEigenvalue problems i.e. seek the flutter speed and frequencyi.e. seek the flutter speed and frequency
Structural Analysis and AerodynamicsStructural Analysis and Aerodynamics V-g MethodV-g Method
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
To find the Flutter Speed (V-g method)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
g: artificial structural g: artificial structural damping (< 0.033)damping (< 0.033)
Mach number and altitude Mach number and altitude are held constantare held constant
V-g plot shows when flutter may occur
AMAFALA outputs a V-g plot
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Flutter: Symmetric VS Antisymmetric
(a) symmetric (b) Antisymmetric
Two primary flutter conditions of interest: symmetric and antisymmetric
For aileron flutter, we are concerned with the antisymmetric case because ailerons are designed to deflect antisymmetrically
We need to look at both symmetric and antisymmetric cases to assess the changes caused by the new fuel tanks
AMAFALA (Airplane Modal Aerodynamic Flutter And Loads Analysis)
A text-based flutter analysis programA text-based flutter analysis program Past 463Q teams worked with itPast 463Q teams worked with it
This is the main tool that we used in our This is the main tool that we used in our analysisanalysis
Hard to learn- took two years for past groups to Hard to learn- took two years for past groups to run the programrun the program
We modified existing input files created by We modified existing input files created by Javier Fuentealba rather than creating new onesJavier Fuentealba rather than creating new ones
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
AMAFALA (Airplane Modal Aerodynamic Flutter And Loads Analysis)
AMAFALA InputsAMAFALA Inputs Geometric Data (layout of wing)Geometric Data (layout of wing) Mass Data (inertial strips)Mass Data (inertial strips) Stiffness Data (inertial strips)Stiffness Data (inertial strips) Aerodynamic DataAerodynamic Data
AMAFALA OutputsAMAFALA Outputs Mode FrequenciesMode Frequencies Mode ShapesMode Shapes V-g PlotsV-g Plots
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Wing Input File Overview
Input file contains geometric and mass data Input file contains geometric and mass data
required to model the flutter characteristics of the required to model the flutter characteristics of the
wingwing
Original input file was complete except for the Original input file was complete except for the
addition of ailerons and wing fuel tanksaddition of ailerons and wing fuel tanks
We modified the original wing input file by We modified the original wing input file by
adding the ailerons and fuel tanks to the wingadding the ailerons and fuel tanks to the wing
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Wing Input File Overview
Visual Representation of Data Contained in Wing Input File
New wing tanks
Aileron
Aileron CG
Results: Case 1 (Original, Antisymmetric Condition) Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
No flutter occurrence is indicated for this condition
Results: Case 1 (with Ailerons, Antisymmetric Condition)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Flutter occurs at roughly 350 knots
Results: Case 2 (New Fuel Tanks, Antisymmetric)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Flutter occurs at roughly 350 knots
Note: This is identical to Case 1
New fuel tanks empty
Results: Case 2 (New Fuel Tanks, Antisymmetric)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Flutter occurs at roughly 290 knots60 knots slower than for no additional tank case
New fuel tanks half full
Results: Case 2 (New Fuel Tanks, Antisymmetric)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
New fuel tanks full
Flutter speed has fallen to 190-200 knotsFlutter is being induced!
Results: Case 3 (Fuel, Symmetric)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
New fuel tanks empty
Flutter occurs at roughly 350 knots
Results: Case 3 (Fuel, Symmetric)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
New fuel tanks half full
Flutter speed has fallen to 200 knots (conservative)Realistically, flutter speed is probably closer to 275 knots
Results: Case 3 (Fuel, Symmetric)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
New fuel tanks full
Flutter speed is now approximately 250-260 knotsFlutter speed is decreasing as fuel is added
Conclusions
Case 1 [aileron, antisymmetric]Case 1 [aileron, antisymmetric] Flutter occurs at around 350 knotsFlutter occurs at around 350 knots
Case 2 [antisymmetric, new fuel tanks]Case 2 [antisymmetric, new fuel tanks] Case 3 [symmetric, new fuel tanks]Case 3 [symmetric, new fuel tanks]
Flutter speed decreases with the addition of Flutter speed decreases with the addition of
fuel to the new tanksfuel to the new tanks This is counterintuitive and undesirableThis is counterintuitive and undesirable Centers of gravity for the new tanks must be Centers of gravity for the new tanks must be
moved closer to the wing leading edgemoved closer to the wing leading edge This will mean less fuel can be carried in the This will mean less fuel can be carried in the
wingwing
Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Conclusion (Recommendations)Outline1) Polen &
Project background
2) Flutter
3) AMAFALA
4) Results
5) Conclusion
Learn AMAFALA ASAPLearn AMAFALA ASAP Develop more precise wet wing modelDevelop more precise wet wing model
i.e, get more information about the structure i.e, get more information about the structure
of the wing and edit wing file accordinglyof the wing and edit wing file accordingly Develop an external fuel tank modeDevelop an external fuel tank mode
Questions?