Lesson 31 Velocity vs. Load Factor (V-n) Diagrams

Slides:



Advertisements
Similar presentations
ANGLE-of-ATTACK Proprietary Software Systems, Inc.
Advertisements

Mig-29 A Flight Model data
Regional Gliding School u Occurs when the wing is no longer capable of producing sufficient lift to counteract the weight of the aircraft. A smooth.
Lesson 17 High Lift Devices
Uncontrolled copy not subject to amendment Principles of Flight.
Aerodynamic Theory Review 2
Aero Engineering 315 Lesson 25 Performance— Power Required and Power Available.
Introduction to Propulsion
A-4 Flight Characteristics
ME 480 Introduction To Aerospace: Chapter 2 Prof. Doug Cairns.
Steep Turns.
AE 1350 Lecture Notes #8. We have looked at.. Airfoil Nomenclature Lift and Drag forces Lift, Drag and Pressure Coefficients The Three Sources of Drag:
U5AEA15 AIRCRAFT STRUCTURES-II PREPARED BY Mr.S.Karthikeyan DEPARTMENT OF AERONAUTICALENGINEERING ASSISTANT PROFESSOR.
ABORT. THROTTLES - IDLE WHEEL BRAKES - AS REQUIRED.
AME 441: Conceptual Design Presentation
Chandelles.
UCSD/General Atomics Design Project: Aeroelastic Wing Enhancement Jose Panza, Project Sponsor Jose Panza, Project Sponsor Dr. James D. Lang, Project Advisor.
6.06 Loads and Load Factor References: FTGU pages 17-18, 34-35
6.06 Loads and Load Factor References: FTGU pages 17-18, 34-35
Lesson 13 Airfoils Part II
Aero Engineering 315 Lesson 30 Turn Performance. “Turning” the tables…
Lesson 24 Performance— Thrust Required and Thrust Available
Aero Engineering 315 Lesson 33 GR3 Review. General strategy  Prior to class Review reading for lessons 23 – 32 Work / review problems #26 – 42 Review.
Lesson 32 Energy Height and Specific Excess Power (Ps)
Aero Engineering 315 Lesson 27 Gliding and Climbing Flight.
Review Chapter 12. Fundamental Flight Maneuvers Straight and Level Turns Climbs Descents.
MAE 4261: AIR-BREATHING ENGINES
Subject: Science Topic: Flight Technology Grades: Teacher Notes.
Takeoff Performance Jet Aircraft Performance
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!” Aerodynamics II Getting to the Point.
Aerodynamic Theory Review 3
Utilizing your notes and past knowledge answer the following questions: 1) Define load factor. 2) Describe the two reasons for understanding load factors.
AE 1350 Lecture Notes #9.
Lecture 7: DESCENT PERFORMANCE
The Boeing 777 can hold a max of 550 passengers on board and 2 crew members.
Real World Design Challenge
Aircraft Systems Operational Limits A-4N/TA-4. Aircraft Systems Operational Limits A-4N/TA-4 STARTER LIMITS ONE OF TWO AVAILABLE ENGINE STARTERS IS INSTALLED.
17-1 Design of UAV Systems Standard atmospherec 2002 LM Corporation Lesson objective - to discuss another UAV Operating Environment The atmosphere Expectations.
Dartmouth Flying Club October 10, 2002 Andreas Bentz
Aero Engineering 315 Lesson 20 Supersonic Flow Part II.
Structural Design Considerations and Airspeeds
Private Pilot Groundschool Session4 Weight & Balance, Aircraft Performance (PHAK Chapters 9&10)
6.07 Stalls References: FTGU pages 18, 35-38
ITA – Instituto Tecnológico de Aeronáutica
MAE 4262: ROCKETS AND MISSION ANALYSIS
Configuration Aerodynamics Mirage Mirage 2000 The Mirage 2000 Aircraft A Class Presentation By Anand Natarajan.
Introduction to Aerospace – Historical Perspective Dr. Doug Cairns.
The ability to maintain and control rotor RPM in the event of an engine malfunction so controlled flight may be continued to the ground. AutorotationAutorotation.
Flight Investigations TEXT BOOK CHAPTER 16 PAGE
AE 2350 Lecture Notes #9 May 10, 1999 We have looked at.. Airfoil aerodynamics (Chapter 8) Sources of Drag (Chapter 8, 11 and 12) –Look at the figures.
VNY FSDO FAASTeam Representative
LSA FAA definition Max gross takeoff weight = 1320 lbs Max stall speed = 45 knots Maximum speed in level flight = 120 knots.
Flight Manual - Sections 5 & 6 Performance Charts and Weight & Balance
비행체 구조설계 Aircraft Structural Design
ROTARY WING AERODYNAMICS
Purdue Aeroelasticity
Aerodynamics Chapter 3 Aerodynamics of Flight.
Theory of Flight 6.08 Loads and Load Factors References:
6.07 Stalls References: FTGU pages 18, 35-38
FP-2 T-44 Ops Limits 5/6/15.
Purdue Aeroelasticity
6.06 Loads and Load Factor References: FTGU pages 17-18, 34-35
West Point Aviation Club Private Pilot Ground Instruction
Matching of Propulsion Systems for an Aircraft
AE 440 Performance Discipline Lecture 9
Using and rearranging the lift calculation
MISCELLANEOUS PERF. The performance data for takeoff and landing an aircraft can be obtained from the aircraft's flight manual or pilot's operating handbook.
Pre-Solo Training Program
ANGLE-of-ATTACK Proprietary Software Systems, Inc.
Basic Stalling The Flight Training Manual - Section 10
Presentation transcript:

Lesson 31 Velocity vs. Load Factor (V-n) Diagrams Aero Engineering 315 Lesson 31 Velocity vs. Load Factor (V-n) Diagrams

V-n Diagram Objectives State reason for each limit in a V-N diagram State limitations and usefulness of V-n diagram Sketch a typical V-n diagram Annotate changes with weight and altitude Define and calculate corner velocity Given a V-n diagram find available and max load factors, stall speeds, maximum velocity, and corner velocity (velocity where max turn rate and min turn radius is achieved) Actual min turn radius and max turn rate may be calculated using corner velocity and max g

V-n Diagrams: Description Commonly known as the “flight envelope” Plot showing various structural and instantaneous performance limits Aerodynamic (stall) limits Structural (g) limits Dynamic pressure (q) limit Many aircraft flight manuals have one of these diagrams Each plot good for one weight, one altitude, one configuration

V-n Diagrams: Limits Note: Flight within the “envelope” is possible without stalling or damaging the aircraft. (Safe operating region = inside the box)

Aerodynamic (stall) limit The aerodynamic limit is a “lift limit” and occurs where the aircraft stalls Varies as a function of the square root of weight and load factor When stalling while above 1 g, it’s known as an “accelerated stall”

Maximum n available prior to stall At any point in flight Solving for n: For a given weight, altitude and aircraft, max n is L = nW = CL r SV2/2 CL r S 2W n = V2 CLMAX r S 2W nMAX = V2 Defines stall limit load factor line, not structural limit load factor

Structural (g) Limit Typical structural limits: Fighter: -3 to +9 g Max design load factor (n) Positive and negative g limit Will vary as a function of weight and configuration Heavier gross weight – lower g limit Flaps and gear down – lower g limit Carrying stores – lower g limit Speed or Mach may also effect structural limit Typical structural limits: Fighter: -3 to +9 g Transport: -1 to +3 g

Dynamic pressure (q) limit Maximum design speed (Mach or KCAS or KEAS) Type and nature depends on specific aircraft Critical mach – controllability, mach tuck etc Aeroelastic effects – Aileron reversal, flutter, etc High q – canopy implosion High Mach – Engine limit, directional stability Sustained High Mach – too high temperature, heating May be affected by load factor Typical q limits: Fighters: Mach 2.5 (heating) Transports: ~ Mach 0.8 (critical mach)

V-n Diagrams: Corner Velocity The corner velocity is the velocity at which the stall limit and the structural limit make a corner on the graph Flight at the corner velocity gives the minimum turn radius and maximum turn rate

Corner Velocity Example An A-10 with a wing loading (W/S) of 92 lbs/ft2 and CLmax = 1.5 has a maximum structural load limit of 7g’s. What is its corner velocity at sea level?

Q: What is the corner velocity (V*) for this aircraft?   Corner Velocity

Q: Where are the positive and negative stall limits for this aircraft? Q: What’s the stall speed at 1g? How about at 4g’s?   Stall speed @ 4g ~165 KCAS Stall speed @ 1g ~80 KCAS

Q: What happens to stall limit when altitude is increased?   Shift as h increases (r decreases)

Q: Where are the positive and negative structural limits for this aircraft? Positive g Limit   No shift as h increases Negative g Limit

Q: What happens when weight is increased?  

May shift as h increases Q: Where is the ‘max q’ limit for this aircraft?   q limit May shift as h increases (M and r changes)

V-n usefulness and limitations Works well for identifying: Instantaneous g capabilities g and speed limitations Corner velocity (point where max turn rate and min turn radius occur) Does not give any indication of: Sustained performance Actual values for turn rate and radius These can be calculated from info on V-n diagram though Performance at other weights, altitudes, configurations, asymmetric load limits etc

Design Considerations To get small r and large w: Minimize wing loading (W/S) Maximize “g” loading Structural considerations Physiological considerations Maximize lift coefficient Use high lift devices (maneuvering flaps, slats)

Example V - n Diagram Vmax = 382 KIAS / 0.7 Mach Page from T-37B Flight Manual

T-38 V-n diagram for 9,600 lbs Vmax = 720 KEAS / 1.62 Mach

T-38 V-n diagram for 12,000 lbs Vmax = 720 KEAS / 1.62 Mach

Homework #38 From the T-38 V-n diagrams… What is the maximum instantaneous load factor for a 12,000 lb T-38 at 15,000 ft and Mach 0.6? What is the maximum instantaneous load factor for a 9,600 lb T-38 at sea level and Mach 0.8? What is the maximum Mach number for a 12,000 lb T-38 at sea level? What is the maximum Mach number for a 9,600 lb T-38 at 15,000 ft? What is the corner velocity for a 12,000 lb T-38 at 25,000 ft? What is the corner velocity for a 9,600 lb T-38 at sea level?

Next Lesson (32)… Prior to class In class Read text 5.13 Complete problems through #39 In class Discuss specific excess power, energy height