Aero Engineering 315 Lesson 27 Gliding and Climbing Flight

Lesson Objectives  Write Equations of Motion for power-off glide  Calculate glide angle, glide range, sink rate, velocity for min sink and velocity for max glide range given T-38 charts or a drag polar Know points where min sink and max glide range occur  State situations appropriate to fly at above speeds  Write Equations of Motion for steady climb  Calculate climb angle, ROC, Max AOC, and Max ROC given T-38 chart or drag polar Know points where max AOC and ROC occur Find the velocities for max AOC and ROC  State situations appropriate to fly at above speeds  Define absolute, service and combat ceilings

When Max Excess Thrust = 0

Climbs and glides summary Gliding Flight  Glide angle  Glide range  Sink rate Climbing Flight  Climb angle  Climb rate  Ceilings Results in just six separate parameters to determine

T-38 Example Given: W = 8,000 lbs h = 10,000 ft Find:R MAX

T-38 Example Given: W = 8,000 lbs h = 10,000 ft Find: ROD MIN

T-37 drag polar example  C D = C L 2  S = 184 ft 2  W = 6,000 lbs  H  sea level  Find (L/D) max P R min

T-38 Example Given: W = 12,000 lbs h = Sea Level Find:  MAX

T-38 Example Given: W = 12,000 lbs h = Sea Level Find: ROC MAX

T-38 Ceiling What happens to T A - T R as we go higher?

Ceilings Based on maximum climb rates  Absolute Ceiling = 0 ft/min ROC  Service Ceiling = 100 ft/min ROC  Cruise Ceiling = 300 ft/min ROC  Combat Ceiling = 500 ft/min ROC

Performance Summary (text p. 173) *for typical non-afterburning turbojet aircraft

Performance Summary RelationshipBest Case Relation between Induced and Parasite Drag for best case Graphical relation for best case Max Climb Angle C Do = kC L 2 - Minimum from T R curve - Tangent point on a line from origin to P R curve Max Climb RateNo set relation - Draw a line parallel to P A curve, and move it down till it is tangent to P R curve Breguet (5.28) or Avg Value (5.27) Max Jet Powered Range C Do = 3kC L 2 - Tangent point on a line from origin to T R curve Breguet (5.26) or Avg Value (5.24) Max Jet Powered Endurance C Do = kC L 2 - Minimum from T R curve - Tangent point on a line from origin to P R curve R = h (L/D) Best Glide Range (angle) C Do = kC L 2 - Minimum from T R curve - Tangent point on a line from origin to P R curve Best Glide Endurance (min sink) 3C Do = kC L 2 - Minimum from the P R curve Climbing Cruise Glides

Next Lesson (T28)…  Prior to class Read text , Complete homework problems #31 and 32 Complete FDP parts a, b, i, j, k, l, r  In class Discuss Cruise Range and Endurance

Fighter Design Project