For Video Lecture of this presentation: https://youtu.be/u7bp9IJqRVM The topics covered in this session are, Slip: Types of slip, Sideslip angle, Sideslip angle sign conventions, restoring yaw moments, physical significance, Calculation of sideslip angle, Measurement of sideslip. Attention! "Gate Aerospace Engineering aspirants", A virtual guide for gate aerospace engineering is provided in "Age of Aerospace" blog for helping you meticulously prepare for gate examination. Respective notes of individual subjects are provided as 'Embedded Google Docs' which are frequently updated. This comprehensive guide is intended to efficiently serve as an extensive collection of online resources for "GATE Aerospace Engineering" which can be accessed free of cost. Use the following link to access the study material https://ageofaerospace.blogspot.com/p/gate-aerospace.html

1. FLIGHT MECHANICS
Presented by - Ganesh Natarajan S
Target Audience: Gate Aerospace, Aeronautical and Aerospace Engineering Students, etc.
SIDESLIP
β
V∞

2. CORE TOPICS
Basics: Atmosphere: Properties, standard atmosphere. Classification of aircraft. Airplane (fixed
wing aircraft) configuration and various parts. Pressure altitude; equivalent, calibrated, indicated
air speeds; Primary flight instruments: Altimeter, ASI, VSI, Turn-bank indicator. Angle of
attack, sideslip; Roll, pitch & yaw controls. Aerodynamic forces and moments.
Airplane performance: Drag polar; takeoff and landing; steady climb & descent; absolute and
service ceiling; range and endurance, load factor, turning flight, V-n diagram. Winds: head, tail
& cross winds.
Static stability: Stability & control derivatives; longitudinal stick fixed & free stability;
horizontal tail position and size; directional stability, vertical tail position and size; lateral
stability. Wing dihedral, sweep & position; hinge moments, stick forces.
SPECIAL TOPICS
Dynamic stability: Euler angles; Equations of motion; Decoupling of longitudinal and lateral-
directional dynamics; longitudinal modes; lateral-directional modes.
SYLLABUS

3. Outline
Let’s Start
SIDESLIP
Previous Lessons Angle of Attack
Slip
• Definition
• Types of Slip
Sideslip Angle (β)
• Definition
• Sideslip Angle (+Ve & -Ve)
• Restoring Yawing Moment
Sideslip
• Physical Significance
• Calculation & Measurement

4. Slip:
A slip is an aerodynamic state where an
aircraft is moving somewhat sideways as
well as forward relative to the oncoming
airflow or relative wind.
• Slip: Un-coordinated Flight.
Types of Slip
 Forward Slip: reduce height
 Sideslip: move the aircraft sideways
1. Crab method
2. Wing low method
Slip & its typesMotionImageryStandardsBoard(MISB)/Publicdomain

5. Sideslip Angle
Definition
The angle between the relative wind (V∞) and the
projection of the airplane’s longitudinal axis is known
as the sideslip angle
• The sideslip angle is symbolized as “ β ”.
• Co-ordinated Flight - zero sideslip angle.
β
V∞
RelativeHeadwind
Relative Crosswind

6. + β
V∞
- β
V∞
Sideslip Angle
Positive Sideslip Angle
Negative Sideslip Angle

7. V∞
- N
V∞
Restoring Yawing Moment
Positive Yawing MomentNegative Yawing Moment
+ N
β = 0

8. Physical Significance: Crosswind landings
In crosswind conditions, the pilot is required to fly at a sideslip angle in order
to maintain alignment with the runway. [Transport airplanes ≤ 15.5 m/s]
Mysid/CCBY-SA(https://creativecommons.org/licenses/by-sa/3.0)

9. Calculation of Sideslip Angle
Y

10. Sideslip Angle Formula
β = sin-1 𝑣
𝑉
i.e. sinθ =
𝑂𝑝𝑝
𝐻𝑦𝑝
α = tan-1 𝑤
𝑢
i.e. tanθ =
𝑂𝑝𝑝
𝐴𝑑𝑗
Similarly
If the sideslip and angle of attack are smaller than. i.e. < 15°
β =
𝑣
𝑉
α =
𝑤
𝑢
Where V = (u2 + v2 +w2)1/2
*The value of α and β values are in radians*
The sideslip (β) and angle of attack (α) can be defined in
in terms of the velocity components, using trigonometry

11. FederalAviationAdministration/Publicdomain
Sideslip Measurement
Yaw String
Turn & Slip Indicator

12. Book Reference
• Flight stability and automatic control (2nd Edition), Dr. Robert C. Nelson;
Pg.No: (21 & 30).
• Pilot's handbook of aeronautical knowledge 2016 - Chapter 5: Aerodynamics
of flight (5-18) Pg No: (117/524)
SIDESLIP

13. Summary
Sideslip
β
Determination
Copyright Notice: Images used in this
presentation are sourced from pixabay.com
under “Pixabay License” which are “Free
for commercial use and No attribution
required” category (or) from other
sources, in which case appropriate
attributions are provided.