Lesson 4c - Minimum Sink

Lesson Objective

The lesson will learn the minimum sink speeds, how they relate to bank angle, and the importance of using the correct minimum sink speeds.

Regulatory Requirement

• Pre-Solo: 14 CFR §61.87(i)(8)
• Private Pilot Candidate: PTS V(A)

Content

• Minimum sink speed for each club aircraft
• Minimum sink speed for differing bank angles
• Glide ratio at minimum sink. Compare with glide ratio at Max L/D
• Minimum sink speed at the minimum pilot weight (solo) and at the glider's maximum gross weight

Completion Standards

The student must be able to perform:

• Straight and Level flight at minimum sink speed
• 30° bank turns at minimum sink speed.
• 45° bank turns at minimum sink speed.

The student must be able to explain:

• The effect of bank angle to minimum sink speed.
• The effect of aircraft loading to minimum sink speed.

Prerequisite Study

• Glider Flying Handbook (2024), Chapter 5, "Glider Polars" Page 5-10
• Glider Flying Handbook (2024), Chapter 7, "Thermalling Speed" Page 10-7
• SSC Cockpit Cards