Helicopter Lessons: Measuring Airspeed

Introduction

• Presenter: Jacob
• Topic: Methods for measuring how fast an aircraft travels through the air.
• Key Terms: Indicated Airspeed (IAS), Calibrated Airspeed (CAS), True Airspeed (TAS).

Types of Airspeed

1. Indicated Airspeed (IAS)

• Definition: Difference in pressure between a pitot tube and a static port.
• Mechanism:
  • Ram air pressure enters a pitot tube (usually on the helicopter's nose).
  • Static pressure is measured at static ports located elsewhere on the aircraft.
  • The difference moves a needle on an airspeed indicator.
• Characteristics:
  • Mechanical instrument.
  • Subject to errors and least accurate.
  • Errors can affect navigation, especially for long-distance flights.

2. Calibrated Airspeed (CAS)

• Definition: Indicated airspeed corrected for instrument errors using charts.
• Process:
  • Manufacturers provide corrective charts based on flight testing.
  • Charts help convert indicated airspeed to calibrated airspeed.
  • Involves comparing indicated airspeed against a line on the chart to find calibrated airspeed.
• Importance:
  • Provides more accurate airspeed for navigation.
  • Differences are minor at helicopter speeds but can be significant for faster or long-distance flights.

3. True Airspeed (TAS)

• Definition: Actual velocity of the aircraft relative to the surrounding atmosphere.
• Factors: Adjusted for temperature and pressure.
  • At sea level, calibrated airspeed equals true airspeed.
  • Differences arise at high altitudes (e.g., mountains).
• Example:
  • At 10,000 feet, a 75 knots indicated airspeed might equate to 80 knots calibrated airspeed.
  • After adjustments, true airspeed could be 94 knots.
• Significance:
  • Affects navigation due to air density variations.
  • Important to understand for accurate flight planning.

Calculation Tools

• E6B Calculator:
  • Used for calculating true airspeed, fuel computations, etc.
  • Does not require batteries and is portable.
• Modern Avionics:
  • Some helicopters have instruments that automatically adjust airspeed readings.

Conclusion

• Understanding differences in airspeed types is crucial for effective navigation.
• Recommended: New pilots should acquire an E6B calculator.
• Encouragement to like, subscribe, and provide feedback.

Closing Remarks

• Presented as part of Helicopter Lessons in 10 Minutes or Less.
• Reminder to stay safe while flying.