Tail Rotor Systems

Question 1

Fenestron (fan in tail design)

Answer 1

1. Uses a fan inside vertical fin enclosed shroud fan w/multiple blades
2. Common to Eurocopters
   ADVANTAGES:
   - safety
   - quieter
   DISADVANTAGES:
   - heavy (CG)
   - expensive
   - less authority more pedal to get what you want

Question 2

NOTAR (no T/R)

Answer 2

1. Tailcone acts as an airfoil
   - low pressure forced through horizontal slots on the tail boom
   - high pressure air from M.R.
   Pressure differential causes horizontal lift (similar to an airfoil)
2. Directional nozzle allows directional control
   ADVANTAGES:
   - maximum safety
   DISADVANTAGES:
   - very expensive
   - high maintenance
   - less responsive (mushy pedals)
   - MD owns it

Question 3

Tail rotor (standard)

Answer 3

1. Most commonly used
2. Uses blades similar to the M.R.
3. 2 blades that spin opposite
   ADVANTAGES:
   - less expensive
   - most efficient
   - very simple
   DISADVANTAGES:
   - exposed, open to persons an obstructions
   - exposed to relative wind
   R44 Tail Rotor:
   - asymmetrical blades
   - delta hinge:
   - allows blades to change pitch while flapping
   - more effective/responsive with less movement
   - creates a greater AOA change with less flapping