PPL » Aircraft Tech Knowledge (H) » Hovering
14.58 Hovering
14.58.2 Explain the effect of the following factors on hovering flight:
(a) density altitude;
- Higher density altitude → reduced air density
- Results in:
- Reduced rotor efficiency (less lift for same blade angle)
- Higher power required to hover
- Possible inability to hover out of ground effect (HOGE)
- Lower density altitude → increased air density
- Improved lift
- Less power required to hover
Summary:
As density altitude increases, hover performance decreases and power required increases.
(b) helicopter gross weight;
- Increased weight → more lift required
- Requires:
- Higher blade angle of attack
- Increased induced drag
- More power to maintain hover
- Reduced weight:
- Less lift required
- Lower power required to hover
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