Ch. 6 Basic Helicopter Performance

Question 1

The types of zero-airspeed hovers over are _____ & _____.

Answer 1

In & out of ground effect hovers

Question 2

_____ implies the ground is not affecting the power required to maintain a constant height.

Answer 2

OGE

It doesn’t mean the rotor wash isn’t hitting the ground, merely the proximity of the ground doesn’t affect power required.

Question 3

While IGE, the effect of the air moving sideways slows down the _____.

Answer 3

Induced flow

Slowing down the induced flow decreases the AOA, which also decreases the drag & lift acting on the blade. This larger reduction in drag than lift at the same AOA, results in less power required to turn the rotor & hover.

Question 4

What are the 5 V Airspeeds?

Answer 4

Vy: minimum power required

Vh: maximum level flight airspeed; “horizontal” airspeed

Vne: velocity never exceed (red line on ASI)

Vne autorotation: velocity never exceed in autorotation or power off flight (blue line on ASI)

Vno: velocity normal operating (normally 10% less than Vne)

Question 5

The power required to maintain level flight changes dramatically with airspeed.

Describe the power required at airspeeds <60 KIAS, between 40-80 KIAS, & >80 KIAS?

Answer 5

<60 KIAS: more power to go slower (500-680hp)

40-80 KIAS: small change in power required (380-500hp)

> 80 KIAS: steep rise in power as airspeed increases (500-800+)

Question 6

What is “the backside of the power curve”?

Answer 6

To maintain level flight at an airspeed less than 60 KIAS, takes more power to go slower & maintain a constant altitude.

Question 7

OGE, the maximum power required is at _____ airspeed.

Answer 7

0

Question 8

IGE, the maximum power to maintain height happens at _____ to _____ knots of airspeed.

Answer 8

8-10 knots