Rotor Blade Airfoils

Question 1

A high aspect ratio blade has a (larger, smaller) span and a (larger, smaller) chord than a low aspect ratio blade.

Answer 1

Larger
Smaller

Question 2

Blade twisting forces can be kept to a minimum by using the ——- airfoil shape and ensuring that the blades centre of gravity, centre of pressure and aerodynamic centre are (on, away from)the blades —— axis.

Answer 2

Symmetrical
On
Feathering

Question 3

Many blades have (wash in, wash out) which mean that blade angles ( increase, decrease) from root to tip.

Answer 3

Wash out
Decrease

Question 4

The main purpose of helicopter blade ( wash in, wash out) is to control the amount of (lift, drag) production from root to tip.

Answer 4

Wash out
Lift

Question 5

The worst combination of blade length and rotor rpm in producing tip speed sonic problems is the ( long, short)rotating at (high, low) rpm.

Answer 5

Long
High

Question 6

Using the sweep-back design near the blade tip permits ( lower, higher) tip speed and —— forward speed.

Answer 6

Higher
Higher