Helicopters

UAVs are becoming important in parcel delivery.

Amazon, Google, UPS all have applied to the FAA for special permissions regarding the UAV policy restrictions.

Most of these are driven by helicopter style rotors. A principle reason is their ability to take off and land vertically.

This propulsion system is very different from helicopters.

A helicopter can:

• take off and land vertically
• can hover
• can fly forward, backward, or laterally
• can be used in congested areas
• rotor provides lift (=weight) and thrust (= drag)

An UAV you are likely to buy

will do all those things. However notice that the power arrangement is different.

A helicopter most likely has a single engine while the UAV has independent engine for each of its rotors.

It is probably more like a tilt rotor (except the rotors tilt only a small angle to achieve forward/backward/lateral flight).

In general the power consumption helicopter type devices is more than for aircrafts - you are paying for versatility.

Rotor Power

Non dimensional Parameters for rotor performance:

Something to keep in mind:

• The ratio of thrust to power T/P is called the Power Loading.
• Pure helicopters have a power loading between 6 to 10 lb/HP.
• Tilt-rotors have lower power loading – 2 to 6 lb/HP.
• VTOL vehicles have the lowest power loading – less than 2 lb/HP.

(Figures from Wikipedia)