Preliminary Design

INTRODUCTION

The preliminary design of a new helicopter is a team effort between the designer, the aerodynamicist, and the weight engineer, with help from other specialists. The effort progresses in cycles of iteration, at the end of which the design converges into its final form, leaving each member of the design team more or less satisfied.

The effort starts with a set of requirements established by the potential customer, by a marketing survey, or by some other means. The requirements that usually have the most influence on the design are:

1. Payload.

2. Range or endurance.

3. Critical hover or vertical climb condition.

4. Maximum speed.

5. Maximum maneuver load factor.

There are always design constraints, either formally stated or understood, that limit the design alternatives in some manner. Some of the most common involve:

1. Compliance with applicable safety standards.

2. Maximum disc loading.

3. Choice of engine from a list of approved engines.

4. Maximum physical size.

5. Maximum noise level.

6. Minimum one-engine-out performance.

7. Minimum autorotative landing capability.

The primary objective of the preliminary design team is to design the smallest, lightest, and least expensive helicopter that simultaneously satisfies all of the requirements and all of the constraints.