TABLE OF CONTENTS As noted in the previous chapter, market intelligence and discussions with potential customers provide the aircraft industry with advance information that new requirements are being considered. Initial concepts are prepared based upon some degree of guesswork. Supposed requirements are listed and, using the company's data bank together with rough calculations by the aerodynamics, structures, and weights departments, an iterative approach is taken to develop a series of possible configurations.
The customer eventually releases the Specific Operational Requirement (SOR) or its equivalent. This is not necessarily intended to lead up to a contract, but is intended to stimulate interest and to start serious design investigations (using company funds). A typical case recently was the advocacy of a 150-passenger transport by some U.S. airlines. The SOR defines the customer's overall needs, including such items as payload/range, takeoff and landing distances, cruise performance, accomodation, cargo to be carried (weight and size), availability date, and special characteristics that depend upon the type of aircraft. Items such as gross weight are not defined these are a fallout, determined by the airframe manufacturer.
The major aerospace companies now have computer programs to perform the iterative analysis mentioned above. The program uses the requirements as input data, adds the data bank stored in its memory, and prints out the aircraft's vital characteristics from which layouts can be made. Among these characteristics are the maximum gross weight and the mean aerodynamic chord (MAC) location.
At this point, no thought...
