1445. Group Weight Estimation for the Advanced Scout Helicopter Design Study

Paper

Abstract

Helicopter group weight estimation is a major part of the preliminary design effort that determines
the size and/or capabilities of a projected helicopter design. This was evident in a recently completed
Advanced Scout Helicopter (ASH) preliminary design study. Five ASH baseline design concepts, using the
Advanced Technology Engine (ATE) and the T700 engine, were studied.
Engine Seating
Single T700 Tandem
Twin ATE Tandem
Single T700 Side-by-Side
Twin ATE Side-by-Side
Single ATE Side-by-Side
Helicopter design characteristics were optimized for each configuration shown above. Approximately 365
variations were explored.
This paper briefly introduces the work done in the ASH preliminary design studies, and focuses on the component
weight estimation that resulted in the current five baseline designs. Weight estimation techniques are divided
into two classes: those component or group weights estimated by using statistical weight equations and advanced
technology factors, and those component weights which were based on semi analytical techniques and are fixed.
Weight equation derivation using multiple linear regression is described on an introductory level. This paper is
separated into weight groups,in accordance with MIL-STD-1374, Summary Weight Statement, Part 1. Each group addresses
the following topics:
* Form of weight equation(s)
* Definition of variables
* Assumptions made
* Variant design effects
After completion of weight equation derivation, the weight equations are calibrated to represent the technology
level in the AH-64 and UH-60. A final adjustment, representing advanced technology and assumed risk level, brings
the weight equations to the technology level expected for an FY81 entry into engineering development. The makeup
and value of all advanced technology factors are described.
The status of weight equations does not remain static. Future generations of weight equations will have increased
flexibility and accuracy in many areas because of the following steps: first, updating and expanding the database
used to generate the weight equations; second,increasing the use of fundamental physical variables, thereby
replacing the existing ratios and dimensionless weight equation variables; third, sensitivity adjustment of weight
equations to various degrees of crashworthiness, survivability, and other criteria resulting from future military
requirements; and fourth, subgrouping of existing weight equation categories, allowing the construction of advanced
concepts (i.e., tilt rotor, ABC, X-wing) from conventional components.