Design Concerns for Flying-Boats

This paper discusses some practical aspects of flying boat design, which may come up as a design progresses beyond the concept stage. These include more detail on bottom loading, impact accelerations, spray intensity, the nature of porpoising instability, the use of standard series and tip float design. A complete set of standard series design calculations is provided. 1 INTRODUCTION In 2021, "A Review of Hydrodynamic Design Methods for Seaplanes" was published in the Journal of Ship Production and Design. In the years since, there has been an unusually high level of interest in seaplanes, and this has been an essential reference. As a result, I've been contacted by both students and professionals to answer questions related to modern flying-boat design. This paper is a summary of what has been learned from researching the answers to all of those questions. In many regards there was a push to greater understand the "why" behind much of the design guidance. This paper should be considered a companion or a Part II of the 2021 paper. Further, there was a major effort at the Davidson Laboratory at Stevens Institute of Technology to digitize the seaplane standard series during the last few years. The distribution of the series was originally very limited, and it was not immediately evident how they were organized as a whole body of work. After using the series to aid in multiple design efforts, the organization and purpose of the series have become clearer. The hull and tip float standard series are discussed and put into context here. Physical limitations prevented more content from being included here; however the standard series and the revised 2024 seaplane course notes are available online from the U.S. Naval Academy and Archive.org. The paper is organized as follows: 1. Introduction 2. Initial Feasibility Sizing Bottom Loading Take-off and landing speed Impact Accelerations 3. Design for Spray Spray Design Charts Spray Intensity Equation 4. Longitudinal Dynamic Stability Porpoising and Skipping 5. Hull Standard Series Overview of available series Complete Sample Calculations 6. Aerodynamic Drag and Thrust 7. Tip Float Design Hydrostatic Roll Stability Hydrodynamic Plow-In 8. Yaw and Pitch Instability Seaplane Accidents 2.