T&R Bulletins & Reports

Please refer to T&R Bulletin 2-29A.

The study presented herein is directed at the evaluation of wave measuring techniques, particularly the schemes which may be used to measure waves in a ship model towing tank.

There has been a considerable investigation, study, documentation, and discussion on the subject of propeller tail shaft failures with much diversity of opinion expressed. In order to assist in the dissemination of information and to provide guidance for investigations on this subject, The Society of Naval Architects and Marine Engineers formed Panel M-8 (Investigation of Tailshaft Failures) under the guidance of the Ships' Machinery Committee of the Technical and Research Program.

This summary report is a chronological outline of the work of Panel M -8 on the investigation of tails haft failures. Particular emphasis is given to the objectives, accomplishments, and recommendations of the panel as well as the related work of others.

This report describes a pilot study investigation of two-dimensional unsteady flow about an airfoil passing through a narrow (or gust). Although the results are primarily photographic records of the flow observed, there are also included comments and sample calculations taken from existing and slightly extended theories of unsteady airfoil behavior. Such work appears in the appendix of the report. One of the main items of interest was the particular flow phenomena around the trailing edge specifically the visualization of the Kutta condition. In this conjunction, medium speed and "Fastax" films were made and should accompany the still photos contained in the report.

A study is made of the optimum characteristics of a short-crested tank facility for model experiments of ship behavior. The general arrangement of the tank is considered and the wave-making system and data analysis procedure are discussed in some detail. Lesser mention is made of the towing carriage, transducers, beach, and recorders. Optimization of the facility as a complete entity is considered from the point of view of compromising between realistic simulation and realistic cost.

Examination of the feasibility of measuring deviation in strain distribution from that predicted by simple beam theory in flange plating of a ship hull is performed on a modern sea-going bulk ore carrier. Bending moments resulting either from adding loads or from shifting loads are investigated. The corresponding primary stress distribution in the envelope plating is predicted by Schade's method. Remarkable and readily measurable strain deviation in the bottom plating is found in several cases.

The objective of this model test program is to obtain hull resistance in smooth water and in irregular head seas of moderate height through towing tests of models of:

a. Original cargo ship CHALLENGER

b. CHALLENGER with 7.7% bulb added 

c. Townsend Series with the same proportions as (a)

d. Townsend Series with 7.7% bulb added

e. Townsend Series with new forebody Incorporating 3.5% bulb.