FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1964
1964 - 0554.PDF
fl'GHT International supplement, 27 February 1964 Air-Cushion Vehicles Kawasaki KAG-3 . . . appraised by P. R. Ashill For the report appraised in the accompanying article we are indebted to Mr Shigenori Ando, chief designer, Engineering Depart- ment, Kawasaki Aircraft Co Ltd, Gifu, Japan. Mr Ando is one of the joint authors. Mr Ashill is at present engaged on , research into the performance and stability of ram wings at the College of Aeronautics, Cranfield. THE KAWASAKI KAG-3 represents one of a first generation of ram-wing craft, descriptions of which have appeared from time to time in this journal. In this review reference will be made to techniques used in the design of other first-generation craft when the various elements of the KAG-3 are discussed. I was naturally pleased to read this report, which is the first that has come to my notice describing the performance and design of a full-scale ram wing. My first reaction was to feel that it is appropriate that the report comes from Japan, since the Japanese were among the first to investigate, theoretically and experimentally, aerodynamic ground effect. This early work led to the con- . elusion that winged craft flying near the ground offer high lift/drag ratios with high operating lift coefficients. Mr Ando's report enables us to decide ; whether or not this promise is vindicatedin practice. Comments on the Design The description and general arrange- ment of the KAG-3 given in the report are to some extent self-explanatory. Unfortunately Mr Ando and his co- workers have not chosen to discuss in any detail the design philosophy of the KAG-3. The interpretation of the design made here represents a certain amount of conjecture, which in some instances may not be correct. The wing aspect ratio of 0.75 com- pares with the value of 1.0 for Vehicle Research Corporation's Columbia pro- ject and approximately 2.0 for the Lockheed "winged hull." The variance of these figures suggests that the over- riding consideration in the choice of aspect ratio may not have been the same for all these craft. In the case of the KAG-3 it would appear to have been chosen for structural reasons. The aerodynamic implications of this choice will be mentioned later. Adjustment of the pitch attitude would seem to be made by trailing-edge Haps on the vee tailplane. It is difficult to decide whether or not these flaps also provide directional control, as at least part of the steering is obtained by altering the direction of the screw. The first photograph of the craft at rest shows this quite clearly. According to the report the tailplane is also intended to damp pitching motions and pre- sumably ensures a certain amount of damping in the lateral sense. Lockheed's "winged hull" has elevators mounted on the main lifting surface whereas the Columbia, like the KAG-3, seems to have separate surfaces for control. The aerofoil section of the Kawasaki is NACA 6409 (6 per cent camber and 9 per cent thickness). This follows the practice of Lockheed and Vehicle Research Corporation, who have also adopted cambered wing sections for their craft. Floats are located at the wing-tips and the fuselage. We are not told whether the wing-tip floats are designed to serve any purpose other than to support the craft during the seaborne phase of its motion. It may be that they are also intended to act as aerodynamic endplates. The second photograph shows the craft almost airborne and it is apparent that there is a large gap between the interface and the side floats. This implies that the endplate effect of the floats is somewhat limited and the induced drag of the craft may be high during the cruise. Vehicle Research Corporation claim to have overcome this difficulty with the aid of side jets, although at the expense of the power required to drive the fans for the side jet air. The Lockheed design has simple aerodynamic endplates at its wing- tips. KAG-3 after modifica- tions. Modified points: 1. The front cover of the screw strut was added before the first trial (in winter). 2. The canopy fairing was added before the second trial (in summer). 3. The "float rear base fairing" was added be- fore the second trial WJTERLINf AT CRUISING 29
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
