Tank Tests of Models of Floats for Single-float Seaplanes First Series.

Large models of the Mark V and Mark VI floats used for single float seaplanes (National Advisory Committee for Aeronautics (NACA) models 41-A and 41-B, respectively) were tested in the NACA tank to provide general test data for typical single floats and a basis for possible improvements of their form. The resistance of model 41-B was greater than that of model 41-A, either when free to trim or at the best trim angle for each. The resistance of model 35-B (a pointed step hull tested free to trim) was less than either of the models at the hump speed, greater at intermediate planing speeds, and less at the speeds and loads near get-away, although the spray was generally worse owing to the absence of transverse flare. The results of the fixed-trim tests of model 41-A were cross plotted to obtain data at the angle for zero trimming moment and at the best trim angle. The trims assumed by models 41-A and 41-B, when tested free to trim, were found to be excessive at the hump speed. The corresponding trim of model 35-B was found to be approximately 3 degrees lower because of the lower angle of afterbody keel used in this model, and the maximum hump resistance was 15 percent lower

Tank Tests of Model 11-G Flying-boat Hull

The NACA model 11-G flying-boat hull, a modification of NACA model 11-A was tested over a range of loadings. The planing bottom of model 11-G has a variable-radius flare, or concavity, at the chines in contrast to the straight V planing bottom of model 11-A. The results are given as curves of resistance and trimming moment plotted against speed for various angles of trim. The characteristics of the form at the optimum angles of trim are given in non-dimensional form as curves of resistance coefficient, best trim angle, and trimming-moment coefficient plotted against speed coefficient. As compared with the original form, model 11-G is shown to have higher resistance at all loads and speeds and higher maximum trimming moments at heavy loads. The spray pattern, however, is generally more favorable, indicating that the service performance of model 11-A would be improved by some form of chime flare

The application of NAVSTAR Differential GPS to civil helicopter operations

Principles concerning the operation of the NAVSTAR Global Positioning Systems (GPS) are discussed. Selective availability issues concerning NAVSTAR GPS and differential GPS concepts are analyzed. Civil support and market potential for differential GPS are outlined. It is concluded that differential GPS provides a variation on the baseline GPS system, and gives an assured, uninterrupted level of accuracy for the civilian community

Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guide book. iii- polyfluorocarbon films special report no. 3

Outgassing studies of polyfluorocarbon films - investigation of polymers as spacecraft construction material

Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guidebook. ii- rtv silicone adhesives and potting compounds special report no. 2

Silicone rubber adhesives and potting compounds - polymeric materials for spacecraf

The Increase in Frictional Resistance Caused by Various Types of Rivet Heads as Determined by Tests of Planing Surfaces

The increase in the frictional resistance of a surface caused by the presence of rivet heads was determined by towing four planing surfaces of the same dimensions. One surface was smooth and represented a surface without rivet heads or one with perfectly flush countersunk rivets. The other three surfaces were each fitted with the same number of full-size rivet heads but of a different type arranged in the same pattern on each surface. The surfaces were towed at speeds representative of the high water speeds encountered by seaplanes during take-off and the range of Reynolds Number covered by the test was from 4 x 10(exp 6) to 18 x 10(exp 6). The rivet heads investigated were oval countersunk, brazier, and round for rivets having shanks 5/32 inch in diameter. The oval countersunk heads were sunk below the surface by dimpling the plating around them. The results of the tests showed that, for the rivet heads investigated, the increase in the friction coefficient of the surface is directly proportional to the height of the rivet head. The order of merit in regard to low resistance is flush countersunk, oval countersunk (whether sunk below the surface or not), brazier, and round

Hydrodynamic and Aerodynamic Tests of Models of Floats for Single-float Seaplanes NACA Models 41-D, 41-E, 61-A, 73, and 73-A

Tests were made in the NACA tank and in the NACA 7 by 10 foot wind tunnel on two models of transverse step floats and three models of pointed step floats considered to be suitable for use with single float seaplanes. The object of the program was the reduction of water resistance and spray of single float seaplanes without reducing the angle of dead rise believed to be necessary for the satisfactory absorption of the shock loads. The results indicated that all the models have less resistance and spray than the model of the Mark V float and that the pointed step floats are somewhat superior to the transverse step floats in these respects. Models 41-D, 61-A, and 73 were tested by the general method over a wide range of loads and speeds. The results are presented in the form of curves and charts for use in design calculations