Pantobase gear. — The similarity of water and snow skis leads immediately to 

 arrangements suitable for operation on water, snow, and ice, and even other "wet" 

 surfaces such as mud and sod. Such arrangements, combined with a conventional 

 landing gear for normal runway use, provides the so-called "pantobase" airplane for 

 universal operation in prepared and unprepared areas. These concepts have been 

 investigated by hydro-ski conversions of a JRF-5 amphibian for Arctic service and of 

 a C-123 assault transport for pantobase service (ref. [12]). The conversions of course 

 increase utility rather than performance, but the principles explored are applicable to 

 high-speed aircraft in other categories without the flight penalties so far incurred. 



The logical ski-wheel configurations for a pantobase gear are indicated in the 

 figure. For water operation, the skis are locked at a positive trim angle for hydro- 

 dynamic lift and stability, while the landing wheels are retracted above the skis to 

 minimize their adverse effect on resistance. For soft surfaces and ice, the skis are 

 free-to-trim as in the case of snow skis to follow surface contours and climb over 

 obstructions. In this case the wheels may or may not be used depending on the nature 

 of the medium. For hard-surface runways, the wheels are extended and the skis 

 retracted above them so that the landing gear can function in a normal fashion. 



Hull auxiliaries. — The employment of existing hull-type seaplanes as test beds 

 for hydro-ski evaluations has confirmed their inherent superiority in rough water and 

 the advantages of the large increase in afterbody clearances provided near take-off. 

 This experience and continued model experiments have suggested the possibility of 

 adding auxiliary skis to high-speed hulls to inprove their hydrodynamic performance. 

 If the existing aerodynamic stability and control permit, the ski can be made very 

 small and extended to completely penetrate the surface during wave impacts and thus 

 provide a larger amount of energy absorption. Because even small skis increase water 

 resistance in the early stages of take-off, they preferably remain retracted in these stages 

 and be jacked out at speeds near getaway where water loads and afterbody interferences 

 are most critical. 



Ditching aids. — In emergency ditchings of land-based aircraft in rough seas, 

 hazardous motions and extensive structural damage result from wave impacts at high 

 water speeds leading to serious casualties and rapid flooding of the fuselage after the 

 airplane comes to rest. The concept of the hydro-ski landing gear offers a positive 

 means of eliminating these hazards from the ditching operation, and greatly increasing 

 the chances of survival and rescue (ref. [13]). In this case, the gear would be used 

 only once and a manual arrangement for extending it would be sufficient, hence its 

 weight should be small as compared to that of a normal installation. It is conceivable 

 that such a device would permit the fuselage to stay intact during a ditching and thus 

 able to float indefinitely while awaiting rescue of the occupants. 



Land-water operation. — Small airplanes have been operated successfully on 

 and off beaches and ramps using snow skis, and several landplanes have been con- 

 verted to water operation by the addition of small hydro-skis to the wheel gear. This 

 experience leads to an entirely new concept to free high-performance aircraft from 

 present runway limitations, and at the same time eliminate the handling, floatation, and 

 low-speed hydrodynamic problems associated with complete water-based systems. 



Essentially the airplane is land-based adjacent to one of the sheltered bodies 

 of water which abound in most parts of the world. To take-off it accelerates down 

 a beach or short prepared ramp to a suitable low planing speed. At this point, it 

 enters the water and completes the high-speed portion of its take-off run on the hydro- 

 skis. Coming back, it reverses the process by landing on the water, decelerating to 

 near the minimum planing speed, and going up the ramp to a convenient point for 

 service and maintenance. 



The essential features of a gear for land-water operation are similar to those 

 for a pantobase gear in that the skis must be free-to-trim on land and fixed in trim 

 on the water and the wheels are preferably retracted during the water runs. Both the 



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