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The report studies the performance characteristics of the air cushioned landing and takeoff system for aircraft during its stiff-operation mode. Stiff-operation is obtained during the early stage of the takeoff period or the later stage of landing. Its chief feature is that the penumatic supply chamber of bleed air is in almost parallel configuration with the ground. The supply air flows vertically down through the bleed holes and is then deflected outward. This part of the report contains the theoretical treatment of the problem. The results are in the form of a cushion pressure ratio in terms of the supply (trunk) pressure. Analysis was performed, based on incompressible viscous theory.

The vehicle-guideway system is modeled as an arbitrary number of lumped, doubly-sprung vehicle mass systems traveling in tandem along simple supported beams. The vehicle load is transmitted to the guideway as a time-varying uniform pressure compatible with vehicle motion. Effects of the dimensionless system parameters on vehicle heave acceleration, and guideway deflections and bending moments at high vehicle speeds are evaluated. Results for a vehicle which includes pitching motion compare favorably with those for a vehicle without pitch where the front and rear masses are uncoupled. By proper choice of parameters, passenger compartment heave accelerations can be minimized, although to keep this acceleration below 0.05g for vehicles traveling 100–300 mph requires systems with low vehicle to beam mass and frequency ratios as well as low vehicle lower to upper mass ratios. The benefits of distributed air cushion pressure to vehicle and guideway design are shown. Also, if the ratio of lower to upper vehicle mass is low, a constant moving pressure conservatively predicts the guideway response.

THIS PAPER SYNTHESIZES THE AVAILABLE DESIGN AND PERFORMANCE DATA FOR EXISTING AND PROPOSED AIR-CUSHION VEHICLES. THE DISCUSSION COVERS SUCH TOPICS AS: STRUCTURAL WEIGHT; MACHINERY AND EQUIPMENT WEIGHT; DISPOSABLE LOAD: CRAFT SIZE AND SPEED; AIR-CUSHION PRESSURE AND SKIRT LENGTH; SPECIFIC POWER AND TRANSPORT EFFICIENCY; TYPES OF ENGINES AND TOTAL POWER REQUIRED. THIS INFORMATION COULD BE USED BY PROGRAM MANAGERS AND DESIGNERS AS A REFERENCE DATUM WHEN COMPARING THE PERFORMANCE OF THE FUTURE AIR CUSHION VEHICLE (ACV) DESIGN CONCEPTS. THE INFORMATION CONTAINED HEREIN IS BASED ON PUBLISHED DATA AND EXPERIENCE WITH ACV'S WHICH HAVE BEEN DESIGNED AND BUILT (OR MODIFIED) UP THROUGH THE EARLY PART OF 1970. /AUTHOR/

1. BRAKE SYSTEMS. — A representative layout is presented and the functions of the various system components are enumerated. Some have developed towards technological simplification and others are now meeting requirements. The latter are given closer consideration : — Reciprocating compressors are faster, and their performance is such that new distribution methods are required. — Pressure regulation can take various forms. What are these forms, and what are the criteria on which their choice depends ? — How can braking stability and efficiency be ensured irrespective of load ? Description of a simple system. The «first stage » type of device. — Brake cylinders can be used to power the parking brake system : — Cylinders with a control rod lock. — Reverse-action brake cylinders. — Air tank protection can be improved. 2. SUSPENSION SYSTEMS. — Pneumatic suspension gives a more comfortable ride by keeping the car on a level keel. Adventages of the variable effective section air cushion. Air cushion pressure control., 1. FREINAGE. — Présentation d’un schéma type et énumération des différentes fonctions à assurer par les appareils. Certains ont évolué dans un but de simplification technologique, d’autres répondent maintenant à des besoins nouveaux. Nous retiendrons particulièrement ceux-ci. — Les compresseurs alternatifs sont plus rapides. Leurs performances imposent de nouvelles techniques de distribution. — La régulation de pression se présente sous différentes formes. Quelles sont-elles ? Quels sont les critères de choix ? — ... Comment peut-on obtenir l’efficacité et la stabilité du freinage quelle que soit la charge ? — Description d’un appareil simple. — Le dispositif dit de premier temps. — Les cylindres de frein peuvent assurer le freinage de stationnement. — Les cylindres à verrouillage de tige. — Les cylindres de frein à action inverse dits «frein à ressort ». — La protection des réservoirs peut être améliorée. 2. SUSPENSION. — La suspension pneumatique améliore le confort en donnant une assiette constante. Intérêt du coussin à section efficace variable. Le contrôle de la pression dans les coussins., Treillet Jean. Rapport V. c-3. L’air comprimé dans le freinage et la suspension des automobiles. In: Le rôle de la mécanique des fluides dans les progrès récents des techniques. 1967.