FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1963
1963 - 2254.PDF
FLIGHT International supplement, 25 July 1963 Air-Cushion Vehicles Obviously, the larger the craft, the greater the range of performance and flexibility in design. Another important factor influencing the choice of size was the desire to demonstrate a military capability. The small test craft built in the early stages had little capability in this regard, and it was considered that general acceptance of military air- cushion craft would be delayed until significant performance could be dem onstrated. The size range of 20-30 tons was thus selected because smaller craft would require such compromises in payload and performance as to seriously limit their usefulness to demon strate operational capability, or serve as a research tool for the collection of data. In the end, the economics of the problem was a determining factor. Although the state-of-the-art might support development of a craft larger than 20 tons, it was deemed prudent to limit size to about 20-25 tons and con serve funds. This process of moving toward larger craft in two distinct steps parallels British efforts. During the summer of 1961, BuShips conducted a design competition for SKMR-1. A contract was awarded to the Bell Aerosystems Co, of Buffalo, NY, in November 1961. The contract consisted of a preliminary design phase, which was completed in April 1962, and a fabrication phase, which was com pleted when the craft rolled out for the beginning of its acceptance testing in April 1963. Basic data for SKMR-1 are given on page 9, and the general configuration can be seen clearly from the illustrations and the large cutaway drawing. The main flotation hull comprises four Fig 2 A general view of the construction of the SKMR-1 in the Wheatfield (Buffalo), NY, factory of Bell Aerosystems Co Fig 3 SKMR-1 air-cushion system. This diagram, taken from the SAEjASNE paper by Capt Stark and Lt Gauthey, shows clearly the manner in which the four lift fans feed a plenum space below the main deck level, discharging into a 45° peripheral jet and longitudinal and transverse stabilizing nozzles (in British parlance, stability jets) STABILIZING NOZZLES PERIPHERAL NOZZLE :y.;s^y.,-..^£aTgjr:cs' ;::::::".:u:^ AIR PASSAGE PROPULSION DUCTS CUSHION FAN DUCTS PILOT HOUSE NOZZLE CONTROL VANES FLOTATION COMPARTMENTS boxes, the rear pair rectangular and the front pair tapered to form a vee bow. Hull assembly is illustrated in Fig 2. The four compartments are rigidly joined, and their adjacent walls are separated to leave transverse and longitudinal stability jets with a total area equal to about two per cent of the total base area. Around the flotation hull is a continuous peripheral jet, inclined inwards at 45° and having an area equal to about five per cent of the base area (Fig 3). Lift is generated by four modified mixed-flow fans, and thrust by two three-blade ducted propellers. As in the Westland SR.N2 there are two separate sets of interconnected fans and propellers, each set being driven by two turboshaft engines. The latter are 1,080 s.h.p. Solar Saturns. One pair of engines is arranged at front and rear on each side of the vehicle, with free- turbine output coupled through an over-running clutch to a horizontal shaft system from which angle boxes drive the two lift fans and propeller on that side. There is no mechanical connection to the shaft system on the opposite side of the vehicle (Fig 4). This arrangement enables power to be varied differentially between the lift and propulsion system on each side merely by varying the pitch of the propeller. It also leaves a clear payload space in the centre of the vehicle measur ing about 8ft by 18ft, access to which is gained at the stern. The cushion fans are of glass-fibre construction and employ variable inlet guide vanes and ten fixed rotor vanes. The inlet guide vanes may be used for trimming the attitude of the craft. The fixed rotor vanes are adjustable, and can be set to alter the speed/cushion- height relationship through a small
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
