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Aviation History
1965
1965 - 0159.PDF
FLIGHT International, 21 January 1965 93 and also allows infinite adjustment within the recline angle provided. Rendering this item leakproof is a main consideration, because hydraulic oil can be very damaging to passengers' clothing. A criticism of recline in the past has been that the occupant tended to slide on the seat-back when the recline was operated, but this objection can be largely overcome by making the seat-back pivot roughly coincident with the hip joint—as in the new Short SM.620 seat. This feature adds appreciably to the standard of comfort. First-class Seat Since it is usual to include a relatively small number of first-class places in an aircraft layout, weight is not as important as it is with other types of seat. With first-class seats the demand is for maximum possible com- fort; so apart from the cushioning being deeper and the covering more luxurious, the seating space is made wider to allow " fidgeting" room for the occupant. These seats are rarely produced as triple units and, at the most, four-abreast seating across the aircraft is the rule. It is possible to provide adequate width with wider armrests while still allowing the required gangway width. Certain items can be incorporated to add to the convenience of passengers. These include such features as adjustable head-rests; centre consoles for magazines, etc; footrests; and even vanity mirrors and coat-hooks. Bearing in mind that the type of seat we are discussing is used for long-distance travel, facilities for sleeping must be included in the design and most first-class units have a fully reclinable back. It is generally considered that a recline angle of 45° is a good compro- mise to allow a reasonable reclined position without interfering with the passenger immediately behind. Upholstery As well as being a main factor governing the standard of comfort, upholstery plays a large part in the appearance and style of a seat. The present trend is for cushions to be filled with polyester foam with easily removable and washable covers, while the rear of the seat-back is covered with a one-piece plastic moulding into which the meal tray can be flush-fitted when stowed, giving a clean and pleasing appearance. Upholstery forms a vulnerable part of any seat and easily sustains incidental damage. Consequently it is Shorts' practice to ensure that all items of covering are readily removable for repair. Whereas it was once acceptable merely to sew covering over the basic struc- ture, it is now important that upholstery should be constructed in sub-units which can be attached to the structure by clips or screws. Spare upholstery items can then be carried by airline operators, enabling them to carry out on-the-spot repairs and increase the serviceability of their seats. SEATS—2 Design for Living By R. J. G. BRAY, MAIAA, AFRA«S* THE airline industry's requirements, when coupled with thoseof the military transport, executive, helicopter and hover-craft operators, call for an extremely wide range of seats. The catalogue grows when the nature of the various types of operation is considered. Whether it be the high-density commuter services, the coach-air industry, the "forward-facing IT, rearward-facing trooping" operator, the long-range two-class prestige airline or the humble bucket-and-spade trade, each demands seats to meet a particular need. The range of the seat manufacturer's products must, therefore, extend from the "royal carriage" type to the canvas paratroop bench. To provide this extensive variety of seats, Rumbold, for instance, have produced, in the last 30 years, over 300 different designs, and are frequently called upon to make a further "one-off" to a pre-war pattern. In assessing the present state of the art, one is forced, for reasons of production economics and the high content of skilled craftsman- ship demanded for small-batch production, to focus on perhaps three or four basic designs, each capable of a limited number of variations to suit the operational requirements of a number of users. In this way, experience of serviceability, etc, is built up and a larger volume of production of a given basic design is achieved. Thus, the manufacturer is able to employ more comprehensive tooling and production methods than in the past. At this juncture, we can refer to the title of this article: "Design for Living" implies two criteria for the seat designer, namely, survival and comfort, in that order. Survival can in this instance be interpreted as "crashworthiness," or the ability to provide the protection required under emergency alighting conditions as defined by the appropriate airworthiness authority. Additionally, of course, it is the duty of the designer to incorporate, within his weight and cost parameters, every further safety feature he can devise. * Chief Designer, L. A. Rumbold and Co Ltd Fig I Seat test rig, utilizing DC-3 undercarriage jacks. A rearward- facing test of a Handley Page seat unit is in progress Testing Airworthiness requirements demand that all prototype seats are subjected to structural testing in a static test rig to prove their integrity under specified factored loads. A hydraulic rig such as that shown in Fig 1 is often used. The loads can be applied incrementally and the deflections recorded to plot an energy- absorption diagram. Being conducted in "slow motion," the test shows the behaviour of the specimen in detail (Fig 2, overleaf). Sometimes a "dynamic" test is called for by a prospective user, although airworthiness authorities do not as yet require this, nor indeed do they accept it as evidence of compliance. Such a test is usually conducted with the aid of a mechanically (NPL) or rocket- propelled (RAE) trolley. The duration of peak loads being of the order of a tenth of a second or less, quite sophisticated instrumenta- tion, together with high-speed photography, is required to record the evidence provided by such an adventure. The results obtained usually show approximately a 1.3 factor when compared with static testing, and are necessarily of a confirmatory nature with respect to
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