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A study was carried out to investigate, experimentally using a wind tunnel, the drag contribution (base drag) due to the flat-end of most van-type semi-trailers used for inter-city tractor-semi-trailer transportation. The study was focused on high cruise-speed operation of such vehicles at about 100 km/h (62.2 mile/h) a speed that can often be maintained for long distances on inter-city runs. It was found that it is possible to reduce overall aerodynamic drags significantly using a modestly tapered after-body terminating in a flat base. It was also shown that such after-bodies can be arranged to permit easy aft-end loading or unloading of trailers and that a reduction of engine fuel consumption at high-speed cruise on a level road of about 14% should be achievable when due allowance is also made for vehicle rolling resistance.

A description is given, with a supporting thermodynamic analysis, of a four-stroke Diesel engine concept with the expansion and exhaust strokes exceeding the induction and compression strokes due to the use of a novel linkage connecting the piston to the crankshaft. The advantage of such an arrangement, after allowing for engine internal friction losses, is a reduction of about 8% in specific fuel consumption relative to an otherwise similar conventional Diesel engine. There is also a corresponding reduction of emissions. An extension of the concept, incorporating a slightly more complex linkage, is applicable to spark-ignition engines. In this case the arrangement can be operated more flexibly since the expansion ratio can be adjusted with the engine running. This capability also allows a constant compression ratio to be maintained independently of the selected expansion ratio.

A description is included of the outboard horizontal-stabilizer (OHS) concept in which horizontal stabilizer surfaces are supported downwind, and outboard, of aircraft wing tips by means of booms. The essential purpose of such a configuration is to place each horizontal-stabilizer surface in the wing upwash. It is thus possible, as has been verified by wind-tunnel tests, to employ the horizontal stabilizers not only for meeting the requirements of providing pitch stability but also, as shown analytically, for generating additional lift efficiently to augment that due to the wing. A comparison is presented of the performances of comparable OHS and conventional light aircraft configurations showing that for equal cruise drags the conventional configurations employ mainplane aspect ratios two to three times those of the OHS units.

A new form of variable geometry, extended expansion, four-stroke internal combustion engine is described that is unable to employ squish over the full operating range. Accordingly a prediction was made of the influence of squish on the production of kinetic energy available for turbulence generation in a representative spark-ignition engine. It was found that the contribution of kinetic energy useable during the combustion process was commonly in the region of about 6% of that due to induction. It was, therefore, deduced that for typical spark-ignition engines the major benefit derived from the provision of squish surfaces is the resultant compactness of the combustion zone. Several techniques to counter the penalty resulting from the elimination of squish were reviewed. It was found that the most promising device was a turbulator incorporating low-pressure, compressed air, injection into the cylinder at the end of induction.

A description is given of a new form of Otto-Atkinson type engine, which does not incorporate variable valve timing, in which the compression ratio is essentially invariant over the full range of operating conditions. A brief review of relevant thermodynamic considerations precedes a discussion of the mechanical aspects of the proposed engine. This is followed by performance predictions. It is shown theoretically, with support from experimental work by others, that the new engine offers the promise of fuel savings of about 21-24% at 30% of full load and of 10% at 80% of full load.

It was demonstrated by analytical means, that the specific work obtainable from a Stirling type engine, with separate power and displacer cylinders, having the power cylinder connected to the hot zone of the displacer cylinder is, for typical operating conditions, about twice that obtainable when the power cylinder is connected to the cold zone. The analysis, which does not reveal any differences in ideal thermal efficiency between cold-zone and hot-zone power cylinder connections, is based on conventional thermodynamic concepts applied in a manner which differentiates explicitly between the conditions applicable to hot-zone versus cold-zone interconnection of the power and displacer cylinders. A new feature of the analysis is the introduction of what have been termed bithermal processes. These involve two regions of different, but constant, temperatures with mass exchange between the regions which communicate freely via the engine regenerator.

The advantages of using extended expansion-strokes are reviewed together with current methods for achieving this. A supporting thermodynamic analysis is presented for both diesel and spark-ignition (Otto) engine cycles employing extended expansion-strokes. It is also shown that such cycles do not generally preclude the use of turbo-charging since sufficient residual pressure prevails in the cylinders at the point of exhaust valve opening for turbo-charger operation. A basic, relatively simple, mechanism, and variants thereof, is described that permits the use of extended expansion strokes. It was concluded that the use of an extended expansion-stroke need not result, for a prescribed swept volume, in a significant increase in engine envelope volume or friction losses nor, in some cases, engine complexity.

The potential advantages of incorporating an extended expansion-stroke in Diesel engines are discussed. It is shown that Diesel engines with extended expansion strokes can be expected to have specific fuel consumptions up to about 8% lower, for typical automotive size units, than those achievable with conventional Diesel engines employing equal compression and expansion strokes. A description is also given of the essential mechanical linkage necessary to achieve an extended expansion stroke in engines of the four-stroke type. The application of the extended expansion concept to engines of the two-stroke, uniflow, type is also described.