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The purpose of this paper is to study the behavior of smoke flow in building fires and optimize the design of smoke control systems.

A total of 435 3-D fire simulations were conducted through NIST fire dynamics simulator to analyze thermal behavior of combined buoyancy-induced and pressure-driven smoke flow in complex vertical shafts, under consideration of influence of heat release rate (HRR) and locations of heat sources. This influence was evaluated through neutral pressure plane (NPP), which is a critical plane depicting the flow velocity distributions. Hot smoke flows out of shafts beyond the NPP and cold air flows into shafts below the NPP.

Numerical simulation results show that HRR of heat source has little influence on NPP, while location of heat source can make a significant difference to NPP, particularly in cases of multi-heat source. Identifying the location of NPP helps to develop a more effective way to control the smoke with less energy consumption. Through putting an emphasis on smoke exhausting beyond the NPP and air supplying below the NPP, the smoke control systems can make the best use of energy.

Because of the chosen research approach, the research results may need to be tested by further experiments.

The paper includes implications for the optimization of smoke control systems design in buildings.

This paper fulfills an identified need to research the behavior of hot smoke in building fires and optimize the design of smoke control systems.

The purpose of this paper is to analyze the variations in the neutral plane when a tall space with unsymmetrical openings is on fire. The neutral plane of the fire scene is an important index of a natural smoke exhaust system. The numerical simulation method and the Schlieren photography technique were used as analysis tools. The results of model experiments and numerical simulation were compared with each other to confirm the rationality of the conclusions. The results were to discuss the characteristics of various cases and showed that the neutral planes of the fire scene were not always horizontal.

The numerical simulation method and the Schlieren photography technique were used as analysis tools. The flow patterns of hot air in various cases were recorded using the flow visualization technique. In addition, the renowned simulation software, fire dynamics simulator (FDS), was used for case analysis. The Schlieren photography technique was used for 1/12.5 model experiments with six smokeless candles burned, and FDS was used for a numerical simulation. In terms of the case of unilateral vents, the exhaust efficiency was discussed when the exhaust vent and air inlet were located on the same side or different sides.

This study demonstrates that makeup air flowing in from the inlets and openings has a significant impact on the effectiveness of natural smoke exhaust systems. The results illustrated that the neutral planes were tilted in some cases. In some cases, the results showed that one side was the air inlet and the other side was the exhaust vent, even if the openings were at the same height in some cases. These phenomena have rarely been discovered or studied in the past. The exhaust efficiency was not always better when the vent was located in the rooftop.

This study analyzed the neutral plane of a fire scene using the common unsymmetrical opening spaces in the Taiwan region as an example. The phenomenon of non-horizontal neutral plane has rarely been studied in the past. The temperature of the discharged hot gas was low because of an efficient exhaust effect, which reduced the heat and smoke storage in the space. The results obtained by these two methods were consistent, and showed that the cases with the same opening area had different smoke extraction efficiencies, meaning the smoke extraction effect cannot be judged only by the opening areas.

An aeroplane adapted to remain controllable at low speeds and high angles of incidence has automatically moving slot‐forming planes along the leading edge of each wing, camber‐varying flaps at the trailing edge interconnected to the stabilising plane and capable of being locked by the pilot in various positions, and additional normally closed slots at the wing tips which open only when the main slots are open and the usual ailerons are depressed. The slot closing element connected to each aileron may also project above the upper surface of the wing to break up the air stream on that side of the machine on which for the time being the aileron is raised. These features are shown applied to a low‐wing monoplane with widely spaced landing wheels. Slot‐forming planes 35, Fig. 4, are carried by curved tubes 40 moving between guide rollers 41 carried by brackets on the front spar of the plane. They normally nest against the leading edge of the plane and move forwards automatically as the stalling angle is approached. Camber varying flaps 29, Figs. 4 and 9, and ailerons 28, Fig. 5, are pivoted to the trailing edge of the wing and have their forward edges so shaped that slots 47 are formed when the flaps or ailerons are depressed, the slots being substantially closed in the neutral and raised positions of the flaps and ailerons. The flaps 29 are interconnected to the stabilising plane 26, the leading edge of which is raised and lowered by links 55, and both are moved simultaneously by a lever 33 provided with a detent engaging with a locking quadrant 51. The air pressure on the plane 26 partially balances that on the flaps as regards their reaction on the lever 33. A rod 53 which actuates the plane 26 is connected to a lever 33a, Fig. 10, and the lever 33 has a quadrant 59 to which the flap cables are connected, the two levers 33, 33a being adjustably connected by screw‐and‐nut mechanism 34 in order to vary the relative adjustment of the stabiliser plane and flaps. At the forward edge of each wing tip opposite each aileron a slot 37, Fig. 5, is formed, which is normally closed at its lower end by a plate 63 connected by a lost‐motion link 64 to the slot‐forming plane 35, and at its upper end by a pivoted quadrant 67 connected to the corresponding aileron by a lost‐motion device 70. When the aileron is depressed, or raised beyond a certain amount, the quadrant is respectively withdrawn into the plane to open the slot or projected beyond the upper surface to disturb the streamline flow and reduce the lift on that wing tip. Springs 71, 72 normally centre the quadrant 67. The plate 63 only moves to open the slot 37 when the main slot is open. The wing spars 88, 89, Fig. 12, are connected to the lower edge of the fuselage and braced to the upper edge by struts 90, 91 with intermediate braces 92, 93, The rear struts 91 may be upwardly arched. The landing wheel axles are carried by hinged struts 95 and supported from the front spars by telescopic struts 96 with shock‐absorbers 82.

THE main object of this paper is to help bridge the gap that exists between the scientific knowledge of materials and the practical application of that knowledge to the production technique of sheet‐metal forming. During the past year the Production Research Group of Lockheed's engineering department has given special attention to this important problem and has worked closely with the production departments in an effort to put sheet‐metal forming on a scientific basis. The following discussion is based largely on the work of the Production Research Group, as reported in various references and in papers yet to be published. Mr. William Schroeder and Mr. G. A. Brewer of this group have been particularly helpful to the author in the preparation and editing of the technical material. Because of the scope of the present paper, detailed discussion and analysis of new developments cannot be undertaken; however, such information will be made available as soon as possible in the form of individual papers by those directly responsible for the work.

BEFORE commencing an inspection obtain the pilot's report on the previous flight. In the course of the following inspections, as with all inspections, components which are found to be damaged or defective must be repaired, if possible, or replaced. However, before repairing a component, the relevant repair instructions must be consulted. Unless otherwise stated, these inspections are carried out every 40 hours.

Fig. 2 shows a blade carried by a head of the kind described in Specification. 435,818. The root of the blade comprises a steel tube 32 provided with a fairing 33, Fig. 3, which is a sliding fit over supporting arm 30 and is rotatable to vary the blade pitch. The outer end of tube 32 is secured to blade spar proper 34. The blade is anchored to the hub by a torsionally resilient tie rod 35 screwed at its outer end into spar 34 and secured by a nut and tapered collet device 36. At the inner end rod 35 is secured into arm 30 and secured by a screwed plug and taper pin assembly 37. The blade is of lancet shape and is arranged so that axis B—B of the spar intersects the flapping and drag pivot axes and in the normal mean position of the blade intersects the axis of rotation at the mean centre of oscillation F of the blade pitch control gear. The masses and aerofoil sections of the blade are such that the centres of mass and mean centres of pressure of all the sections lie along axis B—B. The construction of the blade is such that the “ neutral torsional axis,” defined as the locus of points in the chord at which an applied vertical thrust produces equal degrees of flexure of the leading and trailing edges, is at or slightly in front of the axis B—B. In the latter case increase in lift tends to decrease the angle of incidence of the blade as is shown in Fig. 6 wherein C is the centre of pressure, L the lift force, and 0 the neutral torsional axis. In either arrangement aerofoil sections having a stable centre of pressure travel may be employed. In order to bring the neutral axis forward, the nose portion of the blade, in the case of hollow stressed‐skin construction, may be reinforced by additional layers of material or may comprise material having a higher modulus of elasticity than the remainder. In order to compensate the resulting forward movement of the centre of mass, a small amount of non‐structural mass may bo incorporated in the blade. In one form in which the neutral torsional axis is coincident with the B—B axis, the blade comprises a spar and an aerofoil‐shaped fairing of material of the synthetic resin or plastic group of which the modulus of elasticity is so much lower than that of the spar as not to relieve the latter appreciably of its loads. Fig. 7 shows the method of construction of such a blade comprising a steel spar having a moulded fairing. A first mould comprises upper and lower dies 1, 2 and an interposed core 3. Spar 4 is located by pegs 5 and by rows of spaced raised points 6, and is also fluted to key the moulding. Steel wires 8, 9 are strung in the spaces forming the leading and trailing edges. The blade is formed with a solid nose and with internal ribs 10 and webs 11, the latter being produced by slots formed in the upper side of core die 3. After moulding as shown, dies 2 and 3 are removed, pegs 5 cut off, countersunk, and plugged, Fig. 9, and a lower die 13 placed in position and heat applied to unite the lower skin to ribs 10 and to seal the trailing edge. A suitable plastic material is stated to be “ plastic glass.”

The aim of the research is to conduct a study into a configuration of an aircraft system with a focus on aerodynamics. In addition, trim condition and static stability constraints were included. The main application of this system is suborbital space flights. The presented concept of a modular airplane system (MAS) consists of two vehicles: a Rocket Plane and a Carrier. Both are designed in tailless configurations but coupled formed a classic tail aircraft configuration, where the Rocket Plane works as the empennage. The most important challenge is to define the mutual position of those two tailless vehicles under the assumption that each vehicle will be operating alone in different flight conditions while joined in one object create a conventional aircraft. Each vehicle configuration (separated and coupled) must fulfil static stability and trim requirements.

Aircrafts’ aerodynamic characteristics were obtained using the MGAERO software which is a commercial computing fluid dynamics tool created by AMI Aero. This software uses the Euler flow model. Results from this software were used in the static stability and trim condition analysis.

The main outcome of this investigation is a mutual position of the Rocket Plane and the Carrier that fulfils project requirements. Also, the final configuration of both separated vehicles (Rocket Plane and Carrier) and the complete MAS were defined. In addition, it was observed that in the case of classic aircraft configuration which is created by connecting two tailless vehicles increasing horizontal tail arm reduces static stability. This is related to a significantly higher mass ratio of the horizontal tail (the Rocket Plane) with respect to the whole system. Moving backward, the Rocket Plane has a notable effect on a position of a centre of gravity of the whole system static stability. Moreover, the impact of the mutual vehicles’ position (horizontal tail arm) and inclination angle on the coupled vehicle lift to drag ratio was analysed.

In terms of aerodynamic computation, MGAERO software using an inviscid flow model, therefore, both a friction drag and breakdown of vortex are not considered. But the presented research is for the computation stage of the design, and the MGAERO software guarantees satisfactory accuracy with respect to the relatively low time of computations. The second limitation is that the presented results are for the conceptual stage of the design and dynamic stability constraints were not taken into account.

The ultimate goal of the coupled aircraft project is to conduct flying tests and the presented result is one of the milestones to achieve this goal.

A design process for a conventional aircraft configuration is well known however, there are not many examples of vehicles that consist of two coupled aircrafts where both vehicles have similar mass. The unique part of this paper includes results of the investigation of the mutual position of the vehicles that can fly alone, as well as in coupled form. The impact of the position of the centre of gravity on trim conditions and static stability of the coupled configuration was investigated.

IN a series of articles entitled “Tailless Aircraft and Flying Wings”, concluded last month, the evolution of the tailless aeroplane and the flying wing was treated. The different trends of the development were classified, and a short discussion of the difficulties which had been experienced during experimental work given.

A FEATURE of many of the light alloys now in common use is that the stress and strain curve often does not evidence any well defined region in which the elastic strain becomes plastic strain, and a linear portion of the diagram from the origin, which in the case of so many metals represents a region of proportionality, is sometimes almost non‐existent, the diagram being curved right from the origin so that it is not possible to define any region or limit of proportionality, and the proof stress; by standard definition, has accordingly a relatively low value compared with the ultimate tensile stress of the alloy concerned. (Fig. 1).

An analytical investigation has been carried out for a simply supported rectangular plate with two different loading conditions by using 3D state space approach (SSA). Also, the accurate location of the neutral plane (N.P.) through the thickness of the plate can be identified: the N.P. is shifted away from the middle plane according to the loading condition. The paper aims to discuss these issues.

SSA and finite element method are used for the determination of structural behaviour of simply supported orthotropic composite plates under different types of loading. The numerical results from a finite element model developed in ABAQUS.

The effect of the plate thickness on displacements and stresses is described quantitatively. It is found that the N.P. of the plate, identified according to the values of the in-plane stresses through the thickness direction, is shifted away from the middle plane. Further investigation shows that the position of the N.P. is loading dependant.

This paper describe the effect of the plate thickness on displacements and stresses quantitatively by using an exact solution called SSA. Also, it is found that the N.P. of the plate, identified according to the values of the in-plane stresses through the thickness direction, is shifted away from the middle plane. Further investigation shows that the position of the N.P. is loading dependant.