This paper examines the influence of exit separation, exit availability and seating configuration on aircraft evacuation efficiency and evacuation time. The purpose of this analysis is to explore how these parameters influence the 60-foot exit separation requirement found in aircraft certification rules. The analysis makes use of the airEXODUS evacuation model and is based on a typical wide-body aircraft cabin section involving two pairs of Type-A exits located at either end of the section with a maximum permissible loading of 220 passengers located between the exits. The analysis reveals that there is a complex relationship between exit separation and evacuation efficiency. A main finding of this work is that for the cabin section examined, with a maximum passenger load of 220 and under certification conditions, exit separations up to 170ft will result in approximately constant total evacuation times and average personal evacuation times. This practical exit separation threshold is decreased to 114ft if another combination of exits is selected. While other factors must also be considered when determining maximum allowable exit separations, these results suggest it is not possible to mandate a maximum exit separation without taking into consideration exit type, exit availability and aircraft configuration.

A static model of the hose and drogue used to provide data in a realtime flight simulation of air-to-air refuelling is presented. The model predicts (a) the interference effect of the flow around the nose of a combat receiver aircraft on the pre-contact position of the drogue and (b) the hose shape and the loads induced on the receiver probe during contact. The use of the static model in the pre-contact case is validated for a normal closure speed by comparison with the results from a small perturbation dynamic analysis. At higher closure speed the static model is found to be less satisfactory. In a typical receiver approach a movement of the drogue similar to the drogue radius is predicted.

This paper describes part of an investigation into the prediction and characterisation of limit cycle oscillations occurring in non-linear aeroelastic systems. Through the use of a modified version of normal form theory, it is shown how it is possible to predict the limit-cycle oscillations and characterise their stability. The approach is analytical and does away with the need for an excessive amount of time marching iterative numerical simulation of the system. The methodology is demonstrated upon a simple two degrees-of-freedom aeroelastic wing model with cubic stiffness. A good agreement was obtained between the analytical prediction and numerical simulations.

Civil tiltrotor technology will literally change the way man flies! With the advent of modern vertical flight aircraft, like the tiltrotor, air travel will accede to new levels of convenience, safety, and cost-effectiveness. Tiltrotors can operate in all weather conditions from airports or from smaller facilities called vertiports strategically located to provide convenient access to other transportation systems. In evaluating the economic viability of this mode of travel, the entire cost of the system must be included to realise the benefits of such a system, not just the cost of the aircraft or its cost of operation. When an improved air transportation system is developed, tiltrotors, because of their time savings and cost-competitiveness, will be able to compete in the 50–500 mile range with all types of aircraft as well as high-speed rail and other modes of transportation. While each mode has its advantages, tiltrotor will do well because it can add flexibility to the system and can complement the other modes and make the overall system more efficient. It will also be acceptable to the public at large because of its unique capability and low noise signature.

An experimental study of the supersonic vortices from a 75° swept-back delta wing has been carried out in a Mach 2.49 stream. Five-hole conical probe surveys were conducted at the trailing edge of the planform for 7° and 12° angles-of-attack. The main objective was to determine the Mach number and pressure distributions in the primary vortex. A novel approach of utilising a computational flow solver was used to generate the calibration data for the five-hole probe over a range of Mach numbers and pitch angles. Measurements indicate significant static and total pressure deficits in the vortex core. Both the magnitude and the spatial scale of these deficits increase with the higher incidence angle. The swirl profiles have supersonic peak magnitudes and resemble the low speed Lamb-Oseen vortex. Similar to the case of supersonic wing tip vortices, and contrary to the experimental results from transonic and low speed leading-edge vortices, the axial Mach number distribution in the vortex core is found to have strong wake-like profile.

Hypersonic projectiles are sometimes launched using a castellated sabot which links with matching cavities in the missile. After launch and the removal of the sabot the boundary layer over the vehicle flows past these cavities which act as a kind of roughness. Experiments were made to discover the effect of this ‘roughness’ on the flow over a flap or flare placed downstream of the cavities. Tests were made with both laminar and turbulent boundary layers, the turbulent flow being induced by vortex generators placed near the nose of the models.