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The SFOL pulse is a high accuracy DME/N pulse developed from using Genetic Algorithms. This pulse complies with the current DME/N specifications and is significantly less susceptible to multipaths than previous DME pulses. Recent analysis of the SFOL showed that the multipath-induced ranging error of the SFOL pulse was five times and two and half times less than the conventional Gaussian and Smoothed Concave Polygon pulses. To implement DMEs transmitting the SFOL, first, it would be desirable if modern DMEs currently deployed in the field can be modified to transmit the SFOL pulse without significant changes. It is expected that the biggest modification is required in the pulse shaping process. Currently, we are investigating a pre-distortion of the SFOL pulse for the typical power amplifier of a DME designed to transmit Gaussian pulses. A successful development of the pre-distortion may enable Gaussian pulse-based DMEs to transmit the SFOL pulse with relatively little changes. Second, the terrain in South Korea consists of numerous high mountains that would make it difficult to plan effective DME/DME networks due to the limited line of sights between DMEs and aircraft. Considering the airspace and major airport locations in South Korea, we are developing search algorithms that will result in cost effective DME/DME network layouts in the difficult terrain conditions. The paper will introduce a promising pre-distortion of the SFOL pulse and a strategy in planning of optimal DME/DME networks in South Korea with a recommended network layout.

The effect of sideslip angle on the aerodynamic characteristics of a following aircraft in formation flight is investigated by experiment. Measured data from subsonic wind-tunnel testing are obtained by changing the magnitude of the sideslip angle and the relative distances between the two-5% scaled small sized jet aircraft models. The variations of aerodynamic forces and moments of a following aircraft model are measured at 49 locations on the cross-section area behind a leading aircraft. Results show the considerable changes of the aerodynamic forces and moments of the following aircraft compared to those of a single aircraft alone. The effect of the sideslip on the aircraft in formation flight is a very complex function of relative distances between two aircraft, and has a significant effect on the lateral/ directional stability of the following aircraft. Among the changes of the aerodynamic coefficients, the changes of the rolling moment coefficients are the largest. It is believed that the formation flight itself can be a very dangerous to the safety flight of the aircraft.

This paper presents on the aerodynamic characteristics of a fighter-type aircraft model in formation flight. The effect of longitudinal and lateral distance changes on the aerodynamic characteristics of a trailing aircraft is investigated by experiment. The wind-tunnel testing is conducted with two-5% scaled small sized fighter-type aircraft models. Aerodynamic forces and moments of a trailing aircraft model are measured at 49 locations on the cross-section behind a leading aircraft model. It is observed that the leading aircraft affects the incremental lift and drag of the trailing aircraft significantly. It is also proved that the aerodynamic characteristics of the trailing aircraft can be improved if positioned at proper locations behind the leading aircraft while in formation flight