Flight Investigation of Gyroplane Longitudinal Flight Dynamics

This Paper presents an analysis of test data recorded during flight trials of a gyroplane. This class of rotarywing aircraft has found limited application in areas other than sport or recreational flying. However, the accident rate is such that a study of the configuration's stability and control characteristics is timely, and in addition substantive data is required for a new airworthiness and design standard that is under development. The Paper presents a unique coupling of established parameter estimation techniques with data from a class of aircraft that has received no attention in the contemporary literature. As a consequence, the Paper helps to consolidate the status of system identification as a powerful tool in the analysis of rotorcraft engineering problems. It is concluded that robust estimates of the longitudinal stability and control derivatives have been identified, indicating benign and "classical" longitudinal stability and control characteristics. However, unlike most helicopters, the rotorspeed degree of freedom must be included in the model structure

Weight and Balance Measurements Conducted using VPM M16 Tandem Trainer Gyroplane G-BUZL. Department of Aerospace Engineering report 9818

Weight and balance measurements have been conducted on GBUZL, a VPM M16 Tandem Trainer gyroplane. The purpose of these tests was to determine longitudinal and vertical c.g. position in two configurations: the standard, approved configuration for which an AAN exists; and a modified configuration. In the latter case, the Arrow engine was replaced with a turbocharged Rotax unit. The standard aircraft weight and balance is very similar to that determined previously for a similar machine, G-BWGI, which was used to support the CAA investigation "Aerodynamics of Gyroplanes". The only substantial difference for the modified aircraft weight and balance is the longitudinal c.g. position, which is some 3 in further aft. Recommendations are made in respect of operating limitations, and additions to the flight test schedule that has been proposed to demonstrate the airworthiness of the modified aircraft

Configurational and Instrumentation Aspects of the Flight Test Gyroplane G-ABCD. Aero Dept Int. Rep No. 9713

In the following report a quantitative description of the Montgomerie G-ABCD gyroplane configuration and instrumentation will be presented. This light gyroplane has been acquired by the department in order to enhance the research in the field of rotorcraft flight dynamics. The aircraft configuration is based on a conventional two seater design, with the second seat modified so as to accommodate the instrumentation to be used for the data acquisition. The intention of this report is to document the configuration properties of the airframe such as its dimensions, its weight and balance and aerodynamic properties in order to later on use them as an input to a rotorcraft simulation program. It is also intended to provide an overview of the elements comprising the data acquisition system to be used for the research together with information regarding the manufacturers of the components. The report does not intend to form a detailed document but to serve as a general reference and guide to the aircraft and its instrumentation

Gyroplane Derivative Identification Using a Matlab Routine. Aero Dept Int. Rep No. 9715

In the following report it is described how a routine implemented in the Matlab software package is used for identifying the stability derivatives of a gyroplane. The software is designed to apply a frequency domain least squares approach in order to estimate the longitudinal and lateral force and moment derivatives of the aircraft. The aircraft system itself is represented as a linear state space model. The time histories of the system states in conjunction with the pilot input are analysed in order to perform the identification. Initially the time series are transformed into the frequency domain. Linear regression is then performed over a suitable frequency range and an estimate of the stability derivatives together with the corresponding standard errors, is produced. The method is applied and tested against real data obtained from research conducted in the past within the department

Gyroplane Derivative Identification Using a Matlab Routine. Aero Dept Int. Rep No. 9715

In the following report it is described how a routine implemented in the Matlab software package is used for identifying the stability derivatives of a gyroplane. The software is designed to apply a frequency domain least squares approach in order to estimate the longitudinal and lateral force and moment derivatives of the aircraft. The aircraft system itself is represented as a linear state space model. The time histories of the system states in conjunction with the pilot input are analysed in order to perform the identification. Initially the time series are transformed into the frequency domain. Linear regression is then performed over a suitable frequency range and an estimate of the stability derivatives together with the corresponding standard errors, is produced. The method is applied and tested against real data obtained from research conducted in the past within the department

The Calibration and Testing of the G-BWTP Montgomerie Gyroplane Instrumentation. Aero Dept Int. Rep No. 9823

In the following report a quantitative description will be given of the calibration and testing for the instrumentation of the G-BWTP Montgomerie gyroplane. This light aircraft together with the instrumentation package has been acquired by the department in order to enhance the research in the field of rotorcraft flight dynamics. The gyroplane is due to be flight tested within the next months providing the opportunity to acquire data unique in the rotorcraft field. The intention of this report is to illustrate the way in which parameters relating to the sensor characteristics, such as the calibration constants, were derived and how the sensors themselves were tested using a well established software package. A presentation will also be given of the design of the full software program to be used for the data acquisition and analysis. The key objective of the report is to provide a reference on the way in which instrumentation is set up for the flight testing of a light gyroplane

On the benefit of an active horizontal tailplane to the control of the single main and tailrotor helicopter

Possible helicopter flight mechanics benefits associated with the use of an actively controlled horizontal tailplane are identified, influencing the areas of agility and manoeuvrability. In both cases, control strategies are postulated and implemented by means of control laws. They are then used with mathematical descriptions of the helicopter in digital computer simulations of manoeuvres to quantitfy the benefits. In the field of helicopter agility, use of a relatively small horizontal tailplane is shown to enhance agility, relative to the helicopter with a fixed tailplane. Popup maneouvres to SOm can be flown up to 7% faster with the active tailplane; alternatively, geometrically tighter manoeuvres can be flown to the extent of reducing manoeuvre distance by up to 10%. The control law moves the tailplane proportionally with the contributions of the three rotor controls and helicopter pitch rate to the longtitudinal component of hub moment. It is however suggested that a tailplane control law based on functions of pitch attitude would be applicable to a wider range of manoeuvres than the popups simulated. Helicopter manoeuvrability is enhanced by using the tailplane to decouple the pitch attitude from the flight path. The benefits are demonstrated by simulation of the acquisition and tracking of an airborne target. For a helicopter with the conventional pattern of control, significant changes in flight path result when the target is tracked with fuselage pointing; by comparison, the helicopter with a decoupled flight path and attitude controller changes flight path and speed by a negligible amount. It is suggested that this mode of control may be more generally applicable to control of the helicopter in that it mitigates the speed/flight path/attitude compromise the pilot faces in flying his aircraft, or the possibly large hub moments when accelerating or decellerating. The philosophy behind the use of the active tailplane differs from that of contemporary applications of moveable tailplanes in that it is an integrated element of the flight control system endowing (in its own right) control capabilities on the helicopter that are otherwise precluded by configuration. The addition of this extra control demands active control technology for several reasons: the applications require full control authority; the control laws are multivariable and change with speed; and the cockpit control setup would have to be simplified to the extent of the radical changes facilitated by active control technology

Significant differences in incubation times in sheep infected with bovine spongiform encephalopathy result from variation at codon 141 in the PRNP gene

The susceptibility of sheep to prion infection is linked to variation in the PRNP gene, which encodes the prion protein. Common polymorphisms occur at codons 136, 154 and 171. Sheep which are homozygous for the A<sub>136</sub>R<sub>154</sub>Q<sub>171</sub> allele are the most susceptible to bovine spongiform encephalopathy (BSE). The effect of other polymorphisms on BSE susceptibility is unknown. We orally infected ARQ/ARQ Cheviot sheep with equal amounts of BSE brain homogenate and a range of incubation periods was observed. When we segregated sheep according to the amino acid (L or F) encoded at codon 141 of the PRNP gene, the shortest incubation period was observed in LL141 sheep, whilst incubation periods in FF<sub>141</sub> and LF<sub>141</sub> sheep were significantly longer. No statistically significant differences existed in the expression of total prion protein or the disease-associated isoform in BSE-infected sheep within each genotype subgroup. This suggested that the amino acid encoded at codon 141 probably affects incubation times through direct effects on protein misfolding rates