Browsing by Author "Bennett, Christopher J."

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    The aircraft spin - a mathematical approach and comparison to flight test
    (American Institute of Aeronautics and Astronautics, 2017-06-09) Bennett, Christopher J.; Lawson, Nicholas J.; Gautrey, Jim; Cooke, Alastair
    A Scottish Aviation Bulldog light aircraft operated by the National Flying Laboratory Centre (NFLC) at Cran eld University, modi ed with research equipment including bre optic sensors for wing strain and fuselage pressure measurements, is used to investigate the dynamics of a fully developed spin. A theoretical model is developed to compare with existing ight test data. In particular, the frequency of the aircraft spin is analysed as a function of the mass distribution of the aircraft to determine the e ect of the fuel load. It is found that the spin frequency is minimally a ected by the fuel load since the moments of inertia corresponding to the engine, for example, are far more signi cant. However, it is con rmed that the yawing e ect of the propeller causes the aircraft to spin faster to the right than to the left.
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    CFD simulation of flow around angle of attack and sideslip angle vanes on a BAe Jetstream 3102 - Part 1
    (Elsevier, 2017-03-16) Bennett, Christopher J.; Lawson, Nicholas J.; Gautrey, James E.; Cooke, Alastair K.
    CFD modelling techniques are exploited to investigate the local velocity field around angle of attack and sideslip angle sensors fitted to the nose of a modified BAe Jetstream 3102 small airliner. Analysis of the flow angularity at the vane locations has allowed the vanes response to varying flight conditions to be predicted and errors in the readings to be quantified. Subsequently, a more accurate calibration of the system is applied to the current configuration on the Jetstream, and a better understanding of the position error with respect to the vane locations is obtained. The above aircraft was acquired by Cranfield University in 2003 with subsequent flow angle vane modifications taking place in 2005. The aircraft is currently in operation with the National Flying Laboratory Centre (NFLC) for research and demonstration purposes.
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    CFD simulation of flow around angle of attack and sideslip angle vanes on a BAe Jetstream 3102 - Part 2
    (Elsevier, 2017-03-16) Bennett, Christopher J.; Lawson, Nicholas J.; Gautrey, James E.; Cooke, Alastair K.
    A previous study analysing the local flow around angle of attack and sideslip angle vanes on a BAe Jetstream 3102 turboprop is extended to study the additional effects of bank angle. A full matrix of CFD simulations is carried out to investigate how the introduction of a bank angle affects vane performance for a range of flight conditions. An updated calibration method to convert the raw vane readings into true values of angle of attack and sideslip, incorporating a correction factor as a function of the bank angle, is presented. The results are shown to be accurate for a wide range of flight configurations. Uncertainty analysis indicates that raw vanes reading errors should be below ±0.1°±0.1° to ensure that total calibration errors are restricted to less than 2%2% for angle of attack and 5%5% for sideslip angle.
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    Characterizing instrumentation canister aerodynamics on the FAAM BAe-146-301 atmospheric research aircraft
    (ASCE, 2019-04-30) Bennett, Christopher J.; Wellpott, A.; Lawson, Nicholas J.; Delise, M.; Woodcock, B.; Gratton, Guy; Nott, G. J.
    A computational fluid dynamics (CFD) investigation was aimed at accurately predicting the air flow characteristics in the vicinity of underwing-mounted instruments on the Facility for Airborne Atmospheric Measurement’s (FAAM) BAe-146-301. Perturbation of the free stream airflow as it passes through the region of detection of the underwing instruments may lead to additional uncertainties in the measurement of clouds and cloud particles. The CFD model was validated with flight data from an Aircraft-Integrated Meteorological Measurement System (AIMMS-20) in a wing-mounted instrument canister. Flow predictions showed a consistent slowing from the true air speed of the aircraft in the longitudinal direction and the introduction of horizontal and vertical flows up to 10% of the air speed. The potential impact of these flow perturbations on sizing of particles with cloud imaging probes was modeled. Sizing errors were dependent on the methodology used and the shape of the particle; those due to transverse flows remained very small but mis-sizing due to unaccounted longitudinal flow perturbations were potentially more serious.
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    On the development of flight-test equipment in relation to the aircraft spin
    (Elsevier, 2018-06-29) Bennett, Christopher J.; Lawson, Nicholas J.
    A review of the development of flight test equipment throughout aviation history is presented, focusing specifically on the stall spin. The primitive, yet, ingenious solutions devised in the early twentieth century by the pioneers of this field, paved the way for the advancement in knowledge of the complex aerodynamic properties inherent during a spin. Both in Britain and the US, the dangers associated with stalling and spinning were acknowledged shortly after the birth of aviation, with pilots and academics alike seeking to investigate the causes. Initially, the goal was to design safer aircraft, with more predictable handling, dynamic manoeuvrability, and precise controllability. Both nations were able to independently develop equipment packs which were to become standard for airborne investigations of the spin and other manoeuvres in the following years. These early studies laid the foundations on which we're still building today, now using state-of-the-art technology to enhance our knowledge of spin dynamics ever further.
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    Undercarriage drag prediction for a fixed undercarriage light aircraft
    (AIAA, 2017-06-09) Bennett, Christopher J.; Gautrey, Jim; Lawson, Nicholas J.
    The following paper presents undercarriage drag predictions for a light aircraft with fixed landing gear. A Scottish Aviation Bulldog 120, operated by the National Flying Laboratory Centre (NFLC) at Cranfield University, is considered as the test case for this study. Taking advantage of a recently developed laser scanned model, computational fluid dynamics (CFD) techniques are exploited to investigate the undercarriage drag. Results via standard theoretical and empirical methods are compared to the CFD results. It is found that the established empirical methods matched the CFD predictions to within the stated error bands for moderate angles of attack. However, due to the aircraft flow field at higher angles of attack, some discrepancies in the level of drag predicted are observed. Further flight test data is recommended to confirm these findings