Trajectory Simulations Should Match Flight Tests and Other Lessons Learned in 30 Years of Store-Separation Analysis

Keen, K S; Morgret, Charles; Langham, T F; Baker, William H.

doi:10.2514/6.2009-99

Cited by 18 publications

(8 citation statements)

References 11 publications

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“…Many studies of mutual interference between bodies, predominantly stores and aircraft, at subsonic speeds have been conducted previously 13 . Unfortunately, limited information is available in the open literature on aerodynamic interference between slender bodies in a high-speed flow.…”

Section: Chapter 2 Literature Reviewmentioning

confidence: 99%

Aerodynamic interference between high-speed slender bodies

2010

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Significant aerodynamic interference can occur between high-speed bodies in close proximity. A complex flowfield develops where shock and expansion waves from a generator body impinge upon the adjacent receiver body. The pressure and flow angularity changes which occur across these disturbances modify the body aerodynamics. The aim of this research is to quantify the aerodynamic interference effects for multi-body configurations and understand the relevant flow physics.The interference aerodynamics for slender bodies in a supersonic flow were investigated through a parametric wind tunnel study. The receiver bodies were finned and un-finned configurations. The effect of lateral and axial body separations, receiver incidence and the strength of the disturbance field were investigated. Measurements included forces and moments, surface pressures and flow visualisations. Supporting computations using steady-state, viscous predictions provided a deeper understanding of the underlying aerodynamics and flow mechanisms. Good agreement was found Many people have contributed to the completion of this research. I would like to take time to thank them. My supervisor David MacManus for his guidance and help throughout. I would especially like to thank him for the many occasions when he took my work home with him to read and provide feedback during the writing process. I would like to acknowledge the financial support of the UK MOD. The investigation which is the subject of this report was initiated by the Air Systems Department Dstl and was carried out under the terms of Contract No RD025 -1962. Additional funding was also provided through an ESPRC CASE award. I would also like to thank Dstl for the release of experimental data which greatly enhanced this research. Trevor Birch for his constant support and guidance throughout. In particular, I would like to thank him for making arrangements for me to undertake two placements at Dstl. These aided my research and I enjoyed my time at Dstl immensely. Moreover, I would like to also thank Ben Shoesmith and Kristian Petterson who gave up alot of their own time in order to assist me. Their help with IMPNS and Cobalt was particularly useful.

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Section: Chapter 2 Literature Reviewmentioning

confidence: 99%

Aerodynamic interference between high-speed slender bodies

2010

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“…The launching of the rudder must cause the change of the aerodynamic force and torque of the projectile, and the trajectory of the Separator is difficult to be determined [15][16][17][18]. A series of complex conditions are added to the complex flow interference area, making the separation characteristics of the folded rudder Separator more difficult to determine [19][20][21][22][23]. Therefore, it is very necessary to carry out dynamic test research on the factors affecting the deployment of buried separators in folding rudder separator.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Aerodynamic of Expand Folding Rudder Separator Delivery from Cavity

Xue¹,

Jin²,

Wang³

2020

Int J Astronaut Aeronautical Eng

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In the subsonic, transonic and supersonic wind tunnels, the launching test technology of the buried separators in folding rudder separator is studied. In view of the two different folding modes of the Separator rudder surface, two testing techniques are developed for the horizontal folding and vertical folding of the rudder surface, which can ensure the self locking function before and after the rudder surface is unfolded. The folding and unfolding state is not affected by the start impact of the wind tunnel and the turbulence. At the same time, the position of the rudder surface is expanded to achieve the real launch and expansion of the simulated separator. The developed dual angle of view, high brightness optical path system and six degree of freedom image analysis system can obtain the full trajectory image and aerodynamic parameters of the projectile embedded in the aircraft. The test technology can independently adjust the ejection speed and angular velocity of the release material, and can study the influence of different separation conditions on the separation safety. The non-expansion test technology of the rudder surface has completed the wind tunnel test verification under the condition of supersonic velocity and multi-body interference and complex aerodynamic force, which meets the demand of the launch and wind tunnel test research.

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“…These tendencies have increased the sensitivity to separation-induced transients, 1 potentially leading to large angular rates and attitudes, excessive energy loss, sensor saturation, structural limits, or departure from stable flight modes. 2 The challenge in store separation is thus to ensure safety while also maintaining acceptability across the flight envelope.…”

Section: Overviewmentioning

confidence: 99%

Trajectory Optimization for Guided Store Separation

Carter

Lind

2012

AIAA Guidance, Navigation, and Control Conference

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Combat aircraft utilize expendable stores such as missiles, bombs, flares, and external tanks to execute their missions. Safe and acceptable separation of these stores from the parent aircraft is essential for meeting the mission objectives. In many cases, the employed missile or bomb includes an onboard guidance and control system to enable precise engagement of the selected target. Due to potential interference, the guidance and control system is usually not activated until the store is sufficiently far away from the aircraft. This delay may result in large perturbations from the desired flight attitude caused by separation transients, significantly reducing the effectiveness of the store and jeopardizing mission objectives. The purpose of this paper is to present the investigation of a transitional control system to guide the store during separation. The transitional control system, or "store separation autopilot", explicitly accounts for the nonuniform flow field through characterization of the spatially variant aerodynamics of the store during separation. This approach can be used to mitigate aircraft-store interference and leverage aerodynamic interaction to improve separation characteristics. Optimal control theory is used to determine an openloop optimal trajectory and neighboring optimal control is used to implement a closed-loop store separation autopilot along the optimal trajectory. An example is shown based on a representative store separating from an F-16 aircraft. I. OverviewS tore separation engineering, a subset of aircraft-store compatibility, is concerned with the flight characteristics of a store in proximity of the aircraft and other stores. A store released from an aircraft in flight must traverse a nonuniform and unsteady flow field that may include complex shock interactions, large velocity gradients, regions of locally separated or reversed airflow, and severe flow angularity in the form of sidewash and downwash. Stores released from an internal weapons bay may also be subjected to a wake disturbance from the spoiler, dynamic pressure and velocity gradients across the shear layer, high frequency vibrations due to acoustic noise, and large perturbations in flow properties due to cavity oscillations.Although the region of nonuniform flow near the aircraft is exceedingly small compared to the full length of the ballistic or fly-out trajectory, the effects are significant. The flow field characteristics may cause the store to exhibit behavior that compromises the safety of the airframe and crew or that compromises the effectiveness of the store itself. Prediction of the flight characteristics of the store in the vicinity of the aircraft is therefore vitally important for ensuring the safety and effectiveness of the release.Modern sophisticated "smart" weapons are equipped with sensitive onboard electronics including inertial measurement systems, GPS units, sensors, seekers, and guidance computers. Standoff capability (the desirable ability to release a munition far away from the intended targ...

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Trajectory Simulations Should Match Flight Tests and Other Lessons Learned in 30 Years of Store-Separation Analysis

Cited by 18 publications

References 11 publications

Aerodynamic interference between high-speed slender bodies

Aerodynamic interference between high-speed slender bodies

Investigation of Aerodynamic of Expand Folding Rudder Separator Delivery from Cavity

Trajectory Optimization for Guided Store Separation

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