Hampton, VA, United States

Bihrle Applied Research, Inc.

Hampton, VA, United States
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Ralston J.N.,Bihrle Applied Research, Inc. | Gingras D.R.,Bihrle Applied Research, Inc. | Wilkening C.,Bihrle Applied Research, Inc. | Desrochers P.,Pilot Inc
AIAA Modeling and Simulation Technologies Conference 2012 | Year: 2012

In order to meet training objectives proposed by the Training Subgroup of the International Committee for Aviation Training in Extended Envelopes, (ICATEE), flight simulators will be required to effectively train pilots for stall awareness, recognition, and recovery. Following thorough investigation by the Research and Technology (R&T) Subgroup of ICATEE, recommended stall and post-stall standards have been proposed to which simulators must meet in order to provide advanced stall and Upset Prevention and Recovery Training (UPRT) tasks. Devices to be qualified for this type of training will likely require the augmentation of the flight model database with appropriate data to provide more representative stall and post stall behavior for a given configuration. This paper examines potential empirical and analytical approaches to developing the source data needed to represent an aircraft's stability and control characteristics in the stall and post stall flight regime. The process of integration of these data sources to update an existing Level D flight model is presented. Using a Subject Matter Expert (SME), a subjective evaluation of the updated simulation is presented to detail the effectiveness of the various approaches. © 2012 by Bihrle Applied Research. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.

Mardanpour P.,Georgia Institute of Technology | Hodges D.H.,Georgia Institute of Technology | Neuhart R.,Bihrle Applied Research, Inc. | Graybeal N.,Bihrle Applied Research, Inc.
Journal of Aircraft | Year: 2013

The effects of engine placement and sweep on the flutter characteristics of an aft-swept flying wing resembling the Horten IV are investigated using the Nonlinear Aeroelastic Trim and Stability of HALE Aircraft. The analysis was validated against the published results for divergence and flutter of sweptwings and found to be in excellent agreement. Moreover, the modal frequencies and damping obtained for the Goland wing were found in excellent agreement with published results based on a new continuum-based unsteady aerodynamic formulation. This aircraft exhibits a nonoscillatory yawing instability, expected in aircraft with neither a vertical tail nor yaw control. More important, however, is the presence of a low-frequency "body- freedomflutter" mode. The aircraft center of gravity was held fixed during the study, which allowed the aircraft controls to trim similarly for each engine location and minimized flutter speed variations along the inboard span. The maximum flutter speed occurred for engine placement just outboard of 60% span with engine center of gravity forward of the elastic axis. The body-freedom flutter mode was largely unaffected by the engine placement except for cases in which the engine is placed at thewing tip and near the elastic axis. In the absence of engines, aerodynamics, and gravity, a region ofminimumkinetic energy density for the first symmetric free-free bending mode is also near the 60%span. A possible relationship between the favorable flutter characteristics obtained by placing the engines at that point, and the region of minimum kinetic energy is briefly explored. © 2012 AIAA.

Ratvasky T.P.,NASA | Barnhart B.P.,Bihrle Applied Research, Inc. | Lee S.,ASRC Aerospace Corporation
Journal of Aircraft | Year: 2010

Icing alters the shape and surface characteristics of aircraft components, which results in altered aerodynamic forces and moments caused by air flow over those iced components. The typical effects of icing are increased drag, reduced stall angle of attack, and reduced maximum lift. In addition to the performance changes, icing can also affect control surface effectiveness, hinge moments, and damping. These effects result in altered aircraft stability and control and flying qualities. Over the past 80 years, methods have been developed to understand how icing affects performance, stability, and control. Emphasis has been on wind-tunnel testing of two-dimensional subscale airfoils with various ice shapes to understand their effect on the flowfield and ultimately the aerodynamics. This research has led to wind-tunnel testing of subscale complete aircraft models to identify the integrated effects of icing on the aircraft system in terms of performance, stability, and control. Data sets of this nature enable pilot-in-the-loop simulations to be performed for pilot training or engineering evaluation of system failure impacts or control system design.

Gingras D.R.,Bihrle Applied Research, Inc. | Ralston J.N.,Bihrle Applied Research, Inc.
Aeronautical Journal | Year: 2012

Aircraft upset and Loss of Control (LOC) is a leading cause of accidents in commercial and general aviation aircraft operations. A number of measures have been taken in the commercial segment to improve training and awareness of this problem and several organisations offer in-flight training to enhance awareness. In relative terms, in both commercial and general aviation sectors, the use of Full Flight Simulators (FFS) and Flight Training Devices (FTD) for this purpose is minimal. A key reason for this is the limited capability and coverage of flight models used in these devices. This paper provides examples of the limitations in civilian simulators in contrast to military efforts that have been using full envelope modelling for decades to enhance pilot training. The paper also presents techniques used in full-envelope modelling, their validity, and a regulatory vehicle that is in-line with current international guidelines for application to civilian trainer development.

Gingras D.R.,Bihrle Applied Research, Inc. | Ralston J.N.,Bihrle Applied Research, Inc. | Wilkening C.A.,Bihrle Applied Research, Inc.
AIAA Modeling and Simulation Technologies Conference 2010 | Year: 2010

Upset and Loss-of-Control of aircraft remains one of the leading causes of accidents for commercial and general aviation operations. There are statements in government reports indicating that improved training, particularly in the stall and post-stall flight regime, may help mitigate this situation. Ground-based flight simulators are logical tools to carry out such training. Unfortunately the flight models in these qualified devices are typically not of sufficient fidelity for positive pilot training in these flight regimes. This paper reviews flight simulator requirements associated with the stall and post-stall flight and presents an example of the current level of fidelity of a modern-day device. A model modification process is illustrated that improves flight model fidelity and results are presented. Last, recommendations for improved stall and post-stall flight model requirements for flight simulators proposed. © 2010 by Bihrle Applied Research Inc. Hampton, VA. Published by the American Institute of Aeronautics and Astronautics, Inc.

Ralston J.,Bihrle Applied Research, Inc. | Hultberg R.,Bihrle Applied Research, Inc.
AIAA Modeling and Simulation Technologies Conference 2010 | Year: 2010

The need to model the behavior of propeller driven aircraft throughout their envelope has been a recurring modeling issue for many years, both for engineering and training applications. The complex aerodynamic effects incurred as the airframe is enveloped in the prop wash, particularly at high power, low speed conditions, has presented a difficult modeling problem to simulation developers for many years. This situation is exacerbated by the fact that many simulation models are built with limited flight data, data that does not fully expose the functionalities of these aerodynamic effects. While wind tunnel testing has long been available to identify these data, the associated cost and difficulty in interpreting and implementing the data has resulted in limited application of this approach. The following discussion reviews a recent novel approach to acquire and characterize these effects for a high fidelity simulation application. © 2010 by Bihrle Applied Research Inc. Hampton, VA.

Gingras D.R.,Bihrle Applied Research, Inc.
AIAA Modeling and Simulation Technologies (MST) Conference | Year: 2013

The adverse effects of in-flight icing, on aircraft aerodynamics, are a major cause of accidents in the commercial and general aviation world. To mitigate these incidents and accidents resulting from this problem, mandates are in place to improve pilot training in these dangerous flight conditions. Since flight simulators are extensively used for pilot training at all levels, recommendations have been made to improve flight simulator fidelity in adverse conditions like icing. To meet the requirements for improved fidelity, reliable proven data sources are needed. This paper presents potential data sources and methods for obtaining in-flight icing aerodynamics data, and provides details of a case study of the DH-6 Twin Otter, where data were collected from advanced wind-tunnel tests and implemented in a flight training device and validated with flight data. The validation results showed that the resulting flight model was suitable for the training tasks to be performed using the device.

Bihrle Applied Research, Inc. | Date: 2013-02-02

computer hardware and software systems for flight simulators and simulation designed to provide realistic flight behaviors for aircraft in all flight regimes.

Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase II | Award Amount: 1.07M | Year: 2010

A key limiting factor in the development of transport class aircraft flight models capable of accurately modeling stall and post stall characteristics has been a lack of aerodynamic description, which has arisen due to the industry’s limited testing capability into the post stall region and the lack of requirements to model these behaviors. Reynolds number effects, which are relatively limited for thin airfoil fighter configurations, are much more pronounced for the thick airfoil transport configurations, and complicate the utilization of static and dynamic data in this region. With little or no validation data for these aircraft, application of the wind tunnel test data is historically problematic. This effort will establish a process for collecting and integrating wind tunnel data for use in a high fidelity flight models capable of providing representative flight behavior through stall and beyond for transport configurations. This effort will require the development of testing hardware and methods as well as Re correction methods to enable the direct integration of the collected data. This process will be demonstrated using the Navy’s P-8 aircraft as the demonstrator configuration.

Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase II | Award Amount: 751.74K | Year: 2013

Many existing flight simulators currently lack the aerodynamics modeling required to train pilots for stall/upset conditions. Further, the process of updating an existing simulator database can be difficult and costly due to simulation database rights licensing, complex simulation host architectures, and the need to re-validate updated models. The proposed effort will address this need and overcome these limitations through the introduction of an external hardware/software host called the StallBox. With this solution, the StallBox is integrated with the existing simulator, requiring only minor changes to the existing system software to enable the communication between the StallBox and the simulator host. With the StallBox, the host database remains untouched and the aerodynamic model elements needed to provide the enhanced stall/upset model capability are introduced into the existing simulation only when the simulated aircraft"s flight conditions demand it. In this manner, the existing simulation host architecture and proprietary database remain unmodified, and the validation of the existing configuration is not violated.

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