scholarly journals Empennage sizing with the tail volume complemented with a method for dorsal fin layout

2021 ◽  
Vol 13 (3) ◽  
pp. 149-164
Author(s):  
Dieter SCHOLZ
Keyword(s):  
Statistical Method ◽  
Aircraft Design ◽  
Statistical Correlation ◽  
High Fidelity ◽  
Weak Correlation ◽  
Starting Values ◽  
Dorsal Fin ◽  
Lever Arm ◽  
Volume Coefficient ◽  
Practical Implications

Purpose: Provide good values for the tail volume coefficient and the lever arm as a percentage of the fuselage length. Provide a statistical method for dorsal fin layout. – Methodology: Based on an understanding of flight physics, the statistical correlation of real aircraft parameters is investigated. This is based on the firm conviction that high fidelity parameters for future aircraft need a checked against parameters of existing successful aircraft. – Findings: Typical tail volume coefficients are between 0.5 and 1.0 for the horizontal tail and between 0.03 and 0.08 for the vertical tail depending on aircraft category. Empennage statistics have clear trends. The often weak correlation shows that aircraft design allows for sufficient designer's choice. Only a minority of aircraft feature a dorsal fin. Designers see it as an added surface rather than as part of the vertical tail. It is used to limit the hypothetical risk of vertical tail stall due to high sideslip angles. – Research Limitations: Results obtained from statistics are close to reality, but not a proof to fulfill requirements. – Practical Implications: Methods from the paper can be used for quick initial sizing of a vertical tail with or without dorsal fin or sizing of a horizontal tail. These results can also be used as good starting values for optimization tools in aircraft design. – Originality: Estimation of the tail lever arm is necessary for sizing with the tail volume coefficient, but had not been investigated to any detail. A method for the layout of dorsal fins was missing.

“Never the first time on a patient”: the stakes of high-fidelity simulation for safety training

2018 ◽  
Vol 32 (5) ◽  
pp. 23-25 ◽  
Author(s):  
Lucie Cuvelier
Keyword(s):  
Case Studies ◽  
Design Methodology ◽  
Reading Time ◽  
Safety Training ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Content Type ◽  
Pertinent Information ◽  
First Time ◽  
Practical Implications

Purpose This paper aims to review the latest management developments across the globe and pinpoint practical implications from cutting-edge research and case studies. Design/methodology/approach This briefing is prepared by an independent writer who adds their own impartial comments and places the articles in context. Findings An operative approach is described that is designed to structure the debriefing along three axes. Practical implications The paper provides strategic insights and practical thinking that have influenced some of the world’s leading organizations. Originality/value The briefing saves busy executives and researchers hours of reading time by selecting only the very best, most pertinent information and presenting it in a condensed and easy-to-digest format.

Assessment centers vs situational judgment tests: longitudinal predictors of success

2016 ◽  
Vol 37 (7) ◽  
pp. 899-911 ◽  
Author(s):  
Carrie A. Blair ◽  
Brian J. Hoffman ◽  
Robert T. Ladd
Keyword(s):  
Career Success ◽  
High Fidelity ◽  
Assessment Centers ◽  
Situational Judgment Test ◽  
Situational Judgment ◽  
Situational Judgment Tests ◽  
Content Type ◽  
General Mental Ability ◽  
Utility Company ◽  
Practical Implications

Purpose The purpose of this paper is to provide an empirical comparison of a high-fidelity managerial simulation, assessment center (AC) ratings, to that of a lower fidelity managerial simulation, a video situational judgment test (SJT) in the prediction of manager career success. Design/methodology/approach Archival data were collected from a large utility company. A measure of general mental ability (GMA), an SJT, and an AC were examined as predictors of career success as measured by increases in salary. Findings The AC and the video SJT used in this study appeared to assess different constructs, extending previous findings that ACs and written SJTs measure distinct constructs. Furthermore, the AC dimensions and the SJT remained valid predictors of salary over a six year span following the test administration. In addition, the AC explained significant incremental variance beyond GMA and SJTs in career success six years after the assessment. Research limitations/implications The SJTs and AC used in this study are similar in psychological fidelity, yet the ACs remained a more valid predictor over time. The recommendation is that lower fidelity simulations should not be used as prerequisites for higher fidelity simulations. Practical implications The results lend general support to the value of high-fidelity instruments in predicting longitudinal success. Originality/value The paper offers a comparison of the validity of ACs and video SJTs.

Hydrodynamic Forces Measurement in Still Water Tank and Theoretical Validation of a Bio-Dorsal Fin Propulsive System

2011 ◽  
Vol 105-107 ◽  
pp. 1980-1984
Author(s):  
De Feng Du ◽  
Xiao Qin Jiang
Keyword(s):  
Large Amplitude ◽  
Wave Amplitude ◽  
Periodic Variation ◽  
Lateral Force ◽  
Experimental Result ◽  
Wave Number ◽  
High Fidelity ◽  
Water Tank ◽  
Dorsal Fin ◽  
Force Variation

The simulation level of prototypes mimicking torsional wave propulsion is low at present. A new prototype which uses a combination of crank and rocker mechanisms and pleated-skirt-pattern membrane is presented in this paper. The prototype’s dorsal fin is of high fidelity, the waveform looks pretty smooth and the wave amplitude can reach 85 degrees. In still pool, measurement of thrust and lateral force of dorsal fin were performed with a one-component balance. The experimental results show: 1. the thrust on the dorsal fin has periodic variation, and the frequency of thrust variation is twice the fin frequency. 2. The lateral force on the dorsal fin also has periodic variation, and the frequency of lateral force variation is the same as the fin frequency. 3. The periodic mean thrust on the dorsal fin is proportional to the square of fin frequency, and the influence of fin frequency on dorsal fin is stronger as wave number increases. 4. The computed results of large-amplitude EBT coincide qualitatively with experimental result, but our computed propulsive forces are quantitatively smaller. (This work was supported by the National Natural Science Foundation of China (10572151).)

scholarly journals Gradient-based multifidelity optimisation for aircraft design using Bayesian model calibration

2011 ◽  
Vol 115 (1174) ◽  
pp. 729-738 ◽  
Author(s):  
A. March ◽  
K. Willcox ◽  
Q. Wang
Keyword(s):  
Bayesian Model ◽  
Model Calibration ◽  
Trust Region Method ◽  
Trust Region ◽  
Aircraft Design ◽  
High Fidelity ◽  
First Order ◽  
Gradient Based ◽  
Quadratic Programming Method ◽  
Optimisation Methods

Abstract Optimisation of complex systems frequently requires evaluating a computationally expensive high-fidelity function to estimate a system metric of interest. Although design sensitivities may be available through either direct or adjoint methods, the use of formal optimisation methods may remain too costly. Incorporating low-fidelity performance estimates can substantially reduce the cost of the high-fidelity optimisation. In this paper we present a provably convergent multifidelity optimisation method that uses Cokriging Bayesian model calibration and first-order consistent trust regions. The technique is compared with a single-fidelity sequential quadratic programming method and a conventional first-order trust-region method on both a two-dimensional structural optimisation and an aerofoil design problem. In both problems adjoint formulations are used to provide inexpensive sensitivity information.

Efficient stall compliance prediction method for trimmed very light aircraft with high-lift devices

2016 ◽  
Vol 231 (6) ◽  
pp. 1124-1137
Author(s):  
Nhu Van Nguyen ◽  
Daeyeon Lee ◽  
Maxim Tyan ◽  
Jae-Woo Lee ◽  
Sangho Kim
Keyword(s):  
Wind Tunnel ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Prediction Method ◽  
Aircraft Design ◽  
Design Stage ◽  
High Fidelity ◽  
Configuration Generation

An efficient stall compliance prediction method using quick configuration generation, adapted mesh, high fidelity analysis, and wind tunnel test data for trimmed very light aircraft is proposed. The three-dimensional Navier–Stokes equations are used to determine the characteristics of the flow field around the aircraft, and the [Formula: see text] shear stress transport model is used to interpret the turbulent flow as a solver in the high fidelity analysis. The calibrated mesh and model are developed by comparing the results with the wind tunnel test and adjusting the adapted mesh to match the wind tunnel data. The calibrated mesh and model are applied to conduct the full-scale very light aircraft analysis for the clean and full flap extended flight conditions to comply with the CS-VLA stall regulations. It is recommended that the flap area be increased in the trimmed full flap extended condition. The proposed method demonstrates the feasibility and effectiveness of very light aircraft VLA stall compliance prediction in reducing the development cost and time with small configuration changes at the preliminary very light aircraft design stage.

Overrun causations under advance payment regimes

2017 ◽  
Vol 7 (1) ◽  
pp. 86-98 ◽  
Author(s):  
Olaniyi Isaac Aje ◽  
Oluwole Alfred Olatunji ◽  
Olanrewaju Augustine Olalusi
Keyword(s):  
Additional Data ◽  
Statistical Correlation ◽  
Site Management ◽  
Cost Overruns ◽  
Content Type ◽  
Advance Payment ◽  
Management Literature ◽  
Management Approaches ◽  
The Relationship ◽  
Practical Implications

Purpose Evidence suggests project owners could use advance payments to prevent cost escalations. The purpose of this paper is to elicit the relationships between causations of overruns when advance payments are issued to contractors. Design/methodology/approach In total, 97 responses from a questionnaire survey were analysed. Additional data on 51 projects, completed between 2000 and 2014 under different advance payments regimes, were also obtained and analysed. Findings Project owners issue advance payments to contractors so as to avoid delays. However, statistical correlation between advance payments and overrun causations are not significant. Although cost overruns were higher in large projects than in small projects, schedule overruns were more in small projects than in large projects. Schedule overruns were caused most significantly by contractors’ site management approaches. Design and documentation issues were identified as the most prevalent cause of cost overruns. Regression models are proposed to elicit overruns when advance payments are issued. Practical implications Extant debates on project overruns in construction and project management literature are robust. Nonetheless, the study elicits considerable knowledge gaps regarding the roles of advance payments in fostering project performance. Originality/value This pioneering work indexes the relationship between advance payment and project overruns in Nigeria. It is also the first attempt to document the probability distribution of overruns in Nigeria, particularly under specific advance payment regimes.

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