SAWE Technical Papers

@inproceedings{3770,

title = {3770. Mass Management of a High Energy-Efficient Battery Electric Vehicle},

author = {Pietro Stabile and Federico Ballo and Giorgio Previati},

url = {https://www.sawe.org/product/paper-3770},

year  = {2022},

date = {2022-05-21},

urldate = {2022-05-21},

booktitle = {81st Annual Conference, Savannah, Georgia},

pages = {15},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Savannah, Georgia},

abstract = {The paper presents a detailed analysis of the mass-induced power demand of an ultra-efficient battery electric vehicle. The vehicle belongs to a special class of lightweight quadricycles, designed for participating to efficiency competitions. The influence of reducing the mass of the entire vehicle and the mass of the wheels on the vehicle energy consumption is assessed. A sensitivity analysis is performed by exploiting a “tank-to- wheel” multi-physics model of the vehicle. The model includes the main vehicle subsystems and the principal sources of power dissipation are modelled. A three-step sensitivity analysis is carried out: firstly, the influence of the mass reduction on the energy saving is analysed for two different race tracks; then, two different driving behaviour on the same track are compared; finally, the potential energy saving due to actual lightweighting interventions performed on the vehicle is computed. In this phase, secondary mass reduction effects (battery downsizing) are included in the simulation. Results are expressed in terms of Energy Reduction Value (ERV), a parameter widely used in the literature to quantify the correlation between mass reduction and energy saving. The vehicle studied in this paper shows an ERV due to vehicle mass reduction ranging from 0.23 to 0.36 kWh/(100 km∙100 kg), while wheel lightweighting leads to an ERV ranging from 1.03 to 1.74 kWh/(100 km∙100 kg).},

keywords = {31. Weight Engineering - Surface Transportation, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3767,

title = {3767. Determining Center of Gravity of Irregular-Shaped Bodies via Suspension},

author = {Emma Markovich},

url = {https://www.sawe.org/product/paper-3767},

year  = {2022},

date = {2022-05-21},

urldate = {2022-05-21},

booktitle = {81st Annual Conference, Savannah, Georgia},

pages = {23},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Savannah, Georgia},

abstract = {The precise determination of the center of gravity of an aircraft is essential for the balance, stability, and overall safety of flight. Military aircraft often carry additional attachments, such as wing-mounted surveillance equipment, fuel tanks, or weaponry, which alter the weight and balance characteristics of the aircraft. In the application explored in this paper, a novel suspension system for determining the center of gravity of surveillance pods varying in shape and size is developed. This allows for the calculation of the center of gravity of aircraft attachments utilizing a two-point connection - the same attachment method as used on an aircraft. The tool features a hinged testbed that is suspended from a rigid frame by three load sensing devices. Two measurement sets are taken at different inclinations using an inverted three-point weighing method which allows the center of gravity to be calculated in all three dimensions. To recover measurement accuracy lost due to the limitation of inclination angles to less than 20 degrees, a high precision inclinometer is utilized. Based on the specifications of the sensing equipment and extensive Monte Carlo simulation of errors in force measurement, inclination angle, geometric dimensions, and data sampling, it is expected that the center of gravity can be reliably calculated to within 0.1 inches of the true value. Using the tool, objects ranging from 180 lb to 2000 lb with sizes of up to 12 x 4 x 4 feet can be measured with this accuracy. The modular design of the apparatus, data acquisition methods, and analysis relating to computation of the center of gravity will be presented. Additionally, the paper will discuss error analysis for the measurements, as well as verification and validation methods.},

keywords = {03. Center Of Gravity, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3766,

title = {3766. Mass Properties and Automotive Braking},

author = {Brian Paul Wiegand},

url = {https://www.sawe.org/product/paper-3766},

year  = {2022},

date = {2022-05-21},

urldate = {2022-05-21},

booktitle = {81st Annual Conference, Savannah, Georgia},

pages = {63},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Savannah, Georgia},

abstract = {In 1984, for the 43rd Annual International Conference of the SAWE, this author presented Paper Number 1634, “Mass Properties and Automotive Longitudinal Acceleration”. In that paper the effects upon automotive acceleration of varying the relevant mass property parameters were explored by use of a computer simulation. The computer simulation of automotive longitudinal acceleration allowed for the study of each individual parameter because a simulation allows for the decoupling of the parameters in a way that is not possible physically. The principal mass property parameters involved were the vehicle weight and rotating component inertias, collectively known as the “effective mass”, plus the longitudinal and vertical coordinates of the vehicle center of gravity. 

However, just as it is important for a vehicle to be able to accelerate, it is perhaps even more important for a vehicle to be able to decelerate. The same mass properties that were relevant to the matter of automotive acceleration are also relevant to the matter of automotive deceleration, a.k.a. braking, although for the braking case that collective of vehicle translational inertia and rotational component inertias known as the “effective mass” requires somewhat different handling. As was the case with automotive acceleration, automotive braking will be explored by use of a computer simulation whereby the effect of variation of each of the mass property parameters can be studied independently. However, this task is considerably easier as the creation of a braking simulation is a minor effort compared to the creation of an acceleration simulation. 

Rev B - 2023},

keywords = {31. Weight Engineering - Surface Transportation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3774,

title = {3774. Weight Control For Floating Wind Installation},

author = {A. P. Crowle and P. R. Thies},

url = {https://www.sawe.org/product/paper-3774},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

booktitle = {2021 SAWE Tech Fair},

pages = {10},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {Floating offshore wind is a growing market within the renewable energy sector. The floating offshore wind turbines give access to deeper water sites, with minimal visual impact from land. The paper includes the weight control requirements for Spars, barges, semi submersibles and Tension Leg Platforms (TLPs) as floating wind platforms. 

There are weight control challenges for the various substructure types during the temporary phases of construction and offshore installation. An accurate assessment of the buoyancy of the floating wind turbine for different drafts and trims is required. Allowances need to be included in the weight calculation for temporary buoyancy, sea-fastenings and grillage. 

Weight control for installation has an influence on the weather window for the floating substructures during transportation to the offshore site and mooring and electrical connection. The paper will cover weight calculation methods during early design, detailed design, construction, installation, operation and demolition. 

The installation process for a floating wind turbine varies with substructure type and this paper will give an overview of the weight control requirements for loadout, ocean transport and mooring connection. The floating offshore wind turbine weight and centre of gravity has a direct bearing on draft, intact stability and motions. As part of the weight control process the centre of gravity and radii of gyration need to be accurately determined for each stage of the installation.},

keywords = {13. Weight Engineering - Marine, 24. Weight Engineering - System Design, 35. Weight Engineering - Offshore, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3772,

title = {3772. Scenario-based Prediction of Lightweight Costs - an Approach across Industries},

author = {Florian Wätzold},

url = {https://www.sawe.org/product/paper-3772},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

booktitle = {2021 SAWE Tech Fair},

pages = {38},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {To decide on which technology is best for a vehicle in development, technical and economical constraints need to be considered. The objective of this paper is to provide a generic, conceptual approach to estimating the value (€ or $) per weight unit (kg or lb), referred as lightweight cost, for all industries. It combines general project management and cost estimation techniques with mass property management. As cost and weight are unknown until the actual weighing or billing, this paper focuses on scenario-based assumptions. For an easy understanding, this lens is applied to a recently developed battery concept. 

The described approach integrates basic project management processes such as risk management, estimation considerations and cost assessment. In this pursuit, mass and cost are rolled-up based on the breakdown structure. Taking the uncertainties into account a most likely, best, and worst case are evaluated and a cone of respective lightweight cost is generated. For the ease of use in industrial daily business exactly one value per pound for decision making is derived, condensing the lightweight cost range by superimposing the mass and cost according to their specific scenario probability.},

keywords = {29. Weight Value-Of-Pound, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3768,

title = {3768. Mass Properties Reporting},

author = {Yiyuan Ma and Jin Yan and Ali Elham},

url = {https://www.sawe.org/product/paper-3768},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

booktitle = {2021 SAWE Tech Fair},

pages = {28},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {The Ultra-High Aspect Ratio Wing (UHARW) concept can improve the aircraft's aerodynamic efficiency and reduce fuel consumption. The Twin-Fuselage (TF) configuration is one of the most promising concepts for the UHARW design to reduce the wing bending moments and shear forces. This paper presents the development of a semi-empirical method for the weight estimation of TF aircraft in the initial sizing stage. A physics-based wing weight estimation method is improved for higher aerodynamic analysis fidelity and composite materials, which is used in the design of experiments and the results are applied for regression analysis to establish a semi-empirical method. Eventually, the established semi- empirical weight estimation method is integrated into a TF aircraft conceptual design and performance analysis framework, and a mid-range TF aircraft and a long-range TF aircraft are designed and sized to illustrate its application and efficiency in rapidly estimating the TF aircraft weight breakdown.},

keywords = {10. Weight Engineering - Aircraft Design, 11. Weight Engineering - Aircraft Estimation, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3771,

title = {3771. A Look at Inclining Experiment Heel Angles: Measurement Tools and Sensitivity},

author = {David Tellet},

url = {https://www.sawe.org/product/paper-3771},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

booktitle = {2021 SAWE Tech Fair},

pages = {27},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {An inclining experiment is used to indirectly measure the vertical center of gravity of a ship by measuring resultant heel angles for a given weight moved athwartships. The methods for measuring these angles are considered tried and true even though the uncertainties of their accuracy and precision are not well understood. This paper explores the impact of errors from traditional inclining methods and compares them with modern methods. The paper looks at a simulated inclining experiment and explores the change in results when errors are introduced into the measurements. It then looks at electronic inclinometers used in an actual inclining and discusses how that data can be analyzed and how that might affect the results of the experiment. Finally the paper discusses the advantages and disadvantages of old and new methods and provides recommendations for improved results from future inclinings.},

keywords = {03. Center Of Gravity, 13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3765,

title = {3765. Mass Properties and Automotive Directional Stability},

author = {B P Wiegand},

url = {https://www.sawe.org/product/paper-3765},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

booktitle = {2021 SAWE Tech Fair},

pages = {61},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {The quantification of automotive directional stability may be expressed through various stability metrics, but perhaps the most basic of these automotive stability metrics is the “Understeer Gradient” (Kus). The Understeer Gradient (in degrees or radians per unit gravity) appears extremely uncomplicated when viewed in its most common formulation. Kus =[ Wf / gCsf - Wr / gCsr ] 

This metric appears to depend only on the front and rear axle weight loads (Wf, Wr), and on the front and rear axle cornering stiffnesses (Csf, Csr). However, those last quantities vary with lateral acceleration, and the nature of that variation is dependent upon many other parameters of which some of the most basic are: Total Weight, Sprung Weight, Unsprung Weight, Forward Unsprung Weight, Rear Unsprung Weight, Total Weight LCG, Sprung Weight LCG, Total Weight VCG, Sprung Weight VCG, Track, Front Track, Rear Track, Roll Stiffness, Front Roll Stiffness, Rear Roll Stiffness, Roll Axis Height, Front Roll Center Height, and Rear Roll Center Height. Note that exactly half of these automotive directional stability parameters as listed herein are mass properties. 

The purpose of this paper is to explore, through a skidpad simulation, the relative sensitivity of automotive directional stability (as quantified through the Understeer Gradient) to variation in each of the noted vehicle parameters, with special emphasis on the mass property parameters. 

The simulation is constructed in a spreadsheet format from the relevant basic automotive dynamics equations; the normal and lateral loads on the tires are determined as the lateral acceleration is increased incrementally by a small amount (thereby maintaining a “quasi-static” or “steady-state” condition). The normal loads are used for the calculation of the lateral traction force potentials at each tire, with the required (centripetal) lateral traction forces apportioned accordingly. From those required (actual) lateral tire forces the corresponding tire cornering stiffnesses are determined; this determination is based upon a tire model developed through a regression analysis of tire test data. 

This construction of a fairly comprehensive lateral acceleration simulation from basic automotive dynamic relationships, instead of depending upon commercial automotive software such as “CarSim” (vehicle model) and Pacjeka “Magic Formula” (tire model), constitutes a unique aspect of this paper; this return to basics hopefully provides a clearer view and understanding of the results than would be the case otherwise. Even more unique is this paper’s emphasis on, and exploration of, the role specific mass property parameters play in determining automotive directional stability.},

keywords = {31. Weight Engineering - Surface Transportation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3762,

title = {3762. Artificial Intelligence Techniques for Ship Weight Estimation and Calculation},

author = {Upendra Malla},

url = {https://www.sawe.org/product/paper-3762},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

booktitle = {2021 SAWE Tech Fair},

pages = {9},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {The advancement of computing and data analysis tools gave rise to the development of Artificial Intelligence (AI) tools. The ship weight estimation and calculation are a simple and tedious process which requires a qualitative weight budgets and quantitative calculations. The evolution of ship weight estimation and calculation using Artificial Intelligence techniques is discussed in the paper and compared with the existing techniques used in the shipping industry. Currently there are several in-house tools and software’s which are utilized by design firms and shipyards for the mass properties estimation / calculation, but these tools are not built with any intelligence to make the weight estimate accurate and effective. The implementation of Artificial Intelligence algorithms for the ship weight estimation by considering the constraints like class rules, standards, guidelines etc. 

In this paper at the end, it shows the cost and time savings involved by the implementation of Artificial Intelligence techniques in the ship weight estimate program by means of an example AI tool.},

keywords = {12. Weight Engineering - Computer Applications},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3736,

title = {3736. Hydrogen Fuel Cell Power System Weight Challenges in VTOL Aircraft},

author = {Greg Ray and Joseph D. Rainville},

url = {https://www.sawe.org/product/paper-3736},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {16},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {The 'More Electric Aircraft' movement is maturing past actuation, flight controls and backup power solutions. Starting with Unmanned Aerial Vehicles (UAV) and now growing into the passenger vehicle market, vertical lift aircraft engineers are developing electric driven propulsion systems.One of major limitations with electrification is endurance or range. Batteries only offer so much energy capacity before mass becomes a limiting factor. Hydrogen fuel cells offer another solution for on board electrical generation but present many of their own technical challenges.In cases of typical passenger vertical lift aircraft, electrification supplants traditional gas turbines and liquid fuel tanks with electric motors, power electronics, and either batteries or hydrogen fuel cells for an energy source. For Class I UAVs (55 lbs. total weight) or Class II UAVs (up to 300 lbs. total weight), batteries could be replaced by smaller, simplified fuel cells, electronics and hydrogen storage.The electric powertrain evolution will have a strong impact on several aspects of aircraft technology development, especially mass properties and center of gravity as the emerging technology is not limited to time honored positions and locations of legacy components. This paper researches some of the risks and opportunities with electrifying the propulsion systems of vertical lift aircraft.},

keywords = {11. Weight Engineering - Aircraft Estimation, 34. Advanced Design},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3735,

title = {3735. Weight and Balance Challenges for Hybrid Electric Propulsion System},

author = {Vera Paula and Dr. Florian Vogel},

url = {https://www.sawe.org/product/paper-3735},

year  = {2020},

date = {2020-07-01},

urldate = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {16},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {In the last years electric propulsion systems became increasingly interesting and thanks to many of the technological breakthroughs from automotive companies this technological change is now entering the aviation industry and raises questions about the feasibility, advantages and challenges of the new technologies. In this context, the HEPS weight receives a special attention. The HEPS takes advantage of both electric motor and internal combustion engine and enables the system to be switched on the electrical component of the propulsion for specific flight phases (takeoff and landing).This proposed system has not only the benefit in fuel saving but also a reduction in takeoff noise, emission levels and cost. It also enables to open spaces and can contribute for safety increase, depending on application. This potential benefits are explored by manufacturers for future aircrafts, helicopters, drones and Urban Air Mobility vehicles.In that way, the main objective of this paper is to discuss and analyze HEPS architectures, considering the electric propulsion unit (e-motor and inverter), electric transmission (electrical protections and harness), electric energy source (battery/ fuel cell system and genset power generation) and thermal management (cooling system) from a weight and balance perspective. The aim is basically to answer the questions: which are the main relevant subsystems and components contributing for the weight of the HEPS and which are the challenges associated to it? In order to reach this goal a synthesis of bibliographic review is presented and a description research is proposed for a system with an aircraft application. The outcome of this work is a weight and balance perspective assessment of HEPS subsystem, which contributes to the understanding of this new technology and learning objectives for future aircraft design.},

keywords = {11. Weight Engineering - Aircraft Estimation, 34. Advanced Design},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3734,

title = {3734. Dynamic Computer Simulation of Aircraft Buoyancy},

author = {Peter Stubbers},

url = {https://www.sawe.org/product/paper-3734},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {97},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {IAircraft buoyancy is an important consideration in safe aircraft design. FAR 25.801 requires that in the event of emergency water landings, an aircraft must float long enough for passengers and crew to escape and board life rafts.Current methods do not include any analysis of stability, and each solution must be developed for an exclusive aircraft and configuration.To demonstrate compliance with this regulation, this study describes an improved method using a dynamic computer simulation developed with Simcenter Amesim that models the aircraft's position, orientation, weight, center of gravity, and center of buoyancy during a water landing. Internal geometry is modeled at points where water can leak into the plane as air tanks with variable flow rate orifices, allowing a simulation to show the change in buoyancy characteristics as water leaks into the aircraft and predict how much time passengers and crew will have for safe egress.This method improves upon past methods, allowing for a wider range of testing. Physical validation is beyond the scope of this study.},

keywords = {10. Weight Engineering - Aircraft Design},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3732,

title = {3732. Class II & 1/2 Mass Estimation of Light Aircraft Composite Wings},

author = {Miguel Nuño and K. U. Schröder},

url = {https://www.sawe.org/product/paper-3732},

year  = {2020},

date = {2020-07-01},

urldate = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {12},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {An accurate mass estimation is key to better evaluate aircraft concepts during conceptual and preliminary design. The influence of composite materials on the structural mass estimation of large commercial aircraft has been reviewed on several studies. For light aircraft however, few methods besides applying a fudge factor to scale down masses of an equivalent metallic wing are available. On aircraft concepts deviating from a classical con- figuration statistical methods can not be reliably used for the mass estimation. Therefore Class II & 1/2 and Class III methods, which account for the loading of the structure, are expected to provide a better estimation.In this paper we develop a Class II & 1/2 method to estimate structural masses of composite light aircraft wings. For this, the primary structure of several wings is dimensioned according to static strength criteria. The structure is modeled using a stick beam model. Static aerodynamic loads are calculated using a vortex lattice method. The masses of the dimensioned structures are then compared to the published masses of the considered wings. The comparison is used to calibrate the estimation method and account for sec- ondary structures and miscellaneous items. At last, the deviations between the real masses and the estimated ones using different methods are compared to evaluate the suitability of the developed method.},

keywords = {11. Weight Engineering - Aircraft Estimation, 23. Weight Engineering - Structural Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3709,

title = {3709. A Wing Weight Estimation Method Based on Wing-box Beam Design},

author = {Lu Bai and Zhi Deng and Xintan Zhang and Ming Xia and Jianli Wang},

url = {https://www.sawe.org/product/paper-3709},

year  = {2020},

date = {2020-07-01},

urldate = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {12},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {In this paper, a wing weight estimation method for transport aircraft is presented. By establishing related computational framework, a wing-box model is developed based on wing-box beam design, from where a wing weight estimation method is derived. The key steps of this work include parametric modeling based on structural model simplification, aerodynamic study, finite element method, and aeroelastic analysis. The influence of the mounted pylon has been considered for the wing-box sizing. This method has been validated using data of two different transport aircrafts, which shows that this method is robust and efficient. Outcome of this paper could be rapidly integrated in the conceptual design phase.},

keywords = {11. Weight Engineering - Aircraft Estimation, 23. Weight Engineering - Structural Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3760,

title = {3760. Design for Positive Static Margin for a Radio-Controlled Box-Wing Aircraft},

author = {Charlotte Bellerjeau},

url = {https://www.sawe.org/product/paper-3760},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {12},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {This paper will detail the aerodynamic design of a small unmanned box-wing aircraft to facilitate the study of turbulence by Dr. Brian Argrow at the CU Boulder. A design with no fuselage was necessary for the data collection, which presented a longitudinal stability challenge. The key to eventually achieving a stable design was weight placement for positive static margin. This paper will include the design process used to confront these issues. The initial choices of stagger, gap, decalage, and relative sweep are made using a simple model leveraging previous box-wing research. These, as well as the airfoil selection, are then investigated further using Athena Vortex Lattice (AVL) to analyze lift, drag, and stability. The final airframe design has a gap and stagger of 1 chord length, decalage of 5 degrees, and relative sweep of 30 degrees. A cambered NACA 6412 airfoil on the top wing and a reflexed NACA23112 airfoil on the bottom wing are selected, which combine to induce a positive pitching moment and aid in longitudinal stability. The resulting box-wing aircraft was flight tested successfully and will serve as an ideal platform for research at CU Boulder.},

keywords = {10. Weight Engineering - Aircraft Design, 34. Advanced Design, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3758,

title = {3758. Strategies for the Grid Stiffened Composite Panel Topology Optimization for Minimum Weight},

author = {Mohit Talele and Ali Elham},

url = {https://www.sawe.org/product/paper-3758},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {25},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {In this paper, a topology optimization methodology for the minimum weight of the composite stiffened panel with the constraint on the criticial buckling load is presented. An existing finite element solver [1] for the analysis of the stiff- ened tow steered composite panels is extended to perform the topology optimiza- tion for the minimum weight. The panel and the stiffeners are modelled using 3 node traingular Classical Laminate Plate elements (CLPT) and 2 node timoshenko beam elements, respectively. To achieve the independent meshing of the plate and stringers, the Lagrange multiplier based on a weak formulation of the continuity requirements between the plate elements and the beam elements is used. For a specific critical buckling load, the optimum topology of the stiffeners in the stiff- ened composite panel depends not only on the stiffeners but also on the fiber patten of the composite panel. Therefore, design variables corrosponding to both fiber pattern in the skin and stiffeners needs to be considered. Manufacturing mesh ap- proach presented in [1], is used to define the design variables corrosponding to the fiber pattern. The ground structure method is implemented to optimize stringers topology. The cross-sectional area of the stringers in the ground structure are de- fined as the design variables corrosponding to the stiffeners. To perform the robust the optimization, the analytical gradients of the buckling load and the weight of the stiffened panel with respect to design variables are implemented and verified using finite difference. The optimization for the minimum weight is performed for the varied complexities of the ground structures with the constraints on the critical buckling load.},

keywords = {22. Weight Engineering - Structural Design, 27. Weight Reduction - Materials, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3753,

title = {3753. Theoretical and Experimental Evaluation of the Flexibility of the Test Rig on Inertia Property Measurement},

author = {Giorgio Previati and Gianpiero Mastinu and Massimiliano Gobbi},

url = {https://www.sawe.org/product/paper-3753},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {14},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {In the measurement of inertia properties (mass, centre of gravity and inertia tensor), both the body under investigation and the test rig are commonly considered as rigid bodies. However, in case of heavy or large bodies, these assumptions may not be satisfied. The present paper deals with the consequences of the test rig structure deformations on the measured inertia parameters. In fact, if the forces exchanged by the structure of the test rig and the body are large, the structure may deform changing its geometry and dynamic behavior. These effects, in turn, affect the measured kinematic and dynamic quantities needed for the measurement of the inertia properties.In the paper, by considering the InTenso+ Measuring System of the Politecnico di Milano, a special type of multi-filar pendulum, the effects of the deformation of the test rig on the measurement of the inertia properties is investigated both numerically and experimentally. A flexible multibody model is employed to understand the dynamic effects of the deformations on the mass properties measurement. Several bodies are measured to validate such analyses. A proper mathematical procedure is then derived to measure the inertia properties of bodies when the realization of a sufficiently stiff structure is impractical.},

keywords = {06. Inertia Measurements, 09. Weighing Equipment},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3752,

title = {3752. A Portable Device for Measuring the Cog: Design, Error Analysis and Calibration},

author = {Giorgio Previati and Federico Ballo and Massimiliano Gobbi},

url = {https://www.sawe.org/product/paper-3752},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {18},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {The paper is devoted to the design, error estimation and calibration of a portable device for the measurement of the centre of gravity of rigid bodies. The device consists in a simple but effective implementation of the knife edge method. The design of the device including safety considerations is fully described. An error estimation approach is employed in the very early stage of the design to assess the required instrumentation accuracy and the manufacturing tolerances. A calibration of the portable device is performed by means of proper calibrated masses. After calibration, the accuracy of the device corresponds to the target accuracy defined in the a-priori error analysis.The design procedure described in the paper shows a straightforward approach for the design of devices for the measurement of the inertia properties. By such a procedure, it is possible to identify the most critical design areas and make the correct choices in the early stage of the design process. Also, a deep understanding of the measuring process can be gained allowing the definition of an effective calibration procedure.},

keywords = {03. Center Of Gravity, 09. Weighing Equipment},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3749,

title = {3749. One Fits All? A Comparison of Weight Estimation Methods for Preliminary Aircraft Design},

author = {Arthur Kluender and Andreas Gobbin},

url = {https://www.sawe.org/product/paper-3749},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {17},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {Is there any compelling way to precisely determine the major masses of an aircraft in preliminary design stages? If so, do the results match the real airplane weight properties, when it is built? This paper presents a comprehensive overview of commonly used approaches, highlighting their individual (dis)advantages and eligibility for typical transport missions. The study evaluates widely used, of-the-book-methods for weight estimation and searches for the most accurate approach among them. Each method is applied to determine the masses of four different aircraft, each of them representing a typical aircraft category. The results are put in relation to the real masses, extracted from the corresponding manufacturers manual. In addition, an extended and modified method, already existing and being used at the Department for Aircraft Design and Lightweight Structures at the Technical University of Berlin, is included in the study and tested for its reliability. The overall objective of this paper is to evaluate, whether there is a method that precisely calculates all relevant masses or else, which one delivers the most accurate results for various aircraft types. In order to differentiate even further, the set of required input parameters is considered. In early design phases, typically only a few of those are known. Hence, a method that leads to accurate results with minimal input is favorable for preliminary design. The study indicates that none of the methods covers all the aircraft types. However, tendencies show that some approaches suit certain aircraft types better than others. Most of them provide satisfactory results for an average, jet-engine propelled, single aisle, medium range aircraft in conventional twinjet configuration. Regarding more unusual configurations, for example with turboprop engines, the outcome differs noticeably. Also, for long range aircraft, only a few methods produce realistic numbers. According to this exploration, guidelines on when to use which method are provided. This is followed by an outlook, giving recommendations on the development of new methods. Ultimately, a suggestion on how to consider new technologies and implement them into existing methods of weight estimation is given.},

keywords = {11. Weight Engineering - Aircraft Estimation, 21. Weight Engineering - Statistical Studies, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3743,

title = {3743. FVA30: Application of Probabilistic Mass Estimation Methods to the Design of a Touring Motor Glider},

author = {M. Konersmann and M. Schmidt and S. Neveling and M. Scholjegerdes and F. Diekmann and T. Moxter and Miguel Nuño},

url = {https://www.sawe.org/product/paper-3743},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {16},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {In early design phases the mass and position of many aircraft components is uncertain. So, it is not possible to accurately calculate key aircraft parameters such as the total mass and center of gravity. A possible approach to deal with these uncertainties is using pessimistic and optimistic estimations for every component. This approach considers only the boundary values and can therefore lead to very conservative decisions. To reduce the uncertainty of the calculations and get a better estimation of the expected mass properties probabilistic mass estimation methods can be used.The FVA 30 is a hybrid electric motorglider being developed by students at the Flugwissenschaftliche Vereinigung Aachen (FVA). The configuration of the prototype features two electric engines in the V-tail unit and is therefore especially sensitive to mass changes. In this paper the usage of probabilistic mass estimation and propagation methods to design the FVA 30 is presented. Several methods to estimate probability distributions of different components are described. The propagation of uncertainties is calculated using Monte Carlo simulations with random sampling. At last, the probabilistic calculation results are discussed and compared with the ones using a deterministic method.},

keywords = {11. Weight Engineering - Aircraft Estimation, 21. Weight Engineering - Statistical Studies, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}