This report addresses a project conducted at Saab Aeronautics during the spring of 2018. The goal of the project was to investigate aircraft weight estimations in the conceptual design phase. The work was divided into two major parts: finding new weight estimation techniques and implementing an existing technique called the Berry Weight Estimation in to the Pacelab APD software. Several weight estimation techniques were found during an extensive literature review but in the end, only one was chosen for further investigation. The chosen technique was the NASA Wing Weight Build-Up which proposed calculations for wing weights based on aircraft statistics. It contained material data tables for determining so called K-factors that were used to essentially scale the individual wing weight formulas. The data tables did not include K-factors up to a load factor of 9 which was a requirement from Saab. Extrapolations of the material data tables were done to approximate the missing values. The NASA wing weight build-up showed promising results with little deviation from the actual wing weight for a few chosen aircraft. This weight estimation technique was consequently chosen as a worthy candidate for a future implementation in the Pacelab APD software. The task of implementing the Berry Weight Estimation in Pacelab APD was divided into a fuselage- and a wing part. This was done to ease the implementation since it would resemble the original description of the method. The wing and fuselage weights were both calculated in two steps. The first step was to calculate a gross shell weight. This is the weight of an idealized structure without cut-outs or imperfections. The second step was to add so called weight penalties for various components within the wing or fuselage. Typical aircraft components had associating weight penalty functions described in the Berry Weight Estimation. Most of the implemented calculations used Pacelab APD to get involved parameters automatically. However, some of the needed parameters had to be user specified for the implemented Berry Weight Estimation to work. Once the implementation task was finished, several sensitivity studies were made to establish a perception about the involved parameters impact on the Berry Weight Estimation results. The new implementation gave benefits compared with the Berry Weight Estimation in Bex. One of these was the ability to perform extensive trade- and sensitivity studies. The sensitivity studies gave verdicts on the most influencing parameters of the implemented code and guide lines on future improvements of the calculations. These sensitivity studies show, among other things, that is recommended to increase the number of wing and fuselage stations significantly in order to get a converged result for the Berry Weight Estimation.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:liu-175012 |
| Date | January 2018 |
| Creators | Knöös Franzén, Ludvig, Magnusson, Erik |
| Publisher | Linköpings universitet, Fluida och mekatroniska system, Linköpings universitet, Fluida och mekatroniska system |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | LIU-IEI-TEK-A-18/03188-SE |
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