The estimation of structural weight has a fundamental role in the preliminary phase of the aircraft design process. Traditional procedures for airframe weight estimation, rely upon handbook methods, based on semi-empirical models and statistical surveys from existing aircraft, but are not exhaustive when novel concepts want to be explored. In the meantime, aircraft manufacturers possess their own refined and well-proven formulas, tailored for their particular goals, but they are hardly available for general purposes. Implementing tools like NeoCASS (Next generation Conceptual Aero-Structural Sizing Suite) allow performing airframe sizing from physical principles, complemented by modern semi-empirical methods for non-structural approximations, making the process less dependent on standard methods. This software has been validated for large jet transport aircraft and has a positive performance when industries customize their in-house models. The present work focuses on assessing the potential of using NeoCASS for the preliminary sizing of conventional and non-conventional configurations, particularly for propeller-driven commuter and large regional transports. A survey on regional aircraft is carried out to identify the technological level on this category, and powerplant weight estimation relationships are proposed for both turboprop engines and electrical motors. A total of 20 representative regional aircraft are sized for the validation. A Comparison of the mass fractions results is made with respect to statistical guidelines, the main weight groups are contrasted with the actual data to quantify the estimation error, and correction models are proposed for the adjustment of the Operating Empty Weight for future implementations. Additional sizing for innovative distributed propulsion designs is presented, evaluating the impact in the structural weight when the number of engines is progressively increased and when the thrust fraction for the wingtip engines is modified.
La stima del peso strutturale ha un ruolo fondamentale nella fase preliminare del processo di progettazione degli aeromobili. Le procedure tradizionali per la stima del peso della struttura si basano su modelli semi-empirici e indagini statistiche di velivoli esistenti, ma non sono esaustivi quando si vogliono esplorare nuovi concetti. Nel frattempo, i costruttori di aeromobili dispongono di formule proprie, raffinate e collaudate, fatte su misura per i loro obiettivi particolari, ma sono difficilmente disponibili per scopi generali. L'implementazione di strumenti come NeoCASS (Next generation Conceptual Aero-Structural Sizing Suite) permette di eseguire il dimensionamento della struttura a partire da principi fisici, integrato da moderni metodi semi-empirici per approssimazioni non strutturali, rendendo il processo meno dipendente dai metodi standard. Questo software è stato validato per aerei da trasporto a reazione di grandi dimensioni e ha prestazioni positive quando le industrie personalizzano i loro modelli interni. Il presente lavoro si concentra sulla valutazione del potenziale di utilizzo di NeoCASS per il dimensionamento preliminare di configurazioni convenzionali e non convenzionali, in particolare per velivoli ad elica e grandi trasporti regionali. Per identificare il livello tecnologico di questa categoria viene effettuata un'indagine sugli aerei regionali e vengono proposti rapporti di stima del peso degli impianti di propulsione sia per i motori turboelica che per i motori elettrici. Per la validazione vengono dimensionati complessivamente 20 aerei regionali rappresentativi. Il confronto dei risultati delle frazioni di massa viene effettuato rispetto alle linee guida statistiche, i principali gruppi di peso vengono confrontati con i dati reali per quantificare l'errore di stima, e vengono proposti modelli di correzione per l'adeguamento del peso a vuoto operativo per future implementazioni. Vengono presentati ulteriori dimensionamenti per progetti innovativi di propulsione distribuita, valutando l'impatto sul peso strutturale quando il numero di motori è progressivamente aumentato e quando la frazione di spinta dei motori sull'estremità dell' ala viene modificata.
On the preliminary structural sizing of innovative regional aircraft
TELLEZ VELASQUEZ, ANDRES FELIPE
2018/2019
Abstract
The estimation of structural weight has a fundamental role in the preliminary phase of the aircraft design process. Traditional procedures for airframe weight estimation, rely upon handbook methods, based on semi-empirical models and statistical surveys from existing aircraft, but are not exhaustive when novel concepts want to be explored. In the meantime, aircraft manufacturers possess their own refined and well-proven formulas, tailored for their particular goals, but they are hardly available for general purposes. Implementing tools like NeoCASS (Next generation Conceptual Aero-Structural Sizing Suite) allow performing airframe sizing from physical principles, complemented by modern semi-empirical methods for non-structural approximations, making the process less dependent on standard methods. This software has been validated for large jet transport aircraft and has a positive performance when industries customize their in-house models. The present work focuses on assessing the potential of using NeoCASS for the preliminary sizing of conventional and non-conventional configurations, particularly for propeller-driven commuter and large regional transports. A survey on regional aircraft is carried out to identify the technological level on this category, and powerplant weight estimation relationships are proposed for both turboprop engines and electrical motors. A total of 20 representative regional aircraft are sized for the validation. A Comparison of the mass fractions results is made with respect to statistical guidelines, the main weight groups are contrasted with the actual data to quantify the estimation error, and correction models are proposed for the adjustment of the Operating Empty Weight for future implementations. Additional sizing for innovative distributed propulsion designs is presented, evaluating the impact in the structural weight when the number of engines is progressively increased and when the thrust fraction for the wingtip engines is modified.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/151648