Analiza polijetanja male radio-upravljane letjelice

undergraduate thesis

• Title (english): Take-off analysis for small radio-controlled aircraft
• Author: Filip Rožman
• Mentor: Milan Vrdoljak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2015-03-04, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Cilj ovog rada je analizirati performanse male radio-upravljane letjelice u polijetanju u ovisnosti o masi letjelice, tj. u ovisnosti o masi tereta koji letjelica nosi. Promatrana letjelica je modifikacija letjelice HUSZ Vulture koja je napravljena za natjecanje Air Cargo Challenge 2013. Modifikacija se sastojala od promjene tipa podvozja. HUSZ Vulture ima konfiguraciju podvozja sa stražnjim kotačem, a promatrana letjelica ima konfiguraciju podvozja sa prednjim kotačem. Za analizu polijetanja korišten je model gibanja središta mase nadopunjen jednadžbama gibanja oko središta mase tijekom rotacije letjelice na pisti.

Prije same analize bilo je potrebno prikupiti podatke o letjelici. Prilikom određivanja položaja osovine stražnjih kotača, trebalo se pobrinuti da ona bude tako pozicionirana u odnosu na središte mase da se prilikom propinjanja letjelice oko stražnjih kotača (kad je letjelica još u doticaju sa tlom) središte mase ne nađe iza osovine stražnjih kotača jer bi to onemogućilo polijetanje. Parametri koji se mijenjaju sa povećanjem mase letjelice i čije je promjene važno odrediti su pozicija težišta letjelice i moment tromosti oko lateralne osi. Teretni prostor je tako konstruiran da se dodavanjem utega težište letjelice pomiče samo prema dolje. Budući da je krilo letjelice relativno blizu tlu, u analizu polijetanja uključen je i utjecaj tla.

Rezultati dobiveni analizom sa utjecajem tla i bez njega su uspoređivani kako bi se pokazao značaj utjecaja tla na polijetanje male letjelice. Ustanovljeno je da je utjecaj tla kod malih letjelica značajan. Glavni parametar na temelju kojeg su se ocjenjivale performanse letjelice bila je duljina polijetanja, a rezultati analize su pokazali da letjelica može uspješno poletjeti sa svakim od zadanih tereta. Među rezultatima analize su se također promatrale promjene kuta propinjanja, kuta penjanja, napadnog kuta, kuta otklona kormila visine te brzine i visine leta. Također, promatrale su se promjene brzine pri polijetanju i brzine gubitka uzgona u ovisnosti o masi tereta, kao i prijeđene udaljenosti tijekom pojedinih faza i vrijeme trajanja tih faza.

Abstract (english)

The purpose of this paper is to analyze the perfomance of a small radio-controlled aircraft during take-off in dependence of the weight of the aircraft. The analysed aircraft is a modification of the HUSZ Vulture which was made for the competition Air Cargo Challenge 2013.The modification consisted of a change of the undercarriage configuration. HUSZ Vulture has a taildragger undercarriage, while the modified aircraft carries a conventional undercarriage. The point mass model was used for the take-off analysis.

Prior to analysis, it was necessary to collect certain data. When determining the position of the aft wheel axle, it was important to make sure that the axis is positioned in such a way that the center of mass never shifts behind it. Some parameters (e.g. moment of inertia about the lateral axis, and the position of the center of mass) change with the increase of weight. It was also important to know the manner of their change. The cargo bay is designed in such a way that the center of mass shifts only vertically when adding weights. Since the wing is relatively close to the ground, ground effect is included in the take-off analysis.

Results obtained from the analysis with ground effect are compared to the results without it in order to show the importance of ground effect in small aircraft take-off analysis. It is concluded that the ground effect in small aircrafts is significant. The main parameter for the evaluation of the aircraft take-off perfomance is the take-off length. Results showed that the aircraft can successfully take off with each of the considered loads. Change of pitch angle, climb angle, angle of attack, elevator deflection angle, as well as the change of speed and height during take-off are also observed when analysing the results. In addition, the changes of take-off speed, stall speed, phase times, and phase lengths in dependence of the mass of the load were also shown, and commented in the results of the analysis.

• Keywords: polijetanje; performanse; utjecaj tla; HUSZ Vulture; model gibanja središta mase
• Keywords (english): take-off; small aircraft; point mass model; ground effect; HUSZ Vulture
• Language: croatian
• URN:NBN: urn:nbn:hr:235:265674
• Study programme: Title: Aeronautical Studies; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka zrakoplovnog inženjerstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka zrakoplovnog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 13:18:56