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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Yaw control at high angles of attack by tangential forebody blowing

Crowther, William James January 1994 (has links)
No description available.
2

Control of asymmetric vortical flow over a delta wing at high angles of attack

Greenwell, D. I. January 1993 (has links)
No description available.
3

The evaluation of canard couplings at high angles of attack

Ponton, Anthony J. C. January 1993 (has links)
No description available.
4

Použití bezpilotních bojových systémů v mezinárodním právu / The use of unmanned combat aircraft systems in international law

Halajová, Ludmila January 2016 (has links)
Unmanned combat aircraft systems (UCAS) represent a certain type of modern technology the States use to counter the growing number of security threats coming from the various non-state actors. The thesis focuses on the most common use of UCAS in the fight against these threats, on the practice called targeted killing. The purpose of the thesis is to identify all conditions amongst the norms of international law pertaining to the use of force between States, international human rights law and international humanitarian law, which are relevant for the targeted killing through UCAS. Furthermore, the thesis seeks to set out the circumstances, under which this practice can satisfy the relevant conditions, and when, on the other hand, it is never lawful. The thesis is composed of four chapters. The First Chapter defines the key terms used in the thesis and clarifies the terminology relating to UCAS. It also offers a short overview of their technical specifications and capabilities and identifies the States, which own, develop and sell the technology. The following three chapters represent the analytical core of the thesis and set out the conditions for the use of UCAS found in three systems of international law. The Second Chapter examines the use of UCAS from the perspective of the prohibition on the...
5

Varför dessa helikopterhaverier? : En jämförande studie mellan stridsflygshaverier och helikopterhaverier / Why all these helicopter crashes? : a comparison between fighter jets and helicopter crashes

Sehlberg, Martin January 2010 (has links)
<p>Syftet med uppsatsen är att undersöka, jämföra och diskutera eventuella faktorer till varför det har skett en så kraftig ökning av helikopterhaverier under de senaste tio åren jämfört med stridsflygshaverier. Problemet belyses och analyseras utefter ett MTO- perspektiv (människa, teknik och organisation). Stor vikt i uppsatsen läggs på de haverirapporter som är en följd av haverier mellan 1997 – 2007. Organisationsförändringar, flygmaskiner och utbildning är exempel på några andra delar som också behandlas. Viktigaste slutsatserna med uppsatsen är att helikopterhaverierna till stor del berott på den mänskliga faktorn medan stridsflyget har haft mer varierande orsaker. Faktorer som kan ha påverkat så att helikopterhaverierna har ökat jämfört med stridsflygshaverierna är följande tre.- Sammanslagningen av armeflyget, marinflyget och helikopterverksamheten i Flygvapnet.- Att flygning med helikopter i större omfattning sker på låg höjd.- Fler personer i en besättning kan påverka flygningen.</p> / <p>The purpose of this essay is to investigate, compare and discuss possible factors that have contributedto the big increase in helicopter crashes in the last ten years compared to fighter jets. The problem is looked upon and analyzed from an HTO perspective (human, technology and organisation). A lot of the essay is focused on the investigation reports that has followed all crashes between 1997-2007. Organisational change, different aircrafts and education and training are examples of other factorsthat are discussed in the essay. The most important conclusions that have been drawn are that helicopter crashes are mostly due to human factors reasons. Fighter jet crashes have more variation in the causes. Factors that may have been contributing in increasing helicopter crashes compared to fighter jets are:- The fusion between the army, marine and air force helicopter units- Helicopter flying is more frequently done on a lower altitude- There are more people part of the helicopter crew which can affect the flight</p>
6

Varför dessa helikopterhaverier? : En jämförande studie mellan stridsflygshaverier och helikopterhaverier / Why all these helicopter crashes? : a comparison between fighter jets and helicopter crashes

Sehlberg, Martin January 2010 (has links)
Syftet med uppsatsen är att undersöka, jämföra och diskutera eventuella faktorer till varför det har skett en så kraftig ökning av helikopterhaverier under de senaste tio åren jämfört med stridsflygshaverier. Problemet belyses och analyseras utefter ett MTO- perspektiv (människa, teknik och organisation). Stor vikt i uppsatsen läggs på de haverirapporter som är en följd av haverier mellan 1997 – 2007. Organisationsförändringar, flygmaskiner och utbildning är exempel på några andra delar som också behandlas. Viktigaste slutsatserna med uppsatsen är att helikopterhaverierna till stor del berott på den mänskliga faktorn medan stridsflyget har haft mer varierande orsaker. Faktorer som kan ha påverkat så att helikopterhaverierna har ökat jämfört med stridsflygshaverierna är följande tre.- Sammanslagningen av armeflyget, marinflyget och helikopterverksamheten i Flygvapnet.- Att flygning med helikopter i större omfattning sker på låg höjd.- Fler personer i en besättning kan påverka flygningen. / The purpose of this essay is to investigate, compare and discuss possible factors that have contributedto the big increase in helicopter crashes in the last ten years compared to fighter jets. The problem is looked upon and analyzed from an HTO perspective (human, technology and organisation). A lot of the essay is focused on the investigation reports that has followed all crashes between 1997-2007. Organisational change, different aircrafts and education and training are examples of other factorsthat are discussed in the essay. The most important conclusions that have been drawn are that helicopter crashes are mostly due to human factors reasons. Fighter jet crashes have more variation in the causes. Factors that may have been contributing in increasing helicopter crashes compared to fighter jets are:- The fusion between the army, marine and air force helicopter units- Helicopter flying is more frequently done on a lower altitude- There are more people part of the helicopter crew which can affect the flight
7

Bemannat vs. Obemannat : En komparativ studie av bemannade och obemannade stridsflygplans nyttjbarhet inom ramen för Counterinsurgency-operationer / Manned vs. Unmanned : A comparative study of manned and unmanned combat aircraft utilization within the scope of Counter Insurgency Warfare

Strand, Daniel January 2010 (has links)
<p>Nya typer av krigföring, så som COIN-operationer (Counter insurgency), ställer nya krav på flygstridskrafterna. Utvecklingen av det bemannade stridsflyget har, om man jämför med UAV (Unmanned Aerial Vehicle), trots detta stått relativt stilla. Obemannat stridsflyg har samtidigt utvecklat förmågor som gör funktionen till en värdig konkurrent på det moderna slagfältet. Syftet med denna uppsats är att undersöka huruvida obemannat stridsflyg kan överta det bemannade stridsflygets plats inom ramen för COIN-operationer. Detta avser jag uppnå genom att undersöka hur väl de båda funktionerna svarar uppmot de krav som ställs på ett stridsflygplan i en operation med inslag av COIN. Utifrån detta kommer jag bedöma vilka uppdragstyper som kan samt eventuellt inte kan lösas av en obemannad respektive bemannad flygfarkost. Resultatet i uppsatsen visar att bemannat stridsflyg är bättre anpassat till att genomföra markmålsoperationer inom ramen för COIN-operationer. Främst på grund av en bättre omvärldsuppfattning. Vid uppdragstyper kopplade till flygunderrätteleinhämtning är dock det obemannade stridsflyget bättre anpassat. Främst på grund av en längre uthållighet. Vad det gäller kostnadsaspekten så visar analysen att brukskostnaderna för det obemannade stridsflyget är betydligt lägre än hos det bemannade stridsflyget. Den höga anskaffningskostnaden för ett nytt UAV-system talar dock till dess nackdel. Skyddet som är integrerat i de obemannade plattformarna är sämre än hos den bemannade konkurrenten. UAV får i mångt och mycket lita till sin storlek för skydd. Slutsatsen jag kan dra av arbetet är att bemannat stridsflyg fortfarande har en plats på slagfältet inom ramen för COIN-operationer. Om utvecklingen fortsätter i samma takt och system som förbättrar omvärldsuppfattning för operatören på UAV samt möjliggör ett bättre självskydd kopplat till plattformen kan resultatet snart vara ett annat.</p> / <p>New types of warfare, such as COIN (Counter Insurgency), operations, mean new requirements for the Air Force. The development of the manned combat aircraft has, in comparison with the UAV (Unmanned Aerial Vehicle), shown relativly slow progress. Unmanned combat aircraft has on the other hand developed capabilities that make it a worthy competitor on the modern battlefield. The purpose of this paper is to examine whether unmanned combat aircraft can outrival the manned combat aircraft, in COIN-operations. I will achieve this by studying how well the two functions are responding to the demands of a combat aircraft in an operation with elements of COIN. From this, I will assess the mission types that can and can not possibly besolved by an unmanned, or a manned combat aircraft. The results of this paper show that the manned fighter is better suited to carry out counter land operations within thescope of COIN-operations, mainly due to a better situational awareness. Due to longer endurance, the unmanned combat aircraft is better suited to carry out missions like reconnaissance and surveillance. In the cost aspect, the analysis shows that the cost of using the unmanned combat aircraft is much lower than that of the manned combat aircraft. The high purchase cost of a new UAV-system, however, speaks against it. The protection that is integrated into the unmanned platforms is worse than for its rival. UAVs must largely rely on their size for protection. The conclusion I can draw from this paper is that manned fighter aircraft still has a place on the battlefield as a part of COIN-operations. If the development continues at this pace and systems that improve the situational awareness of the operator of UAVs, and allows for better self protection linked to the platform, the result may soon be another.</p>
8

Bemannat vs. Obemannat : En komparativ studie av bemannade och obemannade stridsflygplans nyttjbarhet inom ramen för Counterinsurgency-operationer / Manned vs. Unmanned : A comparative study of manned and unmanned combat aircraft utilization within the scope of Counter Insurgency Warfare

Strand, Daniel January 2010 (has links)
Nya typer av krigföring, så som COIN-operationer (Counter insurgency), ställer nya krav på flygstridskrafterna. Utvecklingen av det bemannade stridsflyget har, om man jämför med UAV (Unmanned Aerial Vehicle), trots detta stått relativt stilla. Obemannat stridsflyg har samtidigt utvecklat förmågor som gör funktionen till en värdig konkurrent på det moderna slagfältet. Syftet med denna uppsats är att undersöka huruvida obemannat stridsflyg kan överta det bemannade stridsflygets plats inom ramen för COIN-operationer. Detta avser jag uppnå genom att undersöka hur väl de båda funktionerna svarar uppmot de krav som ställs på ett stridsflygplan i en operation med inslag av COIN. Utifrån detta kommer jag bedöma vilka uppdragstyper som kan samt eventuellt inte kan lösas av en obemannad respektive bemannad flygfarkost. Resultatet i uppsatsen visar att bemannat stridsflyg är bättre anpassat till att genomföra markmålsoperationer inom ramen för COIN-operationer. Främst på grund av en bättre omvärldsuppfattning. Vid uppdragstyper kopplade till flygunderrätteleinhämtning är dock det obemannade stridsflyget bättre anpassat. Främst på grund av en längre uthållighet. Vad det gäller kostnadsaspekten så visar analysen att brukskostnaderna för det obemannade stridsflyget är betydligt lägre än hos det bemannade stridsflyget. Den höga anskaffningskostnaden för ett nytt UAV-system talar dock till dess nackdel. Skyddet som är integrerat i de obemannade plattformarna är sämre än hos den bemannade konkurrenten. UAV får i mångt och mycket lita till sin storlek för skydd. Slutsatsen jag kan dra av arbetet är att bemannat stridsflyg fortfarande har en plats på slagfältet inom ramen för COIN-operationer. Om utvecklingen fortsätter i samma takt och system som förbättrar omvärldsuppfattning för operatören på UAV samt möjliggör ett bättre självskydd kopplat till plattformen kan resultatet snart vara ett annat. / New types of warfare, such as COIN (Counter Insurgency), operations, mean new requirements for the Air Force. The development of the manned combat aircraft has, in comparison with the UAV (Unmanned Aerial Vehicle), shown relativly slow progress. Unmanned combat aircraft has on the other hand developed capabilities that make it a worthy competitor on the modern battlefield. The purpose of this paper is to examine whether unmanned combat aircraft can outrival the manned combat aircraft, in COIN-operations. I will achieve this by studying how well the two functions are responding to the demands of a combat aircraft in an operation with elements of COIN. From this, I will assess the mission types that can and can not possibly besolved by an unmanned, or a manned combat aircraft. The results of this paper show that the manned fighter is better suited to carry out counter land operations within thescope of COIN-operations, mainly due to a better situational awareness. Due to longer endurance, the unmanned combat aircraft is better suited to carry out missions like reconnaissance and surveillance. In the cost aspect, the analysis shows that the cost of using the unmanned combat aircraft is much lower than that of the manned combat aircraft. The high purchase cost of a new UAV-system, however, speaks against it. The protection that is integrated into the unmanned platforms is worse than for its rival. UAVs must largely rely on their size for protection. The conclusion I can draw from this paper is that manned fighter aircraft still has a place on the battlefield as a part of COIN-operations. If the development continues at this pace and systems that improve the situational awareness of the operator of UAVs, and allows for better self protection linked to the platform, the result may soon be another.
9

Ion-Nitriding Of Maraging Steel (MDN 250A Grade) For Light Combat Aircraft Applications

Shetty, Kishora 07 1900 (has links)
Maraging steels have got high strength and good toughness. Maraging steel MDN 250A grade is used for slat tracks on the leading edge of the wing of Light Combat Aircraft (LCA). This application requires high strength and good wear resistance. Required wear resistance for this application can be achieved by ion-nitriding (also called as Plasma nitriding or Glow discharge nitriding) process of case hardening. In conventional gas nitriding process the nitriding temperature is 500 – 550 0C, which is above the aging temperature of maraging steel. Ion-nitriding at temperatures lower than 480 0C is thought to be suitable for surface hardening for application of this material in slat tracks of the leading edge of the wing of LCA. Besides this ion-nitriding is stated to improve fatigue & wear resistance properties without significantly affecting other properties. Also this is a process where the thickness requirement is minimum for the wear properties accomplished. Further, no distortion, warpage and such other dimensional inhomogeneity problems are encountered. In ion-nitriding method glow discharge technology is used to introduce nascent (elemental) nitrogen to the surface of a metal part for subsequent diffusion into the material. The plasma assisted surface modification techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties. It has other advantages like nil or very thin white layer after nitriding and there is no machining or grinding involved for complex parts after the process. The hardened surface layers become an integral part of the basic material without any significant reduction in the properties of base material. Aim of the present work is to study ion-nitriding process on Maraging steels, to carry out ion nitriding of Maraging steel MDN 250A grade at different temperatures and evaluation of properties. Presently, the ion-nitrided slat tracks have been cleared for limited usage instead of full expected life. Studies are also needed to understand the fatigue behavior upon nitriding. The main aspects considered in this study are, optimization of thickness of the ion-nitrided layer and properties required for aircraft applications like slat tracks on the leading edge of the wing where wear resistance, corrosion resistance, mechanical properties like tensile strength, impact strength and fatigue strength are important. To establish the variation in the basic properties of maraging steel (MDN 250A Grade) because of ion nitriding. Aging of Maraging steel is done at 480 ± 5 0C with very close temperature control. In industrial ion-nitriding furnaces the temperature control is of the order of ± 10 0C. As a part of this research work ion-nitriding at three different temperatures which are well below 480 0C were chosen. These temperatures are 435 0C, 450 0C and 465 0C and soaking time i.e., ion-nitriding duration is 10 hours. Microstructure is characterized using optical microscope, scanning electron microscope and X-ray Diffraction. Properties evaluated include Hardness, Case depth, Tensile, Low Cycle Fatigue, Impact and Corrosion by Salt Spray. Optical microscopy and SEM examination don’t show change in core microstructure of the material after ion-nitriding. The iron compound formed in the hardened layer is Fe4N for all the three nitriding temperatures. Ion-nitrided specimens exhibit higher surface hardness and good case depth. Salt spray test results shows that there is animprovement in corrosion resistance after nitriding. The nitrided samples shown higher UTS and 0.2 % PS values than un nitrided ones, where as % Elongation and % Reduction in Area are lower for nitrided samples as compared to un nitrided samples. This can be attributed to the surface layer getting hardened because of ion nitriding. Impact strength of nitrided samples is lower compared to un nitrided samples. This is again due to the surface layer getting hardened because of ion nitriding. Low cycle fatigue properties obtained on ion-nitrided samples show improvement in the fatigue strength due to introduction of the residual compressive stresses. The mechanical properties satisfy the design requirements. Thus ion-nitriding of this Maraging steel (MDN 250A Grade) is suitable for parts which are subjected to constant wear and are complex in shape.
10

Localization of Combat Aircraft at High Altitude using Visual Odometry

Nilsson Boij, Jenny January 2022 (has links)
Most of the navigation systems used in today’s aircraft rely on Global Navigation Satellite Systems (GNSS). However, GNSS is not fully reliable. For example, it can be jammed by attacks on the space or ground segments of the system or denied at inaccessible areas. Hence to ensure successful navigation it is of great importance to continuously be able to establish the aircraft’s location without having to rely on external reference systems. Localization is one of many sub-problems in navigation and will be the focus of this thesis. This brings us to the field of visual odometry (VO), which involves determining position and orientation with the help of images from one or more camera sensors. But to date, most VO systems have primarily been established on ground vehicles and low flying multi-rotor systems. This thesis seeks to extend VO to new applications by exploring it in a fairly new context; a fixed-wing piloted combat aircraft, for vision-only pose estimation in applications of extremely large scene depth. A major part of this research work is the data gathering, where the data is collected using the flight simulator X-Plane 11. Three different flight routes are flown; a straight line, a curve and a loop, for two types of visual conditions; in clear weather with daylight and during sunset. The method used in this work is ORB-SLAM3, an open-source library for visual simultaneous localization and mapping (SLAM). It has shown excellent results in previous works and has become a benchmark method often used in the field of visual pose estimation. ORB-SLAM3 tracks the straight line of 78 km very well at an altitude over 2700 m. The absolute trajectory error (ATE) is 0.072% of the total distance traveled in daylight and 0.11% during sunset. These results are of the same magnitude as ORB-SLAM3 on the EuRoC MAV dataset. For the curved trajectory of 79 km ATE is 2.0% and 1.2% of total distance traveled in daylight and sunset respectively.  The longest flight route of 258 km shows the challenges of visual pose estimation. Although it is managing to close loops in daylight, it has an ATE of 3.6% during daylight. During sunset the features do not possess enough invariant characteristics to close loops, resulting in an even larger ATE of 14% of total distance traveled. Hence to be able to use and properly rely on vision in localization, more sensor information is needed. But since all aircraft already possess an inertial measurement unit (IMU), the future work naturally includes IMU data in the system. Nevertheless, the results from this research show that vision is useful, even at the high altitudes and speeds used by a combat aircraft.

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