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Thrust vectoring experiments with gas injectionSekhon, Kalwant Singh, 1938- January 1964 (has links)
No description available.
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Quasi-optimal steady state and transient maneuvers with and without thrust vectoringDwyer, Michael E. 29 September 2009 (has links)
Steady state and transient maneuver problems for a high performance fighter aircraft with and without thrust vectoring are investigated. The steady state aspect of these studies determines control combinations with and without thrust vectoring which optimize selected level-flight point performance criteria including minimum speed, maximum instantaneous range, and maximum sustained turn rate. The transient maneuvers are initiated from straight and level flight and include a longitudinal pitch-up to a desired fuselage pointing angle and a lateral-directional transition (wind-up) to a desired steady level turn rate. For the transient maneuvers, a full six-degree-of-freedom model of the aircraft is used with three conventional aerodynamic controls, throttle control and pitch and yaw thrust vectoring control. Each of the control time histories are parameterized so as to include both the rate and range limits of the controls. A nonlinear programming algorithm is used to determine the control parameter values which yield the minimum time to execute the prescribed maneuvers.
Results indicate that thrust vectoring does not significantly change the steady state behavior in the scenarios investigated. However, flight times for the transient maneuvers are found to be reduced by up to 28%. The greatest effect of thrust vectoring occurs at low Mach number. / Master of Science
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Goddard-problem variantsTsiotras, Panagiotis January 1987 (has links)
The problem of maximizing the altitude of a rocket in vertical flight has been extensively analyzed by many writers since the early days of rocketry. In the beginning, solutions were obtained using the classical theory of the Calculus of Variations, and later using Optimal Control theory. For strict assumptions on the drag law and the thrust, solutions were found, even in a closed, analytic form. Nevertheless, for more realistic conditions, the problem becomes a very complex one, and the solution is far from complete. In addition to this, complexity increases if an isoperimetric constraint is added to the problem. Such a case is, for example, the problem of extremizing the rise in altitude for a given time. In the present work an attempt is made to treat the problem under the most realistic assumptions used so far, for both the system of equations and the drag model. The analysis of the problem reveals that a more complex thrust history exists than the classical sequence of full-singular-coast subarcs, for both the time-constrained case, and for the case of a drag model with a sharp rise in the transonic region. In the first case, a second full-thrust subarc is generated at the end of the singular subarc, owing to the boundedness of the thrust, while, in the second case, a full-thrust subarc appears in transition from the subsonic to the supersonic branch of the singular path. Both are new results, at least for the bounded-thrust case, and the drag law assumed, insofar as the author knows. Discussion is also provided for the limitations of such a switching structure, and it is shown that the composition of an optimal trajectory is heavily dependent on the assumed drag law. / Master of Science
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Energy management for a multiple-pulse missilePhillips, Craig Alan January 1986 (has links)
A nonlinear programming technique is applied to the optimization of the thrust and lift control histories for missiles. The first problem considered is that of determining the thrust history which maximizes the range of a continuously-variable (non-pulsed) thrust rocket in horizontal lifting flight. The optimal control solution for this problem is developed. The problem is then approximated by a parameter optimization problem which is solved using a second-order, quasi-Newton method with constraint projection. The two solutions are found to compare well. This result allows confidence in the use of the nonlinear-programming technique to solve optimization problems in flight mechanics for which no analytical optimal-control solutions exist. Such a problem is to determine the thrust and lift histories which maximize the final velocity of a multiple-pulse missile. This problem is solved for both horizontal- and elevation-plane trajectories with and without final time constraints. The method is found to perform well in the solution of these optimization problems and to yield substantial improvements in performance over the nominal trajectories. / M.S.
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Design of an RF ion thrusterBotha, Johannes Rudolf 04 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Recent years have seen a decline in the rate of space exploration due to the inefficiency
of chemical rockets. Therefore alternative fuel efficient propulsion methods are being
sought to enable cost effective deep space exploration. The high fuel efficiency of electric
thrusters enable a spacecraft to travel further, faster and cheaper than any other propulsion
technology available. Thus electric propulsion has become the propulsion of choice
for scientists and engineers. A typically electric thruster contains some sort of electrode
to ionise the propellant. Although this is feasible for short space missions, it becomes impractical
for more ambitious space missions as electrodes erode over time. The alternative
is to ionise the propellant using electromagnetic fields, which eliminates lifespan issues
associated with electrode based thrusters.
In order to examine methods of improving the lifespan and performance of electric thrusters,
this thesis aimed to study the method of microwave discharge ionisation for an electric
thruster. This includes the design of an RF Ion Thruster with extraction and acceleration
grids to generate thrust. A 600 W 2.45 GHz magnetron (obtained from a conventional
microwave oven), coupled to circular TM010 resonant cavity, was used to ionise neutral
argon gas. The process of electron cyclotron resonance (ECR) was used to ensure the
efficient ionisation of a high density plasma. The thrust was achieved with a three-grid
system biased at high voltages to accelerate positively charged argon ions to high exhaust
velocities.
Results yielded the success of the designed electromagnetic based thruster, measuring
approximatively 1.78 mN of thrust with a specific impulse of Isp = 3786 seconds. The
ECR process produced a high plasma density with a plasma absorption rate of approximately
77% of the total input microwave power. The final results obtained were found
to match the predicted results extremely well and resembled results found in literature.
This demonstrates the efficiency of the RF ion thruster that was designed in this project
and the future use in space exploration activities. However, future research needs to be
undertaken on a controlled feedback system that will ensure optimal operating conditions
for maximum performance. In addition, the method of grid-less acceleration needs to be
studied to achieve maximum thrust and specific impulse. / AFRIKAANSE OPSOMMING: In onlangse jare het ’n afname in die tempo van die verkenning van die ruimte dit te danke
aan die ondoeltreffendheid van chemiese vuurpyle. Derhalwe moet alternatiewe brandstof
aandrywing metodes ondersoek word, om koste-effektiewe diep ruimte-eksplorasie
moontlik te maak. Die hoë brandstof-doeltreffendheid van elektriese ontbranders stel ’n
ruimtetuig in staat om verder, vinniger en goedkoper te reis as enige ander aandrywing tegnologie
wat tans beskikbaar is. Dus het elektriese aandrywing metodes die aandrywings
keuse vir wetenskaplikes en ingenieurs geword. ’n Tipies elektriese vuurpyl/aandrywer
bevat ’n vorm van elektrode om die brandstof (argon gas) te ioniseer. Alhoewel hierdie
elektrode proses van ionisasie effektief is vir kort ruimte missies, word dit onprakties vir
meer ambisieuse ruimte missies as gevolg van verweering van elektrodes met verloop van
tyd. ’n Alternatief is om die dryfmiddel/brandstof te ioniseer deur gebruik te maak van
elektromagnetiese velde. Die elekromagnetiese velde sal die lewensduur van die vuurpyl
vermeerder deur die verweering van elektrodes, wat geassosieer word met tipiese elektrieses
vuurpyle, te elimineer.
Hierdie tesis se doelwit is om die metode van mikrogolf ontslag ionisasie vir ’n elektriese
vuurpyl/aandrywer te bestudeer om ten einde die lewensduur en doeltreffendheid van elektriese
vuurpyl/aandrywer te ondersoek. Dit sluit in die ontwerp van ’n radio frekewensie
ioon vuurpyl/aandrywer met ’n ontginning en versnelling matriks/rooster om stukrag te
genereer. ’n 2,45 GHz magnetron (verkry vanaf ’n konvensionele mikrogolfoond), gekoppel
aan ’n TM010 resonante holte, was gebruik om neutrale argon gas te ioniseer. Die
proses van elektron siklotron resonansie (ESR) was gebruik om die doeltreffende ionisasie
van ’n hoë digtheid plasma te verseker. Die aandrywing/stukrag was behaal met ’n
drie-matriks-stelsel, bevoordeel deur hoë spannings om die positief-gelaaide argon ione te
versnel. Resultate opgelewer, het die sukses van die ontwerp van ’n elektromagnetiese gebaseerde
vuurpyl/aandrywer met ’n benaderde meting van ongeveer 1.78 mN van stukrag/aandrywing
met ’n spesifieke impuls van Isp = 3786 sekondes bewys. Die ECR proses het ’n hoë
plasma digtheid geproduseer met ’n plasma opname persentasie van ongeveer 77% van
die totale inset mikrogolf energie. Die finale uitslae wat verkry was, het bevind dat die
voorspelde resultate baie goed inpas met resultate in beskikbare literatuur. Dit dui op die doeltreffendheid van die RF ioon vuurpyl/aandrywer wat ontwerp is in hierdie projek vir
die toekomstige gebruik in ruimte eksplorasie-aktiwiteite. Toekomstige navorsing moet
op ’n beheerde terugvoer sisteem onderneem word, wat optimale werktoestande verseker
vir maksimum prestasie. Daarbenewens moet die metode van matriks-lose versnelling
bestudeer word, om maksimum versnelling/stukrag en spesifieke impuls te verseker.
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