Miss distance Analysis of Proportional Navigation Using Normalized Equations with Radome Effect, Saturation, and Body Rate Feedback
Seyyed Hamid
Jalali Naini
author
text
article
2012
per
In this paper, the linearized 2-D equations of proportional navigation guidance (PNG) are normalized in order to carry out the missdistance analysis considering acceleration saturation and radome effect. The control system dynamics is modeled using the first-order transfer function. To reduce the missdistance due to radome effect, the body rate feedback is added to the commanded acceleration in the analysis. Using this approach, useful normalized curves are obtained for parametric study and modification of PNG. Finally, the normalized equations of a modified PNG, having nonlinear terms consisting of line-of-sight rate with different powers, are derived.
Journal of Aeronautical Engineering
Shahid Sattari Aeronautical University of Science and Technology-Iranian Aerospace Society
Director-in-Charge:
Dr. Akbar Cheraqi
Editor-in-Chief:
Dr. Farhad Javidrad
Associate Editor:
Dr. Vahid Khalafi
Website Manager:
Amir Ehsan Zamanian
Eng. Nima Mansour Lakouraj
English Text Editor:
Dr. Roohollah Maleki
17359449
14
v.
1
no.
2012
1
11
https://www.joae.ir/article_120414_8578fc1e85a460eb504b6cbc50908a0c.pdf
Experimental Analysis of a Flapping Aeroelastic Wing and Derivation of Genaralized Curves
Seyyed Hossein
pourtakdoost
author
Saeed
Karimian Aliabadi
author
Karim
Mazaheri
author
Abbas
Ebrahimi
author
text
article
2012
per
There are many potentially attractive applications for flapping Micro air vehicles (FMAV) . FMAV have much better performance in low speeds and Reynolds numbers compared to that of fixed wings or MAV. In line with their special advantages of small size, low velocity, high agility and maneuverability, micro or small ornithopters are being potentially considered for applications in rescue missions, remote sensing and spy and reconnaissance operations in small/closed environment. Experimental studies of flapping phenomena are of great importance due to some fundamental challenges faced with theoretical modeling of FMAV. These include complexity in simultaneous modeling of lift and propulsive mechanism, lack of accurate flight dynamic models and a high degree of coupling and nonlinearity of the FMAV dynamic modes. In this research, an elastic flapping wing has been experimentally investigated. The FMAV as well as an instrumented test stand for online measurements of forces, flapping angle and power consumption have been designed and built specifically for this investigation. Moreover, various types of wings having different torsional stiffness, mass and size have been manufactured in order to study the effects of changing both kinematic parameters and mechanical properties of wing, on produced forces and also consumed power. The test results have been achieved for a variety of aerodynamic and mechanical characteristics. A set of new generalized curves have been introduced via dimensional analysis, in which essential parameters of wing such as stiffness, mass, area, frequency and velocity, are grouped together. A new optimization scheme has been introduced based on these general curves, addressing best wing for maximum propulsive efficiency. Flapping performance is shown to be a function of two independent parameters, namely the reduced frequency and the Aeroelastic coefficient. The trends and the generalized curves can be widely utilized in the design of FMAV or other elastic lift-propulsion generating structures.
Journal of Aeronautical Engineering
Shahid Sattari Aeronautical University of Science and Technology-Iranian Aerospace Society
Director-in-Charge:
Dr. Akbar Cheraqi
Editor-in-Chief:
Dr. Farhad Javidrad
Associate Editor:
Dr. Vahid Khalafi
Website Manager:
Amir Ehsan Zamanian
Eng. Nima Mansour Lakouraj
English Text Editor:
Dr. Roohollah Maleki
17359449
14
v.
1
no.
2012
13
25
https://www.joae.ir/article_120425_6c5412da1e6ea2be46a440372dfdbad5.pdf
An investigation on the effect of chromating and anodizing conversion coatings on corrosion resistance in 2024 and 7075 aircraft aluminum alloys
Ali
Yazdani
author
text
article
2012
per
The high ratio of strength to weight in aluminum alloy of 2xxx and 7xxx series has lead to an increase in their applications in aerospace industries. The two important alloys in these series are 2024-T3 and 7075-T6 which are considered due to their high strength. However, the weak corrosion resistance of these alloys can limit their applications. This research investigates the improvement in corrosion resistance of these two alloys due to application of chromate coatings as well as anodizing in various acids. The morphology of the anodized coatings was studied by scanning electron microscope (SEM). In order to investigate the corrosion resistance, different samples were tested by polarization test in a salty solution. Finally the coated samples have gone under salt spray operation after excreting the color. The results revealed that boat of the coating methods improved the corrosion resistance of 2024 and 7075 alloys. The improvement after application of the chromate coating was found to be 78% and 72% for 2024 and 7075 alloys, respectively. In the case of performing anodized coatings these values were measured as 98% and 94%.
Journal of Aeronautical Engineering
Shahid Sattari Aeronautical University of Science and Technology-Iranian Aerospace Society
Director-in-Charge:
Dr. Akbar Cheraqi
Editor-in-Chief:
Dr. Farhad Javidrad
Associate Editor:
Dr. Vahid Khalafi
Website Manager:
Amir Ehsan Zamanian
Eng. Nima Mansour Lakouraj
English Text Editor:
Dr. Roohollah Maleki
17359449
14
v.
1
no.
2012
27
36
https://www.joae.ir/article_120426_b955aae56a1bc60197a5b6d561d01ee9.pdf
Nonlinear Robust Guidance in direction and perpendicular to the LOS for Intercepting Moving Targets
Majid
Zarei
author
Ahmadreza
Vali
author
Vahid
Behnamgol
author
text
article
2012
per
In this paper, guidance laws in the direction and perpendicular to the line-of-sight is designed. The tangential component of missile acceleration is designed for zeroing the LOS rate and the other component is for controlling the closing velocity. In this method, because of using the sliding mode control, the nonlinear equation of motion is used and the acceleration command input is determined considering the target acceleration as an uncertainty. Therefore the guidance laws are robust with respect to target maneuvering and precise measuring or estimating of target acceleration is not required. In these guidance laws there are parameters for adjusting the reaching time to sliding surfaces and for producing smooth command acceleration and removing the chattering phenomenon in control input, continuous approximation method has been applied. Because of using a new sliding condition, the boundary layer is adjust only once and is independent with the designing parameter.
Journal of Aeronautical Engineering
Shahid Sattari Aeronautical University of Science and Technology-Iranian Aerospace Society
Director-in-Charge:
Dr. Akbar Cheraqi
Editor-in-Chief:
Dr. Farhad Javidrad
Associate Editor:
Dr. Vahid Khalafi
Website Manager:
Amir Ehsan Zamanian
Eng. Nima Mansour Lakouraj
English Text Editor:
Dr. Roohollah Maleki
17359449
14
v.
1
no.
2012
37
46
https://www.joae.ir/article_120428_fbca4b3c2d6f6d20670e8205ba46f988.pdf
Three-Dimensional Midcourse Guidance with Moving Waypoints
Reza
Mirjalili
author
Farhad
Tavakoli
author
Seyyed Hamid
Jalali Naeini
author
text
article
2012
per
In this paper, a three-dimensional midcourse guidance law is presented for interception of moving targets using moving waypoints. The waypoints are selected such that the interceptor ascends initially at higher altitudes to fly its trajectory in the thin layers of atmosphere. The interceptor uses proportional navigation guidance with gravity compensation to fly towards the next waypoint. The waypoint positions are modified in case the target changes its course. Simulation results show that the proposed midcourse guidance has better performance for the long range in comparison with classical midcourse schemes.
Journal of Aeronautical Engineering
Shahid Sattari Aeronautical University of Science and Technology-Iranian Aerospace Society
Director-in-Charge:
Dr. Akbar Cheraqi
Editor-in-Chief:
Dr. Farhad Javidrad
Associate Editor:
Dr. Vahid Khalafi
Website Manager:
Amir Ehsan Zamanian
Eng. Nima Mansour Lakouraj
English Text Editor:
Dr. Roohollah Maleki
17359449
14
v.
1
no.
2012
47
56
https://www.joae.ir/article_120429_2d09ad70ba88c0d08039fd3fb326011e.pdf
Prediction of stability lobes in milling of aluminum alloy 7075 using time series analysis
Masoud
Pour
author
Behnam
Motakef Imani
author
Mohsen
Fallah
author
text
article
2012
per
In this paper, a new method is presented for accurate prediction of cutting forces, stability lobes and the surface texture generated during low radial immersion milling process. In the proposed approach, the damping ratio for non-cutting zone is determined by experimental modal analysis, while the process damping ratio of cutting zone is defined using times series analysis techniques. Using correlation sum diagram, the simulation and experimental force signals are qualitatively compared to anticipate the value of process damping. The cutting force simulation algorithm utilizes Time Finite Element Analysis (TFEA) which is an effective method for modeling of cutting dynamics in low radial immersion milling process. The TFEA method enhances the modeling of flip and hopf bifurcation frequencies in low radial immersion milling. These frequencies can highly affect the stability lobes of milling process. Moreover, the effect of cutter deflections and run out are taken into account. The feasibility of proposed model is verified experimentally for side wall machining of Aluminum 7075-T6 using a HSS helical end mill. The compared simulation and experimental results include dynamic cutting forces, 3D surface texture, surface roughness and the boundaries of stability lobe diagram. It is shown that the implemented model can accurately simulate the various aspects of low radial immersion milling process.
Journal of Aeronautical Engineering
Shahid Sattari Aeronautical University of Science and Technology-Iranian Aerospace Society
Director-in-Charge:
Dr. Akbar Cheraqi
Editor-in-Chief:
Dr. Farhad Javidrad
Associate Editor:
Dr. Vahid Khalafi
Website Manager:
Amir Ehsan Zamanian
Eng. Nima Mansour Lakouraj
English Text Editor:
Dr. Roohollah Maleki
17359449
14
v.
1
no.
2012
57
72
https://www.joae.ir/article_120430_2f2eec75545f268751c3dbc6b5fb54e1.pdf
Improvement in a moving mesh algorithm and development of a central difference algorithm for the solution of unsteady flows
Hooman
Shahverdi Moghadam
author
Seyyed Mehdi
Mirsajedi
author
text
article
2012
per
In this research a simple and improved algorithm for simulating of rotational or oscillating motion of body and also solving the governing equations of flow is presented.in order to mesh the solution domain, a hybrid mesh which is combined with quadrilateral and triangle elements is used. In the moving mesh algorithm, rotational or oscillating motion of body is simply practicable so that it does not need any of common methods in moving mesh such as interpolation, insertion or deletion and remeshing. Discretization of solution domain in this research is based on Control Volume based Finite Element Method (CVFEM) and for solving the governing equations Jameson central difference algorithm is developed based on the mentioned discretization method. One of the advantages of this Approach is that it does not require finding information of neighbor elements; this subject is very important in solution of three dimensional problems and it noticeably facilitates the amount of data structure. In addition, in this approach the properties of flow are computed directly on domain vertices, so boundary condition are applied directly on boundary vertices and as a result the flow properties are computed exactly on boundaries. In this research, to accelerate convergence, local pseudo-time stepping, enthalpy damping and residual averaging are used on unsteady and compressible two dimensional forms of Euler equations. At the end, to make sure of the accuracy of the results, these results are compared either with experimental or other numerical available data.
Journal of Aeronautical Engineering
Shahid Sattari Aeronautical University of Science and Technology-Iranian Aerospace Society
Director-in-Charge:
Dr. Akbar Cheraqi
Editor-in-Chief:
Dr. Farhad Javidrad
Associate Editor:
Dr. Vahid Khalafi
Website Manager:
Amir Ehsan Zamanian
Eng. Nima Mansour Lakouraj
English Text Editor:
Dr. Roohollah Maleki
17359449
14
v.
1
no.
2012
73
89
https://www.joae.ir/article_120431_0f72dcfe4606c0a790ef8509f56f2bed.pdf