Introduction to Aircraft Aeroelasticity and Loads

Wright, J.F.; Cooper, Jonathan E.

doi:10.2514/4.479359

Cited by 347 publications

(248 citation statements)

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“…with t the analysis time variable, g w , 0.5m/s, the peak gust velocity and the gust length g L (Wright and Cooper 2007). The gust analysis was performed in the frequency domain using a doublet-lattice panel method at sea level at a speed of 35m/s and at 25ᵒC.…”

Section: Gust Analysismentioning

confidence: 99%

Aeroelastic tailoring using crenellated skins-modelling and experiment

François¹,

Cooper²

2017

Advances in aircraft and spacecraft science

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Section: Gust Analysismentioning

confidence: 99%

Aeroelastic tailoring using crenellated skins-modelling and experiment

François¹,

Cooper²

2017

Advances in aircraft and spacecraft science

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“…2(a). Wagner's function shows that the unsteady lift increases asymptotically in time to reach the quasi-steady value at one degree angle of attack, while it reaches almost 90% of this value after traveling a distance equivalent to 15 semi-chords [67]. Also, Lomax [39] used the linearized Euler equations to derive exact initial values of Wagner's function for a flat-plate airfoil…”

Section: Unsteady Aerodynamic Theoriesmentioning

confidence: 99%

Challenges in the aerodynamics modeling of an oscillating and translating airfoil at large incidence angles

Ghoreyshi

Cummings

2013

Aerospace Science and Technology

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The challenges in the modeling of the unsteady lift of a two-dimensional NACA 0012 airfoil oscillating and translating at large incidence angles are investigated in this paper. Forced oscillation motions with two reduced frequency values of 0.1 and 1.0 were used. The CFD results show that a hysteresis loop was developed in the lift variation with angle of attack; shapes of the loops change significantly with reduced frequency value. A dynamic stall vortex was identified in the pitching and plunging motions with k = 0.1.This vortex delays the onset of flow separation over the upper surface to a higher incidence than would occur in steady conditions. The unsteady lift of the very fast motion is enhanced significantly due to the formation of a compression wave on the lower surface and an expansion wave on the upper surface. The results show clear limitations of unsteady aerodynamic theories for modeling motions at high incidences. Also, the CFD solution of indicial functions show a large oscillation at angles of attack beyond the stall angle, but the predictions of a model based on Radial Basis Function matches CFD values quite well.

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“…Modus getar sebuah wahana terbang dapat ditentukan dengan membagi model kedalam beberapa bagian yang masing-masing diberi kondisi batas yang sesuai. Rigid body modes dilibatkan untuk merepresentasikan konfigurasi terbang sebenarnya yang dialami wahana dimana struktur wahana tidak dikondisi batas kantilever [15][16]. Modus gerak struktur dibagi kedalam modus kaku (ϕ r ) dan modus fleksibel (ϕ r ) yang saling ortogonal [15,17].…”

Section: Pendahuluanunclassified

“…Rigid body modes dilibatkan untuk merepresentasikan konfigurasi terbang sebenarnya yang dialami wahana dimana struktur wahana tidak dikondisi batas kantilever [15][16]. Modus gerak struktur dibagi kedalam modus kaku (ϕ r ) dan modus fleksibel (ϕ r ) yang saling ortogonal [15,17]. Sebagai contoh fuselage dapat bergerak bebas dengan modus translasi vertikal (arah sumbu Z) dan sayap bergerak dengan modus bending.…”

Section: Pendahuluanunclassified

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Flutter Analysis of RX-420 Balistic Rocket Fin Involving Rigid Body Modes of Rocket Structures

Andria

2013

MST

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AbstrakFlutter adalah suatu fenomena yang menyebabkan kegagalan katastropik pada struktur wahana terbang. Pada penelitian ini, flutter dikaji untuk konfigurasi simetri dan antisimetri untuk mengetahui pengaruh modus gerak kaku struktur roket terhadap karakteristik flutter sirip roket. Melalui penelitian ini diharapkan pula tingkat keamanan desain struktur roket RX-420 terhadap flutter dapat diketahui. Model yang dianalisis merupakan model setengah bagian roket. Struktur sirip yang digunakan adalah sirip dengan semispan 600 mm, tebal 12 mm, root 700 mm, tip 400 mm, jenis bahan Al 6061-T651 berkonfigurasi sirip double spar dengan ketebalan kulit sirip 2 mm. Dinamika struktur roket dan kestabilan flutter-nya dianalisis dengan menggunakan metode elemen hingga yang terimplementasi pada software MSC NASTRAN. Analisis menunjukkan bahwa flutter pada sirip lebih rentan terjadi pada konfigurasi antisimetri dibandingkan dengan konfigurasi simetri. Untuk konfigurasi antisimetri flutter terjadi pada kecepatan 6,4 Mach sedangkan untuk konfigurasi simetri flutter terjadi pada 10,15 Mach pada ketinggian permukaan laut. Bila dibandingkan dengan nilai kecepatan maksimum roket sebesar 4,5 Mach pada ketinggian 11 km atau ekivalen dengan 2,1 Mach pada ketinggian permukaan laut, maka dapat disimpulkan bahwa desain struktur roket RX-420 memenuhi batas keamanan dan flutter tidak akan terjadi selama roket terbang. Abstract Flutter Analysis of RX-420 Balistic Rocket Fin Involving Rigid Body Modes of Rocket Structures.Flutter is a phenomenon that has brought a catastrophic failure to the flight vehicle structure. In this experiment, flutter was analyzed for its symmetric and antisymmetric configuration to understand the effect of rocket rigid modes to the fin flutter characteristic. This research was also expected to find out the safety level of RX-420 structure design. The analysis was performed using half rocket model. Fin structure used in this research was a fin which has semispan 600 mm, thickness 12 mm, chord root 700 mm, chord tip 400 mm, made by Al 6061-T651, double spar configuration with skin thickness of 2 mm. Structural dynamics and flutter stability were analyzed using finite element software implemented on MSC. Nastran. The analysis shows that the antisymmetric flutter mode is more critical than symmetric flutter mode. At sea level altitude, antisymmetric flutter occurs at 6.4 Mach, and symmetric flutter occurs at 10.15 Mach. Compared to maximum speed of RX-420 which is 4.5 Mach at altitude 11 km or equivalent to 2.1 Mach at sea level, it can be concluded that the RX-420 structure design is safe, and flutter will not occur during flight.

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Introduction to Aircraft Aeroelasticity and Loads

Cited by 347 publications

References 0 publications

Aeroelastic tailoring using crenellated skins-modelling and experiment

Aeroelastic tailoring using crenellated skins-modelling and experiment

Challenges in the aerodynamics modeling of an oscillating and translating airfoil at large incidence angles

Flutter Analysis of RX-420 Balistic Rocket Fin Involving Rigid Body Modes of Rocket Structures

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