Reearch Journal of Applied Science, Engineering and Technology 5(9): 863-869, 013 ISSN: 040-7459; e-issn: 040-7467 Maxwell Scientific Organization, 013 Submitted: February 05, 013 Accepted: March 0, 013 Publihed: March 0, 013 Environmental Influence on Automatic Landing Error of the Carrier-Borne Aircraft Han Zhimin and Hong Guanxin School of Aeronautic Science and Engineering, BeiHang Univerity, Beijing, China Abtract: The aim of thi tudy i to analyze the movement model of aircraft carrier and tern flow model under the influence of marine port. Alo, we focu on the influence of marine port and aft flow on the landing error of the carrier-borne aircraft under the guidance of the automatic landing ytem in different ea tate level by numerical imulation and calculation. The analyi reult i meaningful to the aircraft carrier due to the fact that environmental factor have a great influence on the error of carrier-borne aircraft landing on aircraft carrier, epecially; marine port and aft flow alway affect the movement of an aircraft carrier and landing proce of carrier-borne aircraft. Keyword: Aft flow, automatic carrier landing ytem, marine port INTRODUCTION Marine port and aft flow in the environmental factor i the major diturbance factor cauing the landing error. When aircraft carrier wa affected by the torm in the ea, it traveling port and perturbation motion will be ix degree of freedom motion and affect the poition of the ideal landing point. Therefore, the aircraft carrier movement preent the characteritic of the random motion. The aft flow of aircraft carrier i very complex and it characteritic include nonlinear, unteady, randomne and o on. The active area of aircraft carrier i big and the marine climate i bad. When the carrier-borne aircraft approach landing, the aft flow behind the aircraft carrier i very diadvantageou to the airplane landing. The diturbance of a whirlwind i an important factor, becaue a whirlwind i tronger, the burble after hip i bigger. And the direction of whirlwind ha a big impact on ditribution characteritic of aft flow. Miion objective of ACLS (Automatic Carrier Landing Sytem) i that fully automatic landing of carrier-borne aircraft on the deck of an aircraft carrier can be achieved under variou weather condition. Sytem tructure chematic diagram of ACLS i hown in Fig. 1 (Huff and Keler, 1978; Qidan et al., 01; Zhu, 009). The ytem baic principle of ACLS i a follow. The deck movement of an aircraft carrier caued by the wave lead to the change of the ideal landing point, at thi time, the change of the ideal landing point i carried on the filter through deck motion compenator (DMC). Then, deck motion compenation intruction and poition information of carrier-borne aircraft are inputted the hip-borne intruction computer together and the intruction computer will combine the information and give the landing flight path/attitude intruction through control equation. In the meantime, the intruction are linked to the carrier-borne aircraft through the wirele data chain, at thi time, Automatic Flight Control Sytem (AFCS) on the aircraft and Approaching Power Compenation Sytem (APCS) operate the altitude control and the accelerator eparately, o that aircraft can fly according to track intruction. The objective of the tudy i to analyze the movement model of aircraft carrier and tern flow model under the influence of marine port. In addition, we analyze the influence of marine port and aft flow on the landing error of the carrier-borne aircraft under the guidance of the automatic landing ytem in different ea tate level by numerical imulation and calculation. MATERIALS The movement pectrum of an aircraft carrier at ea i typical narrowband proce. The frequency generally do not change a lot with the tate of motion and the range of frequency i between 0. rad/ and 0.8rad/. Change of the external condition only can change the peak power, the peak and bandwidth and the form of the pectrum i almot unaffected. Therefore, a implified fitting method can be found poibly and it give the general form of the movement pectrum of an aircraft carrier at ea, uing to analyi the actual frequency pectrum (Peng and Jin, 001; Huixin et al., 011). The pitching frequency pectrum tranfer function correponding Fig. i a follow: Correponding Author: Han Zhimin, School of Aeronautic Science and Engineering, BeiHang Univerity, Beijing, China 863
Re. J. Appl. Sci. Eng. Technol., 5(9) : 863-869, 013 Fig. 1: Sytem tructure chematic diagram of ACLS G () 0.045 0.4 0.6 (1) The heave frequency pectrum tranfer function correponding Fig. 3 i a follow: G Z () 0.03 0.13 0.53 () The Swaying frequency pectrum tranfer function correponding Fig. 4 i a follow: Fig. : Pitching frequency pectrum tranferr function G Y () 0.006 0. 0.45 (3) The implified fitting method uing on movement pectrum of an aircraft carrier at ea i very intuitive and need the imple calculation proce and mall computation load. Therefore, it i a extremely practical and effective project method fitting narrow band tationary random proce frequency pectrum. THE METHOD Fig. 3: Heave frequency pectrum tranfer function The diturbance velocity of aft flow model i compoed a follow (Peng and Jin, 000): Random free atmopheric turbulent flow u 1, v 1, w 1 Steady-tate diturbance of aft flow u, w Periodic diturbance caued by aircraft carrier movement u 3, w 3 Random diturbance of aft flow u 4, v 4, w 4 The total atmopheric diturbance component i calculated a follow: Fig. 4: Swaying frequency pectrum tranfer function u g u1u u3 u4 vg v1v4 w g w1w w3 w 4 (4) 864
Re. J. Appl. Sci. Eng. Technol., 5(9): 863-869, 013 u 1 / (m -1 ) w 1 / (m -1 ) v 1 / (m -1 ) 1 0.5 0-0.5-1 0 50 100 150 00 1 0.5 0-0.5-1 0 50 100 150 00 1.5 1 0.5 0 5.66 Su ( ) 1 (30.48 ) 6.59[1 (11.9 ) ] Sv( ) [1 (304.8 ) ][1 (40.64 ) ] Sw( ) 1 (30.48 ) (5) The unit of the power pectrum in the Eq. (5) i ( m/ ) /( rad / m ), Spatial frequency i and it unit i rad/m. When the numerical imulation reult of the pectrum model were verified, the tatitical characteritic uch a root mean quare and average value mut be conitent with the theoretical value and alo need to inpect whether the correlation coefficient and the power pectral denity are conitent with the theoretical value. A fragment of imulation reult i hown in Fig. 5. It i the patial ditribution of free atmopheric turbulence component at ea u 1, v 1 and w 1 from top to bottom between 0 and 00 m and the origin of coordinate i the pitching center of an aircraft carrier here. Steady-tate diturbance of aft flow: Steady-tate diturbance of aft flow i made up of tatic component of aft flow of aircraft carrier and i hown in Fig. 6. the horizontal component and vertical component i u and w and deck wind peed i Vwod in Fig. 6. The origin of coordinate i the pitching center of an aircraft carrier. And x forward i poitive and backward i negative. When the motion tate of the aircraft carrier i contant, teady-tate component of aft flow won t change. It alo how that the ize of teady-tate component of aft flow i decided by vow in Fig. 4. -0.5-1 0 50 100 150 00 Fig. 5: Fragment of free atmopheric turbulence component at ea u, v, w in the Eq. (4) i the component on the x, y, z axi of wind peed. The axi i defined that the x-axial to the front i poitive, the y-axi to the right i poitive and the z-axi to the under i poitive. Cyclical component of aft flow: Cyclical component of aft flow i produced due to the induction of the cyclical pitch and heave motion of the aircraft carrier. Along with the ditance of the aircraft carrier pitching frequency, the pitching peak-to-peak value, the armor whirlwind a well a the carrier plane to the aircraft carrier changing and on a hip down line of carrierborne aircraft, it can be calculated a following formula: u3 Vwod (. 0.0095 x) C w3 Vwod (4.98 0.0059 x) C In Eq. (6): Freedom atmopheric turbulence component at ea: The free atmopheric turbulence i the low-altitude free atmopheric turbulence component without the relative V V wod x C co 1 poition of the aircraft and the aircraft carrier and it wa t p 0.85 Vwod 0.85 Vwod aniotropic and it pace power pectrum i a follow: 865 (6)
Re. J. Appl. Sci. Eng. Technol., 5(9): 863-869, 013 Fig. 6: Steady-tate component of Aft flow 0.04 0.03 0.0 0.01 0.00 1. 0.8 / V wod 0.4 0.0-800 -600-400 -00 0 00 Fig. 7: (x) and (x) of random turbulence component of aft flow The level diturbance peed i u 3, m/; Vertical diturbance peed i w 3, m/; Pitching angular velocity of aircraft carrier i p, rad/; Pitching amplitude of aircraft carrier i, rad; Deck wind peed i Vwod, m/; Random phae i p, rad; x i the ditance of the pitching center of the aircraft carrier and the direction of movement of the carrier i poitive. When x<-681 m, component u 3 i zero; When x<-773 m, component w 3 i zero. Wind component i not given in Eq. (6) and it mean that v 3 i zero. Random turbulence component of aft flow: The turbulence i random atmopheric turbulence caued by the preence of the aircraft carrier. The power pectrum obtained by the meaurement how that the atmopheric turbulence i aniotropic. The filter calculation uing the white noie i a follow: () x () x R u4 () xj1 0.035Vwod 6.66R w4 v4 3.33 j 1 (7) 866 In Eq. (7), R = [Peudo-random number] [ j j 0.1 ] in(10 t) Deck wind peed i V wod, m/; The root-meanquare of random wake component i (x), m/; Time contant i (x),. With the change of the ditance of the pitching center of the aircraft carrier, (x) and (x) will change, a hown in Fig. 7. When imulating the turbulent flow component, according to the ditance from the center of the aircraft carrier pitching to the location to be imulated, and are read. (x) will be obtained if multiplied V wod and j ω i replaced by Laplace operator in Eq. (7). The random turbulence component model i became the form of the tranfer function. At thi time, (x) and V wod are ubtituted tranfer function, then, imulation will be carrying uing the Simulink toolbox in matlab. Guidance proce imulation of ACLS: Baed on the imulation of natural characteritic of the aircraft and control ytem and according to the phyical image of F/A-18A landing and the work of ACLS (Prickett and Parke, 001), the imulated program of final hip error
Re. J. Appl. Sci. Eng. Technol., 5(9): 863-869, 013 i etablihed and calculated. In the time domain, the entire quantity value imulation i carried and erroneou reult of actual hip i analyzed. MATLAB i a huge CACSD (Computer-Aided Control Sytem Deign) tool package, which contain a large number of numerical imulation of the control ytem algorithm and ha been optimized and tandardized proceing, including tranfer function, ytem of equation of tate and other form of numerical imulation. Depending on the expected flying time, the landing engage time can be judged whether it i le than the 13. If it i greater than 13, DMC doe not work and the height intruction i zero; otherwie, DMC i connected and according to the ideal poition of the landing point, the height intruction compenated can be calculated. The height intruction i tranmitted to the flight control ytem. Then combined with the tate parameter of flight and wind peed, output of autopilot/apcs i calculated and it i elevator input and throttle input of carrier aircraft. At thi time, the flight tate parameter of the next moment i calculated continually. Through loop calculation, when the difference in height between the lowet point of the tail hook and aircraft carrier deck i zero, the loop end. The final landing error can be calculated, it mean that the horizontal ditance between the aircraft landing engagement and the ideal landing point will be obtained. EXAMPLE SIMULATION Known a: aircraft peed i 69.96m/ glide angle i -3.5 deck wind peed i 1.86m/ time delay i 0. (Urne and He, 1985) The ditance between every two block cable of NIMIZ aircraft carrier i 1 m. If the mid-point of the block cable and the block cable 3 i looked a the Ideal landing point, the aircraft i linked to the point in the range of 18 m around the ideal landing point for a afe landing. In the Fig. 8 to 11, at the different ea condition and under the influence of the aircraft carrier movement and aft flow Separately, ditribution map of the airplane hip i obtained, through 50 time imulation. Fig. 8: Landing error under the influence of hip motion at three-level ea tate Fig. 9: Landing error under the influence of aft flow at threelevel ea tate Three-level ea tate Six-level ea tate CONCLUSION According to Fig. 8 and 10, data of the aircraft carrier movement influencing the Landing tandard deviation can be obtained under different ea 867 Fig. 10: Landing error under the influence of hip motion at ix-level ea tate condition. Effect of aircraft carrier under different ea condition i hown a Table 1.
Re. J. Appl. Sci. Eng. Technol., 5(9): 863-869, 013 Table 1: Effect of aircraft carrier under different ea condition Sea tate Landing S.D (m) Probability of landing ucce Three-level 4.93 100% Six-level.78 54% Table : Effect of aft flow under different ea condition Sea tate Landing S.D (m) Probability of landing ucce Three-level 1.1 100% Six-level 7.49 78% Fig. 11: Landing error under the influence of aft flow at ixlevel ea tate With the level of ea tate increaing, the movement amplitude of aircraft carrier increae. Under the three-level ea tate and the guidance of fully automatic landing guidance ytem, carrierbaed aircraft can land 100% afely; under the ixlevel ea tate, due to vice-value increaing and frequency changing fat of aircraft carrier movement, when the automatic landing guidance ytem track ideal landing point, the repone ha the bad trajectory control tability and other reaon and the landing error will increae, in the meantime, random inecurity factor will increae and make the probability of ucceful landing reduce. According to Fig. 9 and 11, data of aft flow influencing the Landing tandard deviation can be obtained under different ea condition. Effect of aircraft carrier under different ea condition i hown a Table. With the level of ea tate increaing, effect of aft flow alo increae. Under the three-level ea tate, landing ucce rate i100%; under the ix-level ea tate, trength of aft flow increae and it make landing ucce rate reduce to 78%. From Table 1 and, we can ee that the impact of the landing error of the aircraft carrier movement i greater than the aft flow. Under the three-level ea tate and ix- level tate, the landing error of the aircraft carrier movement and aft flow i a hown in Fig. 1 and 13. Fig. 1: Comparion of carrier movement and aft flow under three-level tate Under different ea tate, the impact of the automatic landing error of the aircraft carrier movement i greater than the aft flow. Seen from Fig. 1 and 13, the landing error of the aircraft carrier movement i 3 to 4 time than the aft flow. Therefore, the etablihment of a fully automatic landing guidance ytem focu on conidering to eliminate landing error of the aircraft carrier movement. REFERENCES Fig. 13: Comparion of carrier movement and aft flow under ix-level tate 868 Huff, R.W. and G.K. Keler, 1978. Enhanced Diplay, Flight Control and Guidance Sytem for Approach and Landing. AD/A44 869. Retrieved from: http://www.dtic.mil/cgibin/gettrdoc?ad=ada44869&location=u& doc=gettrdoc.pdf. Huixin, T., L. Kun and M. Bo, 011. A novel prediction modeling cheme baed on multiple information fuion for day-ahead electricity price. Proceeding of the Chinee Control and Deciion Conference (CCDC), pp: 1801-1805. Peng, J. and C.J. Jin, 000. Reearch on the numerical imulation of aircraft carrier air wake. J. Beijing Univ., Aeronaut. Atronaut., 6(3): 340-343.
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