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C-130 kargo uçağı için yangın söndürme modülü ön tasarım çalışması

Başlık çevirisi mevcut değil.

  1. Tez No: 75613
  2. Yazar: İSMAİL KILINÇ
  3. Danışmanlar: YRD. DOÇ. DR. CEVDET AYGÜN
  4. Tez Türü: Yüksek Lisans
  5. Konular: Uçak Mühendisliği, Aircraft Engineering
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 1998
  8. Dil: Türkçe
  9. Üniversite: İstanbul Teknik Üniversitesi
  10. Enstitü: Fen Bilimleri Enstitüsü
  11. Ana Bilim Dalı: Uçak Mühendisliği Ana Bilim Dalı
  12. Bilim Dalı: Uçak Mühendisligi Bilim Dalı
  13. Sayfa Sayısı: 124

Özet

ÖZET Bütün canlılar için vazgeçilemez bir ekolojik sistem olan ormanlar gün geçtikçe bilinçli / bilinçsiz bir şekilde yok edilmektedir. Orman yangınları da yok oluşu hızlandıran faktörlerin başında gelmektedir. Orman yangınlarıyla birlikte milli servetlerinin de yok olduğunun bilincine varan ülkeler, günümüzde orman yangınlarıyle etkin mücadelede hava taşıtlarını kullanmaktadırlar. 1950 yıllarında basit bir teknolojiyle uçak içersine yerleştirilen sabit tanklar sayesinde su veya kimyasal maddeler kısa zamanda yangın bölgelerine ulaştırılarak orman yangınlarıyla mücadelede önemli bir adım atıldı. Ancak yangına duyarlı ayların haricinde atıl olarak bekleyen yangın söndürme uçaklarının verimli olmadığı değerlendirilerek 1970'li yıllarda personel / kargo uçaklarına monte edilebilen modüller tasarlandı ve imal edildi. Bu sistemdeki en önemli nokta yangın söndürme modülünün uçakta tadilat yapmaksızın en kısa zamanda yüklenebilmesi ve kullanıma hazır hale gelmesidir. Bu sayede çeşitli kargo ve personel taşıma görevlerinde kullanılan uçaklar daha ekonomik ve verimli kullanılmaktadır. Bu çalışmada amaç, Türk Hava Kuvvetleri'nin envanterinde bulunan C-130E kargo uçaklarının herhangi bir tadilat yapılmaksızın istenildiğinde yangın söndürme uçağı olarak kullanılmasının mümkün olup olamayacağının incelenmesidir. Bu bağlamda 463 L kargo sistemine sahip olduğu için diğer uçak tiplerine göre daha avantajlı olan C-130E uçağında kullanılmak üzere üç tanklı basınçsız bir modüler sistem tasarlanmıştır. Yangın söndürme modülünün tasarımına öncelikle modülde yer alacak olan tankların geometrisinin belirlenmesi ve boyutlandınlması ile başlanıldı. Boyutlandırma işleminde C-130E uçağının kargo kompartımanın boyutlarına ve 463 L kargo sisteminin özelliklerine bağlı kalındı. Boyutlandırma işleminden sonra tasarlanan modülün C-130E uçağının uzunlama kararlığına etkisi yazılan bir bilgisayar programı sayesinde 2.86x1 0"3 s gibi çok küçük bir zaman aralığında incelendi. Bu küçük zaman aralıklarında yüksekliklerin, suyun ilerleme doğrultusunun ve su hızlarının zamanla değişimleri hesaplandıktan sonra su kütlesinden kaynaklanan gross ağırlık ve moment değişimleri hesaplandı. Bu hesaplar T.O.lC~130E-5'de C-130E uçağının gross ağırlık, moment ve ağırlık merkezinin değişimini veren EK-A'daki değerler ile karşılaştınlmıştır. Böylece, uçağm uzunlama kararlığı açısından ağırlık merkezinin limitler içersinde kalıp kalmadığı tesbit edilmiş ve tasarlanan modülünden alçak irtifada ve düşük hızlarda su bırakılması esnasında bu işlemin uçağın uzunlama kararlığına olumsuz etkisi olmadığı gösterilmiştir. Çalışma içersinde farklı hücum açılarında, tasarlanan modülün boşalma süreleri hesaplanmış ve 10 ile 15 derecelik hucüm açılarında boşalma süreleri incelendiğinde aralarında çok büyük farkın olmadığı dolayısıyla 10 derecelik hücum açısı ile su bırakmanın tercih edilmesinin uçuş emniyeti açısından da daha güvenli olacağı anlaşılmıştır.

Özet (Çeviri)

SUMMARY PRELIMINARY DESIGN OF C-130 CARGO PLANE AS A RETARD ANT MODULE The functional value of a tree is 2000 times higher than raw of the wood. The forests supplying the many needs of human are decreasing considerably that causes the destroying of the ecological equilibrium of the world. So developed countries are restricting the use of forests and pushing the construction of new ones. This satisfies controlled use of woods. Next to this precautions, another important thing which threatens the forests and mostly caused by carelessness of the mankind is forest fire. At he woodlands, the fire status changes according to weather conditions; such as increasing temperatures and wind which causes the igniting of woods. Therefore the number of forests around the world are extremely low because of the forest fires. Contraversialy to build up new forests takes quite a long time (60 or 70 years) next to big expenses and efforts. 12.500 hectare of the woodland are burning every year in our country. Comparing the forest fires in other countries like France, Italy, Spain, Greece, USA and Canada; the loss of forest is considerably low which is shown on Table 1. Table 1 Available forest areas and average burning area per year in different countries The beginning of the usage of the planes at forest fires meets in 1950's. Some military planes are converted to fire planes by the joint programme of“State of California”and“U.S. Forest Service”. Firstly, Stearman, PT-17 and N3N planes, which is used for second world war, have been modified [1]. So far many unused planes and helicopters have been changed to fire planes [2]. Water removing and performance capacities of this planes have been investigated [2, 3]. This investigation shows that some cargo planes are replaced with a modüler tanks instead of constant ones. Now four different module exist in the world. One of XIthem, MBB module have pressurezed unique tank having 12 tone water capacity and discharge channel [4]. Furthermore MAFFS module conssists of five pressurezed tanks which have also 12 tone water capacity and two discharge channels [5]. In both modules to disharge the water reserved in the tank, a pipe or disharge channel have been used. Contrary this, RADS module uses unpressurezed 12 tone unique tank and the disharge valve is at the bottom of the tank and goes directly to the atmposphere [6]. Besides, Russian made cargo planes having 42 tone water capacity includes two unpressurezed tanks and water is discharged from the cargo entrance. [7]. The techniques leaving the water to air depends on humidity obtained at ground and changes to the kind of fire between 0.5 and 3.5 liter per square area meter [8,9]. Another parameter effecting the humidity at ground is the discharging time of total water inside the tank. This phenomena is related to the hydraulics. The discharging water problems have been largely investigated by hydraulic engineers[10,12]. The purpose of this study is to search the possibility of the use the cargo planes as a fire planes without doing any modification in the plane named C-130E existing in Turkish Air Force. Since this cargo plane has the module 463L system, it has some advantages comparing to other cargo planes in Turkish Plane Invantory. And three tanks without pressurezing will be designed in this study. The reason why we choose unpressurezed tanks, it is simple and easily manufactured. The modüler system which enables to no modification in the cargo plane have some advantages and listed as follows. a) The plane enables to use for carrying cargo material and people in the season where very few forest fires exist. b) The module can be easily constructed on to plane with a short time aproximately 10-30 minutes. c) The adaption of the module to plane is satisfied with a minumum cost. d) The usage of the module is simple and can be assembled easily. e) There is no need to educate the person who will use the module After determining the geometrical values of the tank dimensions which is placed in cargo department, the formulation of moving water and centre of gravity calculation of the plane is done. It is assumed that the flow is incompressible and flow conditions are uniformly distibuted at each section. And average velocities at each section is calculated. The set of governing equations is based on the formulation DADA which represents uniformly distrubuted open system. The problem is divided in to two sections; tank and discharging pipe. The continuity and Bernoulli equations are used in the tank and momentum theorem is applied during the flow in pipes. Entrance, vane and friction loss coefficients existing in the Bernoulli equation is determined by assuming the turbulent flow. After the vane opened the flow going through pipe is investigated as well as all water discharged from the tank.. Because Xllthe flow in the pipe effects the stabilty of the plane. When the water reached local loss components such as entrance, vane and elbow, the loss coefficients of this components are included in the formulation and after this points it is expected the velocities in the piper will have sudden exchanges. As described above, the solution of this problem is obtained by using successive steps. This steps are shown below. I. Moving of the water from vane to elbow II. Moving of the water till end of the pipe III. Discharghing of the cylindrical tank IV. Discharging of the water till vane V. Discharging of the water till elbow VI. Discharging of the water till end of the pipe. The local loss coefficients are taken account in a different way at each step. Figure 1 The overwiew of the water tank I. Moving of the water from vane to elbow: x - + lB ; y>-r-Cosa veya h> - -Cosa ; The x and y velocity components at vane section during all of the water from the tank is discharging (only water in the pipes),can be written as follows. XIVv. = 2g (AP0 ly) + lBSina + {l\+ rjCosa + y -2“4 t/ ;r-r = v0=- Z-V^3 ^ ?v, = /(y) The moment equation obtained at any time in the pipe (9) (10) mB = h £T+[r+-\Sina 2nrfhlCosa+ x-hy/z^ 2nrx2\x--\Cosa (ll) The first part of this equation shows that the moment from exit of the tank to elbow entrance while second part shows the part from elbow to pipe exit IV.Discharging of the water till vane: 0 < xx H = - ; Y = ^~ ; X = -~- ; X\ = -L dT = -f==.;. A = 4^ ' 2r ' 2r ' \j2 ' \ JUfe n-r2 LT hj2 'M ym”W The numerical solution of this functions are by fourth order Runge-Kutta time stepping scheme. A computer code is written to evaulate the numerical algorithm by using dimensionless time interval AT=0.005 (At=0.005x(4r/g)1/2=2.86xl0"3s). Using this time step, the variations of heights and velocities with respect to time is calculated. Later the water moment and total weight resulted by its motion is determined. The calculated values are stored in a file and these are compared with the values given at Table B.2 which is located at addentum B in this thesis. This enables us to evaluate the limits showing the stability interval of the plane. During the calculation of total weight and total moment, constant weight and moment changes are assumed. The computer code as explained before enables to calculate the time variations of the velocity at free surface of the tank, velocity in the pipe, volume rate, the variation of XVIdistances with time, etc. The code also determines constant and variable moments and collects them. Finally the code finds the center of gravity of the plane. The solution obtained after this steps are not satisfactory, the main parameters are changed till desired solution is obtained. Thanks to this steps, the optimum solution is obtained which enables us to modify the cargo department of the plane without staying the stability limits of the plane. The steps during the optimum soltion are as follows. a) Taking the same distances between tanks for different (a) values, (a = b) b) Taking the different ratios of distances between the tanks while the first tank is constant, ( a/b ) c) Changing the place of second tank while the first and third tanks kept constant d) Changing the moment lenght while the distances between the tanks are constant e) Changing the attack angle of the plane (like 1,5, 10, 15 degree) The optimum solution is obtained by follwing the steps described above. But also a balance weight is placed to 250th station of the C-130E cargo plane to satisfy the design limits. 80000 90000 100000 110000 120000 130000 W (TOTAL WEIGHT) [Lb] Figure 2 Change of total weight with total moment for different b/a values at 3300 lb balance weight Here the stations where center of the gravities are applied for each tank is shown below. 1st line 2nd line XVllBefore a module which is designed according to second line by looking at Figure 2, different angles of attacks during the water discharging and flight has to be taken account. After that the final decision which tells us the cargo plane can be used or not is given. For this reason the module mentioned above, the change of center of gravities of C130-E cargo plane for different angles of attacks is shown in Figure 3. 80000 90000 100000 110000 120000 W (TOTAL WEIGHT) [Lb] Figure 3 Change of total weight with total moment for different angle of attacks at 3300 lb balance weight Here the stations where center of the gravities are applied for each tank is shown below. Angle of Attack a = \ 1st line a = 5 2nd line « = 10 3rd line a = 15 4*1^6 The tanks are replaced to C130-E cargo department to the stations 375, 475, 750 respectively. And the balance weight is replaced to 250th station. This shows that the cargo plane can do a good job to discharge all of the water during the constant velocity flight. When we want to discharge the water by applying angle of attack, increasing of this angle causes the CG comes to the front limit which can be seen easily in Figure 3. Increased angle of attack causes the increasing potantial enegy of the water then the discharging time reduces and humidity at ground increases. Closing to front limit and going out after 13 degree shows us the effect of the horizontal rudder reduces. The reason going out the limits at high angle of attacks is that the moment lenght reduces at different angles. But at rough grounds if we XVllldecide to do a dynamic throwing and during this throw if the angle of attack will be risen 15 degree, the balance weight should be taken 1 100 Lb. n 2 j ^60000000 H Z w O J 55000000 ?< H O H W (TOTAL WEIGHT) [Lb] Figure 3 Change of total weight with total moment for different angle of attacks at 1 100 lb balance weight Here the stations where center of the gravities are applied for each tank is shown below. Ljjinch] 370 370 370 370 Lifindi] 475 475 475 475 Lşjmçhl 700 700 700 700 Angle of Attack a = l - a = 5 a = 10 a = 15 - 1st line 2nd line 3rd line 4th line The negative effect of 15 degree angle of attack has been removed by reducing the balance weight nearly half. A module designed at different angles of attack at 1 100 Lb balance weight together with effect of center of gravity change is shown in Figure 4. The total time of discharging water and throwing time from the plane is shown in Table 2. The difference between this two time description shows the time passing till vane. Table 2 Total discharging times of the tanks XIXIf we evaluate the throwing times from the plane, nearly 8 seconds at a=l, 6 seconds at a=5, 5 seconds at a=10 and 4.5 seconds at a=15. This state increases the humidity rate at different kind of fires. If we look at Table 2 carefully, the humidity rate at a=10 is very close to the humidity rate at a=15. For this reason it is recommended not to fly and throw the water above 10 degree. As well as the succession of the modification of the cargo plane as a fire plane, it is also important which leaving technique of the water is used. Throwing the water not the target where the fire exist causes spending money and time. Therefore, before a technique is decided by the pilot, the land conditions, effect of fire ( such as heat, turbulance, not enough oxygen, damage of foreign material, limiting sight because of smoke) and the performance of the plane has to be evaluated throughly. Constant flight is recommended because of the formation of smoke and fire. This method is easy and satisfy hitting the mark. The disadvantage of this method is that the plane pass over the fire. If it is not possible to make a flight over a fire, a throwing technique while returning must be chosen. This method is difficult and the percentage of the hitting the mark is low. At dynamic throwing, the plane comes to 15 degree pitch. This technique is useful since it satisfy a strong humudity intensity at small lands. At constant pitch, the pitch angle is taken nearly 5 degree and the throwing process is done. While the plane does its job at this position (constant pitch), weak/middle humidity intensity is obtained at large lands. The humidity density forms a trace increasing from side to middle at every throw. The length, width and density of this trace depends on the throwing technique, throwing velocity, altitude and direction of wind and imntensity. Furthermore, in order to have more dense humidity at ground, the water should be released 30-75 meters from the ground. If the water released from this height, it is pulvarized and loses its effect to extinguish the fire. For this reason, the fire pilots has to make a close flight to the ground. But this is not easy, in order to have high humidity rate the pilot should fly 1.2-1.3 times higher than stall limit. Besides during the throwing water, sudden change of center of gravity of the plane and negative atmospheric conditions makes the plane not to have easy flight over a fire. This risks can be summarized as follows. Flying very close to ground, conditions of land, effect of fire (heat, turbulence, not enough oxygen, damage of foreign material), limiting sight because of smoke, modifying the cargo planes as a fire planes, changing the center of gravity during real flight and mistakes of pilots. Having an effective fire plane depends on designed module which changes the performance of the plane and knowledge of the pilot. XX

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