A STUDY OF AIRCRAFTS TO BE OPERATED IN HIGH ALTITUDES OF NEPAL Manish Neupane, Nirajan Adhikari, Prashant Raj Neupane Department Of Mechanical Engineering, IOE, Pulchowk Campus Abstract This report presents a short study of the available aircrafts and the best aircraft that is suitable to employ in high altitude regions of Nepal. Presently only Dornier and Twinotter aircrafts are in operation. This study deals with the comparison of various aircrafts and chooses the most suitable one to be brought into operation. The basis for the selection of aircraft is based on the topography, condition of the airports and the weather conditions at the high altitude regions of the country. In Nepal air transportation has to be developed in a better way for high altitudes because in such areas, the road transportation is not possible due to the land structure. Also it is economically not feasible to develop the means of road transportation too. Hence air transportation proves to be a better option for the means of transport. Places like in Mustang, Lukla where four wheeled vehicles have difficulty in finding destination, aircrafts can show the way to a pretty good solution. Hence air transportation needs to be developed in such places. However, all aircrafts that are available in the country may not prove to be the good performer in such altitudes. Hence this report has somehow tried to cover up the problems of the airports at such high altitudes and give a better choice of the aircrafts that can be beneficial in operation, performance and cost to be operated in these places of the country. Keywords: turboprops, monoplane, de-icing, commuter aircraft Preprint submitted to IOE Journal August 26, 2014 1. Introduction High altitude aircrafts are those aircrafts which can be operated in the high altitude regions. In case of Nepal, the high altitude refers to the altitude above 2400m. All the high ltitude airports in Nepal are of STOL (Short Take Off And Landing) type and all these airports permit only VFR traffic. Most of the airports are seasonal. Also there are no refuelling activities in any of the airports situated at the high altitude region of the country. 2. Requirements For High Altitude Aircrafts • Take-Off Weight should be as less as possible • The engine should be able to operate in cold regions. Also at high altitude, the engine should be able to reduce emissions • High Wing Configuration results in preventing the wing to touch the runways and it is the most necessary requisite in cast of Nepal where the airport runways are unpaved • In case of Nepal, aircraft to be operated at high altitude should have high rate of climb to be able to take off in short runways. 2 3. Airport Networks In Nepal Nepal has a large airport network, made up of a total of 48 airports. They are distributed all over the country, although in the eastern and western regions they are more assembled, especially because of the complicated terrain which makes difficult by other means of transport to reach them. 4. Airports In High Altitude Regions In high altitude regions of Nepal i.e. in the Himalaya region, the airports are located in the following places: 1. Dhorpatan: Aerodrome flight information service provided by the assistants. Grass runway with length of 366m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 2728m. 2. Dolpa: Aerodrome flight information service provided by the assistants. Grass Runway with length of 457m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 2500m. 3. Jomsom: Aerodrome flight information service provided by the air traffic controllers. Runway paved with length of 610m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 2682m. 4. Jumla: Aerodrome flight information service provided by air traffic controllers and assistants. Runway paved with length of 670m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 2591m. 5. Lukla: Aerodrome flight information service provided by the air traffic controllers. Runway paved with length of 488m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 2591m. 6. Langtang: Aerodrome flight information service provided but unmanned due no flight movements. Grass Runway with length of 421m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 3658m. 7. Mugu: Aerodrome flight information service provided by the assistants. Grass Runway, airport accessible by foot trail and horse track only. 3 8. Manang: Aerodrome flight information service provided by the assistants. Grass Runway with length of 610m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 3353m. 9. Syangboche: Aerodrome flight information service provided but unmanned due no flight movements. Grass Runway with length of 405m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 3748m. 10. Simikot: Aerodrome flight information service provided by the assistants. Grass Runway with length of 549m and width 18m, airport accessible by foot trail and horse track only. Airport situated at the height of 2818m. 11. Taplejung: Aerodrome flight information service provided by the assistants. Grass/gravel runway with length of 594m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 2377m. trail and horse track only. Airport situated at the height of 2377m. 12. Phaplu: Aerodrome flight information service provided by the assistants. Grass Runway with length of 670m and width 30m, airport accessible by foot trail and horse track only. Airport situated at the height of 2431m. 4 5. Possible Aircrafts In Nepal 5.1. Beechcraft 1900D Fig1: Beechcraft 1900D The Beechcraft 1900D is a regional airliner seating up to 19 passengers and powered by two PT6A-67D Pratt and Whitney Canada turboprops, each with a 1,279 engine shaft horsepower (SHP) rating. The aircraft has a 17,120 lb. maximum takeoff weight (MTOW) and has a range of 680 nautical miles (NM) with a full passenger load, while cruising at 25,000 ft. in ISA conditions at High Speed Power. However, flights are more typically 220 to 260 NM in distance and on average 60 minutes in duration. Beechcraft 1900D under operational improvements can reduce fuel consumptions and associated fuel emissions. Thus in high altitude airports where there is unavailability of refueling, Beechcraft 1900D can be the best alternative. Also it is capable of operating out of short runways together with its high speed and increased load capacity, hence in high altitude airports like in Bajhang, Dolpa, Jomsom, Lukla with short runways, it can give the best performance. 5 5.2. Antonov An-28 Fig2: Antonov An-28 The airplane features a high-wing monoplane configuration powered with two turboprop engines Pratt and Whitney Canada PT6A-65B turboprops, 960 shaft horse power (720 kW) each, with wing bracing strut, non-retractable landing gear, two fins are arranged at stabilizer ends. This aircraft can be the best choice for high altitude airports where there is dry, precipitation and snow covered runways. Suitable for the places like in Lukla, Jomsom, this aircraft has take-off and landing at maximum wind speed of 24m/s while the maximum wind speed in Nepal is 13.5m/s. 6 5.3. Dornier 228-212 Fig3: Dornier 228-212 Dornier 228-212 is a multipurpose aircraft well-reputed for its reliability, versatility, economy and ruggedness. According to requirements it can transport up to 19 passengers but it is also suited to carry cargo or operate in a variety of patrol, scientific and support missions. As a true and robust STOL (short take-off and landing) aircraft it is capable to start and land on unpaved runways. Hence it is quite popular and extensively used aircrafts in high altitudes of Nepal. Dornier 228-212 employs Garrett TPE 331-10 engines. It provides an exceptional horse power response and is best in fuel-class economy. Also these engines provide quick throttle response for shorter take-offs, good power-to-weight ratio and long maintenance intervals. 7 5.4. TwinOtter DHC-6 Fig4: Twinotter DHC-6 The hardy Canadian-built DHC-6 Twin Otter is designed for flying in the challenging environment of countries like Nepal with rough and short airfields carved out of mountain sides. According to pilots, the plane handles well, needs minimal maintenance, is built to last, and can take a lot of punishment which must be why Twin Otters are affectionately called Land Rovers with wings. This aircraft’s fixed tricycle undercarriage, STOL abilities and high rate of climb have made it a successful cargo, regional passenger and high altitude operational airliner in context of Nepal. 8 5.5. L-410 UVP-E Fig5: TurboLet L-410 UVP-E The L-410 UVP-E is an unpressurized all-metal high-wing commuter aircraft, with Avia V 510 five-blade propellers. It is equipped with a retractable undercarriage. The aircraft uses two hydraulic circuits: main and emergency. The main electrical system operates with 28V DC. The de-icing system is leading edge pneumatic deicers and electrical heating of propellers, cockpit windshields and pitot-static system heads. Maximum take-off weight of the L-410 UVP-E is 6400 kg with the possibility of an increase to 6600 kg for the E9 and E20 variants, seating capacity 17 to 19. Cruise speed is 170 KIAS, maximum range about 770 nautical miles (1,430 km). The airplane is certified for IFR operation, CAT I ILS approach, and flights in icing conditions. The present of de-icing equipment has made it able to give a well-proven performance in high altitude mountain regions of Nepal like in Jiri, Lukla, Syangboche, Mustang, etc. 9 Table 1: Comparison Of Different Aircrafts • The maximum take-off weight refers to the weight the aircraft at which the pilot is able to take off due to structural and other limits. Maximum take-off weight is independent of altitude, temperature or the length of runway however it depends on the condition of runway. In 10 context of Nepal where there is grassy runway or unpaved runways or runways with snow, there is more rolling friction causing the airplane to accelerate more slowly. Hence aircrafts with maximum take-off weight should be avoided in airports with such grassy and unpaved runways to prevent the accidents from occurring. • Power plant refers to the aircraft engines that provides power to the engine. The Pratt and Whitney PT6A engine has been found to be the most efficient one in case of aircrafts. The PT6A engine is capable of providing good operating conditions in cold regions. Also new aerodynamic and material technologies have enabled the PT6A engine to gain more power without significantly increasing in size. Other innovations have reduced emissions, increased maintenance intervals and further enhanced ease of operation with the introduction of digital electronic control to small gas turbine engines. • It is necessary to take rate of climb of aircraft into account because in airports with short runways, aircrafts with better rate of climb would prove to be fruitful. Considering above points, Twinotter DHC-6 Series is more suitable it most of the high altitude regions of Nepal. However due to lack of de-icing equipment like in Let-410 UVPE, this aircraft faces difficulty in operating at high altitudes like in Dolpa, Lukla and Jomsom where there is possibility of ice formation due to high altitudes and also there is snowfall most of the times a year. 11 Table 2: A list of aircrafts that are presently in use in Nepal 12 Table 3: Aircraft Accidents In Nepal 13 6. Summary Air transportation needs to be developed in Nepal. It has been seen that Nepal serves a major problem in air-transport especially in the high altitudes where transportation is possible only by the means of air. People living in those regions should also access development in all the sectors of the country. Most domestic airports of Nepal are below standards, the aviation sector in Nepal has a long way to go and we can expect at least some decades to pass before a properly managed and well-facilitated airways service comes into effect in Nepal. It is also seen that the seasonal variation affects the transportation in a huge manner. This implies the people in such areas have access to the center of the country only for some periods throughout the year. This report has however tried to compare the various possible aircrafts that can be operated in Nepal for mitigating the problems of air-transportation in the high altitudes. The topography and climate of Nepal has also been one of the major problem in frequent accidents that has occurred which has been tabulated above. Hence this report somewhat provides some knowledge regarding the aircrafts which can be operated as per the prevailing topography and climatic conditions of the country. References [1] www.aviation-safety.net/database/country/country.php?id=9N [2] NATIONAL AIRPORTS PLAN Current Situation and Diagnostic DRAFT, SEPTEMBER 2012, Civil Aviation Authority of Nepal [3] en.wikipedia.org [4] SPECIFIC AIRWORTHINESS SPECIFICATION for Antonov An-28, 2008, European Aviation Safety Agency [5] Annual Report 2010, Nepal Airlines [6] www.traveldesknepal.com/domestic/domestic-airline-nepal [7] www.airlines-inform.com/commercial-aircraft/An-28.html 14