Conceptual Design of 13-Seater STOVL Aircraft for Rural Air Mobility in Nepal VAAYU YAAN

Abstract

At Present, in Aviation industry there is a strong and rapid growing interest in the development of Urban/Rural Air Mobility (U/RAM) networks, which are aerial transportation systems in, and around major metropolitan areas and rural hilly region where less possibilities of operating big passenger aircraft to cover short distance in challenging geographical location. STOVL capabilities for fixed-wing aircraft is one application of this technology. For rural passenger transport missions in remote area of Nepal, it is risky and difficult during landing in Hilly and Himalayan region due to geographic land structure and slope runway to operate big size passenger or cargo aircraft. Hence, the sole aim of this paper is to present the practical alternative to these problems in the early days of rural air transportation in aviation industries in Nepal. Here, we discuss about the air accidents that occurred in Nepali sky and along with their reason so we decided to try our level best to come up with solution i.e., our proposed design VAAYU YAAN. This paper clarifies the main motive of deploying VAAYU YAAN over conventional aircrafts. It is designed in a such a way that it can solve the problem of fatal accidents in aerial transportation in Hilly and Himalayan region faced as result of topographical difficulties, slope and small runway issues along with air traffic problems and helps in enhancing the public transportation all over the country for regional mobility due to short takeoff and vertical landing capacity. As a result of this feature, due to less risk in mobilization of aerial vehicle in Hilly and Himalayan places, people across the country will be connected and benefited.

Introduction

I. INTRODUCTION

A short take-off and vertical landing aircraft (STOVL) is a fixed wing aircraft that can take-off from a short runway and land vertically. Recent years have seen an increase in interest in the development of Urban/ Rural air mobility (U/RAM) networks, which would provide public access to aerial transportation within metropolitan areas and rural places people living in Hilly and Himalayan region of Nepal where no possibilities of operating large passenger aircraft.

Current and future urban and regional and rural air mobility may be implemented using short take-off and vertical landing (STOVL) vehicles.

STOVL aircraft can take off from very short runways (often made of dirt or grass) and land vertically in any topographical region. Reports show that STOLs aircraft also fails during landing in some cases in hilly region due to land structure and many lives has been lost due to this problem. Thus, we are focusing on rural air mobility, but it is not only connecting people from rural area to city it is about connecting rural agricultural centres, commercial centres and remote mines with the world using the best available commercial technologies which allows agricultural hubs to export their fruit, vegetables, flowers, fresh meat or fish to the major markets and helps in Air cargo services to major metropolitan cities. This technology helps in city aerial mobilization and can be used as best mode of transportation in future.

II. LITERATURE REVIEW

In order to get an answer to our question, Why Nepali Sky is considered as the most risky and unsafe sky in the World? And why it is still in backlist by European Union Aviation safety standard? So, we started a survey regarding Nepali sky, Land Topography, Runway details, Region of Operation, Accidental spots, and Aircraft operating in that fleet. In preliminary conclusion, we came to know due to geographical difficulties and lack of situational awareness Nepal is facing great problems in Rural Air transportation. Due to operation of aircraft with unmatchable topographical design the most of the accident was occurred in many rural places of Nepal. Hence, here we came up with the design of VAAYU YAAN to solve the problems faced by Nepali Sky and Aviation sector. Here below we present a list of Air Accidents which we have collected during our survey.

TABLE 1. List of Air Accident in Nepal

NOTE:

P.O.B = Passenger On-Board

N.O.F = Number Of-Fatalities

III. OUR DESIGN PHILOSOPHY

A. Stovl Aircraft — Characteristics Required

The paramount characteristics of STOVL aircraft are as follows:

1. Aircraft must have capability to takeoff from short & rough runway and can land vertically in any place irrespective of its geographical topography
2. Aircraft should offer minimum passenger capacity of 13+2 (crew) and cargo with rectangular cabin for maximum usable space.
3. A high wing configuration with small wing area and high lift coefficient is required to make easy landing and takeoff at very low speed.
4. Pilot visibility is an important element of aircraft design, so there should be proper pilot visibility.

B. Proposed Design OF VAAYU YAAN

C. Design Methodology

The workflow developed for the conceptual design of VAAYUYAAN is shown in Figure 2. It takes all the main features of the aircraft design (e.g., aerodynamics, propulsion system, mission performance, weight estimation) into account. Accordingly, four main blocks can be identified:

1. Aircraft’s Requirements & Technological Assumptions: with regards to proposed design here we will discuss specifications of VAAYUYAAN.
2. Aerodynamics: here we discuss about detail aerodynamic design of VAAYUYAAN along with aerofoil selection and wing structure.
3. Propulsion System: here we discuss about the VAAYUYAAN propulsion system and power generation and thrust supplied by aircraft engine.
4. Mission Performance:  with reference of flight mechanics equation here we judge the VAAYUYAAN performance
5. Weight Estimation: here we carried out the weight estimation of VAAYUYAAN by breaking down weight configuration of the aircraft into sub-topics i.e., empty weight, payload weight, crew weight, fuel weight etc.

a. Aircraftss Requirements and Technological Assumptions:  The initiative of the aircraft design is the introduction of the aircraft requirements (e.g., range, cruise speed, payload and runway requirements). In the context of the Urban and Rural Air Mobility (U/RAM), the scenario is currently open-ended, as the U/RAM potential market is still under research and development. Hence, at least in the conceptual design phase, Aircraft Requirements are more related to the passenger STOVL configuration and to its potential performance. The base aircraft requirements are listed in Table 2;

                                                              Table 2. Parameters for Designed Model (VAAYU YAAN)

b. Aerodynamics: Our Aerodynamic assumption for VAAYUYAAN is based on wind tunnel data and aerodynamic results obtained from research paper and industrial practiced airfoil selection in aerospace industries which incorporates the flight range condition for proposed STOVL aircraft (i.e., take-off, transition and hover) including ground effects. Here we have proposed to use supercritical wing this is because its structure is atypical, consisting of a box formed from different integrally-milled alloy panels for different components of the wing. The main advantage of deploying this wing over conventional one includes reduction in weight (approximately 14%), elimination of rivets and reducing the workloads of aircraft manufacturers.  The Aerodynamics module judges aircraft drag polar, which is necessary to properly evaluate the overall aircraft performance, both in terms of power required and in mission profile performance. Here, we proposed semi-monocoque fuselage since it can withstand considerable damage because of its longerons that absorbs the bending stresses. The total drags induced in VAAYUYAAN, is calculated by using the software ANSYS Fluent.

• Estimation of CL MAX of Airplane: For VAAYU YAAN, we are using different airfoil at different position of the wing. The VAAY  YAAN has a geometrically twisted wing in which NACA 23012 airfoil is using at the tip of the wing and NACA23015 is using at the root of the wing. In both of the airfoil the maximum chamber is placed at 15% of the chord length and the thickness are 12% and 15% respectively. Using of these different thicknesses of airfoil produce structural strength to the wing and aerodynamically the NACA 23015 stalls at a small angle of attack than NACA 23012 airfoil. From the numerical analysis of both of these airfoils using ANSYS workbench we get the ???????????????????? as 1.5 for NACA 23015 and 1.4 for NACA 23012.

c. Propulsion System: Here as per the proposed design, the VAAYUYAAN is supposed to be powered by two Garrett TPE-331-5-252D engines each driving a four bladed Hartzell HC-B4TN-5ML/LT 10574 constant speed, fully feathering, reversible pitch propellers of dia. 2.69 m & rpm 1591. Nominal engine power is 715 SHP (flat rated at ISA +18 deg C, sea level). The engine is manufactured under license from Honeywell at HAL (Hindustan Aeronautics Limited) Engine Division and is featured by

• Propeller Control system.
• Anti-icing and Foreign Object damage resistance.
• Reverse thrust.
• Negative torque sensing.
• Low emission, low noise.

e. Weight Estimation: Weight is the force generated by the gravitational attraction of the earth on the airplane. Each part of the aircraft has a unique weight and mass, and for some problems it is important to know the distribution. But for total aircraft manoeuvring, we only need to be concerned with the total weight and the location of the centre of gravity.

IV. ACKNOWLEDGMENT

Project VAAYUYAAN became a reality with the kind support and help of many individuals, we are deeply grateful to our advisor, Dr. P. Karunakaran for his guidance, patience and support. We are much obliged to our Head of the Department Dr. S.P. Venkatesan and faculty members of Department of Aeronautical Engineering, Excel Engineering College for their enlightening suggestions and encouragements which motivated us throughout our project. We owe many thanks to our classmate and all of our colleagues. They always helped us in exchanging ideas regarding research and gave the enjoyable environment for our project VAAYUYAAN. We are most grateful to our parents; they have always loved us and supported our every choice which helped us in successful execution of project VAAYUYAAN.

Conclusion

The objective of this research report was to propose and design an Aircraft (VAAYU YAAN) that can meet the needs of Nepali sky at present scenario to avoid the future air accidents. The following are the key conclusions and findings from this study which we have obtained from our survey: 1) The most important conclusion from this project in our opinion (Author’s opinion) is that there has been frequent air accident in Nepali Sky and the main reason behind is ramp land structure and small runway. Wind is almost always a cause factor while flying over a mountainous terrain. Dependent upon the direction and speed of the wind, its interaction with the terrain can lead to updrafts, downdrafts and turbulence which may exceeds aircraft limitations or performance capability and leads to horrible accidents as a result of collision with high hills and mountains. 2) Keeping the above conclusions in consideration, we made an approach to put all our efforts and try our level best for solving this matter of Aviation concern of Nepalese Aviation Industry with our impeccable design of VAAYU YAAN. VAAYU YAAN is not just a conceptual design, it is pie in sky, hope of flame for Nepali people which may drastically change the scope of aerial transportation in Hilly and Himalayan region of Nepal. 3) Although, the VAAYU YAAN is specially designed for passenger and cargo mode but it is also designed to be used to promote Nepalese Mountain Tourism through Mountain sightseeing of Highest Peaks of the world out of which, majority are situated in Nepal (i.e., 8 out 14 highest peaks having height more than 8000 meters). Along with this, it may be also used for different roles such as Search and Rescue, Aerial Survey, Arms and Ammunitions transport, Casualties Evacuation etc., in upcoming future.

References

[1] John. D Anderson, Fundamentals of Aerodynamics, Fifth Edition, McGraw Hill Education (India) Private Limited. [2] John. D Anderson, Aircraft Performance and Design, 2010 Edition, Tata McGraw Hill Education Private Limited. [3] Daniel P. Raymer, Aircraft Design: A Conceptual Approach, Sixth Edition, AIAA Education Series. [4] www.airfoiltools.com [5] https://ijisrt.com/numerical-analysis-of-aerodynamic-performance-characteristics-of-naca-2312-and-naca-2412 [6] Raymer D., AIRCRAFT DESIGN: A Conceptual Approach, Third Edition, American Institute of Aeronautics and Astronautics, Washington, D.C. [7] https://www.1001crash.com/transport-page-plane_database-lg-2-plane-accident-country-nepal-aircraft-history.html [8] https://timesofindia.indiatimes.com/world/south-asia/major-plane-crashes-in-nepal-a-timeline/articleshow/10115233.cms [9] STOVL Aircraft Simulation for Integrated Flight and Propulsion Controls Research, NASA [10] https://en.wikipedia.org/wiki/Category:Aviation_accidents_and_incidents_in_Nepal [11] Jackson, Paul. Jane\'s All the World\'s Aircraft: 2010-2011. Coulsdon: Jane\'s, 2010. Print. [12] McCrea, M., O’Brimski, F., Strickland, P., and Raymer, D., Breaking the Paradigms: Catapulting STOVL, International Powered Lift Conference, Oct. 2000 [13] Large-Scale Instabilities in a STOVL Upwash Fountain, A.J. Saddington,, K. Knowles, in Engineering Turbulence Modelling and Experiments 6, 2005,Science Direct [14] https://caanepal.gov.np/safety-management-division/Accidents/Incidents-CAAN

Copyright

Copyright © 2022 Pradeep Kandel, Rakesh Kumar Shah, Dr. Karunakaran P, Sumit Pandit, Ajay Kumar Yadav. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.