Short Takeoff And Landing Research Articles

Techniques of Fluidic Thrust Vectoring in Jet Engine Nozzles: A Review

Thrust vectoring innovations are demonstrated ideas that improve the projection of aerospace power with enhanced maneuverability, control effectiveness, survivability, performance, and stealth. Thrust vector control systems following a variety of concepts have been considered for modern aircraft and missiles to enhance their military performance. Short Take-off and Landing (STOL) and control effectiveness at lower aircraft speeds can be achieved by employing Fluidic Thrust Vectoring Control (FTVC). This paper summarizes a range of ideas for FTVC that have been designed and tested both computationally and experimentally to determine the thrust vectoring performance of supersonic propulsion system nozzles. The conventional method of thrust vectoring involves mechanical means to deflect the direction of flow of the exhaust gases, whereas the most recent method involves fluidic-based thrust vectoring techniques. Fluid-based thrust vectoring has the advantages of simplicity and low weight over mechanical-based thrust vectoring, which has complex geometry and adds extra weight to the aircraft. The fluidic vectoring control nozzles are divided into seven categories: shock vector, bypass shock vector, counterflow, co-flow, throat skewing, dual throat, and bypass dual throat nozzle control. This paper provides a summary of each fluidic thrust vectoring technique with its characteristics, design, classification, and different operational criteria developed to date and compares the intrinsic characteristics of each technique. Based on the present literature, it is concluded that among all the fluidic control techniques, the bypass dual-throat nozzle control can achieve better thrust vectoring performance with large vector angles and low thrust loss.

Performance analysis and flow mechanism of channel wing considering propeller slipstream

The development of the Urban Air Mobility concept has proposed stringent requirements for the fixed-wing vehicle’s Short/Vertical Take-Off and Landing (S/VTOL) performance. With its lift-enhancing impact, the channel wing, can improve aircraft low-speed performance and Short Take-Off and Landing (STOL) capability. It is critical for the performance analysis and flow mechanism study of a channel wing that considers the influence of propeller slipstream to guide the design of S/VTOL aircraft. The law and mechanism for the effect of the enclosing angle of the arc wing, the phase angle of the propeller, the tip clearance, the rotational speed and the chordwise position of the propeller on the channel wing are explored utilizing the quasi-steady multi reference frame method. A channel wing with a larger enclosing angle has a better ability to enhance lift and reduce drag using propeller slipstream. The effect of propeller phase angle on channel wing aerodynamic forces is periodic and weak. Increasing propeller rotational speed is helpful to enhance lift and resist flow separation for channel wing. It can reduce drag for tractor configuration but increase drag for pusher configuration. However, the nose-down pitching moment of a channel wing will grow dramatically, making longitudinal trimming in aircraft layout design challenging.

Technology readiness assessment and performance forecast on a 19 seats E-STOL EIS 2032

The European Flightpath 2050 connectivity goal, to enable European people to reach any desired destination, door to door, in 4 hours, increases the interest in Small Air Transportation (SAT), to enhance global connectivity.The connectivity goal should come alongside with environmental target: FlightPath 2050 aims to reduce by 75% C02 emissions and by 90% NOx emissions. Within the EU Clean Sky 2 framework, a future affordable and green commuter belonging to EASA CS 23 has been designed, collecting all the novel technologies developed in the CleanSky 2 frame [1].This work presents a further step on the 19-seater development: a technology readiness and assessment to electrify the short take-off and landing (STOL) aircraft is presented, considering the expected entry into service (EIS) in 2032, rationalizing the design choices considered as most suitable to obtain a hybrid electric E-STOL and the consequent gains in terms of emission reduction on a typical mission range.

Numerical investigation of short takeoff and landing exhaust system using bypass dual throat nozzle

Bypass dual throat nozzle (BDTN) is a new kind of fluidic thrust vectoring nozzle. Based on the excellent performance of BDTN, a short takeoff and landing (STOL) exhaust system as a substitute for the complex tilt rotor is investigated. The STOL exhaust system consists of a downward-bending transition part and a BDTN part. As the thrust vectoring angle reaches more than 35° in a separate BDTN, the transition part enables the actual thrust vectoring angle to reach a maximum of over 70° in STOL mode. In cruise mode, thrust vectoring effect of BDTN compensates the inherent deflection angle of the transition part, the thrust vectoring angle reaches nearly 0°. The transition part is designed with three area-laws and two centerline-laws. Results indicate that centerline-law II leads to less total pressure distortion than centreline-law I. Area-law B is the best area-law since it leads to the moderate change rate of cross-section, it makes the total pressure distribution at the outlet of the transition part more uniform. Then, the integrated STOL exhaust system is investigated, the performances are presented. The thrust direction can be changed by controlling two valves in BDTN, the redundant tilting mechanical structure of traditional tilt rotors is replaced by this way, the structural weight is reduced, and flight safety improves. Finally, the best configuration is selected according to the results of the numerical investigation, and the thrust coefficient is more than 0.920 in STOL and cruise mode. The thrust vectoring angle is -73.37° in STOL mode, and it's -1.81° in cruise mode. The design satisfies the basic requirements for STOL and cruising flight. Hence, the STOL exhaust system is worthy of further study.

Strategi Pemilihan Pesawat Angkut Militer Produksi PT. Dirgantara Indonesia Untuk Mendukung Industri Pertahanan Dalam Negeri

Indonesian Navy flights as an integral part of the SSAT have several functions, one of which is to provide rapid logistical support. Based on considerations of function and mobilization capabilities, medium-sized military transport aircraft are the main choice in providing rapid logistical support. The advantages of this function and mobility also make military transport aircraft capable of carrying out additional tasks assigned to their guiding squadron, namely the 600 Air Wing Squadron. The additional tasks are Search and Rescue (SAR), Air Medical Evacuation (EMU) and VIP Flights. Currently, there are 11 elements of the NC212-200 aircraft owned by Puspenerbal, with a description of 7 active elements, 4 disposal processes. In 2017, Puspenerbal received the Beechcraft King Air 350i light transport aircraft, but several operational requirements were not met to carry out the main function as an element of fast logistics support provider, so this element was prioritized to carry out additional functions such as VIP flights. The results of the analysis using the Analytic Hierarchy Process (AHP) method with the help of the Expert Choice 11 Application show the weight of the criteria for selecting medium military transport aircraft, namely Navigation and Communication Equipment 46.4%, Short Take-off and Landing (STOL) Ability 31.7 %, Transportability 15.3%, and Flying Ability 6.7% with an Inconsistency value of 0.07. This shows that the calculation of the correspondent is still within the inconsistency threshold, which cannot be more than 0.1. While the order of priority for the alternative types of medium military transport aircraft from high to low is the CN 295 type 80.5% and the Alenia C27J Spartan type 19.5%. Based on this value, it can be seen that the CN 295 Medium Military Transport Aircraft is the right alternative to be chosen.

Custer Channel Wings for Short Takeoff and Landing of Unmanned Aircraft

The channel wing is a lift-enhancement concept pioneered by Willard Ray Custer in the late 1940s in an effort to provide a fixed-wing aircraft with short takeoff and landing (STOL) capabilities. This paper experimentally investigates the possibility of using Custer channel wings for slow flight and STOL of small (under 35 kg) fixed-wing unmanned aerial vehicles. The Custer unmanned aircraft developed at the University of Southampton is introduced in this paper, including details of the installed channel wings and other systems necessary for slow-flight operation. Results from wind-tunnel tests are presented, showing a significant lift increase due to the channel wings in the range of airspeeds of interest. Flight tests are carried out to demonstrate the slow flight and STOL capabilities of the aircraft, showing superior stall characteristics and a two-thirds reduction of the runway length required when using the channel wings. Flight-test comparisons to a conventional wing–propeller configuration show superior slow-flight performance and 7–9% lower cruise speed of the channel-wing aircraft.

Takeoff Performance Analysis of a Light Amphibious Airplane

The performance analysis of a light amphibious airplane during takeoff from the water surface has been presented in this paper. The airplane is one of the light amphibious airplane series built in Thailand with a bi-wing configuration. The conceptual design aims to build a short takeoff and landing (STOL) amphibious airplane. The mathematical model cooperated with several complicated parameters is presented and solved by MATLAB. The water-drag resistance of the airplane is estimated from typical seaplane hull NASA technical information, which enhances the correctness of the model at takeoff configuration. The simulation reveals that the seaplane can successfully takeoff from calm water in 24.5 seconds at the speed of 54 KCAS and an approximate distance of 890 feet with the AOA of 10 degrees.

Effects of nozzle geometry and active blowing on lift enhancement for upper surface blowing configuration

Upper Surface Blowing (USB) has been regarded as a promising lift enhancement technique for short-take-off and landing (STOL) applications. The present study conducted numerical investigations to further explore the potential capability of USB technique by passive and active flow control strategies. Computations were accomplished by a Reynolds-averaged Navier-Stokes solver enclosed by the two-equation k-ω shear stress transport turbulence model. The propulsion effect of the up-mounted engine was represented by the Turbine Powered Simulator (TPS). Results show that aerodynamic lift of using USB system is significantly enhanced due to the attenuation of plume edge roll-up vortex which is beneficial to the Coanda effect. Varying nozzle geometries can augment lift by alleviating the three-dimensional edge effect and thus delaying the rollup of plume with a thinner jet sheet. Compared to the passive flow control method by nozzle geometry modification, active constant blowing flow control technique shows a more promising potential for lift enhancement for USB powered system. Within the test cases, a 50% lift increment can be achieved by using constant blowing on the USB system.

Innovation design analysis of the optimal aerodynamic adaptive smart structures for disk-body solar Hybrid Electric aircraft and airship concepts

The innovation integrated design analysis of the concept of finding any optimal aerodynamic structure with adaptive intelligent systems as a means of changing facility of the geometric shape of the surface by integrating the disc wing-body of a solar Hybrid Electrical aircraft (HEA) and an airship to reduce weight, power and fuel sources is very relevant today and focused on the international research EC programs of future green ecology air transportation. The universal digital method for optimizing the CAD aircraft design is presented which is focused on achieving the goal of minimum weight-drag-frontal stability of the layout from the virtual center of mass allows us to get the layout of the aircraft from the conditions of reducing the time of full flight operation of E-Mobility and low cost for priority with realize a short take-off and landing (STOL) with high angle of the flight path and compact infrastructural restrictions in the terminal slot configurations of modern urban airport infrastructure and achieving zero toxic & noise regulation by IATA/ICAO. The joint results of EC international R&D collaboration to accelerate the synergy effect of new aircraft concepts.

Numerical position optimization of an over-the-wing mounted engine installation

The Collaborative Research Center 880 is investigating different technologies and configurative variants for the purpose of short take-off and landing (STOL) capabilities, ranging from high-lift systems with Coandӑ flaps to unusual but potentially more efficient engine arrangements. The present study focuses on the reference configuration 3 (REF3). This configuration is characterized by an UHBR over-the-wing nacelle (OWN) located above the wing trailing edge. Starting from the wing/body configuration the installation effects of the OWN were investigated. A fully automatized surrogate based optimization was used to evaluate the impact of an engine position variation in vertical and horizontal direction to observe fundamental aerodynamic interactions between wing and OWN in cruise flight conditions. Due to the presence of OWN and pylon, a distinct disturbance on the wing upper surface could be observed leading to significant interference effects. Nevertheless, the overall cruise drag of REF3 could be improved by 37 drag counts or nearly 11% due to the position optimization.

Mass, primary energy, and cost: the impact of optimization objectives on the initial sizing of hybrid-electric general aviation aircraft

For short take-off and landing (STOL) aircraft, a parallel hybrid-electric propulsion system potentially offers superior performance compared to a conventional propulsion system, because the short-take-off power requirement is much higher than the cruise power requirement. This power-matching problem can be solved with a balanced hybrid propulsion system. However, there is a trade-off between wing loading, power loading, the level of hybridization, as well as range and take-off distance. An optimization method can vary design variables in such a way that a minimum of a particular objective is attained. In this paper, a comparison between the optimization results for minimum mass, minimum consumed primary energy, and minimum cost is conducted. A new initial sizing algorithm for general aviation aircraft with hybrid-electric propulsion systems is applied. This initial sizing methodology covers point performance, mission performance analysis, the weight estimation process, and cost estimation. The methodology is applied to the design of a STOL general aviation aircraft, intended for on-demand air mobility operations. The aircraft is sized to carry eight passengers over a distance of 500 km, while able to take off and land from short airstrips. Results indicate that parallel hybrid-electric propulsion systems must be considered for future STOL aircraft.

Sizing Method and Sensitivity Analysis for Distributed Electric Propulsion Aircraft

Compared with conventional unmanned aerial vehicles (UAVs), the propulsion systems of vertical takeoff and landing (VTOL) and short takeoff and landing (STOL) UAVs with distributed electric propulsion (DEP) are more complex. This paper analyzes the impact of VTOL and STOL requirements and of the DEP system on the takeoff mass and flight performance of UAVs. Analytical models are developed to investigate these properties of DEP VTOL and STOL UAVs. The results of the initial sizing were compared with the parameters of a DEP STOL demonstrator that was actually built. A sensitivity analysis of the design parameters of the DEP STOL UAV was carried out based on the analytical models, and the impact of key design parameters on the takeoff mass and endurance was calculated and discussed. The results show that the propulsion system mass and cable mass of the demonstrator account for 27 and 7% of the takeoff mass, respectively, which are significantly higher than those of conventional UAVs. The key design parameters are the battery energy density, mass-specific power of the motor, lift-to-drag ratio, endurance, and electric-ducted fan efficiency, of which battery energy density has reached a technological limit. The sensitivity of takeoff mass and endurance to the key design parameters varies with the level of technology available, indicating that some currently impractical configurations may perform well at the next level of technology.

Propeller Selection by Means of Pareto-Optimal Sets Applied to Flight Performance

Selection process of the propeller for short take-off and landing (STOL) category aircraft is described. The aim is to achieve the highest possible performance with fixed propeller, i.e., high maximal horizontal and cruise speed, short take-off and high rate of climb. These requirements are contradictory and so Pareto sets were used in order to find the optimal propeller. The method is applied to a family of geometrically similar propellers that are suitable for 73.5 kW (100 hp) piston engine designed for ultralight category aircraft with maximal take-off weight of 472.5 kg. The propellers have from two to eight blades, blade angle settings from 15° to 40° and diameter from 1.1 m to 2.65 m. Pareto frontier is designed for each pair of flight conditions, and the optimal propeller is selected according to these results. For comparison, the optimal propeller selection from the propeller family by means of a standard single-optimal process based on the speed power coefficient cs is also used. Use of Pareto sets leads to considerable performance increase for the set of contradictory requirements. Therefore, high performance for a low price for the given aircraft can be achieved. The described method can be used for propeller optimization in similar cases.

Feasibility Study of a Multi-Purpose Aircraft Concept with a Leading-Edge Embedded Cross-Flow Fan

The research presented focuses on investigating the use of Cross-Flow Fan (CFF) as a high-lift device for a Short Take-off and Landing (STOL) aircraft. The wing-embedded fan performance analysis is mostly addressed from an aerodynamic perspective and focuses on using such Active Flow Control (AFC) technology in the conceptual aircraft design process. In particular, the design trade study of an aircraft featuring the fan as a high-lift device applied to a conceptual design of a medium-range multi-purpose aircraft is performed. A sensitivity analysis is employed to investigate the impact of the technology on the aircraft weight, aerodynamics, stability and control, and fight performance. The aircraft design modifications are introduced to maximize the aircraft mission performance given the fan specifications and constraints. Results indicate a reduction of the take-of field length by 18% with the payload penalty of 14%. The aircraft ferry range is also decreased by 7% compared to the baseline aircraft design. The scaling analysis of the aircraft concept is performed to determine the potential market for such technology. The results show that a light General Aviation (GA) airplane or a medium-large size Unmanned Aerial Vehicle (UAV) could benefit more from the wing-embedded CFF compared to more heavy airplanes.

INCREASE OF CONTROL SURFACES EFFICIENCY OF A SUBSONIC AIRCRAFT OF SHORT TAKEOFF AND LANDING

A steady growth of aviation transportation (4-5% per year) causes excessive saturation at numerous major airports. As a result, many flights are delayed. One of the ways to deal with this growing problem is to transfer regional propeller aircraft maintenance to suburban airports. It will require both a modernization of local airports and the design of a new generation of regional aircraft with short takeoff and landing (STOL). The aircraft ability to operate from short runways depends not only on wing unit loading and on high-lift capacities but also it is determined by the control surfaces efficiency. The latter often becomes one of the major reasons for limitation of the amount of lift used in STOL configuration. Thus, the successful application of high-lift devices stipulates the necessity for both the efficiency increasing of existing aircraft control surfaces and the development of some alternative form of lateral control not requiring a significant wingspan proportion. The forms of a lateral control, this article considers, include the interceptor, drooped ailerons, ailerons fitted with mini-flap and one of the alternative forms which uses differential flap section deflection. Several mini-flaps with a various chord are also considered to increase the available rudder yawing moment. The efficiency of the above-mentioned control surfaces has been studied in TsAGI low speed wind tunnel on a model of a twin-engine light aircraft with an enhanced level of lifting capacity on take-off and landing configurations. The tests were conducted at a Reynolds number of 1.0×10 6 and Mach number of 0.15.

Propeller Selection by Means of Pareto Optimal Sets Applied to Flight Performance

Selection process of the propeller for short take-off and landing (STOL) category aircraft is described. The aim is to achieve the highest possible performance with fixed propeller. The requirements are following: high maximal horizontal and cruise speeds, short take-off, high rate of climb and fixed propeller. These requirements are contradictory and so Pareto sets were used in order to find the optimal propeller. The method is applied for a family of geometrically similar propellers that are suitable for 73.5 kW (100 hp) piston engine designed for ultralight category aircraft with maximal take-off weight 472.5 kg. The propellers have from two to eight blades, blade angle settings from 15° to 40° and diameter from 1.1m to 2.65m. Pareto frontier is designed for each couple of parameters and the optimal propeller is selected according to these results. For comparison, the optimal propeller selection from the propeller family by means of a standard single-optimal process based on the speed power coefficient cs is also used. Using of Pareto sets leads to considerable performance increase for the set of contradictory requirements. So, high performance power system with low price (fixed pitch propeller) for STOL category aircraft can be designed. The described method can be used for the propeller optimization in similar cases.

Hybrid Buoyant Aircraft: Future STOL Aircraft for Interconnectivity of the Malaysian Islands

Hybrid buoyant aircraft are new to the arena of air travel. They have the potential to boost the industry by leveraging new emerging lighter-than-air (LTA) and heavier-than-air (HTA) technologies. Hybrid buoyant aircraft are possible substitutes for jet and turbo-propeller aircraft currently utilized in aviation, and this manuscript is a country-specific (Malaysia) analysis to determine their potential market, assessing the tourism, business, agricultural, and airport transfer needs of such vehicles. A political, economic, social, and technological factors (PEST) analysis was also conducted to determine the impact of PEST parameters on the development of buoyant aircraft and to assess all existing problems of short takeoff and landing (STOL) aircraft. Hybrid buoyant aircraft will not only result in reduction of transportation costs, but will also improve the economic conditions of the region. New airworthiness regulations can lead to greater levels of competition in the development of hybrid buoyant aircraft.

Numerical Simulation of Powered High-Lift Flow

To achieve short-take-off-and-landing (STOL) performance, numerous airframe/propulsion integration (API) technologies have been developed for military and commercial transports. Powered lift technology refers to a concept of utilizing the propulsion exhaust flows to increase lift through an increase in wing circulation []. Over the past seventy years, various concepts have been explored to accomplish this goal. From the point of view of technical characteristics, powered lift concepts can be sorted into three groups: a circulation control wing, blown flaps, and jet wing. Most of other concepts are slight deviations of these three.

Modeling and Approximation of STOL Aircraft Longitudinal Aerodynamic Characteristics

Flight dynamics deals principally with the natural response of the aircraft to longitudinal perturbations that typically consist of two underdamped oscillatory modes having rather different time scales. One of the modes has a relatively short period and is usually quite heavily damped. This is called the short period mode. The other mode has a much longer period and is rather lightly damped. This is called the phugoid mode. The required degree of dynamic stability is specified by the time it takes the motion to damp to half of its initial amplitude. The dynamic characteristics of an airplane is important in assessing its handling or flying qualities and for designing autopilots. This paper investigates the dynamic characteristics of short take off and landing (STOL) airplanes employing root locus technique and state space approach. The nonlinear differential equation of motion of an airplane developed from Newton’s second law of motion was linearized using the small disturbance theory. Different phugoid approximations for longitudinal modes were developed and compared with the exact solution formulated using statistical software. Further research work about active control technology to improve aerodynamic efficiency which results in potential fuel savings should be carried out.

Design and Computational Studies on Plain Flaps

In this paper, Computational fluid Dynamics (CFD) is used to predict accurately the incremental lift due to use of passive lift -augmentation device 'Flap'. In a 2-D wing, lift at a given angle of attack can be increased by increasing camber. In aircraft design, values of Maximum Lift Coefficient (CL max ) are used to determine the take-off and landing distances, on the assumption of usage of some type of lift- enhancing device. Passive lift enhancement device, such as a trailing edge plain flap, is relevant to most of the aircraft designs except Short Take Off and Landing (STOL) However, accurate analytical solutions to complex non linear equations of aerodynamics are a far cry and one has to depend largely on support from experimental results. It is here that CFD analysis makes the task simpler. Computational study of a typical plain flap with NACA (National Advisory Committee for Aeronautics) 0012 airfoil is taken up to predict its influence on incrementing the lift during critical phases of flight at low speed. The flow analysis is done using CFD tool FLUENT 6.3 along with GAMBIT 2.2. Effect of Plain flaps on basic aerodynamic parameters such as CP, CL , CD are studied by analyzing the flow over an airfoil with plain flap. The results obtained from the analysis are compared with analytical solutions to establish the influence and relevance of flap as an effective high lift device.