Speed Wind Tunnel Research Articles

A Tunnel Fire Detection Method Based on an Improved Dempster-Shafer Evidence Theory

Tunnel fires are generally detected using various sensors, including measuring temperature, CO concentration, and smoke concentration. To address the ambiguity and inconsistency in multi-sensor data, this paper proposes a tunnel fire detection method based on an improved Dempster-Shafer (DS) evidence theory for multi-sensor data fusion. To solve the problem of evidence conflict in the DS theory, a two-level multi-sensor data fusion framework is adopted. The first level of fusion involves feature fusion of the same type of sensor data, removing ambiguous data to obtain characteristic data, and calculating the basic probability assignment (BPA) function through the feature interval. The second-level fusion derives basic probability numbers from the BPA, calculates the degree of evidence conflict, normalizes the BPA to obtain the relative conflict degree, and optimizes the BPA using the trust coefficient. The classical DS evidence theory is then used to integrate and obtain the probability of tunnel fire occurrence. Different heat release rates, tunnel wind speeds, and fire locations are set, forming six fire scenarios. Sensor monitoring data under each simulation condition are extracted and fused using the improved DS evidence theory. The results show that there is a 67.5%, 83.5%, 76.8%, 83%, 79.6%, and 84.1% probability of detecting fire when it occurs, respectively, and identifies fire occurrence in approximately 2.4 s, an improvement from 64.7% to 70% over traditional methods. This demonstrates the feasibility and superiority of the proposed method, highlighting its significant importance in ensuring personnel safety.

Pengkondisi Sinyal RTD Presisi pada Terowongan Angin Indonesian Low-Speed Tunnel

The temperature of the Indonesian Low-Speed Tunnel (ILST) wind tunnel test section was measured using a Pt100-type Resistance Temperature Detector (RTD) sensor. With the upgrade of the Indonesian Low-Speed Tunnel - Data Acquisition and Reduction System (ILST-DARS) using Ethernet communication, an integrated RTD linearization circuit was designed with the Conditioning Unit (CU) Mk3 to replace the Newport 267B 16-bit parallel and DAS-Hub as the current RTD interface. In this research, the design of the signal conditioner uses the RTD_Linearization_v7.xls program from Texas Instruments, the LTspice simulator software, and the AMP01E precision instrumentation amplifier. Based on the calibration results in the range of 20 – 50 0C, this signal conditioner has an average deviation value of 0.38 0C (1.31%). In the wind tunnel speed variation testing with a range of 30 – 65 m/s, the RTD signal conditioner had an average deviation of 0.41 K (0.14%). The Repeatability Test procedure was carried out at a wind speed of 65 m/s with an angle of attack for the test model from -90 to 200 and data were collected 10 times at each angle. The average deviation of temperature against variations in the angle of attack of the test model in this procedure is 0.25 K (0.08%) and the average deviation of wind speed against variations in the angle of attack of the test model is 0.03 m/s (0.04%).

Icing wind tunnel measurements of supercooled large droplets using the 12 mm total water content cone of the Nevzorov probe

Abstract. Supercooled large droplet (SLD) icing can occur behind the protected surfaces of an aircraft and create severe aerodynamic disturbances, which represent a safety hazard for aviation. Liquid water content (LWC) measurements in icing conditions that contain SLDs require instruments that are able to sample unimodal and bimodal droplet size distributions with droplet diameters from 2 to 2000 µm. No standardized detection method exists for this task. A candidate instrument, which is currently used in icing wind tunnel (IWT) research, is the Nevzorov probe. In addition to the standard 8 mm total water content (TWC) collector cone, a novel instrument version also features a 12 mm diameter cone, which might be advantageous for collecting the large droplets characteristic of SLD conditions. In the scope of the two EU projects, SENSors and certifiable hybrid architectures for safer aviation in ICing Environment (SENS4ICE) and ICE GENESIS, we performed measurement campaigns in SLD icing conditions in IWTs in Germany, Austria and the USA. We obtained a comprehensive data set of measurements from the LWC sensor, the 8 mm cone sensor and the 12 mm cone sensor of the Nevzorov probe, and from the tunnel reference instrumentation. In combination with measurements of the particle size distribution, we experimentally derive a collision efficiency curve that is based on a suitable functional form for the new 12 mm cone for median volume diameters (MVDs) between 12 and 58 µm and wind tunnel speeds from 40 to 85 m s−1. Knowledge of this curve allows us to correct the LWC measurements of the 12 mm cone (LWC12) in particular for the inevitably high decrease in collision efficiency for small droplet diameters. In unimodal SLD conditions, with MVDs between 128 and 720 µm, LWC12 generally agrees within ±20 % with the tunnel LWC reference values from a WCM-2000 and an isokinetic probe. An increase in the difference between LWC12 and the WCM-2000 measurements at larger MVDs indicates better droplet collection properties of the 12 mm cone. Similarly, the favorable detector dimensions of the 12 mm cone explain a 7 % enhanced detection efficiency compared to the 8 mm cone; however this difference falls within the instrumental uncertainties. Data collected in various bimodal SLD conditions with MVDs between 16 and 534 µm and LWCs between 0.22 and 0.72 g m−3 also show an agreement within ±20 % between LWC12 and the tunnel LWC, which demonstrates the suitability of the Nevzorov sensor head with the 12 mm cone for measurements of LWC in Appendix O icing conditions.

Acoustic Lucky Imaging for microphone phased arrays

Acoustic imaging methods are used to detect and quantify aerodynamic noise sources in aeroacoustic experiments. In wind tunnels with an open jet test section the sound wave propagating from an aeroacoustic source to a microphone array is distorted by the shear layer in the propagation path. The velocity fluctuations caused by the turbulence in the shear layer continuously alter the propagation time between source and observer causing reduction of the coherence between two microphone signals. The reduction in coherence is stochastic and dependents on the relative position between source and microphone. This leads to blurred acoustic source images with reduced peak Sound Pressure Level. This paper presents the Acoustic Lucky Imaging methodology, based on a methodology in astronomy to correct for image distortion due to turbulence present in Earth’s atmosphere. Furthermore, a model for coherence loss is derived to explain the loss of acoustic image resolution and allow for a-priori estimates on acoustic image blurring. The methodology is applied to an acoustic data set obtained in the open jet of a large industrial wind tunnel. It is shown that the presented methodology can restore a loss of 6 dB peak Sound Pressure Level by 3 dB and increase the resolution of the acoustic image at 8 kHz, a wind tunnel speed of 34 m s−1, and a shear layer thickness of ∼1 m.

Validation of a Wind Tunnel Propeller Dynamometer for Group 2 Unmanned Aircraft

This paper presents an approach to validate a wind tunnel propeller dynamometer applicable to Group 2 unmanned aircraft. The intended use of such a dynamometer is to characterize propellers over a relevant range of sizes and operating conditions, under which such propellers are susceptible to low-Reynolds-number effects that can be challenging to experimentally detect in a wind tunnel. Even though uncertainty analysis may inspire confidence in dynamometer data, it is possible that a dynamometer design or experimental arrangement (e.g., configuration and instrumentation) is not able to detect significant propeller characteristics and may even impart artifacts in the results. The validation method proposed here compares analytical results from Blade Element Momentum Theory (BEMT) to experimental data to verify that a dynamometer captures basic propeller physics, as well as self-similar experimental results to verify that a dynamometer is able to resolve differences in propeller diameter and pitch. Two studies were conducted to verify that dynamometer experimental data match the performance predicted by BEMT. The first study considered three propellers with the same 18-inch (0.457 m) diameter and varied pitch from 10 to 14 inches (0.254 to 0.356 m). The second study held pitch constant and varied diameter from 14 to 18 inches (0.356 to 0.457 m). During testing, wind tunnel speeds ranged from 25 ft/s to 50 ft/s ( 7.62 to 15.24 m/s), and propeller rotational speeds varied from 1500 to 5500 revolutions per minute (RPM). Analytical results from a BEMT code were compared to available experimental data from previous work to show proper application of the code to predict performance. Dynamometer experimental results for thrust coefficient and propeller efficiency were then compared to BEMT results. Experimental results were consistent with the expected effect of varying pitch and diameter and were in close agreement with BEMT predictions, lending confidence that the dynamometer performed as expected and is dependable for future data collection efforts. The method used in this study is recommended for validating wind tunnel propeller dynamometers, especially for Group 2 unmanned aircraft, to ensure reliable performance data.

A Wind-Tunnel Assessment of Parameters That May Impact Spray Drift during UAV Pesticide Application

The objective of this study was to investigate the impact of varying wind speeds (1.5, 3.0, and 4.5 m/s), initial payload volumes (2 and 10 L), and nozzle droplet size characteristics (fine, medium, coarse) on drift during spray applications from an unmanned aerial vehicle (UAV) hovering freely in a wind tunnel. Along the length of the wind tunnel, glass slides were used to collect spray droplets at 14 points distributed in upwind, in-swath, and downwind distances. Analysis of the results showed that there are distinguishable shifts of up to 2 m in-swath as wind speed increases. Downwind of the UAV, a regression of the combined variables indicated that tunnel wind speed changed deposition the most overall, followed by nozzle/droplet size. Initial payload volume was less impactful. Overall, faster wind speeds, finer droplet sizes, and a heavier initial payload were associated with more drift on average. Wind directions and speeds were also measured on a finer scale of tunnel locations to record airflow pattern variability especially closer to the UAV. These findings may provide guidance to regulators and applicators to identify operating conditions for UAVs that limit off-target movement during applications.

Study on Structural Performance of Horizontal Axis Wind Turbine with Air Duct for Coal Mine

Considering the characteristics of narrow underground space and energy distribution, based on blade element momentum theory, Wilson optimization model and MATLAB programming calculation results, the torsion angle and chord length of wind turbine blade under the optimized conditions were obtained. Through coordinate transformation, the data were transformed into three-dimensional form. The three-dimensional model of the blade was constructed, and the horizontal axis wind turbine blade under the underground low wind speed environment was designed. The static structural analysis and modal analysis were carried out. Structural design, optimization calculation and aerodynamic analysis were carried out for three kinds of air ducts: external convex, internal concave and linear. The results show that the velocity distribution in the throat of linear air duct is relatively uniform and the growth rate is large, so it should be preferred. When the tunnel wind speed is 4.3 m/s and the rated speed is 224 rad/s, the maximum displacement of the blade is in the blade tip area and the maximum stress is at the blade root, which is not easy to resonate. The change rate of displacement, stress and strain of blade is positively correlated with speed. The energy of blade vibration is mainly concentrated in the swing vibration of the first and second modes. With the increase in vibration mode order, the amplitude and shape of the blade gradually transition to the coupling vibration of swing, swing and torsion. The stress and strain of the blade are lower than the allowable stress and strain of glass fiber reinforced plastics (FRP), and resonance is not easy to occur in the first two steps. The blade is generally safe and meets the design requirements.

Validity of bicycle mounted pitot tubes for real-time analysis of cyclists’ drag area for outdoor testing

Wind tunnel experiments were conducted to assess the validity of the outdoor use two commercially available bicycle-mounted static pitot tubes (BMPT), viz the Notio KonectTM [NK] and AeropodTM [AP]. Three different experiments were conducted by comparing wind tunnel speed to the measured wind speed by both BMPTs. The sensors are tested, firstly, in a wide range of wind speed (8 to 20 m/s); secondly in a range of yaw angles (0° to 20°) and, thirdly, for three riders’ positions. The results show that both sensors require calibration to ensure that the measured wind speed matches that of the wind tunnel. After calibration at 14 m/s, the measured wind speed of the NK is within 0.22% over the velocity range up to 20 m/s. Instead, an error is present in the wind speed measured by the AP, which grows with the velocity offset to that of the calibration and reaches -2.51% at 20 m/s. Further both the NK and AP did not measure the wind speed accurately when yaw angles were introduced, this resulted in an error of 5.8% for the AP and 3.9% with a yaw angle of 20degrees. Besides, rider position influences the measurement of the wind speed for both the NK and AP. We concluded that both the NK and the AP are not suitable for outdoor testing when crosswinds occur. Furthermore, before every position changes, it is necessary to do a calibration run to collect accurate results.

Wind Tunnel Wind Speed Control System Based on PLC Fuzzy Algorithm

With the deterioration of wind erosion, wind tunnel test has become an important method to study wind erosion. Wind speed control and data collection and processing are essential links in wind tunnel testing. The performance of wind speed control system directly affects the efficiency of wind tunnel test and the accuracy of test data. An incremental PLC fuzzy algorithm is used to realize the stable control of wind speed and improve the accuracy and reliability of the test, thus providing accurate and reliable experimental data for the study of wind speed control system in wind tunnel. And under the condition of large delay and instability, the PLC fuzzy algorithm can control the wind speed of wind tunnel more obviously. This paper takes the PLC fuzzy algorithm as the theoretical basis of the research, uses the fuzzy algorithm as the main research algorithm, integrates its important content to carry on the analysis research to the PLC fuzzy algorithm realization PID control to optimize the wind speed control system of the wind tunnel. Based on the classical wind tunnel wind speed control system, the PID control system is optimized and improved. PLC fuzzy algorithm can be regarded as a node sorting algorithm, so it can be used to construct wind tunnel wind speed control system. The experimental results show that this study has a better effect on the optimization design of wind speed control system by using PLC fuzzy algorithm to realize PID control.

Effect of Viscosity and Scale on De-/Anti-Icing Fluid Flow-Off

The flow-off process of de-/anti-icing fluid on a flat plate subjected to an accelerating airflow was studied both experimentally and using computational fluid dynamics (CFD) simulations. The effect of fluid viscosity on the fluid flow-off was examined experimentally in a wind tunnel. Two models with different chords (0.6 and 1.8 m) were experimented with. Type I fluid with different viscosities and Type IV fluids were tested. The CFD simulations considered only 0.6 m plate model. The effect of viscosity alteration causes an ensemble of consequences, which together caused a delay and decrease in the initial flow-off rate. These are the alterations in the wind tunnel speed for wave onset, in the wave speeds and in the flow-off process at the trailing edge. The CFD simulations supported most of the reasoning for fluid viscosity effects on fluid flow-off. However, the effect of viscosity was considerably exaggerated in simulations. Based on a simplified relation between air velocity and fluid flow-off rate, a scaling model for wind tunnel tests was created. A dimensionless parameter was found to scale the model dimensions and to consider the wind tunnel speed sequence.

Self-Induced Roll–Yaw Oscillations of an Aircraft Model in a Wind Tunnel

Wind tunnel oscillatory testing is a technique conventionally used for the measurement of dynamic aerodynamic loads on subscale aircraft models. Oscillatory testing is commonly used for identification of dynamic stability derivatives for flight mechanics models. Model oscillation is normally driven by a rig drive mechanism, or with the use of its control surfaces. This paper presents a new test technique in which self-induced coupled roll and yaw oscillations are driven purely by the aircraft’s natural modes of motion when constrained in translation and in pitch rotation. This method does not require external mechanisms to drive the motion, nor the use of aircraft control surface inputs to sustain the oscillation. Without these sources of error, it is potentially advantageous for identification of dynamic stability derivatives using parameter estimation techniques. The mechanics of and requirements for this self-induced oscillation are discussed. Computational simulation and dynamic wind tunnel tests of a subscale BAe Hawk model are used to demonstrate the self-induced roll–yaw oscillations and their results are compared. Effects of varying parameters such as wind tunnel speed and the addition of spring stiffness onto the aircraft rotation axes on the frequency and stability of the oscillation are investigated.

Modeling and Wind Flow Analysis of an Eiffel (Open) Type Sub-Sonic Wind Tunnel

Wind tunnel (WT) is a device that artificially produces airflow relative to a stationary body and measures aerodynamic force and pressure distribution, simulating the actual conditions with an important aspect of accurately feigning¬ the full complexity of fluid flow. The aim of the present study is to design the three dimensional geometry of a small, open-circuit (also known as Eiffel Type), and subsonic (low speed) wind tunnel (WT) capable of demonstrating or acting as a vital tool in aero-mechanics research. The project and fabrication itself, poses as an onerous task with the cynosure/central theme being the delineation/depiction of wind tunnel components such as Test Section, contraction cone, diffuser, drive system and settling chamber.

Real-World Vehicle Emission Rate of Particle Size Distributions Based on Measurement of Tunnel Flow Coefficient

This study aims to analyze the seasonal number concentrations corresponding to each particle size derived from the measurements of exhausts from approximately seven million vehicles on real-world using a pair of the scanning mobility particle sizer to determine the vehicle emission rate. The actual tunnel flow coefficient was investigated for car emission rate based on the measurements of individual physical parameters (i.e., cross section area and length of the tunnel, tunnel wind speed and traffic volume). The mode of particle diameter according to temperatures in respective seasons exhibited a high correlation together with rapid changes at temperature above the breakthrough point. The temperature acted as major cause of determination of final condensation diameter, which is also dependent on diverse environmental effects comprising particle number concentration. The traffic volume of ordinary cars increased by more than twice as much in the period of Asian New Year, the traffic volume of buses/RVs/trucks decreased by more than 25% during weekdays. As a result, the particle number concentration discharged from a unit vehicle was 6.96 × 1012 N/veh·km during weekdays, and the values of weekends appeared as 6.08 × 1012 N/veh·km. The overall averaged particle number concentration based on the actual seasonal road measurements shows 5.82 × 1012 N/veh·km.

Wind Tunnel Aerodynamic Study of a VTOL-UAV for Wide Range of Angles of Attack and Sideslip Angles

This article presents the design, manufacturing and wind tunnel tests conducted on a 1:4 scaled Vertical Take Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV). A brief description of the VTOL model, identifying characteristic dimensions, along with the manufacturing process for the scale model and the measurement equipment is presented. Results of the wind tunnel experiments are conducted varying both angle of attack and sideslip angle for a wide rage of the angles, and several wind tunnel speeds, thus allowing to characterize the full flight envelope for all three flight phases of the VTOL-UAV: axial, transition and cruise flight phases. A description of the wind tunnel measuring setup and the methodology used is presented, along with the subsequent analysis and corrections considered for all the data obtained, presenting a discussion about the results and its comparison with numerical analysis obtained with CFD studies. Finally, some conclusions and recommendations are made with the main objective of establishing a basis for future tests.

Influence of Ultrasonic Wind Sensor Position on Measurement Accuracy under Full-Scale Conditions.

A system designed for making field measurements of wind action on engineering structures is described. The system is composed of sonic anemometers, differential pressure sensors, a barometer, and a thermohygrometer. The focus of this study is to determine the indications of sonic anemometers; to accomplish this goal, wind tunnel tests were performed. The tests did not involve checking the accuracy of the devices themselves, but determining their indications under field measurement conditions where certain unavoidable errors resulting from their installation can appear. The anemometer measurement uncertainty with respect to wind speed and angle was determined. The devices were rotated in a horizontal plane and inclined against and with the mean wind speed direction in a wind tunnel. Different tunnel wind speeds were tested. The results indicate stable device readings at different horizontal plane positions at different wind speeds and a low sensitivity to changes in inclination against the inflow.

Experimental Study on Inflow Estimation Using Pressure Sensor Mounted on Spinner of Horizontal Axis Wind Turbine

The spinner anemometer can measure the wind velocity in front of rotor by ultrasonic wind sensors mounted on the spinner. To estimate the undisturbed wind speed in far upstream, the detail calibration is required. This study proposes the wind speed measurement by pressure sensors mounted on the spinner as a new technology. The inflow wind speed and the inflow angle are estimated with the pressure sensors mounted on a spinner. The performance of wind speed measurement is evaluated by wind tunnel measurements with a model HAWT. The measured wind speed by stagnation and static pressures show good agreements between reference wind tunnel speed and accuracy of measured wind speed was assessed.

Experimental Investigation of Vortex-Tube Streamwise-Vorticity Characteristics and Interaction Effects with a Finite-Aspect-Ratio Wing

An experimental study is conducted to analyze a streamwise-oriented vortex and investigate the unsteady interaction with a finite-aspect-ratio wing. A pressurized vortex tube is used to generate streamwise vortices in a wind tunnel and the resulting flow behavior is analyzed. The vortex tube, operated at various pressures, yields flows that evolve downstream under several freestream wind tunnel speeds. Flow measurements are performed using two- and three- dimensional (2D and 3D) particle image velocimetry to observe vortices and their freestream interactions from which velocity and vorticity data are comparatively analyzed. Results indicate that vortex velocity greater than freestream flow velocity is a primary factor in maintaining vortex structures further downstream, while increased supply pressure and reduced freestream velocity also reduce vortex dissipation rate. The generated streamwise-oriented vortex is also impinged on a finite-aspect-ratio airfoil wing with a cross-section of standard NACA0012 airfoil. The wingtip-aligned vortex is shown to investigate the interaction of the streamwise vortex and the wingtip vortex region. The results indicate that the vorticity at the high vortex-tube pressure has a significant effect on the boundary layer of airfoil.

Evaluation of the noise impact of flap-tip fences installed on laminar wings

The aeroacoustics of laminar wings and the noise abatement provided by flap-tip fences are studied experimentally on a scaled model installed in the closed test section of a subsonic wind tunnel. The activity has been developed under an international project funded by the European Union through the H2020 Framework Program. The model reproduces an innovative regional aircraft mounting aft-engines and adopting the Natural Laminar Flow concept. Both take-off and landing settings are tested for several combinations of wind tunnel speeds and angles of attack; these configurations being the most critical from the viewpoint of airframe noise generation. A baseline configuration without flap-tip fences is also tested for a comparative study. Noise sources are identified by measuring pressure fluctuations through a phased microphone array. Data are processed using both Conventional Beamforming and CLEAN-SC algorithms to retrieve the sound source maps and the integrated spectra over the areas of interest. Directivity effects are investigated as well by moving the microphone array in different axial positions corresponding to different aircraft polar directivity angles. The wind tunnel data are eventually extrapolated to full scale and projected to flight condition allowing the analysis of the results in terms of Effective Perceived Noise Level (EPNL). Tests provided an extensive characterization of the acoustic behavior of the analyzed model demonstrating the capability of measurements carried out in a non-anechoic environment, to provide reliable data. The longitudinal traversing of the microphones array allowed us to compute, even though qualitatively, the EPNL and thus demonstrated the feasibility of a procedure that can be a reference for the design of future aeroacoustic tests. The effectiveness of the flap-tip fences to successfully reduce the flap side-edge noise has been definitely verified both through the analysis of the acoustic maps retrieved from the beamforming investigation and by the estimation of the overall variation of the EPNL with respect to a baseline reference configuration without low-noise devices.

차량 배출량 산정을 위한 터널유동계수 연구

PM2.5 is well known to be greatly affected by the vehicle emissions, which can affect climate change and the human body. Recently, the number of vehicles has been increasing continuously in Korea. However, there are still very few studies on the relationships between chemical components actually emitted from vehicles. Therefore, this study aims to analyze the actual tunnel flow coefficient for car emission rate based on the measurements of individual physical parameters (e.g., tunnel wind speed and traffic volume). As a result, the average tunnel flow coefficient were shown as 187, 335, 294, and 219 ㎥/vehicle·km in Summer, Fall, Winter, and Spring, respectively. The overall average of tunnel flow coefficient was determined as 259 ㎥/vehicle·km for vehicle emission rate. The emission factors can apply to investigate the both seasonal and chemical unit of vehicle emissions in real atmosphere, which can contribute to calculate the total road emissions related to their environmental effects.

Experimental Investigation of Propeller Induced Flow on Flying Wing Micro Aerial Vehicle for Improved 6DOF Modeling

In this research effect of propeller induced flow on aerodynamic characteristics of low aspect ratio flying wing micro aerial vehicle has been investigated experimentally in subsonic wind tunnel. Left turning tendencies of right-handed propellers have been discussed in literature, but not much work has been done to quantify them. In this research, we have quantified these tendencies as a change in aerodynamic coefficient with a change in advance ratio at a longitudinal trim angle of attack using subsonic wind tunnel. For experimental testing, three fixed pitch propeller diameters (5 inch, 6 inch and 7 inch), three propeller rotational speeds (7800, 10800 and 12300 RPMs) and three wind tunnel speeds (10, 15 and 20 m/s) have been considered to form up 27 advance ratios. Additionally, wind tunnel tests of 9 wind mill cases were conducted and considered as baseline. Experimental uncertainty assessment for measurement of forces and moments was carried out before conduct of wind tunnel tests. Large variation in lift, drag, yawing moment and rolling moment was captured at low advance ratios, which indicated their significance at high propeller rotational speeds and large propeller diameters. Side force and pitching moment did not reflect any significant change. L/D at trim point was found a nonlinear function of propeller diameter to wingspan ratio D/b, and propeller rotational speed. Rate and control derivatives were obtained using unsteady vortex lattice method with propeller induced flow effect modeled by Helical Vortex Modeling approach. In this research, we have proposed improved 6-DOF equations of motion, with a contribution of advance ratio J. It is concluded, that propeller induced flow effects have a significant contribution in flight dynamic modeling for vehicles with large propeller diameter to wingspan ratio, D/b of 22% or more.