Analysis of the Hulls Floater Distance in the Manoeuvrability of the N219 Floatplane: An Experimental Approach in the Open Water Test

. Floatplanes necessitate the utilization of floaters that possess the capacity to facilitate aircraft manoeuvring activities, hence safeguarding passengers against potential hazards associated with sea-based crashes. This paper is to analyse the impact of the manoeuvrability of the N219 floatplane on multiple variables, such as the distance between catamaran hulls, trim angle, and cruising speed. The selection of the open-free-running test method for the testing model is based on its advantages, including its costeffectiveness, simplicity, and demonstrated accuracy in yielding reliable outcomes. The floatplane model is outfitted with a remote-control system that is connected through a wireless communication system. The trajectory of the floatplane model is documented using a Global Positioning System (GPS) device, and the collected data is subsequently transformed into a trajectory line for the purpose of enabling analysis. The turning model test is used to find the best hull distance variation out of three options considering the parameters of tactical diameter (TD), advance (A), transfer (T), and radius (R). The tests are undertaken for three different combinations of trim angle and speed. The results show that S/L 0.5 is the ideal distances between the floater hulls while a trim angle of 0°, and a Froude number of 0.064. The condition defines the ratio of parameters and the length of the ship (Lpp), which includes the values of TD/Lpp, A/Lpp, T/Lpp, and R/Lpp as 2.49, 1.59, 1.60, and 1.26, respectively


Introduction
Floatplanes confront unique difficulties when navigating on the water's surface [1].Operating a floatplane entail utilizing aerodynamic and hydrodynamic controls to alter the aircraft's direction or position.Precision in maneuverability is crucial as it can impact the stability, equilibrium, and safety of the aircraft [2] [3].Given the scarcity of research on this subject, it is imperative to examine the maneuvers of floatplanes, particularly when they are taxiing on water.Regard the floater body as a dual hull, like a catamaran vessel.Multiple factors must be examined while studying the hydrodynamic capabilities of floatplanes, such as the primary dimensions and configuration of the floats, the spacing between catamaranstyle floats, trim, steering, and speed.Many studies have been done on the floatplane's hydrodynamic performance.These have looked at things like how the trim angle affects the porpoising phenomenon [4], the magnitude of resistance [5] at high speeds, and how landing symmetrically affects the bottom of the hull [6].
This report presents a maneuvering investigation of the same floater design as a continuation of the hydrodynamic performance study.The ship maneuver analysis typically employs three methods: numerical analysis, empirical equations, and model testing.The open water test technique was selected for model testing due to its compatibility with current facilities and its track record of effective and precise maneuver testing [7].However, the researcher is concerned about the methodology earlier researchers suggested for gathering ship maneuvering trajectory data, such as image processing [8] and use of the Global Positioning System (GPS) [9], particularly in the context of open water tests.Every technique possesses its own set of benefits and drawbacks.Precise test findings are crucial, along with ensuring the correctness of instrumentation, calibration, and model testing.
This paper investigates the navigational capabilities of the floatplane, which employs floaters as flotation devices for seaplane operations in water.The primary aim is to examine the impact of mobility on the N219 floatplane across multiple variables, such as the separation distance of the catamaran's hull, trim angle, and cruising speed.The test method employed, specifically the unrestricted open test, is selected for its benefits in terms of affordability, straightforwardness, and precision in generating dependable results.The trajectory data of the floatplane model is captured using a Global Positioning System (GPS) device and subsequently processed for the purpose of analysis.The turning test maneuver is conducted to determine the optimal variation in hull distance (S/L) from the three offered options.

Methodology
The experimental framework is specifically developed to thoroughly investigate the maneuverability of the N219 floatplane, with a special emphasis on examining the impact of changes in floater hull distance, trim angle, and speed.Figure 1 illustrates the sequence of maneuver testing for the floatplane model, comprising three distinct phases: preparation, testing, and data processing.The experimental preparation entailed the creation of a 3D design and the construction of scaled-down models of the floater and fuselage, representing the N219 floatplane, at a ratio of 1:9.6.The model is fitted with a propulsion system located on both wings and the rudder systems on both floaters, together with a remote-control system for maneuvering the model on an open pond.The Ublox M-7N GPS sensor is equipped to accurately track and record the trajectory of a floatplane during the turning test.The process involves utilizing GPS devices to collect maneuver trajectory data, which can then be analyzed in detail after the experiment.
In second stage, the maneuver testing is performed in open pools, where three conditions are combined including hull distance, trims, and speeds.The testing process includes three repetitions of each test case to assess the reliability of the results.The GPS data is recorded online through wireless communication system.The final step involves processing maneuver data on the mission planner to analyze maneuver parameters, including tactical diameter (TD), advance (Ad), transfer (T), and radius (R).The ideal configurations obtained are validated and refined by iterative testing, considering calm sea and calm wind circumstances.

Turning circle experiment :
With 3 variations of hull distance and 3 variations of speed and 2 trim conditon

Result and discussion :
Discussion of the maneuvering result comparisons

Design and building the model:
The floatplane is built with 1:9.6 scale of factor, and printed with 3D printing machine

Rudder and propulsion system:
The propulsion of the floatplane is located in wings of fuselage and the rudder is located in afterbody of floaters Sensor : GPS and Gyro sensors are use to record maneuvering trajectory and motion

Data acquisition:
The output of this experiment are maneuvering trajector (STD, TD, Ad, Tr, R)

Modelling
The floatplane model utilized is a prototype of the N-219 aircraft manufactured by PT.DI, currently in the design development phase of the N219A seaplane model.The aircraft has the same dimensions as the N219 type, with the addition of a floater device positioned beneath the fuselage.The floater model is developed with consideration of the floatplane's displacement capacity when operating on the water's surface.Therefore, it is crucial to focus on displacement, construction weight, and the shape of the floater hull.Size chart and threedimensional (3D) model design of the floatplane is depicted in Table 1 and Figures 2-3.

Instruments on the Floatplane
There are a lot of devices that are necessary in order to make the operation of the test model in the pool easier while testing maneuvers are being performed in open pools.The several types of instrument equipment are employed, including the steering system, the remotecontrol system, and the propulsion system.All of the components that are shown in Figure 4 require a source of direct current (DC) power, which is most commonly a battery, in order to get the necessary electrical power.The weight of the floatplane model including all equipment and instrument is quantified to arrange the placement of the all components so that the model in equilibrium position or even keel, as shown in Figure 4.
In Figure 5, there is a ducted brushless motor that has a voltage capability of 4500 kV and a current need of 2A.Additionally, the motor has a diameter of 70 mm and a total of 5 propellers.The number of motors that are utilized in this investigation is two, and the motors are positioned on the left and right wings of the floatplane according to their respective positions.A cylinder plug connects this brushless ducted motor to the ESC.This connection is necessary for the process of drawing power from the battery and controlling the rotation of the motor.According to the specifications shown in Figure 6, the steering wheel has a span size of 75 mm, a chord size of 40 mm, and a total area of 132.72 cm 2 .A servo is a device that is beneficial for controlling and moving serrations with the assistance of a DC motor that is included within it.The output of the servo is expressed as the rotation of the servo arm, and the range of the rotating angle is from 0 to 360 degrees.The operation of the steering system on the floater unquestionably plays a significant part in the process of turning maneuvers.This is due to the fact that the form and size of rudder, and the rotating angle of the rudder have a significant impact on the maneuverability of the floatplane.

Turning Maneuver Test
The pool location for the turning maneuver test which is selected considering the appropriate open pool size for maneuver scenarios of the floatplane, is the pool 8 ITS as shown in Figure 7(c) and 8.The several scenarios of testing are carried out within speed and distance of floater hull as shown in Table 2.There are three variations of speed and floater distance, which is combined into nine cases of model test.Additional two cases are considered to two conditions of trim including trim by bow, and by stern for one configuration of floater distance and speed.The total case study is eleven as assigned a numbering code for example a case 301 denote a S/L distance of 0.3 and Fr 0.064 (0.315 m/s).The maneuver testing is described in several steps consisting of, first, before testing conducted do measuring wind speed, water temperature, and mapping of testing area, as well as cleaning surface water as shown in Fig. 7.The testing is only run in a quite wind speed about maximum 0.3 m/s to avoid the wind disturbance and to keep a calm water.However, the testing results can confirm whether the wind give disturbance during the test.The calibration of the instrumentation devices the second step.This includes the DC motor voltage settings that are required to create the model speed as well as the servo rotation settings that are required for the steering angle.It is necessary for both of these devices to be able to be operated precisely from a distance via a remote-control system.Calibration is also performed on the GPS data gathering equipment in order to ensure that the output that is produced is accurately read in accordance with the precise position of the model movement.As shown in Figure 8, the speed test is conducted with a straight trajectory, whereas the steering test is conducted with a circular trajectory.Third, the maneuvering test is carried out in accordance with the case scenarios that are presented in Table 2, and a video camera is used to capture each test case.The model enters the testing area in a straight line, and then the rudder is rotated at an angle of 35 degrees so that it goes towards the portside to form a circular trajectory.After three spins, the model is steered out of the testing area with the intention of completing the test.The GPS system is responsible for recording the trajectory data that it obtains and then transferring it to the computer-PC online over wireless communication means.

Maneuver Data Retrieval
The gathering of maneuver trajectory data involves the utilization of several auxiliary pieces of equipment, such as the procedure of reading and storing the trajectory data.The GPS U-Blox M-7n is used to obtain the precise coordinates of the model.The APM 2.8 at the Mini-PC analyzes these coordinates.The resulting data is then communicated wirelessly or across a router to TeamViewer for recording the test results.The flowchart in Figure 9 illustrates the many processes involved in the data retrieval process.The data format ".kmz" may be converted to ".kml" using the "Google Earth" program.Subsequently, transform the data expressed in latitude and longitude degrees into distance units (meters) by multiplying the data by the conversion factor of 111319.888meters per degree.Figure 12   The figures also indicate the values for tactical diameter (TD), transfer (T), advance (A), and radius (R), along with their corresponding parameter values.However, it can also be observed that each maneuver curve exhibits variations in the magnitudes of TD, A, T, and R with respect to their corresponding X and Y-axis values on the curve.The test results on all scenarios shown in Table 2 are recapitulated in Table 3 by presenting non-professional values in the form of ratios between TD, A, T, and T with floater length, Lpp, as well as IMO standards in evaluating the ship's ability to maneuver.IMO RESOLUTION MSC.137(76) explains that the maneuverability limit of a ship is that the TD should not be more than 5 times the ship's length, Lpp, and the advanced (A) is not more than 4.5 times the ship's length.According to Table 3, the optimal S/L spacing configuration is 0.5.This is determined by the smallest TD/Lpp ratio value compared to S/L spacings of 0.4 and 0.3 when the model test is performed at the same speed.Table 4 presents the relationship between the S/L distance and the floatplane's manoeuvrability in a more systematic way.Case 503 (S/L 0.5) exhibits a 5.16% improvement over Case 303 (S/L 0.4).This difference in percentage grows as the Froude number value falls.Specifically, in Cases 502 and 501, the improvement is 9.47% and 11.25%, respectively, compared to Cases 302 and 301, respectively.Comparing the S/L distance of 0.5 with the S/L distance of 0.4, it is found that the former has a superior TD/LPP ability by 1.76% in the instance of Fr 0.267.The disparity increases significantly to 4.79% and 5.09% as the Froude number value lowers to 0.160 and 0.064, respectively.
A description of the extent of the influence that speed has on the maneuverability of floatplanes may be found in Table 5.When the Froude number value is reduced to 0.160 and 0.064, respectively, the manoeuvrability increases by 4.39% and 7.64%, respectively, in the case of S/L 0.3 and Fr 0.267.It is also observed that the same thing occurs in the  5.Additional examination of the manoeuvrability of the floatplane as a result of the state of the hull trim is presented in Table 5.This research reveals that trim by bow contributes favourably, up to 1.88%, whereas trim by stern condition contributes negatively, up to 1.07%.The pictures in Figures 15-18 show, one after the other, how the floater hull spacing parameter changes the speeds of all four parameters (TD, A, T, of course).Generally speaking, the Froude number value grows with varying degrees of decline, and the gradient of the linear graph demonstrates that all parameter values fall linearly as the Froude number value increases.In Figure 19, it is demonstrated that the influence of floater hull trim is not particularly substantial.In spite of this, the state of the hull trim near the stern is still taken into consideration whenever the floatplane is manoeuvring.Generally speaking, the findings of the tests explain that the S/L distance of 0.5 on the floater hull has a positive influence on manoeuvrability.This indicates that the effect of flow interaction between the two hulls is quite influential.The more flow contact that takes place, which is shown by the decreasing distance between the hulls, the more detrimental the effect is to the manoeuvrability of the vessel.

Conclusion
A floatplane maneuvering test is done by utilizing the open-free-running test method to examine the impact of the spacing between two floater hulls.The study looks at how well nine different mixes of hull spacing (S/L) and speed work in four types of maneuverability: tactical diameter (TD), advanced (A), transfer (T), and radius turn (R).Overall, the test findings validate that S/L 0.5 offers optimal maneuverability across all Froude number scenarios.The fluid interaction between the two hulls of the floater affects its maneuverability.Specifically, as the distance between the hulls is narrower, the maneuverability decreases.This decrease might be as much as 11.25% at the same speed, Fr 0.064.Furthermore, the augmentation in maneuvering speed exacerbates maneuverability, reaching a maximum deterioration of 13.57% when the S/L distance is 0.5.The impact of adjusting the trim of the floater hull on the agility of a floatplane is rather small.Specifically, adjusting the trim towards the stern negatively affects mobility by a mere 1%, whereas adjusting the trim towards the bow positively affects maneuverability by up to 1.8%.

Figures 10 and 11
Figures 10 and 11  show the measured data from the GPS, GYR, and Mini PC devices, as well as the router used to send data from the model to the computer PC located by the pool.The mission planning application retrieves and produces location coordinates in the form of latitude and longitude axes during the maneuvering test.The program generates telemetry logs in the ".tlog" format, as seen in Figure12(a).In addition, the ".tlog" file format is transformed into a ".kmz" file format through the utilization of the mission planner (b) displays the plotted circular trajectory form based on the obtained conversion data findings.The length of the tactical diameter, transfer, advance, and radius may be estimated by analyzing the trajectory plotted in unit length coordinates.

Table . 3
. Recapitulation of the maneuvering test results

Table . 4
. Percentage differences of S/L in the maneuvering test results