A Study on Estimation of Propulsive Power for Wing in Ground Effect (WIG) Craft to Take-off

Abstract

This paper estimated the propulsive power required for Wing in Ground effect (WIG) craft to take-off. The hull form design of the WIG craft incorporates a stepped planing triple hull, since the planing hull is well known to give result and assist in lifting off the water surface effect. In order to determine the power required for WIG craft to take-off, the craft prototype was built into 1 to 6 model scale. In numerical calculation, the required thrust motor of model to take-off was calculated by summation of water drag; aerodynamic drag and the weight of model. The water drag was estimated by Savitsky’s method, and the aerodynamic drag by a MATLAB programming based on Vortex Lattice Method (VLM). In the experiments, the relationship propeller RPM against thrust motor was obtained from the calibration tests. At the flight tests of the model, the propeller RPM of the model was measured to determine the total thrust motor and the propulsive power required to take-off by using the Froude’s Momentum Theory. The required propulsive power for craft scaled model was found to give the total thrusts of 33.85 N, and the effective power estimates required for WIG model to take-off per propeller was 128Watt at the design speed. It was also observed during most of the flight tests, the craft is attempting to enter into ground surface effect at design speed. Kertas kerja ini mengira jumlah kuasa bagi bot Wing in Ground effect (WIG) untuk terbang. Perekabentuk bot WIG menggunakan badan bot planing, yang terkenal untuk membantu dan mengangkat badan bot ke atas permukaan air. Dalam mendapatkan kuasa bagi bot WIG untuk terbang, model bot dibina dalam skala 1 berbanding 6. Pengiraan kuasa bagi model WIG adalah pengiraan jumlah rintangan model pada setiap halaju, terhadap tambahan rintangan udara, rintangan air dengan jisim model. Kaedah yang digunakan dalam pengiraan jumlah rintangan model adalah dua kaedah iaitu kaedah berangka dan eksperimen. Dari kaedah berangka, rintangan air telah dikira menggunakan simulasi Savitsky, dan rintangan udara telah dikira menggunakan simulasi MATLAB berasaskan kaedah Vortex Lattice Method (VLM). Dari kaedah eksperimen, ujian kalibrasi dilakukan terlebih dahulu untuk mendapatkan hubungan antara RPM melawan daya dorong. Kemudian ujian terbang dilakukan untuk mendapatkan RPM untuk setiap halaju model sebelum terbang. Nilai RPM daripada ujian ini digunakan untuk mendapatkan jumlah daya dorong daripada ujian kalibrasi dan jumlah kuasa didapatkan dengan menggunakan persamaan hukum Froude’s Momentum. Keputusan jumlah daya dorong bagi model diperlukan untuk terbang daripada dua kaedah adalah 33.85 N, dan jumlah kuasa untuk satu kipas iaitu 128Watt. Daripada pengamatan ujian terbang, model WIG telah terbang dalam Ground Effect (GE) di atas permukaan air.