Air-to-air refueling for a fighter platform is a force multiplier in terms of increasing its combat radius and payload carrying ability. Adapting for such a facility especially for an aircraft under design and development is a challenging task. It requires rigorous ground and flight testing to meet the certification standards. One of important flight test parameter that needs to be validated for structural impact load calculations and certification needs is the closure velocity. The air-to-air refueller was equipped with a Ram-air-turbine powered drogue and chute system. An innovative methodology of estimating the closure velocity between the drogue of the mother aircraft and the in-flight refueling probe of the receiving aircraft was evolved. The method was employed and validated during the air-to-air refueling trials of a prototype fighter platform. The intention of this paper is to explain the methodology employed and deliberate the results obtained with respect to the air-to-air refueling certification.

Aircraft electrical system needs to be robust enough to cater for electrical power requirements of all the systems of the aircraft and all the safety/degraded mission critical systems in failure modes. Designing such a robust electrical system for a developmental aircraft program is a challenge. A developmental aircraft during its various phases would involve integration of additional systems and new weapons (in case of fighter aircraft). Integration of newer systems imposes fresh challenges in managing the electrical system architecture especially in failure modes. Weapon integration in a prototype fighter program is dynamic as newer contemporary weapons are developed at faster pace and ever evolving. Power crisis through existing on-board power generation systems in failure mode was felt during an indigenous aircraft development program. A novel idea of introducing a Ram Air Turbine and utilize the power generated during main alternator failure for critical systems was studied. The intention of this paper is to cover the details of the study carried out towards utlisation of such a Ram Air Turbine in landing phase for extraction of energy in case of main alternator failure.

Ram Air Turbines (RAT) are used for emergency on-board power generation on aircraft and associated systems. Many studies on usage of RATs have shown promising results in terms of using RATs as a source of emergency on-board power generation. Many external podded systems on aircraft utilise RATs for self-sufficient adaptation. These pods generate their own power using RATs for their power requirements instead of depending on the mother aircraft power. Commercial cargo planes use RATs for generating emergency hydraulic power. A RAT was suggested to be used for emergency power, during failure of main alternator on a prototype aircraft. A specific requirement of the RAT was also to produce high drag for aerodynamic braking when deployed and concurrently generate electrical energy. Three models with different solidity were studied in wind tunnel at different wind speeds for suitability of this drag-energy combination. This paper presents the results of the study. Based on the results, a suitable RAT was selected for further analysis and ground trials.

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