RM.V.G.K. Rao, head of the Fiber Reinforced Plastic (FRP) division at the Bangalore-based National Aerospace Laboratories (NAL), describes the period from end 1996 to May 1998 as the most exhilarating and traumatic period in the life of many NAL scientists and technicians. One could understand the exhilaration: the second prototype of NAL's Hansa, the country's first all-composite aircraft, had just rolled out. But what was the reason for the trauma? After the rollout, NAL scientists got a shock. Weighing 888 kg (including the weight of two pilots and the fuel), Hansa had exceeded the weight-limit of small-trainer aircraft by 138 kg. If NAL could not reduce the weight, the aircraft would have had to go through the more rigorous and expensive certification process meant for larger aircraft. The problem generated a fierce debate among NAL scientists. A large number of them felt that it was impossible to reduce the weight. An equal number felt that it was possible, and worth trying. After a year and a half of effort, Hansa 3 rolled out, weighing only 750 kg, and was formally certified by the Director-General of Civil Aviation (DGCA) on February 16.The 50-odd scientists who worked on the Hansa consider the weight reduction as one of their greatest achievements. The pilot and the fuel together weigh 225 kg, without compromising on the strength of the aircraft. How they achieved this is a story in itself. Behind it is a bigger story of the development of state-of-the-art composite materials. Hansa is now widely recognised as being as good as the best aircraft in its category; the Diamond Katana. Priced at Rs 40 lakh, it costs about Rs 8-10 lakh less than the latter. In addition, it has at least one feature which the Katana lacks: lightning protection. If marketed well, the Hansa can sell in large numbers across the world. In fact, enquiries have already come from firms in the US, Canada and Australia. Says R. Mashelkar, director-general of the Council of Scientific & Industrial Research (CSIR): "No one could have imagined that an aircraft built in India would fly in foreign skies." NAL, a CSIR laboratory, had over the years built up facilities and expertise in several areas of aerospace engineering. Among its several recent achievements is the development of the software which determines the minimum separation distance of landing aircraft at London's Heathrow airport, and the development of parallel supercomputers. Roddam Narasimha, ex-director of NAL, felt the need to bring together all this expertise to design and build an aircraft. To gain experience, NAL first bought a design and built a small aircraft in 1989. The next stage was Hansa, a small lightweight trainer aircraft, badly needed by flying clubs in the country. NAL decided to use only composites for the design of this aircraft. And the real work began. Compared to metals, composites are lighter and stronger. But when used in an aircraft, it presents several challenges, especially to those who don't have experience in manufacturing. Existing composites also have an irritating feature. They absorb moisture and degrade. The aircraft has to be built keeping in mind this degradation. As a safety margin, designers normally make the airframe 150% stronger than required. If you use composites to allow for the degradation of that, they have to add another 150% of that. It means that the airframe should withstand loads 225% more than the maximum. In theory, making a glass fibre composite was simple. Stretch the glass cloth over the mould and dab the resin. Apply vacuum to take out the excess resin and also to blend the resin well. Remove the mould. But applying and blending the resin, as well as squeezing out the right amount of resin is a difficult task. The original aim was to make an aircraft quickly. The design was sophisticated with computer modeling, theoretical studies and later wind-tunnel tests of models (to learn the airflow characteristics), but the weight of the aircraft was not a consideration. For the second prototype, NAL scientists made calculations to reduce the weight but ended up with an excess of 138 kg. "It was clear we had to learn more," says S.S. Desi, head of NAL's Computational and Theoretical Fluid Dynamics division. Each part was put under the microscope. Material properties were studied more carefully. It turned out that to balance the weight properly about 20 kg of ballast had been put. A redesign removed this ballast. All the padding was removed by detailed study. The thickness of the foam and the glass were varied judiciously. The wings were made thicker near the hull and thinner near the tip. And then someone hit upon an idea. Make the wing as one part.Earlier, to make transportation easier, the two wings were made separately. One large wing was difficult to make but it reduced the weight. And finally, the engine was replaced with a lighter and more state-of-the-art one. The aircraft was ready for certification. So thought the NAL team, but the DGCA had other ideas. Like NAL, the DGCA also was inexperienced. Hansa was the first aircraft it was certifying. It was necessary to be cautious. The testing was rigorous. Moreover, DGCA insisted on two additional features: night flying capability and lightning protection. It felt that it is better that a pilot is trained in night flying on the same aircraft. The features added 10 kg, but NAL managed within the 750-kg limit. Says NAL director T.S. Prahlad: "The DGCA has his role to play in making this a world-class product." NAL had an agreement with Taneja Aerospace & Aviation Ltd (TAAL) for manufacturing and selling the aircraft. But NAL will now make the first five aircraft on its own and sell it to the flying clubs, the first one is ready to be delivered to the Madras Flying Club. Later, TAAL will take over. The real advantage of the aircraft is its cost, while having all the features that other competing aircraft do. In fact, NAL was lucky in many ways. For example, the testing equipment for lighting protection is expensive ($1 million, at least). But the Centre for Airborne Systems at Bangalore had installed it for testing the light combat aircraft and lent it to NAL cheaply. In another country, the cost of this equipment would have been added to that of the aircraft. Also, on even a conservative estimate, the aircraft has gone through 50,000 man-hours of testing. In a developed country, even this cost would have been added on to that of the aircraft. Here, thanks to the Centre for Airborne Systems, NAL got off cheap.In the US, where flying is a popular hobby, small aircraft are made in the backyards of houses. These are not certified aircraft. One can buy the kit, assemble and fly the planes, but not sell them. Says B.K. Parida, head of the structural integrity division of NAL: "No aircraft exists in this category which has been so thoroughly designed and tested and documented like the Hansa." About 100 people worked round-the-clock on the project for 10 years. The real competitor is the Austrian firm Bombarier's Katana, which costs $120,000. The full-fledged version of Hansa will be priced at Rs 45 lakh. About 400-500 Katanas are flying in Europe and the US. Says M. Shivakumaraswamy, project director of Hansa: "If we can penetrate the US market, Hansa can be sold in hundreds."  There is no bilateral agreement between the DGCA and US certifying authorities, so the US certification will still have to be achieved. 
Already, Noiss-Air, a small Canadian firm, has approached NAL for getting the aircraft certified in Canada using the existing documentation. Flying clubs here, which are using the 30-year old Pushpak developed by Hindustan Aeronautics, can look forward to some variety at last.