SARA aims to be head of the class

The growth in African air travel has significantly increased demand for new generation aircraft, especially those linking regional centres. Sam Basch looked at one, which is taking shape.

South Africa’s Denel Group aims to fill a niche in the aviation market. A full-scale mock-up of its Small Regional African Aircraft (SARA) was shown at the Africa Aerospace & Defence exhibition in Pretoria earlier this year.
“We envisage SARA as a cost-effective 21st Century transportation system for Africa, capable of point-to-point travel, employing short take-off and landing operations from small semi-prepared regional runways,” explained Victor Xaba, deputy CEO Denel Aerostructures.
Denel’s design was inspired by the findings of an international study into future community airliner concepts, notably in the 20-passenger class, and focused on ‘green’ technologies. “We opted for a concept that featured a natural laminar airflow fuselage in a pressurised 24-seat dual turboprop-powered aircraft design,” said Xaba.
SARA has received support from the South African Government’s joint aerospace steering committee (JASC) as a ‘national aerospace flagship programme’ and as a human capital development programme.
According to Xaba, SARA is currently used to further eight post-graduate studies of PhD and Masters students.
Although Denel leads the programme, an array of the country’s aerospace community is involved. This includes universities, several government departments – notably the trade and industry department’s aerospace industry support initiative (AISI) – industry stakeholders and prominent research entities like the Council for Scientific and Industrial Research and the National Research Foundation.
“A market study undertaken by Lufthansa Consulting, co-funded by South Africa’s Industrial Development Corporation (IDC) and two government departments, has presented a positive outlook for SARA,” said Xaba. “Not only will it deepen the country’s industrial base, but also contribute significantly to skills development (some 300 engineering jobs) and development of an aerospace special economic zone.
“The programme would create 2,000 technical jobs over 15 years. Importantly, the study attributes a market for SARA in six developing economic regions of the world and break-even at 200 aircraft within the first 10 years of production.”
The twin-engined turboprop, with high-wing design, is envisaged to be pressurised to fly above the weather, with a maximum take-off weight of 8,400kg and a range of 1,500 nautical miles. This would enable a flight from Lusaka with 15 passengers to reach as far as Libreville or Cape Town, or even Antananarivo.
Lufthansa Consulting’s study indicated best-in-class capacity and performance, as well as the lowest seat-kilometre costs.
The design shows an oval-shaped cabin cross-section, 24-seat four-abreast (2+2) passenger configuration (a first for this size aircraft) or full cargo version, or a combination. The high wing leaves the cabin unobstructed with stand-up capacity in the centre aisle.
Xaba explained that the design team opted for a natural laminar airflow fuselage design. By ‘fattening’ and shortening the fuselage and by moving the maximum diameter forward, total drag is reduced and aerodynamic efficiency significantly increased.
An 18-month feasibility study now leads to a pre-development phase, followed by a five-to seven-year development phase before a prototype is likely to emerge.
Denel is using the mock-up to consider lean manufacturing concepts, a jigless assembly process, stress analysis for high density embarking and disembarking, and cockpit and cabin ergonomics. It will further look at provision for three-seater variants – 24, 20 and 12 seats – and permutations for the cargo/combi versions.
Denel is characterising the material properties of an epoxy resin/flax fibre composite laminate in the interior liners of the SARA programme.
In a statement by the trade and industry department’s AISI programme, natural fibres are promoted as a substitute for synthetic glass fibres. “Aircraft interiors are one area where natural fibres may be employed in composites, as they offer a good strength-to-weight ratio,” it stated.
Natural fibres are already successfully used in the automotive and other commercial applications.
According to Alcino Cardoso, Denel Aerostructures chief engineer, aerospace manufacturers are turning to alternative materials to build lighter aircraft that are reliable and environmentally friendly.
He said flax “shows the greatest promise to be accepted as a structural fibre for aerospace structures” as flax fibres have inherent safety advantages that make them suitable for aircraft interiors, doors for baggage compartments and cabin floors.
While the aerospace industry has taken an interest in natural fibres, stringent safety, quality and certification requirements will be likely to delay the inclusion of these materials in aircraft structures for some time. However, Cardoso argued that Denel could “activate the natural fibres value chain to break into the lucrative global composites market”.
Denel is at pains to stress that SARA is very much aligned with the South African Government’s industrial policy action plans as contained in the National Development Plan (NDP).
“Not only has SARA now been designated a ‘national aerospace flagship programme’, but importantly, independent market studies have validated our belief that it provides a good business case,” said Xaba. “The mock-up represents its evolution from a concept to reality – proving that SARA is, indeed, on the move.”