NAL/HAL RTA-70

There you go - India seems rather keen on going ahead with plans for a turboprop regional aircraft, which it is calling the RTA-70 (model above).

Diehl unveiled a proposed cabin mock-up (below) at India Aviation 2010 that it produced in consultation with the National Aerospace Laboratories, which is leading the efforts to develop the RTA-70.

NAL officials say that they plan to design the RTA-70 with the Indian market in mind, adding that existing turboprops do not meet those requirements. These include higher fuel efficiency, short landing and take-off capability, and the ability to transport cargo.

This will give the aircraft 25% lower acquisition costs, 25% lower operating costs and 50% lower maintenance costs than existing turboprop regional aircraft, says NAL.

The 70-seat aircraft will have a range of 1,100nm (2,000km), and require a take-off field length and landing field length of 900m (2,950ft). The aircraft would have a length of 28.6m and a wing-span of 29.4m. The aircraft would have a service ceiling of 30,000ft, a cruising speed of 300kt, and the noise level would meet Stage 4 criteria.

The cabin, which would be able to seat four abreast, would have a length of 3.01m and height of 3.35m. The cargo hold would have a volume of 25m³ (880ft³).

NAL is eyeing a composite airframe. The aircraft will be powered by two "next generation turboprop engines", it adds. It would have a fly-by-wire control system, open distributed modular avionics, ADS-B navigation capabilities, and advanced displays.

This will primarily compete with ATR turboprop aircraft if the Indians go ahead. As to why they seem to think the world needs another regional aircraft is another issue altogether.

Exclusive : India's regional transport aircraft (RTA-70)



The photograph you see to the right is the first real glimpse of how India's National Aerospace Laboratory (NAL) envisages its ambitious RTA-70, a national regional transport aircraft programme that's been strictly on paper for almost a decade now, but announced formally last year. In 1996, then Prime Minister HD Deve Gowda (in between yawns, no doubt) said in his speech during Aero India that his government had given the scientific establishment the task of developing a 50-seater turboprop airliner and a 100-seat jet airliner. These visions changed somewhat, and the current government, in its first stint in power sanctioned the development of a 70-110 seat civilian airliner for the Indian market. While the money has already begun to flow into the programme, so far only preliminary conceptual studies have been carried out on the RTA-70 pictured above. These studies, according to NAL, include "computational fluid dynamics, wind tunnel studies and multidisciplinary design optimisation (MDO) studies".

NAL is developing the RTA-70 as a platform "capable of reliable and safe operation from airports with minimal infrastructure and instrumentation facility under all-weather conditions." It is not yet clear if the RTA-70 will also be spun off into a military variant for transport and special operations. Remember, HAL (which is a development partner to NAL for the RTA-70) is also steeped in build studies for the Multirole Transport Aircraft (MTA) that it is developing in a joint venture with Ilyushin of Russia.

In May 2008, it was decided that technologies required the programme included a laminar flow wing, hydrophobic coatings, use of low cost composites, fly-by-wire controls, advanced avionics that will enable use of ill-equipped airfields and integrated vehicle health monitoring. Pratt & Whitney engines have almost been finalised for the platform.

On the airframe, structural technologies identified as crucial included use of piezo and SMA related smart materials for flutter and gust control, structural topology, structural health monitoring (SHM) and low cost materials. Architectures for avionics, active noise control systems flight control systems (fly by wire) and synthetic vision were additionally identified. Structural health monitoring, in fact, is being developed as a core technology of the RTA-70.

The RTA-70 will be developed and built using extensive private sector participation, and NAL is understood to also be hunting for a foreign collaborator. When ready, the RTA-70's makers envisage it as having about a 35% lower flyaway and ownership cost than aircraft it will ultimately be pitched against, those manufactured by Embraer, Bombardier and ATR.

The first prototype is expected to fly in 2013.

India unveils details of indigenous 70-seat turboprop

India has adopted a turboprop design for its first indigenous regional aircraft and has released preliminary specifications for the planned 70-seater.
National Aerospace Laboratories is looking for foreign partners for the Regional Transport Aircraft RTA-70 and hopes to secure additional government funding later this year.
NAL officials say that they plan to design the RTA-70 with the Indian market in mind, adding that existing turboprops do not meet those requirements. These include improved fuel efficiency, short landing and take-off capability, and the ability to transport cargo.
This will give the aircraft 25% lower acquisition costs, 25% lower operating costs and 50% lower maintenance costs than existing turboprop regional aircraft, says NAL.

"Many towns and cities remain unconnected due to the cost of operations. Short take-off and landing abilities, capability to land on ill-equipped airfields, including all weather operations, can be of very high benefit," NAL says in its RTA-70 brochure.
"Given the high cost of fuel and its implication to operating economics, developing an aircraft that is fuel-efficient compared with present regional aircraft can be very promising. Lower weight, lower drag can mean higher performance and lower emissions. Capability to carry cargo means additional revenue to an operator," NAL says.
"Initial seed funding has enabled preliminary studies preliminary studies to start," it adds. This has been used for work on aerodynamics including computational fluid dynamics and windtunnel studies, it adds, while preliminary studies on sizing, specifications and performance are in progress.
NAL is eyeing a composite airframe. The aircraft will be powered by two "next-generation turboprop engines", it adds. It would have a fly-by-wire control system, open distributed modular avionics, automatic dependence surveillance - broadcast navigation capabilities, and advanced displays.
The aircraft will have better "energy efficiencies" than its current rivals, says NAL. However, it is unable to say when it hopes to move into the detailed design phase and begin the production of the aircraft.
India's state-owned Hindustan Aeronautics will manufacture the aircraft. This agreement will be similar to a deal to produce the Saras utility/transport turboprop, which NAL has developed primarily for the military, and the Tejas light combat aircraft.
NAL is seeking international partners to help it in several areas. Diehl has come on board to help design the cabin and the two teams unveiled a proposed cabin at India Aviation 2010 in Hyderabad.

India's first indigenous regional aircraft, the RTA-70, could be powered by turbofan engines, with the government viewing it as a stepping stone to larger aircraft.

Although the RTA-70 (regional transport aircraft-70) was originally envisaged as a 70- to 90-seat turboprop, the Indian government asked National Aerospace Laboratories to investigate the use of turbofans. NAL is studying the two options, and will report to the government in April 2011, after which a decision will be made.

"The government asked us to look at the turbofan option, and after we conduct a feasibility study, we will decide," says NAL director AR Upadhya. "Previously, we were focusing only on a high-wing turboprop design. If all goes well, by the end of 2011 we will have full go-ahead to create the aircraft."

NAL has been in talks with jet engine producers, including General Electric, Pratt & Whitney, Rolls-Royce and Snecma. It says all have shown interest in the project.


© NAL


"Initially, we were looking only at the turboprop option because of the high price of fuel," says Upadhya. "Lifecycle costs were our key concern. The government then asked us to look at the turbofan option, because they see it as a stepping stone to the high end."

NAL foresees demand for regional aircraft in India reaching 250 by 2025. This is driven by India's increasingly wealthy middle class, and its demand for flights on low-cost carriers. In addition, industries are moving into India's smaller cities, increasing the viability of regional flights to those destinations.

NAL also sees possible demand for 150 military variants to replace the Indian air force's Antonov An-32 fleet.

Irrespective of the RTA-70's powerplant, it is likely to come in two variants - a shorter one with 70-90 seats and a longer one with 80-100 seats. Its range will be 1,350nm (2,500km), suitable for most long sectors in India. Avionics are likely to be produced locally, and include an indigenous fly-by-wire control system to save weight.

Upadhya estimates the aircraft could be in service as soon as 2017, and NAL is open to international and local partners. The aircraft would be produced by government-owned Hindustan Aeronautics.

If India were to produce the RTA-70 as a jet, it would find itself in the increasingly crowded field of 50- to 100-seat regional jets. Competitors would include the Bombardier CSeries, Comac ARJ21 Embraer's E-Jets and the Sukhoi Superjet.