Archive for the 'R&D' Category

The chief designer of the LCH programme, B Pandaji Nath Rao, spelt out the milestones: The LCH design was finalised and frozen this March; the first technology demonstrator (TD-1) will fly by March 2009, testing the LCH’s flying systems; by July 2009, the second technology demonstrator (TD-2) will fly, fitted with all the weapons and electronic sensors. By the end of 2009, the Indian Air Force (IAF), the primary users of the LCH, will be conducting flight tests on the TD-3.

But HAL Chairman Ashok Baweja also points out the LCH’s many new features, which have made engineering a challenge. The two pilots in the LCH sit one behind the other, compared to side-by-side in the Dhruv. So all the flight controls, the hydraulics and the fuel system had to be redesigned for the sleeker, heavily armoured LCH. The LCH’s many stealth features also necessitated redesigning the fuselage. And the new crash-resistant landing gear allows pilots to survive even when the LCH smacks into the ground at more than 10 metres per second.

The performance of the LCH will have to match up with contemporary light attack helicopters like Eurocopter’s Tiger or China’s ultra-secret Zhisheng-10 (Z-10). But experts say the LCH’s flying performance will be hard to match, designed as it is for India’s high altitudes. It can take off from an altitude of 10,000 feet, operate weapons up to 16,300 feet, and engage targets like UAVs that are flying at altitudes of up to 21,300 feet.

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Light Combat Helicopter mock up

LCH specifications

The first problem current helicopters have operating at high altitudes is their inability to generate power. Turbines have to suck air for combustion, if your not sucking enough air (it becomes thinner the higher you go) the engine will underspeed (it’s like driving a car up a steep hill in a high gear) This limits the amount of torgue that can be applied to the rotor system, and torque is power. To compensate for the loss of power available the aircraft max gross weight will be reduced. The next hurdle is loss of tail rotor effectiveness. The tail rotor overcomes the torque in the rotor blades which is trying to yaw the aircraft in the opposite direction of the rotation of the main rotor blades. This is more of problem for some designs, and less of a problem for others. Finally the rotor system itself becomes less effective at higher density altitudes making them increasingly difficult to control. I’ve flown Blackhawks as high as 16,000 feet to take advantage of winds aloft on ferry flights, nothing like getting a 340 knot ground speed in a helicopter!. At that altitudue helicopters really wallow, controls are sloppy and the collective lever is raised to nearly the travel limits which Never occurs at low altitudes. Finally every design will reach a density altitude whereby the rotor system is no longer capable of producing meaningful lift. These condtions all become a serious problem when your trying to accomplish a landing because you will most likely be terminating your landing approach to a hover, and hovering requires more power than forward flight. Finally, service ceiling is a misleading term, in avaiation service ceiling is defined as the point in which the aircraft is no longer capable of climbing at or above 500 feet per minute, which is a standard rate of climb during instrument flight. For short hops to resupply mountain bases exceeding the service ceiling is not that big of an issue, your flights will be short anyway so trading fuel weight for cargo weight becomes SOP.

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The Ultimate aim.

The Apache helicopter

Apache long bow

Apache  Specifications

General characteristics

• Crew: 2: pilot, CPG (co-pilot/gunner)
• Length: 58.17 ft (17.73 m) (with both rotors turning)
• Rotor diameter: 48 ft 0 in (14.63 m)
• Height: 12.7 ft (3.87 m)
• Disc area: 1,809.5 ft² (168.11 m²)
• Empty weight: 11,387 lb (5,165 kg)
• Loaded weight: 18,000 lb (8,000 kg)
• Max takeoff weight: 21,000 lb (9,500 kg)
• Powerplant: 2× General Electric T700-GE-701 and later upgraded to T700-GE-701C & T700-GE-701D (1990-today) turboshafts, -701: 1,690 shp, -701C: 1,890 shp -701D 2,000 shp (-701: 1,260 kW, -701C: 1,490 kW) each
• Fuselage length: 49 ft 5 in (15.06 m)
• Rotor systems: 4 blade main rotor, 4 blade tail rotor in non-orthogonal alignment

HAL Light Combat Aircraft

General characteristics

• Crew: 2
• Length: 15.8m (51ft 8in)
• Rotor diameter: 3.55m (11ft 6in)
• Height: 4.7m (15ft 4in)
• Disc area: m² (ft²)
• Empty weight: 2550 kg (5621 lb)
• Loaded weight: 4000 kg (8818 lb)
• Useful load: 2950 kg (6503 lb)
• Max takeoff weight: 5,500 kg (12125 lb)
• Powerplant: 2× Shakti turboshafts, 900 kW (1200 hp) each