Top technologies for 2002

---

December 2002
More 1 2 3

New tire design for Concorde

The NZG (Near Zero Growth) tire from Michelin has been designed to withstand low- and hig-speed foreign-object damage and very high stress levels.

An aircraft tire being developed by Michelin meets stringent new safety criteria necessary for operating the Anglo-French designed and built Concorde, said the company.

Michelin has been developing the new NZG (Near Zero Growth) tire since 1999. After the Concorde crash in July 2000, the European Aeronautic Defence and Space Co. (EADS—formed by the merger of Aerospatiale Matra, CASA, and DaimlerChrysler Aerospace) contacted tire manufacturers across the world inquiring about new techniques that would result in tires with improved foreign-object damage (FOD) resistance. Michelin responded with details of its NZG technology. In January 2001, EADS witnessed tests and as a result, it asked Michelin to develop its new tire technology for the Concorde. The NZG tire is said to be more damage resistant and lighter than conventional tires. At a media briefing shortly before the 2001 Paris Air Show, Michelin publicly announced the existence of NZG and its potential for contributing to the Concorde's possible return to service.

Michelin has not released full details of NZG but said in Paris that the NZG technology proposed for the Concorde's main wheel tires is based on the use of new "high modulus" materials that reduce structural deformation. By limiting carcass growth when the tire is inflated (less than 3% compared to 6% for a nylon-reinforced radial tire), the tread rubber works under less tension and is much less vulnerable to shocks and damage. Moreover, as the structure is more abrasion-resistant, the tire has a longer service life. Compared to a Michelin bias-ply tire designed for the Concorde, the NZG has about half the number of layers, which brings a weight reduction of about 20%.

The Michelin bias tire construction consists of six bead wires, 18 casing plies, two crown protection plies at 45°, and a tread pattern with five to six grooves.

A key requirement for the Concorde's new tires concerns the mass of tire debris projected in the event of tire destruction. To demonstrate NZG's ability to meet criteria, a "wide range" of laboratory tests were completed. These included being subjected to deliberate damage and endurance under extreme conditions. This work was carried out at Michelin's Test Center and at the Centre d'Essair Aeronautique (CEAT).

The first Michelin NZG tire was sent to Dunlop Aerospace Braking Systems (makers of the Concorde's wheels and carbon brakes) to verify the tire fitted perfectly onto the main wheel and to perform the necessary tests for approval of its use on the wheel. An acceleration/maximum energy-braking test was performed on a CEAT dynamometer to prove that the Michelin NZG tire was compatible with the carbon brake.

The NZG tire is made up of two bead wires, four casing plies, seven crown plies, one crown protection ply, and a tread pattern with four grooves.

A bias tire was used for comparative test results. At 10 km/h, the tread and several structural layers of the bias tire were slashed, but it remained inflated and no debris was projected. However, a similar test at 20 km/h saw the tire burst with projection of debris. When the NZG underwent the 20 km/h test, only the tread was slashed. Further testing followed at Michelin's test rig at Clermont-Ferrand. The NZG tire then went to CEAT for the specific qualification test (TSS 5.3) for the Concorde application, which involved a series of takeoff and landing cycles under wide-ranging conditions of load and pressure together with tests simulating particular conditions, including doubling of load, rejected or completed takeoff, and takeoff with under-inflated tires.

In March, a blade test was carried out at the high speeds defined in the specification (324 and 382 km/h). Again, it was a comparative test. The bias tire burst while the NZG tire "remained fully functional."

For more information from Michelin, circle 27

Metallic foams and aerospace

Aerospace applications for metallic foam are being considered by Saab and BAE Systems. Although the material's potential for automotive applications is established, the companies believe the aerospace dimension needs to be explored. Metallic foams have enormous potential as structural and functional materials in lightweight designs.

One of the new projects of the Saab/BAE Systems Gripen AB's industrial cooperation in connection with a future Gripen fighter aircraft contract is focusing on this new material. As a result, an Austrian company, Alulight International, has become a partner in the project.

Alulight's task is to develop and manufacture customer-specific and advanced high-tech aluminum products. Research into potential uses for metal foams in the automobile industry and in other industrial areas and the optimization of the materials and manufacturing processes are within the scope of the project.

Metallic foam has a density of just 15-20% of the solid metal, offering enhanced specific properties such as vibration and sound damping, high strength and stiffness, and thermal and electrical properties. Metal foams also have a low environmental impact.

The companies say that the primary goal for their joint project is to forge alliances between Alulight and Swedish, British, and internal industry, which have a demand for lightweight metal with the specific characteristics of aluminum and other metallic foams. Great interest for metallic foam has been seen in the Swedish automotive area, but the companies believe aerospace applications could prove to be the next important field.

For more information from Alulight, circle 28

Fuel-cell-powered aircraft unveiled at Oshkosh

The Helios, an unmanned electric airplane developed by Paul McCready, CEO of AeroVironment Corp., is slated to be outfitted with a regenerative fuel-cell system in 2003, enabling it to potentially fly around the clock, powered solely from the sun's energy.

The non-profit Foundation for Advancing Science and Technology Education (FASTec) showcased its fuel-cell-powered aircraft at the Experimental Aircraft Association AirVenture 2001 held at Oshkosh, WI.

The new Electric Plane, or E-Plane, is a high-speed, all carbon French DynAero Lafayette III, built and donated by American Ghiles Aircraft. It is in the process of being converted in three stages from a combustion engine to electric propulsion. The first flights, which are planned for next year, will be on lithium-ion batteries. The following flights will be powered by lithium-ion batteries augmented by a fuel cell. The final configuration of the aircraft will be powered totally by a hydrogen fuel cell with a range of 500 to 800 mi.

FASTec also is investigating fuel-cell technology for use on other applications such as a catamaran and the CarterCopter gyroplane, an aircraft that takes off and lands like a helicopter but flies at the speed of a small jet. Fuel-cell technology, which generates electricity by using hydrogen combined with oxygen, is being explored as a power source for a variety of vehicles.

The Helios, an unmanned electric airplane developed by Paul McCready, CEO of AeroVironment Corp., operates on solar power and recently flew to an altitude of 76,000 ft. This aircraft is also slated to be outfitted with a regenerative fuel-cell system in 2003, enabling it to potentially fly around the clock, powered solely from the sun's energy.

For more information from FASTec, circle 29 ; for more information from AeroVironment, circle 30

More 1 2 3