BY DR NUR AZAM ABDULLAH

SUSTAINABLE flight is a dream for the development of modern aircraft . However , most existing aircraft use aviation gas ( AVGAS ) as an energy source and contribute to the harmful environmental issue , so-called carbon emission contribution on the sky .

Hence , it would trigger the increment of global average temperature over the year that will significantly affect climate change with air transport worldwide . The data global airline industry shows that 4,723 million passengers used air transport over the whole year before the pandemic ( pre-Covid-19 ).

Nevertheless , the number has decreased to 1,763 million passengers during the post-Covid-19 in 2021 . The number will increase drastically when the pandemic ends .

Let ’ s look at the positive side of introducing Clean Sky Joint Undertaking ( CSJU ), a public-private partnership between the European Commission and the European aeronautics industry that regulates and finances research ventures to produce significantly more reserved and numerous environmentally favourable aircraft .

One of the elements in the four focus areas or subsectors outlined in the Malaysian Aerospace Industry Blueprint 2030 is the Aero-Manufacturing , where the aerostructure focuses on the employment of composite and metallic materials .

The composite would be an excellent replacement for the conventional metallic or aerospace alloys aircraft components such as fuselage , wing , tail , and engine pylon . The utilisation of composite structures in aircraft manufacturing has led to less weight and reduced the AVGAS consumption for aircraft propulsion .

But , how is this approach eachable in

the timeline ? According to NASA , green aviation is a terminology adopted to represent exercises in the business that improve aircraft efficiency and reduce noise contamination and greenhouse gases , which drops carbon emissions .

On the strategic insight , this application has increased the aircraft endurance for long-range operation , especially for lowering the travelling cost in this era . Moreover , researches on multifunctional composite structures seek the advancement in combining structural-energy functions .

Thus , enabling the structural capabilities , i . e ., load-bearing and energy generation / storage application . One of the focuses in the structural-energy topics is the piezoelectric energy harvesting technology .

In another perspective , the development of UAVs has been of concern for military applications for several decades . The focus lately was on creating small UAVs , known as micro (< 10 cm in length ) or mini ( 10-30 cm in length ) UAV , which can be small enough to be carried and deployed by soldiers in the battle territory .

Top strategic management

A small military UAV is specifically designed to deliver steadfast intelligence , surveillance , reconnaissance and targeting ( ISRT ) missions . Some people , especially at the top strategic management , may question its feasibility for this purpose .

However , they can be designed to fulfil several distinct duties . One limitation of currently available mini UAVs is their endurance or best flight conditions . In addition , mini UAVs are tiny and lightweight .

Consequently , they cannot be regulated with some large fuel payloads during the flying . Specifically , in electric-powered mini UAVs , the rechargeable batteries are

utilised to propel the aircraft , often comprise a substantial number of the overall aircraft mass , so increasing the battery size to enhance endurance is not feasible .

Additionally , an energy storage scheme with a multifunctional structural battery in the WASP pack and the Black Widow UAV would be applied for this intention .

Indeed , nature is a special gift to humankind . For instance , the air would generate a mechanical movement through this vibrational motion and trigger the structural deflection on an object depending on its shape and sizing .

The concept is straightforward ; a travel freestream air carries energy that would be transferred when it interacts with a structure and , consequently , excites its particle . The design may be excited to the maximum deflection peak once its exciting frequency is near the natural frequency .

Simultaneously , the atmospheric conditions such as temperature , air density , gust flow may differ based on the altitude from the sea level . Thus , the amount of harvested energy may vary due to the exciting mechanism based on the generated aerodynamic load .

On the other hand , several windstructure interactions would be observed in our daily life . For example , the most popular Tacoma Bridge that collapsed in 1940 would be the benchmark of this event .

The finding has revealed that the structural damping of the bridge could not resist the vibrational load inducing the flowing air , hence resulted in the bridge collapse unfortunate event .

In 2010 , Erturk and his team coined piezoaeroelastic energy harvesting in their research paper entitled “ On the energy harvesting potential of piezoaeroelastic systems ”.

For the first time , they elaborated on fundamental issues concerning harvesting the energy via the structural vibration exerted by an aeroelastic condition , i . e ., coupling between aerodynamic loads and structural elasticity .

In a recent development , energy harvesting can be exemplified for a wing with a high aspect ratio . Frequently , high aspect ratio wings produce more extra lift and permit sustained , endurance flight , while low aspect ratio wings imply the most desirable for fast manoeuvrability .

Concept of piezoelectric

Specifically , a high aspect ratio wing UAV class is called High-Altitude Long-Endurance ( HALE ). UAV primarily operates for 30 to 50 hours of flight between 50,000 ft and 70,000 ft of altitude . Recently , there has been some other research for solarpowered energy harvesting and control for this type of UAV .

Such aircraft may also be of advantage for surveying missions to lessen navigational hazards in extreme regions . Due to some reasons , a significant gain is an economic expense that corresponded to satellite systems and the most trivial ecological impact .

For example , the immense geographical latitudes that are of particular concern