In my introduction letter, I mentioned my strengths, weaknesses and goals that I had set myself to achieve. In this reflection essay, we will discuss our progress throughout this module. This will split up into two segments, Module Learning and Project Learning.

Module Learning

We previously noted that my main strength is my presentation skills. I also did mention that I want to improve it further by “bring[ing] it to the next level”. I did not go too deep into the specifics of what this theoretical level is. This was so that I did not colour my thoughts on improving my presentation skills in one specific area. After attending this module, I can say that I was truly humbled by this experience. This module was able to expose my biggest flaw in my strength, which was to improvise along as I presented my slides. From this, I learned to cut out that habit and make it a point to do mock presentations before the actual presentation.

Secondly, my other goal was to be able to find the appropriate tone when sending out emails. This module improved my emailing skills, as we are constantly replying and sending out emails to our professor. Our professor has instilled us good emailing ethics and habits that I will be using in the future. Being able to strike the right tone and emailing others confidently, I can safely say, is my biggest learning outcome from this module.

Project Learning

The biggest highlight of this module was the research project aspect. I hold this project close in regard as was a personal project of mine that I currently undertaking. Being able to present this idea that I had previously kept as a secret, felt very empowering. It gave me the confidence to continue grinding through it. The biggest achievement in the module was presenting this idea to the Mapletree Challenge. It was that leap of faith that brought me to where I currently stand today. To be able to present this idea, to a panel of judges and industry experts, is something that I did not expect when I first started this module. Through this entire ordeal, my team has their presentation skills and their ability to think on their feet. We also learned skills outside the scope of our course. We learned what makes a company successful, how to sell the idea and how to do a business plan. These are some skills that we would not have learnt if we did not sign up for this challenge in the first place. Its amazing and humbling to see how something so simple, such as signing up our names on the registration website, will bring us to places we previously had thought to be far-fetched or simply impossible.

 It is this learning outcome, that I hope my teammates will bring along with them as they go on with their lives.

*Acknowledgments:

I would like to thank my teammates Hilmi, Yong Xun and Yong Wei for being with me on this journey. And lastly to Professor Brad Blackstone, for pushing and motivating us to join the competition.

Thank you

In the article, “ Bending behaviour of sandwich composite structures with tunable 3D-printed core materials,” Department of Mechanical Engineering, State University of New York (2017) has stated that they successfully manufactured a novel class of sandwich composites with 3D-printed core materials and Carbon Fiber Reinforced Polymer face sheets. They accomplished this through numerical analysis using Finite Element Analysis simulations and real-life experiments. This was done to bridge the two data types together, to prove its scalability and its feasibility. Three-point bending tests were done on three different types of sandwich cores, to investigate the bending behaviour on the cores.
They stated that the structures that the cores had were: Truss, Conventional Honeycomb, and Re-entrant Honeycomb. Through the study of the structure, they discovered that the latter structure, an auxetic structure, possesses a negative Poisson’s Ratio. They stated that this has many mechanical advantages such as “increased indentation resistance, shear resistance, plain strain fracture toughness, and energy absorption”.
Through experiments and computer simulations, they showed that the truss structure has the best overall stiffness, whereas the Re-entrant honeycomb proved to have the least amount of stiffness with peak forces of 600N, and 450N respectively. However, due to the high stiffness of the truss structure, it made the structure to have the least amount of flexibility. The re-entrant was opposite of the truss structure, with it being able to have a flexural displacement of 15mm before plastic failure, compared to the truss structure’s displacement of only 2.5mm.
The data gathered from this paper illustrates to us the potential of tunable cores. Cores that can be tuned to produce specific properties for its specific intended use. Components that need ultimate tensile strength can be obtained using cores with truss structures. Likewise, components that need flexural strength, can rely on re-entrant honeycomb cores.

References

Li, T., & Wang, L. (2017). Bending behavior of sandwich composite structures with tunable 3D-printed core materials. Composite Structures, 175, 46–57. doi: 10.1016/j.compstruct.2017.05.001

An Affordable Carbon-Fiber Bicycle For The Masses

Team name: Lapis Bikes

Lecturer: Professor Brad Blackstone

Module: MEC1281

Date:

Group Members:	Matriculation No:
Zulhusni (Leader)	1901740
Hilmi	1901699
Yong Wei	1901761
Yong Xun	1901704

Proposal

Contents

Executive Summary

Introduction

Background

Problem Statement

Purpose Statement

Proposed modification

Benefits

Evaluation

Limitations

Methodology

Concluding Statement

References

Appendix: A 

Boi. 

Executive Summary

Background

Today, the cost of a carbon fibre bicycle ranges from $2000 to upwards of $10,000. A majority of the costs incurred is due to the research and development required to develop these bicycles for the market. 

According to Becker (2018), the cost of a mold of a carbon fibre bicycle “costs between $60,000 and $100,000 depending on a number of variables”. The high costs are due to a number of factors. Firstly, in some production methods, molds are subjected to high pressure and temperatures. As a result, these molds need to be made out of strong materials that can withstand such pressures and temperatures without deformation. In addition, costs can be driven up due to the complexity and design tolerance of the design. The more complex the part to be produced is, the more complex the mold will be. Tighter design tolerances for some of the parts of the design will also require more precise molds to be produced. Once produced, molds are impossible to modify, hence requiring another mold should there be any changes to the design. If multiple iterations are required the costs are further increased.

In standard carbon fiber production, the carbon fibre mold is required to undergo high temperatures in order to bind the resin and carbon together. This process requires a huge amount of heat, which is necessary to burn off the non-carbon molecules in the chemical, which requires a large amount of energy. Energy is expensive, and manufacturers must use a massive amount of energy to bring internal oven temperatures to the thousands of degrees necessary to force this chemical process. Additionally,  non-carbon molecules are industrial pollutants and must be carefully—not to mention, expensively—disposed of in order to prevent pollution. 

Another reason for the high cost is the manufacturing methods adopted by companies. These include unidirectional prepreg, resin transfer moulding and filament winding. 

The most popular method would be unidirectional prepreg method, due to the higher specific properties and a more straightforward specific fibre angle lay-up. To make the carbon fibre weave, a lot of manpower is required, thus increasing costs.

Resin transfer molding is a closed-mould process for medium-volume manufacturing. Molds typically consist of matching metal tools into which a dry fibre preform is inserted. The mold is then closed and clamped shut before pumping resin into the tool cavity to thoroughly wet-out the fibres. It will then be heated to cure the resin, after which the part can be removed from the tool.

For filament winding, construction starts with dry fibre, where fibre tows pass through a resin bath and wound at various angles onto a speed-controlled rotating mandrel, controlled by a fibre feeding mechanism.

All these are complicated processes involved in manufacturing carbon fibre bikes, which results in high costs. The cost of carbon fibre is still expensive for mass manufacture. According to a report by Meredith, J. et al (2015), the cost of carbon fibre is USD 8.31/kg, as compared to steel and aluminium at USD 0.39/kg and USD 1.75/kg respectively. As such, the costs of carbon fibre bicycles will also be more expensive.

The ideal bike frame is a sustainable carbon fiber frame made through eco- friendly manufacturing process while maintaining the same performance.

Problem Statement

Current bike frames in the market are too expensive to manufacture due to tooling and R&D cost​. Also, materials such as aluminium and carbon fiber are used excessively and wastefully due to current machining techniques

Purpose Statement

The purpose of this report is to introduce the concept of 3D printed carbon bikes and molds to independent bike companies that do not have the budget required to compete with other companies in terms of R&D cost. This way they are able to construct a bike without having to invest too much money into it

Problem Solution

A hybrid carbon fibre frame coupled with 3D printed sandwich structure created from a 3D printed mould​.

Figure 1. Rendering of proposed bike frame

3D printed sandwich structure

A sandwich composite structure is composed of a core material, that is sandwiched between two pieces of composite fiber layers. This structure is used widely in aerospace, naval and automotive applications due to their high stiffness/weight and strength to weight ratio. According to Li,. et al(2017), Conventional honeycomb cores are mainly used in applications due to their superior properties over its foam core. They stated that they were able to show the correlation flexural stiffness and strength as the relative density of the core material increases. Through this insight, we can safely say that we are able to tune the stiffness and the strength of our frame through the use of a sandwich structure. By implementing 3D printing technology, we can optimise the topology of the core with relation to the forces that the component will experience. WIth this, we can keep the carbon fiber layup as simple as possible. We can further optimize the core, by using different types of thermoplastics. Different thermoplastics have varying properties that we can take advantage of. For example, Polyethylene terephthalate(PETG) has excellent impact resistance or Nylon that is durable and wear-resistant. Using a blend of thermoplastics, we can alter the characteristics of the bike frame to however we want it to function.

Figure 2. Cross section of a 3D printed core material that goes into the bottom bracket

3D printed mould

A 3D printed mould will reduce the tooling cost, as we will be moving away from aluminium as the raw material and instead replace it with a thermoplastic. According to ClintonAluminium(2017), they stated that 7075 Aluminium, Aircraft grade, is used extensively for prototyping tooling moulds. According to MidWestSupply.com, 7075 Aluminium costs $20,984 USD/m3. In contrast, the thermoplastic material only cost (insert price here). Using 3D printed technology, further optimization can be made to reduce the amount of material being used. By only reinforcing the parts of the mould that will undergo stress, further reduction of the material used in the mould can be done.

Figure 3. Female 3D printed mould

Manufacturing Process

The manufacturing process that we are proposing will use elements of the above mentioned processes. By combining the use of the 3D printed moulds and cores, we are able to manufacture a bike that has the stiffness properties of a full carbon fiber bike, without the high cost of tooling and R&D. The proposed process is that the designer of the bike has to take into account the forces that the bike frame will undergo. From here, using Finite Element Analysis, we are able to simulate forces that the bike will undergo. Using this data, the designers are able to design a 3D printed core with the required density that is needed. Penultimately, the designer just has to add layers of carbon fiber weave. Lastly, all of this materials will then be consolidated using the 3D printed mould, that will provide the compression force that the carbon fiber needs.

Benefits 

Sustainability

One benefit of this method of manufacturing process is the reusability of the moulds. As moulds are made from thermoplastics, used moulds can be re-melted back and reused to make new moulds. This method reduces the amount of wastage as the 3D printed parts can be reused to create new iterations of designs. According to Tian (2017), “continuous carbon fiber and PLA matrix was recycled in the form of PLA impregnated carbon fiber filament from 3D printed composite components and reused as the raw material for further 3D printing process.” Even after reusing the thermoplastics, materials such as continuous fiber reinforced thermoplastic composites (CFRTC) showed no compromise during the recycling process. Instead, the material gave an increase in 25% higher bending strength than its original form.

https://www.sciencedirect.com/science/article/pii/S0959652616320017

Reduced Cost

As stated above, 3D printed moulds can reduce the tooling cost. This manufacturing process allows lesser wastage compared to conventional processes such as Computer Numerical Control(CNC) machining. For example, products made from CNC came from a block of aluminium. The block of aluminium is then machined down to its specified dimensions to create the product. Excess materials may be recycled but it requires high amounts of energy to recycle.

(- r&d cost) 

https://www.emerald.com/insight/content/doi/10.1108/RPJ-07-2013-0067/full/html

Limitations and Evaluation

There are two categories of cyclists. The first being a serious athlete, whereby every milligram shaved off his bicycle contributes greatly to his performance. Next would be a cyclist who enjoys the sport but does not take part in competitive racing. A hybrid carbon fibre frame at half the price of the commercial carbon fibre bicycle at the slight expense of weight would be sure to appeal to the second group of cyclists.

Despite the reduction in cost, the hybrid carbon fibre frame coupled with 3D printed sandwich structure will experience an increase in weight due to the addition of the core material. This unfortunately will bring down the performance of the bicycle.

However, weight is just one factor taken into consideration. The choice when buying a new bicycle involves other factors such as the feel, stability, comfort, geometry of bike, sizing, aesthetics, functions and presence of mounting holes in the frame. In addition, we could focus more on gravel bicycle, where weight is not such an important factor. 

When it comes to a new product, everyone will have their doubts if the product is truly credible. This is especially the case for our product because our core material is plastic. When it comes to plastic, the word strong and sturdy does not come to mind. It will instill doubt on whether the frame is truly as sturdy as stated.

However, a series of tests on our hybrid carbon fibre frame such as the rockwell hardness test, lateral load fatigue test, falling mass fork impact test etc, with comparison video to the other more commercialized frame will allow customers to have greater faith in our product.

Methodology

Secondary research sources were used as a reference to obtain relevant information for the completion of the report. In addition, prototypes were also developed as a proof of concept. FEA (finite element analysis) using ABACUS was also done to simulate the forces acting on the components. 

Secondary Research

A thorough research on the materials used and the printing method was conducted in order to determine the best combination for the production of the bicycle structure and mold. The team used manufacturer websites and secondary sources to back up our findings. We used official product websites to get the pricing of the bicycles to set it as a benchmark. Secondary sources were then used to explain the high costs of traditional carbon fibre bikes, and to explain the advantages and disadvantages of using 3D printing technique.  

Concluding Statement

This manufacturing process is still in its infancy stage, and requires more time and research to be a fully viable solution. In its current stage, we are able to 3D print the core and the mould. More simulations and optimisations needs to be done, in order to find a perfect ratio of plastic core to carbon fiber. However, when it is fully realised, we will arrive at a bike frame that is sustainable for the environment, and a cheaper alternative to full carbon fiber bikes.

References

Becker, K. (2018, May 18). Carbon Fiber Bike Frames May Become A Whole Lot Cheaper. Retrieved March 2, 2020, from https://www.digitaltrends.com/outdoors/arevo-3d-printed-bike-frame/

Carruthers, J. (2018, April 25). What is Resin Transfer Moulding (RTM)? Retrieved March 2, 2020, from https://coventivecomposites.com/explainers/resin-transfer-moulding-rtm/

Filament Winding. (2019, January 24). Retrieved March 2, 2020, from https://netcomposites.com/guide/manufacturing/filament-winding/

How carbon fibre bicycle frames are made. (2018, January 4). Retrieved March 2, 2020, from https://cyclingtips.com/2018/01/how-carbon-fibre-bicycle-frames-are-made/

Li, T., & Wang, L. (2017). Bending behavior of sandwich composite structures with tunable 3D-printed core materials. Composite Structures, 175, 46–57. doi: 10.1016/j.compstruct.2017.05.001

Meredith, J., Bilson, E., Powe, R., Collings, E., & Kirwan, K. (2015). A performance versus cost analysis of prepreg carbon fibre epoxy energy absorption structures. Composite Structures, 124, 206–213. doi: 10.1016/j.compstruct.2015.01.022

Renner, L. (2018, December 10). The Rise of Carbon Fiber. Retrieved March 2, 2020, from https://blog.propelx.com/what-is-carbon-fiber/

Swaby, R. (2013, June 17). Why Is Carbon Fiber So Expensive? Retrieved March 2, 2020, from https://gizmodo.com/why-is-carbon-fiber-so-expensive-5843276

The Best Aluminum Alloys For Molds. (2017, May 22). Retrieved from https://www.clintonaluminum.com/the-best-aluminum-alloys-for-molds/#:~:text=6061

Why Are Injection Molds So Expensive? – Reading Plastic. (2019, March 29). Retrieved March 2, 2020, from http://readingplastic.com/why-are-injection-molds-so-expensive/

In the article, “The RoboBee Flies Solo,” Harvard John A. Paulson School of Engineering and Applied Sciences (2019) has stated that after decades worth of research, they have successfully developed the lightest ever vehicle to maintain sustained untethered flight on solar power.

They stated they have developed an extremely lightweight circuit and integrated high-efficiency solar cells to tackle the trade-off between mass and power. The addition of an extra pair of wings and a more efficient transmission gave the vehicle the extra lift it needed to forego the power cord and instead, integrates the smallest commercially available solar cells. These weigh in at 10 milligrams each and can harvest 0.76 milliwatts of power per gram, weighing the vehicle at 259 milligrams with a power consumption of 120 milliwatts. It stated their next aim was to add a control board to fly it outdoors.

What the team behind the RoboBee project has accomplished is remarkable. They were able to develop a drone that can sustain untethered flight, in a package that is no heavier than 259 milligrams. However, the RoboBee is still in its infancy stage and is unable to operate outside of controlled lab conditions but regardless, its implementation of untethered flight may be closer to reality than its predecessors.

The most compelling factor as to why the RoboBee is not ready to explore the outdoors is how the solar panels are being utilised. According to Jafferis et al. (2019), it requires the intensity of 3 suns to power the circuitry. They were able to replicate this in the lab by using large Halogen lamps pointing directly at the solar panels. However, stated in the article, the team later reassured that they are planning to work on a model that is 25 per cent times bigger than its current iteration. This would reduce the number of suns to 1.5, much closer to reality.

The second most compelling factor as to why it is not ready for the outdoors is that

it has no battery power reserve. This means that the solar panels that are affixed atop the RoboBee only power the actuators and circuitry. Without a power reserve, any change in pitch or yaw that causes the solar panels to divert away from the light source will cut off the power supply that is powering the actuators. According to  Jafferis et al. (2019), the RoboBee only flew for about 0.5seconds before it flew outside the illuminated area. This reinforced the idea that flying out of the illuminated area, will cause the RoboBee to crash land.

However, it needs to be said that, RoboBee is not the first of its kind to have been developed. Researchers in the University Of Washington unveiled the RoboFly at the IEEE International Conference on Robotics and Automation in Brisbane, Australia in 2018. RoboBee and RoboFly have similar ideas of attaining untethered flight. However, the RoboFly is powered by a laser which is pointed at its photovoltaic cell, which can harvest 250 milliwatts to power the drone. Much like RoboBee, when the light source misses its target, the drone will stop flying. According to James et al. (2018), they stated that they will develop a laser that will track the drone’s photovoltaic cell.

When these two concepts of untethered flight are compared, it seems that RoboBee has a greater potential of flying outdoors than its counterpart. Although there is the issue of requiring three suns to power the RoboBee, it is a more practical solution as there is no need for a laser to track the drone’s movement. The implementation of lasers outdoors to power a drone does not seem practical, especially in huge numbers.

Reference

Jafferis, N. T., Helbling, E. F., Karpelson, M., & Wood, R. J. (2019, June 26). Untethered flight of an insect-sized flapping-wing microscale aerial vehicle. Retrieved from https://www.nature.com/articles/s41586-019-1322-0

James, J., Iyer, V., Chukewad, Y., Gollakota, S., & Fuller, S. B. (2018). Liftoff of a 190 mg Laser-Powered Aerial Vehicle: The Lightest Wireless Robot to Fly. 2018 IEEE International Conference on Robotics and Automation (ICRA). DOI: 10.1109/icra.2018.8460582

The RoboBee flies solo. (2019, June 27). Retrieved from https://wyss.harvard.edu/news/the-robobee-flies-solo/

In the article, “The RoboBee Flies Solo,” Harvard John A. Paulson School of Engineering and Applied Sciences (2019) has stated that after decades worth of research, they have successfully developed the lightest ever vehicle to maintain sustained untethered flight on solar power.

They stated they have developed an extremely lightweight circuit and integrated high-efficiency solar cells to tackle the trade-off between mass and power. The addition of an extra pair of wings and a more efficient transmission gave the vehicle the extra lift it needed to forego the power cord and instead, integrates the smallest commercially available solar cells. These weigh in at 10 milligrams each and can harvest 0.76 milliwatts of power per gram, weighing the vehicle at 259 milligrams with a power consumption of 120 milliwatts. It stated their next aim was to add a control board to fly it outdoors.

What the team behind the RoboBee project has accomplished is remarkable. They were able to develop a drone that can sustain untethered flight, in a package that is no heavier than 259 milligrams. However, the RoboBee is still in its infancy stage and is unable to operate outside of controlled lab conditions.

The biggest factor as to why the RoboBee is not ready to explore the outdoors is how the solar panels are being utilised. According to the paper ”Untethered flight of an insect-sized flapping-wing microscale aerial vehicle,” Jafferies .et al. (2019) it requires the intensity of 3 Suns to power the circuitry. They were able to replicate this in the lab by using large Halogen lamps pointing directly at the solar panels. However, stated in the article, they later reassured that they are planning to work on a model that is 25 per cent times bigger than its current iteration. This would reduce the number of suns to 1.5, much closer to reality.

The second biggest factor as to why it is not ready for the outdoors is that it has no power reserve. This means that the solar panels that are affixed atop the RoboBee only power the actuators and circuitry. Without a power reserve, any change in pitch or yaw that causes the solar panels to divert away from the light source will cut off the power supply that is powering the actuators. Stated by Jafferis” Flights lasted for approximately 0.5s before the vehicle flew outside the illuminated area”. This reinforced the idea that flying out of the illuminated area, will cause the RoboBee to crash land.

However, it needs to be said that, RoboBee is not the first of its kind to have been developed. Researchers in the University Of Washington unveiled the RoboFly at the IEEE International Conference on Robotics and Automation in Brisbane, Australia in 2018. RoboBee and RoboFly have similar ideas of attaining untethered flight. However, the RoboFly is powered by a laser which is pointed at its photovoltaic cell, which can harvest 250 milliwatts to power the drone. Much like RoboBee, when the light source misses its target, the drone will stop flying. In the article, “ Liftoff of a 190 mg Laser-Powered Aerial Vehicle: The Lightest Wireless Robot to Fly,” James, et al. (2018), it stated that they will develop a laser that will track the drone’s photovoltaic cell.

When comparing the two implementations of untethered flight, it seems that RoboBee has a greater potential of flying outdoors than its counterpart. Although there is the issue of requiring three suns to power the RoboBee, it is a more practical solution as there is no need for a laser to track the drone’s movement. The implementation of lasers outdoors to power a drone just does not seem practical, albeit difficult to do, especially in huge numbers.

Reference list

Jafferis, N. T., Helbling, E. F., Karpelson, M., & Wood, R. J. (2019, June 26). Untethered flight of an insect-sized flapping-wing microscale aerial vehicle. Retrieved from https://www.nature.com/articles/s41586-019-1322-0

James, J., Iyer, V., Chukewad, Y., Gollakota, S., & Fuller, S. B. (2018). Liftoff of a 190 mg Laser-Powered Aerial Vehicle: The Lightest Wireless Robot to Fly. 2018 IEEE International Conference on Robotics and Automation (ICRA). doi: 10.1109/icra.2018.8460582

The RoboBee flies solo. (2019, June 27). Retrieved from https://wyss.harvard.edu/news/the-robobee-flies-solo/

In the article, “The RoboBee Flies Solo,” Harvard John A. Paulson School of Engineering and Applied Sciences (2019) has stated that after decades worth of research, they have successfully developed the lightest ever vehicle to maintain sustained untethered flight on solar power.

They stated they have developed an extremely lightweight circuit and integrated high-efficiency solar cells to tackle the trade-off between mass and power. The addition of an extra pair of wings and a more efficient transmission gave the vehicle the extra lift it needed to forego the power cord and instead, integrates the smallest commercially available solar cells. These weigh in at 10 milligrams each and can harvest 0.76 milliwatts of power per gram, weighing the vehicle at 259 milligrams with a power consumption of 120 milliwatts. It stated their next aim was to add a control board to fly it outdoors.

What the team behind the RoboBee project has accomplished is remarkable, to say the least. They were able to maintain untethered flight, in a package that is no lighter than 259 milligrams. However, the project is still in its infancy stage and is unable to operate outside of controlled lab conditions. 

The biggest factor as to why the RoboBee is not ready to explore the outdoors is how the solar panels are being utilised. Currently, it requires the intensity of 3 equivalent Sun lumens to power the circuitry. They were able to replicate this in the lab by using large Halogen lamps pointing directly at the solar panels. However, stated in the article, they reassured that they are planning to work on a model that is 25 percent times bigger than its current iteration. This would reduce the number of suns to 1.5, much closer to reality. 

The next factor is that the current iteration does not have any onboard batteries. The solar panels that are affixed atop the RoboBee only power the actuators and circuitry. This means that if the solar panels are not directly facing the light source, due to a change in pitch or yaw, it would face a disrupt in power supply. This is evident in their test flight video, that demonstrates the RoboBee taking off, but a second later, it comes crashing down. The disrupt in power supply could be a cause of this. As stated before, a larger model of the RoboBee is being developed, and as such, will have space to hold batteries.

The last factor is that it currently does not have any flight control on board. In a closed environment, the RoboBee can maintain sustained flight. However in the outdoors without a flight control system, the RoboBee is unable to take into account external forces such as the speed of the air. This will cause the RoboBee to go haywire. A flight control system is imperative if the RoboBee is to fly outdoors.

It needs to be said that, RoboBee is not the first of its kind to have been developed. Researchers in the University Of Washington unveiled the RoboFly at the IEEE International Conference on Robotics and Automation in Brisbane, Australia in 2018. Both have similar ideas of attaining untethered flight, by using alternative sources of energy. Remarkably, the RoboFly is powered by a laser being pointed at its photovoltaic cell, which can harvest 250 milligrams to power the drone. However, when the laser misses its target, the drone will be powerless and will come down crashing. They stated that their next move was to develop a laser that will track the drone. This may not be so practical  Thus, comparing the 2 drones, it can be said that the RoboBee, could be a more viable concept of untethered flight outdoors. 

References

https://spectrum.ieee.org/automaton/robotics/robotics-hardware/laser-powered-robot-insect-achieves-lift-off

https://spectrum.ieee.org/automaton/robotics/robotics-hardware/solar-powered-robobee-xwing-flies-untethered

https://www.nature.com/articles/s41586-019-1322-0

In the article, “The RoboBee Flies Solo,” Harvard John A. Paulson School of Engineering and Applied Sciences (2019) has stated that after decades worth of research, they have successfully developed the lightest ever vehicle to maintain sustained untethered flight on solar power.

They stated they have developed an extremely lightweight circuit and integrated high-efficiency solar cells to tackle the trade-off between mass and power. The addition of an extra pair of wings and a more efficient transmission gave the vehicle the extra lift it needed to forego the power cord and instead integrate the smallest commercially available solar cells. These weigh in at 10 milligrams each and are able to harvest 0.76 milliwatts of power per gram, weighing the vehicle to 259 milligrams and power consumption of 120 milliwatts. It stated their next aim was to add a control board to fly it outdoors.

Reference list:
Harvard John A. Paulson School of Engineering and Applied Science. (2019, June 26). The RoboBee Flies Solo: Cutting the power cord for the first time untethered flight. ScienceDaily. Retrieved from http://www.sciencedaily.com/releases/2019/06/190626133712.htm

In the article, “The RoboBee Flies Solo,” Harvard John A. Paulson School of Engineering and Applied Sciences (2019) has stated that after decades worth of research, they have successfully developed the lightest ever vehicle to maintain sustained untethered flight with the help of solar power.

They stated they have developed an extremely lightweight circuit and integrated high-efficiency solar cells to tackle the trade-off between mass and power. The addition of an extra pair of wings and a more efficient transmission gave the vehicle the extra lift it needed to forego the power cord and instead integrate the smallest commercially available solar cells. These weigh in at 10 milligrams each and are able to harvest 0.76 milliwatts of power per gram, weighing the vehicle to 259 milligrams and power consumption of 120 milliwatts. It stated their next aim was to add a control board to fly it outdoors.

Dear Professor Brad Blackstone

My name is Muhammad Zulhusni Bin Jumat and I am a student from MEC 1281, and the purpose of this letter is to explain to you my educational background and my interest in mechanical engineering. Also, I will be discussing about my strengths and weaknesses in communication, and two specific goals I aim to achieve by the end of this module.

My interest in Engineering started since I was in primary school, when I was tasked to build a model of our solar system. It was during the project, that sparked my interest for Engineering as I contemplated on how the world works and I wanted to learn more. Hence,  I decided that I would study Mechanical Engineering at Ngee Ann Polytechnic to further my curiosity. 

It was through my Final Year Project (FYP) in polytechnic that I discovered my strengths and weaknesses. My strength is that I feel confident and I am able to project that confidence when presenting. It was critical that our presentations to our advisors and professors were accurate so that they would understand our project well.

My weakness however, is when I am writing letters and emails to my advisors. I struggle to be able to illustrate my ideas when I am not speaking to them face to face. I lack the finesse to write an email that clearly strikes the right tone and find the appropriate vocabulary to describe my idea.

Hence, I want to learn how to communicate my ideas through email more effectively, as I lack the opportunities to practice more. Secondly, I want to reinforce my presentation skills and bring it to the next level.

Thank you for your time and have a great week ahead.

Sincerely

Muhammad Zulhusni Bin Jumat

MEC 1281 T4