Flying by Solar Power

Published on Tuesday, 01 June 2010 11:48

By Rachael Olajide

With approximately 6000 flights per day worldwide, we have come a long way since that first flight by the Wright brothers. Aviation fuel has been the primary source of energy for airplanes for a long time, but as the Solar Impulse HB-SIA makes a successful landing in its first ever 36 hours non-stop flight completley powered by solar energy, we debate the future of Solar energy within the aviation industry.

The harnessing of solar energy by humans dates back hundreds of years. Solar powered air travel however dates back to just 1980, when Aerovironment Inc in conjunction with NASA's Dryden Flight Research Centre began experimenting with modern alternative aircraft design and so far, has achieved several altitude records with its Solar Challenger, Pathfinder and Pathfinder-Plus aircraft.

In Europe, solar powered travel reached new heights with the invention of the Solar Impulse when Bertrand Piccard came up with his idea following the Orbiter 3 program.

 

For the past seven years, a team based in Switzerland and led by Piccard and André Borschberg has been developing a new solar powered aircraft. The prototype aircraft is made of lightweight materials, weighs only 3,500 pounds, has a wingspan of 210 feet and is powered entirely by the 11,000 solar cells covering its wings.

Their main objective as stated on the Solar Impulse website (www.solarimpulse.com) is to show what can be achieved using solar energy and encourage its further development and wider use. Piccard states "We want a strong symbol capable of striking people's minds. In this respect, Solar Impulse will be our ambassador. The message we want to share is that it is essential to develop new technologies to allow our society to reduce its energetic consumption. As it is almost unthinkable that people will accept to diminish their life standards, we must develop efficient equipments that consume less, as well as alternative sources of energy and first of all solar energy".

Following Solar Impulse's recent test flight success we spoke to three industry experts to get their views . Jared Smith is a Senior Systems Engineer at Sparta which specializes in the development, delivery and support of leading edge aerospace and defense systems in the air, on land and sea. Bronwyn Ximm who is a Green Consumerism Writer and Stuart Walker; a Principal Consultant at Dakota Ridge Technologies LLC which specializes in Avionics and Systems for Aerospace Applications speak to Rachael Olajide for Ask the Experts.

RO: Hello Jared. What are your current thoughts after the recent 36 hours nonstop flight completely powered by Solar Energy?

JS: The 36 hour flight with a passenger (one or more) is certainly now looking achievable. In fact, if you can stay aloft for 24 hours and flight duration is only really limited by human endurance, equipment failure or degradation. Note that duration record flights of many days were set in the 1920s and 1930s using gliders, which in the end analysis are solar powered as well. Duration record efforts were cancelled due to safety issues associated with human fatigue. Today, gliders compete for distance and speed, able to average 80 to 100 mph over hundreds of miles in favourable conditions.

RO: Does this mean that a solar powered passenger aircraft being built is imminent?

JS: If you mean a very specialized, single purpose system intended to set or break endurance records with one or more people aboard, then yes. If you mean a schedule airline-like operation with paying passengers who demand the same reliability and safety as what is the currently standard, then no. From the solar impulse web site; Project CEO, André Borschberg, says, "Anything that doesn't break is potentially too heavy! There are not the structural margins suitable for passenger travel yet".

RO: What is the effectiveness of solar powered technology? Some say it is unclear if it will work?

JS: The problem is not necessarily the technology, but the power supply. The cell area can't exceed the area on the upper surface of the aircraft. Also, the non-orthogonal presentation to the Sun and night periods mean that you can only use about a third of the power generated by the collection system for flight on average. Perhaps using cell technology and directed energy could work, but directed microwave technology seems simpler at present.

RO: What are the major things to overcome today to make solar powered travel useful and widely developed?

JS: Long distance, low loss power transmission systems and large scale industrial electrical power storage are what is needed.

The Solar Impulse aims to have an airplane take off and fly autonomously, day and night, propelled uniquely by solar energy, right round the world without fuel or pollution. This makes it appealing to green groups and anyone concerned about the environment

RO: How will this aim be received by environmental groups?

BX: A solar-powered aircraft is an environmentalist's dream, so I imagine it will be received very positively. However, widespread love and devotion among conservationists will come only if economies of scale can be achieved that make riding on the craft affordable to regular folk like you and me.

RO: What will be the main benefits of renewable energy to the aviation industry?

BX: Currently air travel brings with it an abominable carbon footprint, so this has the potential to green an industry that few people thought would ever be greenable

Discussing the possibility of replacing solar airlines with conventional ones, the Solar Impulse website maintains that currently, technology only allows the transport of a single person on a flight of 24 hours.

RO: So Stuart, what is the immediate future of the Solar Powered Aircraft?

SW: I think there will be many versions of Solar Powered Unmanned Aerial Vehicles (UAV's).

There are some in development now, mostly for defence applications. Applications like communication relay stations, border monitoring, surveillance, high altitude science and long term high altitude flight will dominate the uses for solar powered aircraft.

It is worth noting that air ships in the form of blimps are also being developed. Defense departments are funding most of the development in the US. There are also very small applications in the form of small UAVs and little hoppers that can move from one place to another and provide monitoring. These aircraft would fit in the palm of your hand and are called Nano-UVs.

The Solar Impulse is set for a solar powered around the world flight in 2012. By then, it is expected to fly both day and night without fuel.

Related Videos & Links

Solar Impulse

NASA

Test of Round The World Solar Power (Video)

Take off (Video)

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