Solar Powered UAV to Set Aviation Endurance Record?

Iddo Genuth writes to mention that a group of Israeli students is hoping their latest unmanned aerial vehicle (UAV) will soon break the world aviation record for endurance that has stood for over 17 years. The piece features a short history of solar power aviation and an interview with the students.

Comments

Low-cost Satellites

[writerjosh]

This is why solar powered flight is important:

"Called the Zephyr, it's an aircraft that can fly continuously using nothing but solar power and "low drag aerodynamics". The combination of solar panels on the upper wing surface and rechargeable batteries allows Zephyr to be flown for many weeks and even months. The first flight trial of the Zephyr were conducted recently by QinetiQ in White Sands Missile Range, New Mexico.

Two aircraft were flown for four and a half and six hours respectively, the maximum flight times permitted under range restrictions. The maximum altitude attained was 27,000 feet above sea level. The ultra-light aircraft is designed to fly at altitudes as high as 132,000 feet (25 miles/40km), above normal commercial air-lanes and most weather.

QinetiQ believes that stratospheric platforms will rapidly become commercially viable and revolutionize future communications. High altitude platforms of this sort could provide a cheaper alternative to satellites in remote areas and developing countries. They can also enable observation of natural disasters and humanitarian crises."

http://www.treehugger.com/files/2006/03/solar_powe red_p_2.php

Re:Low-cost Satellites

[nsayer]

Among the advantage to stratospheric platforms over geostationary orbit satellites:

1. Antenna aiming isolation. The same downlink frequency can be shared by many more users since the downlink antennas could be directional enough (like satellite dishes are) to reject other sources. This is true of geostationary orbit satellites, but the locations can only really be varied along an arc over the equator. Aeronautical platforms can be moved in two dimensions (obviously they really are in 3 dimensions, but the antenna aiming will still simply be azimuth and elevation).

2. Better geographical isolation. Because they're lower, their horizon area will be much, much smaller. This means their service areas can be more easily limited. This can be done with antenna geometry for geostationary orbit satellites, but in general they can still see almost an entire hemisphere of the earth, so they can still raise the noise floor in otherwise out-of-service areas.

3. Less delay. Geostationary orbits are far enough away that they introduce a delay that is unacceptable for most duplex applications (such as telephone or Internet traffic). Aeronautical platforms would be close enough to the ground that that delay would likely not be a factor.

4. More servicable. The cost of launching geostationary payloads means that the payloads must be designed for a long service life, which raises the cost of the payload significantly, as well as the risks. Aeronautical platforms simply have to come down for a landing, be serviced, and then take off and fly back to station.

5. Less chance of solar outages. Twice a year, there are a few days in a row where geostationary satellites transit the sun. Often, their signal gets drowned out when that happens. Aeronautical platforms stationed outside of the tropics, the problem can be avoided pretty easily (simply place the station to the north of the service area for the Northern hemisphere or to the south of the service area for the Southern hemisphere).