The next generation of low-flying manned and unmanned aircraft will incorporate more technology to reduce their daytime visibility. Current generation aircraft designs emphasize reducing radar and heat signature, so they can't be successfully detected by enemy air defense when they fly at altitudes of 20,000 feet and higher. The farther away from sensors on the ground, the more effective such "stealth" measures are.
However, high-powered microwave weapons to scramble electronics and "cyberwar" electronic attacks on enemy command-and-control networks, both require the attacking platform to get relatively close to the target within a kilometer or less. Unmanned aircraft and combat helicopters have to close to within "the whites of their eyes" range in order to perform their missions. Finally, long-endurance UAVs have bigger wing-spans and airframes and fly more slowly to have the endurance for missions of 14 hours and longer; such aircraft are much more visible from the ground than a typical fighter and can't simply dash in and out of a target area.
The U.S. has been experimenting with reducing visual "signature" over the past 20 years and the need to be in close range for electronic warfare attacks has revived interest in the field. Initial attempts to have aircraft skins that could be lighted or change texture were initially very impractical, being too heavy and soft to use on high-speed aircraft. Currently, DARPA has several classified projects experimenting with electronic "skins" that can be changed to make surfaces more or less reflective depending on the aircraft's background, but weight and power requirements are making it a challenge to put a system on a UAV.
Critics are skeptical that systems can be built to provide 360 degree coverage on an aircraft that are fast enough to successful allow an aircraft to blend in with its background. However, a crude version of an "invisibility cloak" has been built by a Japanese scientist, so the underlying technology and principles for visual stealthy have been demonstrated by a third party working with unclassified gear. Doug Mohney