Pentagon crazytech researchers look to be revisiting a long-speculated-upon idea: that of helicopter blades which could extend or shorten in length during flight. This would offer major performance benefits, and such options as whisper mode or easier operations in confined spaces.
The latest development in the telescoping rotor blade world originates at DARPA, the Pentagon tech barbershop where they only know one style - Lunatic Fringe. DARPA has just kicked off a new extendy-shrinky-copter push under the rather dull name "Mission Adaptive Rotor", or MAR.
According to the Pentagon propellor-heads:
The goal of the Mission Adaptive Rotor (MAR) program is to develop “on-the-fly” morphing rotor technology and demonstrate the dramatic benefits possible using this capability to reconfigure the rotor in flight, either during each rotor revolution, between mission phases, or both. Applications for both tilt rotors and edgewise rotors are equally acceptable.
DARPA will be holding an industry day tomorrow, to get a sense of how many people think they can make a morphing rotor blade. There will probably be quite a few, judging by prior examples of the idea such as this.
It would obviously be excellent to have variable-length rotors on a V-22 Osprey style tiltrotor - though some would argue that the plane/copter combo is already complicated enough. The ability to have a large rotor disc pointing up for good hover performance and a smaller one pointing sideways for good aeroplane performance would definitely help.
DARPA believe that a more ordinary morphcopter unable to swivel its rotors would still be excellent - the agency's boffins expect that there would potentially be gains of 30 to 40 per cent in payload or range, a halving of acoustic detection range due to increased quietness, and a huge 90 per cent reduction in vibration.
One might alse choose to use the morphblade tech in unexpected ways: for instance a big chopper might actually shrink its rotor disc on setting down, so losing some performance but gaining the ability to land in a tighter space than would normally be possible/safe.
The whole thing sounds a trifle questionable - a helicopter is already a chancy enough proposition without making it even fiddlier. Still, if DARPA have no luck with this notion they might with one of their other crazy whirlycraft programmes: the Heliplane, the saucercopter, the robotic whisper-gunship or the Casimir-effect gecko hovership. The agency appears to be of the opinion that there's no such thing as a long shot, as long as you use a multibarrelled autohowitzer triple-shotted with barrels of cash.
Then there'll just be the little matter of getting it to turn into a giant robot, pickup truck etc. ®