DARPA developmentsDARPA wants shrink-blade helicopters
DARPA is looking at a helicopter — or “morphcopter” — with shrinking blades; adjustable shrinking blades would offer performance benefits and options such as whisper mode for easier operations in confined spaces
Here is an idea DARPA researchers are revisiting: helicopter blades which could extend or shorten in length during flight. This would offer performance benefits, and such options as whisper mode or easier operations in confined spaces (on whisper mode for UAVs, see 24 January 2009 HS Daily Wire). DARPA has just kicked off a new shrinking-helicopter push under the name “Mission Adaptive Rotor,” or MAR. According to DARPA:
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 held an industry day to get a sense of how many people think they can make a morphing rotor blade. Lewis Page writes that there should be quite a few, judging by earlier examples of the idea being floated.
It would be a good idea to have variable-length rotors on a V-22 Osprey style tiltrotor — even if some would argue that the plane/copter combination is already complicated enough. Page notes that the ability to have a large rotor disc pointing up for good hover performance and a smaller one pointing sideways for good airplane performance would definitely help.
DARPA believe that a more ordinary morphcopter unable to swivel its rotors would still be excellent — the agency’s researchers expect that there would potentially be gains of 30 to 40 percent in payload or range, a halving of acoustic detection range due to increased quietness, and a huge 90 percent reduction in vibration. There are other advantages in choosing to use the morphblade tech: 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.
Whether or not taking a helicopter, which is already a chancy enough proposition, and making it even more complicated is a good idea or not is a good question. Such questions, however, never appeared to stop DARPA from trying new things. Just consider some of their earlier, and more fringe-hugging, programs: 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,” writes Page.
