The US Army has canceled the Boeing Hummingbird:

This month, the Army planned to deploy to Afghanistan an unusual new drone: an unmanned eye-in-the-sky helicopter programmed to use high-tech cameras to monitor vast amounts of territory. But now the drone might be lucky to be deployed at all, as the Army has moved to shut down production — possibly ending the program forever.

That drone would be the A160 Hummingbird, which the Army planned to equip with the powerful Autonomous Real-Time Ground Ubiquitous Surveillance Imaging System, or Argus. But earlier this month, the Army issued a stop-work order — one step away from termination — to the drone’s developer Boeing. The reason? A high “probability of continued technical and schedule delays,” costs and risks that have “increased so significantly that program continuation is no longer in the best interest of the government,” said Donna Hightower, the Army’s acting product manager for unmanned aerial systems modernization.

The A160 was set to be one of the Army’s most radical new drones. The chopper-drone could loiter for 20 hours at up to 15,000 feet, with a range of 2,500 nautical miles. It could observe up to 36 square miles, thanks to its Argus sensors. Also, Argus has a 1.8 gigapixel camera. Viewed through 92 five-megapixel imagers and 65 video windows for zooming in at ultra-high resolution, the the A160 drone would have been well-suited for spying on enemy fighters in vast and remote terrain like in Afghanistan, where three of the drones were scheduled to deploy this month. The A160 has also been sent on special operations workouts.

It appears that there were problems with the sensor suite, but perhaps more significantly, the aircraft experienced vibration problems during a flight test, and it’s innovative variable speed rotor system was supposed to address this, so it puts the basic architecture in question.