The U.S. Army has ordered three LEMV (Long-Endurance Multi-intelligence Vehicle) UAVs from Northrop Grumman, for $173 million each. The LEMVs are to be delivered by 2013. Northrop Grumman is using an old aircraft research project to get all this design, manufacturing and testing done in time. LEMV is based on the existing (and tested) Hybrid Air Vehicle ( HAV), which was an aerodynamic blimp built to transport cargo. HAV looks like a flattened blimp, a wide airship with much better handling qualities. LEMV is an unmanned blimp that can carry 1.1 tons of sensors, stay aloft for 21 days at a time, supply 16 kilowatts of power and move at up to 148 kilometers an hour at 6,400 meters (20,000 feet) altitude.
The idea of a cargo carrying blimp has been around for over three decades, and the concept is simple. An aerodynamic blimp is a helium filled aircraft, with a rigid, but lightweight, shell that is aerodynamic (like an airplane wing.) Thus the aerodynamic blimp takes off and flies like an aircraft, gaining additional lifting power in the process, and able to carry heavy and bulky cargoes using low power (and low fuel consumption) engines. All past efforts to make aerodynamic blimps practical have failed because these aircraft are still lighter than air vehicles, and difficult to handle on the ground or whenever it's windy. They are also large and bulky compared to conventional transports. But the LEMV avoids the handling problems, because the aircraft only lands once every three weeks. The LEMV would be able to lift up to five tons, with most of that being fuel for the 21 day mission.
Northrop Grumman believes that advances in materials and automated flight controls make these aerodynamic blimp UAVs practical. But, so far, no one has created a commercially viable example of the concept for carrying cargo. DARPA believed that the problems were soon going to be solved, and helped keep the competing P-791 development going, and into the air. Now, LEMV will take a P-791 competitor, the HAV, out of the lab, and onto the battlefield. The army wants LEMV to provide radar and photo coverage of large areas in Afghanistan, for extended period. LEMV would do it better and cheaper than existing UAVs. LEMV would use existing UAV sensors and communications, and would basically act like a Predator or Global Hawk, but with more cameras.
This is an example of an evolutionary technology. Engineers (and some tech savvy historians) understand how some of these crazy ideas eventually do become economically practical. The problem is figuring out when the needed technologies will all mature and make it possible to build workable, and commercially self-sustaining, products. Get involved too early, and you spend a lot of money, with little return. Get in too late, and you just end up another competitor in a crowded market. Lockheed seems to sense that the sweet spot (the time when the first commercially viable products can be built, and the highest profit margins are available) is on the horizon, and they got there first by turning HAV into LEMV.