The U.S. Air Force likes to think ahead, and they love expensive heavy bomber projects. So it's no surprise that the Hypersonic Cruise Vehicle (HCV) is being proposed as the air force's next heavy bomber. Projected (by people who are more into PR than engineering) to enter service in 2025, the HCV could fly high enough to go into a low orbit, thus being speedy enough to reach any point on the earth within two hours. The air force wants to replace air craft carriers for dealing with overseas hot spots. The major problem with the HCV is the laws of physics. It takes a lot energy (fuel) to get up that high, and you want to carry a useful bombload (at few tons). The HCV will not have a crew, but will be operated remotely and by onboard software. While progress, in the last few decades, has been made in producing new engine designs that could make the HCV work, the air force is asking for a blank check to make it happen in the next twenty years. It won't be cheap, and it may not work. Look at the B-2. So expensive that only 21 were built (at about two billion dollars each), they have seen little use. The half century old B-52 is still the heavy bomber of choice. But the HCV is the kind of project that gets the competitive juices flowing in engineers, defense executives and politicians who want to spread those big HCV bucks around to get re-elected. "Will it work?" is of less importance than "will be fully funded." Hang on to your hats, and your wallets, as this is going to be a rough and expensive ride.