How can the B-2 Spirit fly without vertical stabilizers?
The B-2 Spirit provides the US Air Force (USAF) the penetrating flexibility and effectiveness inherent in manned bombers. Its low-observable, or “stealth,” characteristics give it the unique ability to penetrate an enemy’s most sophisticated defenses and threaten its most valued, and heavily defended, targets. Its capability to penetrate air defenses and threaten effective retaliation provides a strong, effective deterrent and combat force.
The revolutionary blending of low-observable technologies with high aerodynamic efficiency and large payload gives the B-2 important advantages over existing bombers. Its low-observability provides it greater freedom of action at high altitudes, thus increasing its range and a better field of view for the aircraft’s sensors. Its unrefueled range is approximately 6,000 nautical miles (9,600 kilometers).
The B-2’s low observability is derived from a combination of reduced infrared, acoustic, electromagnetic, visual and radar signatures. These signatures make it difficult for the sophisticated defensive systems to detect, track and engage the B-2. Many aspects of the low-observability process remain classified; however, the B-2’s composite materials, special coatings and flying-wing design all contribute to its “stealthiness.”
The B-2 features all these capabilities in an airframe without vertical stabilizers.
How can it fly without vertical stabilizers?
“A vertical stabilizer is a simple, easy way to get yaw control. A vertical stabilizer plus rudder offers a quick, cheap mechanism for yaw authority.
“You don’t need a vertical stabilizer. You can gain yaw authority by using things like control surfaces that give you differential drag on the trailing edges of the wings, or even by using asymmetric thrust.
“But here’s the thing: doing that is hard. It requires constant active control. An aircraft without a vertical stabilizer is not stable without constant adaptive control, that’s why the original Flying Wings (such as the YB-49) crashed.”
“Birds have constant adaptive control. They have a brain and nervous system that allows nonstop fine-tuning, generally through differential drag—they can change the position of their feathers to control yaw.
“It’s only been recently that avionics by means of computer assistance have allowed aircraft (such as the B-2 and the future B-21 Raider) to do the same.”
Photo credit: U.S. Air Force