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Here is a B-2 Spirit:

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enter image description here

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Many different things can get in the way with a design like a B-2. Although it has really good stealth and looks, does it have any disadvantages that come with the good stealth and looks?

  1. What kind of disadvantages would this aircraft have of an airliners design or another bombers design like the B-52 or B-1?

  2. What system does this aircraft use to overcome not having stabilizers?

  3. Why have only 22 ever been built?

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    $\begingroup$ By looks I mean its one cool looking aircraft. $\endgroup$
    – Ethan
    Sep 17, 2015 at 21:45
  • $\begingroup$ Related. (As many other questions about flying wing) $\endgroup$
    – Manu H
    Jun 3, 2018 at 22:41

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The main problem with the B-2 Spirit (or any flying wing aircraft, for that matter) is that they are statically unstable.

Flying wing stability

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If the lift vector of the wing acts before the center of gravity (as is the usual case when only wings are considered), any perturbation which results in an increase in angle of attack results in a positive moment about the center of gravity, which further increases the angle of attack an so on.

The only way to control such an aircraft is through computers, which continuously detect any changes in the aircraft attitude and apply corrections as required, as it is near impossible (or incredibly taxing) for human pilots to fly the aircraft.

This is the method used in order to 'fly' the B-2 Spirit in the absence of a horizontal stabilizer. If there is any problem with the flight computer (which is remote) or with the sensors supplying data to it, the aircraft will become unflyable and crash.

Another control issue with the B-2 is that the aircraft has little directional stability with no vertical tail. The swept wing offers some stability, though not in the same level as a vertical tail.

Aircraft Directional stability

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Actually, only 21 of these were built, for the following reasons:

  • The B-2 is costly; by costly I mean probably the most expensive aircraft ever built. With a total program cost of over 45b USD, each aircraft costs a whopping 2.1b USD (which was caused due to reduction in numbers from the initial 132). Also, the (hourly) operating costs of B-2 are twice that of other bombers in the USAF fleet.

  • With the dissolution of the Soviet Union, the B-2 had effectively become an aircraft without a mission, as it was primarily designed to penetrate Soviet air defence systems.

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    $\begingroup$ That's about as expensive as a Shuttle, and more expensive than a Nimitz-class nuclear supercarrier (barring airplanes). That's pretty expensive. $\endgroup$
    – Nathan Tuggy
    Sep 18, 2015 at 18:59
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    $\begingroup$ If they'd built the number they meant to build they'd only have cost about $500m each, so give the guys a break. ;-) $\endgroup$
    – Dan Sheppard
    Jun 3, 2018 at 19:22
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    $\begingroup$ Flying wing is not necessarily statically unstable. There were plenty of prehistoric flying wings without any computers and they flew just fine. It just takes a correct choice of airfoil (and S-curved one with negative camber near the trailing edge), or, with sufficient sweep angle, a significant negative wing twist. $\endgroup$
    – Zeus
    Jun 4, 2018 at 3:16
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    $\begingroup$ Another instance where the complete nonsense of unstable flying wings is repeated. But it doesn't become true – flying wings can be made perfectly stable. Low damping is harder to eliminate, though. $\endgroup$
    – Peter Kämpf
    Nov 22, 2019 at 23:38
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    $\begingroup$ There are r/c model B-2s that fly just fine, along with the Dunne biplane of the early 20th century. The B-2, with its swept wings and serrated trailing edge, has enough length to be reasonably stable. The computers may be more needed for fuel saving "relaxed stability" required for very long missions. Also, the "gigantic keel" of a paper airplane is little more than vertical stabilizer. Try making paper airplanes with varying degrees of dihedral and "keel". Owing to their much greater surface area to weight ratio, these are predominantly aerodynamic creatures. $\endgroup$
    – Robert DiGiovanni
    Nov 24, 2019 at 1:34
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If you’re talking about flying wings, which is what a B-2 Spirit is, they offer the following advantages and disadvantages:

ADVANTAGES

  • Extremely clean design. The absence of a fuselage, empennage, Engine pylons, etc. eliminates virtually all parasite drag from form and skin fraction drag associated with these structures. Elimination of all OML structural features outside of the wing optimizes top structure to the pure task of generating lift, offering faster speeds and better fuel efficiency. To my knowledge, the B-2 is the fastest subsonic aircraft in existence today with an Mmo of Mach 0.95.

  • Low Radar Cross Section. Something known since WWII when the German Horton brothers developed flying wings. Combines with advanced radar absorbent materials, shaping, edge alignment, and some other ‘secret sauce’, flying wings become very difficult to detect on radar. The B-2 is said to have an RCS ‘in the insect category’.

  • Reduced airport footprint. Flying wings are shorter and more compact than conventional airplanes.

DISADVANTAGES

  • Lateral and directional stability problems due to shifting CL and no tail moment arm. This can be alleviated using advanced digital flight computers to provide artificial stability.
  • More complex to manufacture due to their shaping and size.
  • Unsuitable for transport category aircraft due to impracticality of seating positions not on C/L or emergency egress from aircraft.

As mentioned above a B-2 is a fly-by-wire aircraft and uses digital flight control systems to manage Cp as well as differential spoilerons at the wingtips to provide directional control. The airplane would be unflyable without them.

The Advanced Technology Bomber program of the 1980s, which became the B-2, originally envisaged buying 132 aircraft as replacements for the existing B-52 airplane. Development delays and cost overruns resulted in the first B-2s leaving the production lines at around 520 million per airplane in 1990 USD. With the demise of the Soviet Union in the early 1990s, the major threat the airplane was to counter disappeared. This combined with dwindling defense budgets reduced the procurement number down to 21 airplanes, which each having to bear more of the development costs, resulted in an average unit cost of 2.2 billion USD, making it the most expensive plane to ever fly from a runway.

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