The Mysteries of the B2
August 23, 2002
Page 6
B2 Air Intakes. Final Reflections.
Let's examine them more closely. On page 7, we read that the aircraft is powered by four non-afterburning General Electric F118-GE-100 engines (noting in passing that these engines, already used in the B1 among other platforms, did not require any new study and cannot explain the B2's exorbitant cost). The Spirit's speed is 1,094 km/h (given as corresponding to "high subsonic") with a ceiling of 15,000 meters. Still on page 7, we learn that to prevent turbine blades from reflecting radar echoes, the engines are housed within the wings, recessed inward. This aligns with the images of the air intakes shown on pages 14 and 15.
The left engine's air intake. Leading edge shaped like a "sawtooth."
Similarly, a boundary layer trap is visible near the wing surface.
At the center, apparently a partition separating the flows destined for the two turbojets (both lacking afterburners). It is specified that this incoming airflow, captured by these "boundary layer traps," is later mixed with the exhaust gases to reduce the infrared signature. The following image shows this air intake from another angle.
On the photo located at the top left of page 15, despite the image being somewhat flattened by this near-frontal view, a "zig-zag" connection ("hairpin junction" in the text, meaning a hairpin-shaped joint) can be seen on the upper part of the engine nacelle. It is known that this zig-zag structure helps attenuate electromagnetic signals re-emitted by any leading or trailing edge, which behave like antennas. The zig-zag shape is a classic feature in stealth design, ensuring that facing parts mutually reduce each other's echo signals. A zig-zag cut can be found not only on all parts of the aircraft serving as leading or trailing edges, but also on all junctions between materials of different types (or even the same type, as with all the aircraft’s hatches, such as landing gear doors). On the photo from the brochure, this zig-zag cut is visible on the upper part of the engine nacelle. This suggests a system designed to ensure stealth in the air intakes. The wall responsible for deflecting airflow from the wing's upper surface toward the engine compressor would be transparent to radar waves. Immediately behind it would be a 45° reflector, redirecting these waves upward through a window also transparent to radar waves, with the zig-zag cut indicating the boundary—the junction with a stronger material forming the intake cover, which must withstand significant stresses (perhaps metallic).
We have a side view showing how the engine nacelles protrude from the upper surface of the wing:
Here is what the engine installation would look like (in rear position: they are short because they lack afterburners, as indicated in the brochure).
As stated in the brochure, the four standard General Electric F118-GE-100 engines are housed within the wing in such a way that radar waves cannot reach the turbine blades, either at intake or exhaust. This suggests a stealth-ensuring device. For this, it suffices that the partitions deflecting the exhaust gases be transparent to radar waves, and that, as indicated, metallic partitions reflect them toward the stars (a system analogous to that of the F-117A's air intakes, described in my book). However, stealth-related issues still remain. The brochure states on page 38 that the B2's wing lacks leading-edge flaps. Its 33° sweep implies a fairly nose-up attitude during landing.
The B2's wing features a sharp leading edge in the section ahead of the fuselage (which does not contribute to lift). In contrast, the following photos show that the leading edges of the "wings proper" are very rounded. This is consistent with a subsonic wing design, but results in a large frontal surface that strongly reflects radar waves. We are told the aircraft's surface is covered with a special coating, both very thick (7 to 10 cm) and extremely fragile (requiring B2s to be quickly stored in hangars), and even sensitive... to weather. All this is difficult to understand, given that an aircraft flying at 15,000 meters or intended for "all-weather missions" is subject to considerable meteorological stress—whether rain, hail, or radiation.
It should also be noted that this famously thick protective coating appears to be absent from the landing gear doors or other photos showing bomb bay doors. If anyone has an explanation...
The brochure gives a few brief details about the absorption technique, consisting of embedding fine metallic particles within the coating's thickness. This is also said to apply to the cockpit windshield, which is likewise claimed to be 7 to 10 cm thick.
It is specified on page 14 that the B2, combining its satellite positioning system (GPS), its "ring-laser gyro platform," and a star-tracking system (astro-tracker), knows its position to within a few meters at all times. On the same page, it is stated that the 7 to 10 cm thick windshield contains two grids of gold wires, which act as reflectors/diffusers for both incoming and internally emitted radar waves. Pilots can eject through the cockpit roof; the ejection points are indicated by dashed lines. On the most recently built models (from "Block 30"), the leading edges of both wings are made in one piece, avoiding "hairpin" joints (hairpin-shaped connections).
The B2's wing sweep (33°) implies a nose-up attitude during landing. If the leading edge were "knife-edged," it would need to be able to pivot downward to adjust the airfoil's camber accordingly and prevent stall. The alternative chosen for the B2 was to adopt a very rounded leading edge, clearly visible in photos taken from page 20. The drawback of this design is its poor stealth characteristics against radar waves approaching from the front. On page 20, it is also specified that aircraft are stored in hangars as soon as possible to protect the radar-absorbing coating from environmental damage (what environment? It cannot be solar radiation, since these aircraft are designed to fly at 15,000 meters altitude. It is hard to imagine that this coating could be sensitive... to weather (as stated in the brochure!). In our view, there must be a completely different reason, which remains to be determined.
On page 22, it is stated that the B2 cannot be photographed from the rear, as the exhaust gas discharge system, visible from that angle, is "classified."
Conclusion.
The great, unavoidable mystery of the B2 is its price: $2 billion per unit. Let us note that a B-52 costs $50 million. Therefore...