Editing Northrop B-2 Spirit (section)

====Radar====
The B-2's clean, low-drag [[flying wing]] configuration not only provides exceptional range but is also beneficial to reducing its radar profile.<ref name="croddy 341-2" /><ref>{{harvnb|Siuru|1993|pages=114–115}}</ref> Reportedly, the B-2 has a [[radar cross-section]] (RCS) of about {{convert|0.1|m2|ft2|abbr=on}}.<ref>{{harvnb|Richardson|2001|p=57}}</ref> The bomber does not always fly stealthily; when nearing air defenses pilots "stealth up" the B-2, a maneuver whose details are secret. The aircraft is stealthy, except briefly when the bomb bay opens. The flying wing design most closely resembles a so-called infinite flat plate (as vertical control surfaces dramatically increase RCS), the perfect stealth shape, as it would lack angles to reflect back radar waves (initially, the shape of the Northrop ATB concept was flatter; it gradually increased in volume according to specific military requirements).<ref name="SpiritofInnovation">{{cite web |url=https://www.northropgrumman.com/wp-content/uploads/B-2-Spirit-of-Innovation.pdf |title=B-2: The Spirit of Innovation |website=Northrop Grumman Corporation |access-date=15 October 2023 |archive-date=8 April 2023 |archive-url=https://web.archive.org/web/20230408033411/https://www.northropgrumman.com/wp-content/uploads/B-2-Spirit-of-Innovation.pdf |url-status=live}}</ref> Without vertical surfaces to reflect radar laterally, side aspect radar cross section is also reduced.<ref>{{cite web|url=https://nationalinterest.org/blog/buzz/americas-new-b-21-stealth-bomber-vs-russias-s-300-or-s-400-who-wins-36137|title=America's New B-21 Stealth Bomber vs. Russia's S-300 or S-400: Who Wins?|first=Kris|last=Osborn|date=15 November 2018|website=nationalinterest.org|access-date=16 November 2018|archive-date=15 November 2018|archive-url=https://web.archive.org/web/20181115195225/https://nationalinterest.org/blog/buzz/americas-new-b-21-stealth-bomber-vs-russias-s-300-or-s-400-who-wins-36137|url-status=live}}</ref> Radars operating at a lower frequency band (S or L band) are able to detect and track certain stealth aircraft that have multiple control surfaces, like canards or vertical stabilizers, where the frequency wavelength can exceed a certain threshold and cause a resonant effect.<ref>{{cite web|url=https://nationalinterest.org/blog/buzz/how-russia-could-someday-shootdown-f-22-f-35-or-b-2-stealth-bomber-35512|title=How Russia Could Someday Shootdown an F-22, F-35 or B-2 Stealth Bomber|first=Dave|last=Majumdar|date=8 November 2018|website=nationalinterest.org|access-date=21 November 2018|archive-date=20 November 2018|archive-url=https://web.archive.org/web/20181120221212/https://nationalinterest.org/blog/buzz/how-russia-could-someday-shootdown-f-22-f-35-or-b-2-stealth-bomber-35512|url-status=live}}</ref>

[[File:B-2 radar reflection.jpg|thumb|left|upright=1.35|Illustration of the B-2's basic radar reflection angles]]
RCS reduction as a result of shape had already been observed on the [[Royal Air Force]]'s [[Avro Vulcan]] strategic bomber,<ref>Dawson 1957, p. 3.</ref> and the USAF's [[Lockheed F-117 Nighthawk|F-117 Nighthawk]]. The F-117 used flat surfaces ([[faceting]] technique) for controlling radar returns as during its development (see [[Lockheed Have Blue]]) in the early 1970s, technology only allowed for the simulation of radar reflections on simple, flat surfaces; computing advances in the 1980s made it possible to simulate radar returns on more complex curved surfaces.<ref name="rich4">{{harvnb|Rich|1994|p=21}}</ref> The B-2 is composed of many curved and rounded surfaces across its exposed airframe to deflect radar beams. This technique, known as ''continuous curvature'', was made possible by advances in [[computational fluid dynamics]], and first tested on the [[Northrop Tacit Blue]].<ref>{{cite book|author=Christopher Lavers|title=Reeds Vol 14: Stealth Warship Technology|url=https://books.google.com/books?id=wMB3Pg3vtbsC&pg=PA13|year=2012|publisher=Bloomsbury Publishing|isbn=978-1-4081-7553-8|page=13|access-date=19 October 2016|archive-date=5 February 2021|archive-url=https://web.archive.org/web/20210205102939/https://books.google.com/books?id=wMB3Pg3vtbsC&pg=PA13|url-status=live}}</ref><ref name="SpiritofInnovation"/>