Editing Relaxed stability (section)

== Unstable aircraft ==
[[Image:Usaf.f117.750pix.jpg|thumb|The [[Lockheed F-117 Nighthawk]] is not an inherently stable design.]]

Modern military aircraft, particularly low observable ("[[stealth aircraft|stealth]]") designs, often exhibit instability as a result of their shape. The [[Lockheed Martin|Lockheed]] [[F-117]] Nighthawk, for instance, employs a highly non-traditional fuselage and wing shape in order to reduce its [[radar cross section]] and enable it to penetrate air defenses with relative impunity. However, the flat facets of the design reduce its stability to the point where a computerized [[fly-by-wire]] system is required for it to fly.<ref name=asc>{{cite book |title=Airplane stability and control: a history of the technologies that made aviation possible |year=2002 |publisher=Cambridge Univ. Press |location=Cambridge [u.a.] |isbn=978-0-521-80992-4 |pages=335–337 |url=https://books.google.com/books?id=D-ctX2Q-CSIC |first1=Malcolm |last1=Abzug |edition=2 |first2=E. Eugene |last2=Larrabee}}</ref>

Relaxed stability designs are not limited to military jets. The [[McDonnell Douglas MD-11]] has a neutral stability design which was implemented to save fuel. To ensure stability for safe flight, an LSAS (Longitudinal [[Stability Augmentation System]]) was introduced to compensate for the MD-11's rather short horizontal stabilizer and ensure that the aircraft would remain stable.<ref name="Boeing">{{cite journal |title=The Effect of High Altitude and Center of Gravity on The Handling Characteristics of Swept-wing Commercial Airplanes |journal=Aero Magazine |volume=1 |issue=2 |url=https://www.boeing.com/commercial/aeromagazine/aero_02/textonly/fo01txt.html |access-date=29 June 2022 |publisher=Boeing}}</ref> However, there have been incidents in which the MD-11's relaxed stability caused an "inflight upset".<ref>{{cite news |last1=Pasztor |first1=Andy |title=FedEx Jet Has Control Issues |url=https://www.wsj.com/articles/SB123776874104009733 |access-date=1 October 2015 |agency=WSJ |date=March 24, 2009}}</ref>