Editing Airframe (section)

=== Postwar ===

Postwar commercial airframe design focused on [[airliner]]s, on [[turboprop]] engines, and then on [[jet engine]]s. The generally higher speeds and [[tensile stress]]es of turboprops and jets were major challenges.<ref>{{cite book |author= Charles D. Bright |title= The Jet Makers: the Aerospace Industry from 1945 to 1972 |publisher= Regents Press of Kansas |year=1978 |url= http://www.generalatomic.com/jetmakers/index.html }}</ref> Newly developed [[aluminium]] [[alloy]]s with [[copper]], [[magnesium]] and [[zinc]] were critical to these designs.<ref>{{cite book |work= Key to Metals Database |title= Aircraft and Aerospace Applications |publisher= INI International |year= 2005 |url= http://www.key-to-metals.com/PrintArticle.asp?ID=96 |url-status= dead |archive-url= https://web.archive.org/web/20060308194218/http://www.key-to-metals.com/PrintArticle.asp?ID=96 |archive-date= 2006-03-08 }}</ref>

Flown in 1952 and designed to cruise at Mach 2 where [[skin friction]] required its [[heat]] resistance, the [[Douglas X-3 Stiletto]] was the first [[titanium]] aircraft but it was underpowered and barely [[supersonic]]; the Mach 3.2 [[Lockheed A-12]] and [[Lockheed SR-71|SR-71]] were also mainly titanium, as was the cancelled [[Boeing 2707]] Mach 2.7 [[supersonic transport]].<ref name=AW161121/>

Because heat-resistant titanium is hard to weld and difficult to work with, welded [[nickel steel]] was used for the Mach 2.8 [[Mikoyan-Gurevich MiG-25]] fighter, first flown in 1964; and the Mach 3.1 [[North American XB-70 Valkyrie]] used brazed [[stainless steel]] [[Honeycomb structure|honeycomb]] panels and titanium but was cancelled by the time it flew in 1964.<ref name=AW161121/>

A [[computer-aided design]] system was developed in 1969 for the [[McDonnell Douglas F-15 Eagle]], which first flew in 1974 alongside the [[Grumman F-14 Tomcat]] and both used [[boron fiber]] composites in the tails; less expensive [[carbon fiber reinforced polymer]] were used for wing skins on the [[McDonnell Douglas AV-8B Harrier II]], [[McDonnell Douglas F/A-18 Hornet|F/A-18 Hornet]] and [[Northrop Grumman B-2 Spirit]].<ref name=AW161121/>