Editing Convair F-102 Delta Dagger (section)

===Major redesign===
[[File:Convair YF-102A on ramp E-2551.jpg|thumb|upright|YF-102A with pinched "area rule" fuselage, narrower canopy and redesigned intakes]]

During mid 1953, Convair concluded that it needed to take action to address the F-102's shortcomings to prevent its cancellation, and promptly embarked on a major redesign effort.<ref name = "Becker p.7273"/> It was decided to incorporate the recently discovered [[Whitcomb area rule|area rule]], the application of which simultaneously simplified both production and maintenance of the aircraft.<ref>{{cite web |last1 = Baals |first1 = Donald D. |title = WIND TUNNELS OF NASA. Chapter 5 - The Era of High-Speed Flight. The Area Rule and the F-102 Story |url = https://history.nasa.gov/SP-440/ch5-10.htm |website = history.nasa.gov |publisher = US Library of Congress, Supt. of Docs. no.: NAS 1.21:440 |access-date = 16 July 2014 |url-status = live |archive-url = https://web.archive.org/web/20130607031028/http://history.nasa.gov/SP-440/ch5-10.htm |archive-date = 7 June 2013}}</ref> This redesign entailed the lengthening of the fuselage by 11&nbsp;ft (3.35&nbsp;m), being "pinched" at the midsection (dubbed the "[[Coke bottle#Contour bottle design|Coke Bottle]] configuration"), with two large fairings on either side of the engine nozzle, with revised intakes and a new, narrower canopy. A more powerful model of the J57 was installed while the aircraft structure was also lightened.<ref name="Gunston F102 p513-4">Gunston 1957, pp. 513–514.</ref><ref name="Wegg p201">Wegg 2000, p. 201.</ref>

In parallel to this effort, the wing was also redesigned to be both thinner and wider. The [[leading edge]] was reprofiled with a conical droop, with the apex at the root, as to improve handling at low speeds. Because the droop remained within the shock cone of the leading edge, the drag rise at supersonic speeds was minimal. A second, inboard fence was also added at the time.<ref>Mendenhall 1983, p. 27.</ref><ref>Jones, Lloyd S. ''U.S. Fighters'', Aero, 1975. pp. 272-274.</ref> A new canopy was also adopted while the tail was shifted slightly aft. The level of changes that could be implemented were restrained by the redesign having occurred at such an advanced stage of development.<ref name = "Becker p.74">Becker 2012, p. 74.</ref> Yet, the overall changes made were so substantial that two-thirds of the roughly 30,000 tools created to manufacture the YF-102 were scrapped or modified before quantity production had even commenced.<ref name = "Becker p.73"/>

On 20 December 1954, the first revised aircraft, designated ''YF-102A'', made its first flight only 118 days after work on the redesign had started.<ref name = "Becker p.74"/> The next day, it exceeded Mach&nbsp;1 for the first time.<ref name="Wegg p201"/><ref name = "Becker p.7475">Becker 2012, pp. 74-75.</ref> The revised design quickly demonstrated that it could attain a speed of Mach&nbsp;1.22 and a ceiling of 53,000&nbsp;ft (16,154&nbsp;m). These performance improvements were sufficient for the USAF to agree to procure the F-102; accordingly, a new production contract was signed during March 1954.<ref name="Knaack p166">Knaack 1978, p. 166.</ref> On 24 June 1955, the first flight of a production standard F-102 occurred.<ref name = "Becker p.75">Becker 2012, p. 75.</ref> From the 26th production aircraft onwards, a taller vertical tail with a 40 percent greater surface area was fitted to counteract flutter and a lack of directional control at high speeds; existing aircraft were also retrofitted with this change.<ref name = "Becker p.76">Becker 2012, p. 76.</ref>