Editing Lockheed F-104 Starfighter (section)

===Further development===
Based on the testing and evaluation of the XF-104, the next variant, the YF-104A, was lengthened and fitted with a General Electric J79 engine, modified landing gear, and modified air intakes.<ref name="Cacutt1988p159">Cacutt 1988, p. 159.</ref> The YF-104A and subsequent models were {{convert|5|ft|6|in|abbr=on}} longer than the XF-104 to accommodate the larger GE J79 engine. The YF-104 initially flew with the GE XJ79-GE-3 turbojet which generated 9,300 pounds of dry thrust (14,800 with afterburner), which was later replaced by the J79-GE-3A with an improved afterburner.<ref name="Upton2003p38">Upton 2003, p. 38.</ref>

Seventeen YF-104As were ordered by the USAF on 30 March 1955 for further flight testing.<ref name="Pace1992p23">Pace 1992, p. 23.</ref> The first of them flew on 17 February 1956 and, with the other 16 trial aircraft, was soon carrying out aircraft and equipment evaluation and tests. On 1 May 1957 one of the prototypes was destroyed when the ailerons malfunctioned, resulting in the aircraft tumbling wildly. The pilot ejected safely.<ref>{{cite web |last1=Dowling |first1=Stephen |title=The ejector seats that fire through the floor |url=https://www.bbc.com/future/article/20220802-why-some-aircraft-had-downward-firing-ejector-seats |website=www.bbc.com |access-date=6 August 2022 |language=en}}</ref> Lockheed made several improvements to the YF-104A throughout this testing period, including strengthening the airframe, adding a ventral fin to improve directional stability at supersonic speed, and installing a [[boundary layer control|boundary layer control system]] (BLCS) to reduce landing speed.<ref name="Upton2003p38"/>

Problems were encountered with the J79 afterburner; further delays were caused by the need to add [[AIM-9 Sidewinder]] air-to-air missiles. On 28 January 1958, the first production F-104A to enter service was delivered to the [[83d Fighter Weapons Squadron|83rd Fighter Interceptor Wing]].<ref>{{cite book |editor-first=Bruce |editor-last=Robertson |title=United States Army and Air Force Fighters 1916–1961 |publisher=Harleyford Publications Limited |location=Letchworth |date=1961 |lccn=61-16739 |page= 132}}</ref>