Editing Avro Vulcan (section)

===Avro 707 and Avro 710===
[[File:Avro Vulcan VX770 VX777 FAR 13.09.53 edited-2.jpg|thumb|right|The prototype Vulcans (VX777 front, VX770 rear) with four [[Avro 707]]s at the [[Farnborough Air Show]] in September 1953: The large [[delta wing]]s of the Vulcan quickly gave it the affectionate nickname of "Tin Triangle".<ref>{{cite magazine |last=Jerram |first=Mike |date=June 1993 |title=Can Vulcan be Saved? |url=https://books.google.com/books?id=RMXnUv3iIjoC&pg=PA38 |magazine=Flying Magazine |publisher=[[Hachette Filipacchi Media U.S.|Hachette Filipacchi]] |access-date= 24 March 2020 }}</ref>]]
{{main|Avro 707}}

As Avro had no flight experience of the delta wing, the company planned two smaller experimental aircraft based on the 698, the one-third scale model 707 for low-speed handling and the one-half scale model 710 for high-speed handling. Two of each were ordered. The 710 was cancelled when it was considered too time-consuming to develop; a high-speed variant of the 707 was designed in its place, the 707A.<ref>Laming 2002, p. 27.</ref> The first 707, [[United Kingdom military aircraft serial numbers|VX784]], flew in September 1949, but crashed later that month, killing the [[Aeroplane and Armament Experimental Establishment]]'s chief test pilot Squadron Leader Samuel Eric Esler, DFC, AE.<ref>Hewitt 2003, Ireland's Aviator Heroes of World War II, p. 168.</ref> The second low-speed 707, VX790, built with the still uncompleted 707A's nose section (containing an [[ejection seat]])<ref>Laming 2002, p. 29.</ref> and redesignated 707B, flew in September 1950 piloted by Avro test pilot Wg Cdr [[Roland Falk|Roland "Roly" Falk]]. The high-speed 707A, WD280, followed in July 1951.<ref name="blackman21">Blackman 2007, p. 21.</ref>

Due to the delay of the 707 programme, the contribution of the 707B and 707A towards the basic design of the 698 was not considered significant,<ref>Laming 2002, p. 32.</ref> though it did highlight a need to increase the length of the nosewheel to give a ground incidence of 3.5°, the optimum take-off attitude.<ref>Blackman 2007, p. 33.</ref> The 707B and 707A proved the design's validity and gave confidence in the delta [[planform (aeronautics)|planform]]. A second 707A, WZ736, and a two-seat 707C, WZ744, were also constructed, but they played no part in the 698's development.<ref name="blackman21"/>