Editing Delta wing (section)

==Design variations==
{{Anchor|ogee delta}}
{{anchor|cropped delta|tailed delta}}

[[File:Concorde on Bristol.jpg|thumb|Aérospatiale-BAC [[Concorde]] shows off its ogee wing]]

Variants of the delta wing plan offer improvements to the basic configuration.<ref>{{Cite book|title=Introduction to aerospace engineering with a flight test perspective|last=Corda|first=Stephen|publisher=John Wiley & Sons|year=2017|isbn=9781118953372|location=Chichester, West Sussex, United Kingdom|pages=408–9|oclc=967938446}}</ref>

'''Cropped delta'''&nbsp;– tip is cut off. This helps maintain lift outboard and reduce wingtip flow separation (stalling) at high angles of attack. Most deltas are cropped to at least some degree.

In the {{Anchor|compound delta|double delta|cranked arrow}}'''compound delta''', '''double delta''' or '''cranked arrow''', the leading edge is not straight. Typically the inboard section has increased sweepback, creating a controlled high-lift vortex without the need for a foreplane. Examples include the [[J 35 Draken|Saab Draken]] fighter, the experimental [[General Dynamics F-16XL]], and the Hawker Siddeley HS. 138 VTOL concept. The '''ogee delta''' (or '''{{anchor|ogival delta}}ogival delta''') used on the Anglo-French [[Concorde]] [[supersonic airliner]] is similar, but with the two sections and cropped wingtip merged into a smooth [[ogee]] curve.

{| align=center style="text-align:center;"
|-
|[[File:Wing tailless delta.svg|112px|alt=" "]]<br />Tailless delta
|[[File:Wing cropped delta.svg|112px|alt=" "]]<br />Cropped delta
|[[File:wing compound delta.svg|112px|alt=" "]]<br />Compound delta
|[[File:wing cranked arrow.svg|112px|alt=" "]]<br />Cranked arrow
|[[File:Wing ogival delta.svg|112px|alt=" "]]<br />Ogival delta
|[[File:Wing delta.svg|112px|alt=" "]]<br />Tailed delta
|} <!-- table originally copied from [[Wing configuration]] -->

'''Tailed delta'''&nbsp;– adds a conventional tailplane (with horizontal tail surfaces), to improve handling.  Common on Soviet types such as the [[Mikoyan-Gurevich MiG-21]].

'''Canard delta'''&nbsp;– Many modern fighter aircraft, such as the [[JAS 39 Gripen]], the [[Eurofighter Typhoon]] and the [[Dassault Rafale]] use a combination of [[Canard (aeronautics)|canard]] foreplanes and a delta wing.

===Tailless delta===
[[File:Saab Draken.jpg|thumb|The [[Saab 35 Draken]] was a successful tailless double-delta design]]
Like other [[tailless aircraft]], the tailless delta wing is not suited to high wing loadings and requires a large wing area for a given aircraft weight. The most efficient aerofoils are unstable in pitch and the tailless type must use a less efficient design and therefore a bigger wing. Techniques used include:
* Using a less efficient aerofoil which is inherently stable, such as a symmetrical form with zero camber, or even reflex camber near the trailing edge,
* Using the rear part of the wing as a lightly- or even negatively-loaded horizontal stabiliser:
**Twisting the outer leading edge down to reduce the incidence of the wing tip, which is behind the main centre of lift. This also improves stall characteristics and can benefit supersonic cruise in other ways.
**Moving the centre of mass forwards and trimming the elevator to exert a balancing downforce. In the extreme, this reduces the craft's ability to pitch its nose up for takeoff and landing.
The main advantages of the tailless delta are structural simplicity and light weight, combined with low aerodynamic drag. These properties helped to make the [[Dassault Mirage III]] one of the most widely manufactured supersonic fighters of all time.

===Tailed delta===
A conventional tail stabiliser allows the main wing to be optimised for lift and therefore to be smaller and more highly loaded. Development of aircraft equipped with this configuration can be traced back to the late 1940s.<ref>Allward 1983, pp. 11–12.</ref>

When used with a T-tail, as in the [[Gloster Javelin]], like other wings a delta wing can give rise to a "[[deep stall]]" in which the high angle of attack at the stall causes the turbulent wake of the stalled wing to envelope the tail. This makes the elevator ineffective and the airplane cannot recover from the stall.<ref>{{Citation | url = http://www.thunder-and-lightnings.co.uk/javelin/history.php | title = Gloster Javelin History | publisher = Thunder & Lightnings | date = 4 April 2012 | place = UK | access-date = 10 February 2011 | archive-date = 9 June 2011 | archive-url = https://web.archive.org/web/20110609224809/http://www.thunder-and-lightnings.co.uk/javelin/history.php | url-status = live }}.</ref> In the case of the Javelin, a [[Stall (fluid dynamics)#Warning and safety devices|stall warning device]] was developed and implemented for the Javelin following the early loss of an aircraft to such conditions.<ref name ="pat 6">Patridge 1967, p. 6.</ref> Gloster's design team had reportedly opted to use a tailed delta configuration out of necessity, seeking to achieve effective manoeuvrability at relatively high speeds for the era while also requiring suitable controllability when being flown at the slower landing speeds desired.<ref>Patridge 1967, pp. 3–4.</ref>

===Canard delta===
[[File:Eurofighter 9803 2.jpg|thumb|The [[Eurofighter Typhoon]] has a canard delta wing configuration.]]
A lifting-canard delta can offer a smaller shift in the center of lift with increasing Mach number compared to a conventional tail configuration.

An unloaded or free-floating canard can allow a safe recovery from a high angle of attack. Depending on its design, a canard surface may increase or decrease longitudinal stability of the aircraft.<ref>{{Citation |last=Probert |first=B |publisher=NATO |url=http://ftp.rta.nato.int/public//PubFulltext/RTO/EN/RTO-EN-004///$EN-004-19.pdf |title=Aspects of Wing Design for Transonic and Supersonic Combat |url-status=dead |archive-url=https://web.archive.org/web/20110517202722/http://ftp.rta.nato.int/public/ |archive-date=17 May 2011 }}.</ref><ref>{{Citation |publisher=Mach flyg |url=http://www.mach-flyg.com/utg80/80jas_uc.html |title=Aerodynamic highlights of a fourth generation delta canard fighter aircraft |url-status=dead |archive-url=https://web.archive.org/web/20141127200736/http://www.mach-flyg.com/utg80/80jas_uc.html |archive-date=27 November 2014 }}.</ref>

A canard delta foreplane creates its own trailing vortex. If this vortex interferes with the vortex of the main delta wing, this can adversely affect the airflow over the wing and cause unwanted and even dangerous behaviour. In the close-coupled configuration, the canard vortex couples with the main vortex to enhance its benefits and maintain controlled airflow through a wide range of speeds and angles of attack. This allows both improved manoeuvrability and lower stalling speeds, but the presence of the foreplane can increase drag at supersonic speeds and hence reduce the aircraft's maximum speed.