Previous posts in this discussion:
PostVariable-Sweep Wings on Military Aircraft (Brian Blodgett, USA, 02/10/19 4:44 am)
In response to John E's question to Michael Sullivan, there are aircraft with variable-sweep wings. As the article mentioned, variable-sweep wings were an "expensive characteristic of many high-performance aircraft designs of the 1960s" (Daverede, 2017).
Variable-sweep wings, also known as swing wings, are wings that can be swept back (and returned to the original position as well) during flight. This shifting of the wings is more suitable for high speeds is actually most beneficial to those that will fly at high and low speeds, i.e. mainly military aircraft. Additionally the addition of these wings allows aircraft to carry more fuel or payload and it improves takeoffs and landings. The downfall of the sweep-wing is the penalty is that while it can carry more fuel or payload, its configuration also is heavier than conventional-winged aircrafts and is complex in design and therefore maintenance.
As Daverede mentioned, it was in aircraft designs of the 1960s but was actually introduced in 1931 with the Westland-Hill Pterodactyl IV that was tailless and had wings that could sweep at a very small angle during flight. The Messerschmitt Me P.1101 had a design that would allow the angle to be changed on the ground, but not during flight. With World War II ending in Europe before the first light of the P.1101, the US took it back to America for study and the US late developed the Bell X-5 that could sweep its wings during flight, unlike the P.1101. Barnes Wallis (who had studied the Wild Goose of an earlier discussion) filed for a US Patent for "high-speed aircraft wing and tail surfaces having variable sweepback" on March 7, 1950 and was awarded Patent Number 2,744,698 on May 8, 1956.
While Wallis was awaiting his patent, the US tried the variable-sweep wing on the Grumman F10F Jaguar in 1952 but like the P.1101, it never entered service as it had poor flying characteristics and "rather vicious spin tendencies." Meanwhile, the Soviets were also developing sweep-wing aircraft and found they could adapt it from the swept-wing SU-7 and created the Su-17 (foreign variants are the Su-20 and Su-22). Other Soviet aircraft, such as the MiG-23, the MiG-27, the Su-24, the Tu-22M, and the TU-160 all had variable-sweep wings. As a note, the Tu-160, which was produced into 1992, was the last type of aircraft in the world built with variable-sweep wings. However, in 2015, Russian announced plans to start producing the Tu-160 again in 2020.
The jointly developed Panavia Tornado (developed by Italy, the UK, and West Germany) had its first flight in 1974 and entered service in 1979. In the US, the F-111 wad is first flight in 1964 and was introduced in 1967, the Grumman F-14 Tomcat had its first flight in 1970 and became active in 1974, and the B-1 Lancer had its fist flight in 1974 but did not become active until 1986. Both had variable-sweep wings.
On the civilian side, Boeing looked at sweep wings for a supersonic transport, the 2707, but abandoned the thought for the more common delta-wing design.
B-1 - USA (in service)
F-111 - USA (retired 1998) and Australia (retired 2010)
F-14 - USA (to 2006) and Iran (in service)
MiG-23 - Russia, Angola, Bulgaria, Cuba, Democratic Republic of the Congo, Ethiopia, Kazakhstan, India, Libya, North Korea, Sudan, and Syria (in service). Many other counties formerly used this aircraft.
MiG-27 - Russia, India, and Kazakhstan (in service). A few other countries used to use this aircraft.
Su-17 / Su-20 / Su-22 - Angola, Iran, Libya, Poland, Peru, Syria, and Vietnam (in service). Many other counties formerly used this aircraft.
Su-24 - Russia, Algeria, Iran, Libya, Sudan, Syria, and Ukraine (in service)
Tornado - UK, Germany, Italy, and Saudi Arabia (in service).
Tu-22M - Russia (in service)
Tu-160 - Russia (in service).
Daverede, Alex. (2017). "What happened to the American SST?" Retrieved from https://declassification.blogs.archives.gov/2017/07/28/what-happened-to-the-american-sst/
Espacenet (n.d.) "High-speed aircraft wing and tail surfaces having variable sweepback." Retrieved from https://worldwide.espacenet.com/publicationDetails/originalDocument?CC=US&NR=2744698A&KC=A&FT=D&ND=3&date=19560508&DB=EPODOC&locale=en_EP#
Wikipedia. (n.d.). "Variable-sweep wing." Retrieved from https://en.wikipedia.org/wiki/Variable-sweep_wing#Variable-sweep_aircraft
JE comments: Very informative, Brian! For my layperson's brain, the gist is this: spread-out wings provide more lift for takeoff and better stability while landing, while tucked-back wings reduce drag for higher speeds. Makes lots of sense.
And what's there not to love about a plane called the Westland-Hill Pterodactyl IV? I cribbed an image off the 'Net. This one does look like it would be a handful to fly...but try piloting an actual pterodactyl.
Westland-Hill Pterodactyl IV