Editing Sub-orbital spaceflight (section)

==Flight profiles==
[[File:Mr3-flight-timeline-simple.png|thumb|upright=1.5|Profile for the first crewed American sub-orbital flight, 1961. Launch rocket lifts the spacecraft for the first 2:22 minutes. Dashed line: zero gravity.]]
[[File:Science and Mechanics Nov 1931 cover.jpg|thumb|''[[Science and Mechanics]]'' cover of November 1931, showing a proposed sub-orbital spaceship that would reach an altitude {{convert|700|mi|km}} on its one-hour trip from Berlin to New York.]]

While there are a great many possible sub-orbital flight profiles, it is expected that some will be more common than others.

[[File:X-15.jpg|thumb|The X-15 (1958–1968) was launched to an altitude of 13.7 km by a [[Boeing B-52 Stratofortress|B-52]] [[mother ship|mothership]], lifted itself to approximately 100 km, and then glided to the ground.]]

===Ballistic missiles===
The first sub-orbital vehicles which reached space were [[ballistic missiles]]. The first ballistic missile to reach space was the German [[V-2 rocket|V-2]], the work of the scientists at [[Peenemünde]], on October 3, 1942, which reached an altitude of {{convert|53|mi|km}}.<ref>Germany's V-2 Rocket, Kennedy, Gregory P.</ref> Then in the late 1940s the US and [[USSR]] concurrently developed missiles all of which were based on the V-2 Rocket, and then much longer range Intercontinental Ballistic Missiles (ICBMs). There are now many countries who possess ICBMs and even more with shorter range [[IRBM|Intermediate Range Ballistic Missiles]] (IRBMs).{{citation needed|date=May 2024}}

===Tourist flights===
[[Space tourism|Sub-orbital tourist flights]] will initially focus on attaining the altitude required to qualify as reaching space. The flight path will be either vertical or very steep, with the spacecraft landing back at its take-off site.

The spacecraft will shut off its [[engine]]s well before reaching maximum altitude, and then coast up to its highest point. During a few minutes, from the point when the engines are shut off to the point where the atmosphere begins to slow down the downward acceleration, the passengers will experience [[weightlessness]].

[[Megaroc]] had been planned for sub-orbital spaceflight by the [[British Interplanetary Society]] in the 1940s.<ref>{{cite web|url=http://www.bbc.com/future/story/20150824-how-a-nazi-rocket-could-have-put-a-briton-in-space|title=How a Nazi rocket could have put a Briton in space|first=Richard|last=Hollingham|website=bbc.com|date=25 August 2015 |access-date=4 May 2018|url-status=live|archive-url=https://web.archive.org/web/20161114032515/http://www.bbc.com/future/story/20150824-how-a-nazi-rocket-could-have-put-a-briton-in-space|archive-date=14 November 2016}}</ref><ref>{{cite web|url=http://www.bis-space.com/what-we-do/projects/megaroc|title=Megaroc|website=www.bis-space.com|access-date=4 May 2018|url-status=live|archive-url=https://web.archive.org/web/20161030133900/http://www.bis-space.com/what-we-do/projects/megaroc|archive-date=30 October 2016}}</ref>

In late 1945, a group led by M. Tikhonravov K. and N. G. Chernysheva at the Soviet NII-4 academy (dedicated to rocket artillery science and technology), began work on a stratospheric rocket project, [[Project VR-190|VR-190]], aimed at vertical flight by a crew of two pilots, to an altitude of 200&nbsp;km (65,000&nbsp;ft) using captured [[V-2 rocket|V-2]].<ref>{{Cite book |author=Anatoli I. Kiselev |author2=Alexander A. Medvedev| author3=Valery A. Menshikov |title=Astronautics: Summary and Prospects |translator=V. Sherbakov |translator2=N. Novichkov |translator3=A. Nechaev |publisher=Springer Science & Business Media|date=December 2012|pages=1–2|isbn=9783709106488}}</ref>

In 2004, a number of companies worked on vehicles in this class as entrants to the Ansari X Prize competition. The [[Scaled Composites SpaceShipOne]] was officially declared by [[Richard A. Searfoss|Rick Searfoss]] to have won the competition on October 4, 2004, after completing two flights within a two-week period.

In 2005, [[Richard Branson|Sir Richard Branson]] of the [[Virgin Group]] announced the creation of [[Virgin Galactic]] and his plans for a 9-seat capacity SpaceShipTwo named [[VSS Enterprise|VSS ''Enterprise'']]. It has since been completed with eight seats (one pilot, one co-pilot and six passengers) and has taken part in captive-carry tests and with the first mother-ship [[WhiteKnightTwo]], or [[VMS Eve|VMS ''Eve'']]. It has also completed solitary glides, with the movable tail sections in both fixed and "feathered" configurations.  The [[hybrid rocket]] motor has been fired multiple times in ground-based test stands, and was fired in a powered flight for the second time on 5 September 2013.<ref>{{cite web |url=http://www.scaled.com/projects/test_logs/35/model_339_spaceshiptwo |title=Scaled Composites: Projects - Test Logs for SpaceShipTwo |access-date=2013-08-14 |url-status=live |archive-url=https://web.archive.org/web/20130816140953/http://www.scaled.com/projects/test_logs/35/model_339_spaceshiptwo |archive-date=2013-08-16 }}</ref> Four additional SpaceShipTwos have been ordered and will operate from the new [[Spaceport America]]. Commercial flights carrying passengers were expected in 2014, but became cancelled due to the [[VSS Enterprise crash|disaster during SS2 PF04 flight]]. Branson stated, "[w]e are going to learn from what went wrong, discover how we can improve safety and performance and then move forwards together."<ref>"Branson on Virgin Galactic crash: 'Space is hard – but worth it'". CNET. Retrieved August 1, 2015.</ref>

===Scientific experiments===
A major use of sub-orbital vehicles today is as [[scientific]] [[sounding rocket]]s. Scientific sub-orbital flights began in the 1920s when [[Robert H. Goddard]] launched the first [[liquid fuel]]ed rockets, however they did not reach [[space]] altitude. In the late 1940s, captured German [[V-2 rocket|V-2 ballistic missiles]] were converted into [[V-2 sounding rocket]]s which helped lay the foundation for modern sounding rockets.<ref>{{Cite web|title = ch2|url = https://history.nasa.gov/SP-4401/ch2.htm|website = history.nasa.gov|access-date = 2015-11-28|url-status = live|archive-url = http://archive.wikiwix.com/cache/20151129091504/https://history.nasa.gov/SP-4401/ch2.htm|archive-date = 2015-11-29}}</ref> Today there are dozens of different sounding rockets on the market, from a variety of suppliers in various countries. Typically, researchers wish to conduct experiments in [[microgravity]] or above the atmosphere.

===Sub-orbital transportation===
Research, such as that done for the [[X-20 Dyna-Soar]] project suggests that a semi-ballistic sub-orbital flight could travel from Europe to North America in less than an hour.

However, the size of rocket, relative to the payload, necessary to achieve this, is similar to an ICBM. ICBMs have delta-v's somewhat less than orbital; and therefore would be somewhat cheaper than the costs for reaching orbit, but the difference is not large.<ref>{{cite web|url=http://www.thespacereview.com/article/1118/1|title=The Space Review: Point-to-point suborbital transportation: sounds good on paper, but...|website=www.thespacereview.com|access-date=4 May 2018|url-status=live|archive-url=https://web.archive.org/web/20170801074751/http://www.thespacereview.com/article/1118/1|archive-date=1 August 2017}}</ref>

Due to the high cost of spaceflight, suborbital flights are likely to be initially limited to high value, very high urgency cargo deliveries such as [[courier]] flights, [[military]] fast-response operations or [[space tourism]].{{opinion|date=April 2012}}

The [[SpaceLiner]] is a hypersonic [[suborbital spaceplane]] concept that could transport 50 passengers from [[Australia]] to [[Europe]] in 90 minutes or 100 passengers from Europe to [[California]] in 60 minutes.<ref>{{Cite journal|doi=10.1016/j.actaastro.2010.01.020| author = Sippel, M. | title = Promising roadmap alternatives for the SpaceLiner |journal = Acta Astronautica |issue = 11–12 |volume = 66 |date = 2010| pages = 1652–1658 | bibcode = 2010AcAau..66.1652S | url = https://elib.dlr.de/64605/1/AA3731.pdf }}</ref> The main challenge lies in increasing the reliability of the different components, particularly the engines, in order to make their use for passenger transportation on a daily basis possible.

[[SpaceX]] is potentially considering using their [[SpaceX Starship|Starship]] as a sub-orbital point-to-point transportation system.<ref name=trati20190530>{{cite news |last=Ralph|first=Eric |url=https://www.teslarati.com/spacex-elon-musk-wants-starship-spaceliners/ |title=SpaceX CEO Elon Musk wants to use Starships as Earth-to-Earth transports |work=Teslarati |date=30 May 2019 |access-date=31 May 2019 }}</ref>