Editing Ballistic missile (section)

== Throw-weight ==

Throw-weight is a measure of the effective weight of ballistic missile [[payload]]s. It is measured in [[kilogram]]s or [[tonne]]s. Throw-weight equals the total weight of a missile's [[warhead]]s, [[reentry vehicle]]s, self-contained dispensing mechanisms, [[penetration aids]], and any other components that are part of the delivered payload, and not of the rocket itself (such as the launch [[Booster (rocketry)|rocket booster]] and launch fuel).<ref>{{Cite news |date=15 July 1991 |title=What is throw weight? |url=https://www.nytimes.com/1991/07/15/world/what-is-throw-weight.html |access-date=13 April 2024 |work=[[The New York Times]] |page=10, Sec. A}}</ref> Throw-weight may refer to any type of warhead, but in normal modern usage, it refers almost exclusively to [[fission bomb|nuclear]] or [[thermonuclear weapon|thermonuclear]] payloads. It was once also a consideration in the design of naval ships and the number and size of their guns.

Throw-weight was used as a criterion in classifying different types of missiles during [[Strategic Arms Limitation Talks]] between the [[Soviet Union]] and the [[United States]].<ref>James John Tritten, [http://www.airpower.maxwell.af.mil/airchronicles/aureview/1982/nov-dec/tritten.html Throw-Weight and Arms Control<!-- Bot generated title -->] {{Webarchive|url=https://web.archive.org/web/20071123235939/http://www.airpower.maxwell.af.mil/airchronicles/aureview/1982/nov-dec/tritten.html |date=2007-11-23 }}, ''Air University Review'', Nov-Dec 1982.</ref> The term became politically controversial during debates over the arms control accord, as critics of the treaty alleged that Soviet missiles were able to carry larger payloads and so enabled the Soviets to maintain higher throw-weight than an American force with a roughly comparable number of lower-payload missiles.<ref>[https://www.nytimes.com/1991/07/15/world/what-is-throw-weight.html What Is Throw-Weight?] {{Webarchive|url=https://web.archive.org/web/20221126000600/https://www.nytimes.com/1991/07/15/world/what-is-throw-weight.html |date=2022-11-26 }}, New York Times, July 15, 1991.</ref>

The missiles with the world's heaviest payloads are the Russian [[SS-18]] and Chinese [[DF-5|CSS-4]] and {{asof|2017|lc=y}}, Russia was developing a new heavy-lift, liquid-propellant ICBM called the [[RS-28 Sarmat|Sarmat]].<ref name=":0" />

=== Depressed trajectory ===
[[File:FobsEnglishTrans.svg|thumb|400px|Example of Depressed trajectory: [[Fractional Orbital Bombardment System]]]]
Throw-weight is normally calculated using an optimal [[ballistic trajectory]] from one point on the surface of the Earth to another. A "minimum-energy trajectory" maximizes the total payload (throw-weight) using the available [[impulse (physics)|impulse]] of the missile.<ref name=":3">{{Cite journal |last1=Druckmann |first1=Erez |last2=Ben-Asher |first2=Joseph |date=28 Aug 2012 |title=Optimal In-flight Trajectory Modifications for Ballistic Missiles and Rockets |url=https://arc.aiaa.org/doi/abs/10.2514/1.54538?journalCode=jgcd |journal=Journal of Guidance, Control, and Dynamics |volume=35 |issue=2 |page=462 |doi=10.2514/1.54538 |via=Aerospace Research Central}}</ref> By reducing the payload weight, different trajectories can be selected, which can either increase the nominal range or decrease the total time in flight.

A depressed trajectory is non-optimal, as a lower and flatter trajectory takes less time between launch and impact but has a lower throw-weight. The primary reasons to choose a depressed trajectory are to evade [[anti-ballistic missile]] systems by reducing the time available to shoot down the attacking vehicle (especially during the vulnerable burn-phase against space-based ABM systems) or a nuclear [[first-strike]] scenario.<ref>Science & Global Security, 1992, Vol. 3, pp.101–159 Depressed Trajectory SLBMs: A Technical Evaluation and Arms Control Possibilities [http://www.princeton.edu/sgs/publications/sgs/pdf/3_1-2gronlund.pdf] {{Webarchive|url=https://web.archive.org/web/20130318120315/http://www.princeton.edu/sgs/publications/sgs/pdf/3_1-2gronlund.pdf|date=2013-03-18}}</ref> An alternate, non-military purpose for a depressed trajectory is in conjunction with the [[spaceplane]] concept with use of [[airbreathing jet engine]]s, which requires the ballistic missile to remain low enough inside the atmosphere for air-breathing engines to function.

In contrast, a "lofted" trajectory is frequently used for testing purposes, as it reduces the range of the missile (allowing for a controlled and observed impact), as well as signals a lack of hostile intention with the test.<ref>{{Cite news |date=2022-12-16 |title=Why North Korea's missile tests are going higher and further |url=https://www.reuters.com/graphics/NORTHKOREA-MISSILES/TESTING/byvrllmjmve/ |access-date=2024-04-13 |work=Reuters |language=en}}</ref><ref name=":3" />