Supersonic speed

<h2 id="early-meaning">Early meaning</h2>
<p>The word supersonic comes from two <a href="/facts/Latin_influence_in_English/jm5Xs8Gc">Latin derived words</a>; 1) <i>super</i>: above and 2) <i>sonus</i>: sound, which together mean above sound, or faster than sound.
</p><p>At the beginning of the 20th century, the term "supersonic" was used as an adjective to describe sound whose frequency is above the range of normal human hearing. The modern term for this meaning is "<a href="/facts/Ultrasound/31Pa5IH9">ultrasonic</a>", but the older meaning sometimes still lives on, as in the word <a href="/facts/Superheterodyne_receiver/S2SA0NCV">superheterodyne</a>
</p>
<h2 id="supersonic-objects">Supersonic objects</h2>

<p>The tip of a <a href="/facts/Bullwhip/eJczs6SD">bullwhip</a> is generally seen as the first object designed to reach the speed of sound. This action results in its telltale "crack", which is actually just a <a href="/facts/Sonic_boom/Hfnr1Vlz">sonic boom</a>. The first human-made supersonic boom was likely caused by a piece of common cloth, leading to the whip's eventual development.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> It's the <a href="/facts/Wave_motion/I3EeyInV">wave motion</a> travelling through the bullwhip that makes it capable of achieving supersonic speeds.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a><a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> 
</p><p>Most modern <a href="/facts/Firearm/GuHx4aGE">firearm</a> <a href="/facts/Bullets/VgJXCI0b">bullets</a> are supersonic, with rifle <a href="/facts/Projectiles/kaDpG3N7">projectiles</a> often travelling at speeds approaching and in some cases<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> well exceeding <a href="/facts/Mach_(speed)/Ee01MIgw">Mach 3</a>.
</p><p>Most <a href="/facts/Spacecraft/YQqQaUw0">spacecraft</a> are supersonic at least during portions of their reentry, though the effects on the spacecraft are reduced by low air densities. During ascent, launch vehicles generally avoid going supersonic below 30 km (~98,400 feet) to reduce air drag.
</p><p>Note that the <a href="/facts/Speed_of_sound/dYtbt1nf">speed of sound</a> decreases somewhat with altitude, due to lower temperatures found there (typically up to 25 km). At even higher altitudes the temperature starts increasing, with the corresponding increase in the speed of sound.
</p><p>When an inflated <a href="/facts/Balloon/o9JQ2ykA">balloon</a> is burst, the torn pieces of <a href="/facts/Latex/IPBJbKnd">latex</a> contract at supersonic speed, which contributes to the sharp and loud popping noise.
</p>
<h3>Supersonic land vehicles</h3>
<p>To date, only one land vehicle has officially travelled at supersonic speed, the <a href="/facts/ThrustSSC/nhI48ADQ">ThrustSSC</a>. The vehicle, driven by <a href="/facts/Andy_Green_(RAF_officer)/mRvcevMF">Andy Green</a>, holds the world land speed record, having achieved an average speed on its bi-directional run of 1,228 km/h (763 mph) in the <a href="/facts/Black_Rock_Desert/FQ6YxEba">Black Rock Desert</a> on 15 October 1997.
</p><p>The <a href="/facts/Bloodhound_LSR/3elm1qFF">Bloodhound LSR</a> project planned an attempt on the record in 2020 at <a href="/facts/Hakskeenpan/GLYRV9kw">Hakskeenpan</a> in South Africa with a combination jet and hybrid rocket propelled car. The aim was to break the existing record, then make further attempts during which (the members of) the team hoped to reach speeds of up to 1,600 km/h (1,000 mph). The effort was originally run by <a href="/facts/Richard_Noble/lfa1R4FA">Richard Noble</a> who was the leader of the ThrustSSC project, however following funding issues in 2018, the team was bought by Ian Warhurst and renamed Bloodhound LSR. Later the project was indefinitely delayed due to the <a href="/facts/COVID-19_pandemic/0xTsh7Ut">COVID-19 pandemic</a> and the vehicle was put up for sale.
</p>
<h3>Supersonic flight</h3>
<p class="note">Main article: <a href="/facts/Supersonic_aircraft/Spue1MRH">Supersonic aircraft</a></p>
<p>Most modern <a href="/facts/Fighter_aircraft/NuIvaGJg">fighter aircraft</a> are supersonic aircraft. No modern-day passenger aircraft are capable of supersonic speed, but there have been <a href="/facts/Supersonic_transport/vtbRALKG">supersonic passenger aircraft</a>, namely <a href="/facts/Concorde/TAMElD6g">Concorde</a> and the <a href="/facts/Tupolev_Tu-144/1pFjI2rg">Tupolev Tu-144</a>. Both of these passenger <a href="/facts/Aircraft/EhC4mBep">aircraft</a> and some modern fighters are also capable of <a href="/facts/Supercruise/4h2k11nH">supercruise</a>, a condition of sustained supersonic flight without the use of an <a href="/facts/Afterburner/aDeuyqp3">afterburner</a>. Due to its ability to supercruise for several hours and the relatively high frequency of flight over several decades, Concorde spent more time flying supersonically than all other aircraft combined by a considerable margin. Since Concorde's final retirement flight on November 26, 2003, there are no supersonic passenger aircraft left in service. Some large <a href="/facts/Bombers/S65BPSLX">bombers</a>, such as the <a href="/facts/Tupolev_Tu-160/PTrWQMYC">Tupolev Tu-160</a> and <a href="/facts/Rockwell_B-1_Lancer/K2I9IkJc">Rockwell B-1 Lancer</a> are also supersonic-capable.
</p><p>The <a href="/facts/Aerodynamics/Cn6Lnl3H">aerodynamics</a> of <a href="/facts/Supersonic_aircraft/Spue1MRH">supersonic aircraft</a> is simpler than subsonic aerodynamics because the airsheets at different points along the plane often cannot affect each other. Supersonic jets and rocket vehicles require several times greater thrust to push through the extra <a href="/facts/Aerodynamic_drag/vdl4jF7I">aerodynamic drag</a> experienced within the <a href="/facts/Transonic/F7SV9hrt">transonic</a> region (around Mach 0.85–1.2). At these speeds <a href="/facts/Aerospace_engineer/2Ib02w7f">aerospace engineers</a> can gently guide air around the <a href="/facts/Fuselage/vVXlHEE4">fuselage</a> of the aircraft without producing new <a href="/facts/Shock_wave/CqrG1Xm5">shock waves</a>, but any change in cross area farther down the vehicle leads to shock waves along the body. Designers use the <a href="/facts/Supersonic_area_rule/k6lQBIF1">Supersonic area rule</a> and the <a href="/facts/Whitcomb_area_rule/k6lQBIF1">Whitcomb area rule</a> to minimize sudden changes in size.
</p>

<p>However, in practical applications, a supersonic aircraft must operate stably in both subsonic and supersonic profiles, hence aerodynamic design is more complex.
</p><p>The main key to having low supersonic drag is to properly shape the overall aircraft to be long and thin, and close to a "perfect" shape, the <a href="/facts/Nose_cone_design/GgygdjK3">von Karman ogive</a> or <a href="/facts/Sears-Haack_body/XLuS2Lzj">Sears-Haack body</a>. This has led to almost every supersonic cruising aircraft looking very similar to every other, with a very long and slender fuselage and large delta wings, cf. <a href="/facts/SR-71_Blackbird/ESfv9oFq">SR-71</a>, <a href="/facts/Concorde/TAMElD6g">Concorde</a>, etc. Although not ideal for passenger aircraft, this shaping is quite adaptable for bomber use.
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<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Area_rule/k6lQBIF1">Area rule</a></li>
<li><a href="/facts/Hypersonic_speed/QUsQbhur">Hypersonic speed</a></li>
<li><a href="/facts/Sonic_boom/Hfnr1Vlz">Sonic boom</a></li>
<li><a href="/facts/Supersonic_aircraft/Spue1MRH">Supersonic aircraft</a></li>
<li><a href="/facts/Supersonic_airfoils/V7BwqYLs">Supersonic airfoils</a></li>
<li><a href="/facts/Transonic/F7SV9hrt">Transonic speed</a></li>
<li><a href="/facts/Vapor_cone/sTKcJ4Bo">Vapor cone</a></li>
<li><a href="/facts/Prandtl%E2%80%93Glauert_singularity/QfDyBgw9">Prandtl–Glauert singularity</a></li>
<li><a href="/facts/Supersonic_(Oasis_song)/MoqbRdlf">Supersonic (Oasis song)</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://books.google.com/books?id=PyEDAAAAMBAJ&dq=motor+gun+boat&pg=PA72">"Can We Ever Fly Faster Speed of Sound", October 1944, Popular Science</a> one of the earliest articles on shock waves and flying the speed of sound</li>
<li><a href="https://books.google.com/books?id=NSEDAAAAMBAJ&dq=popular+science+January+1946&pg=PA114">"Britain Goes Supersonic", January 1946, Popular Science</a> 1946 article trying to explain supersonic flight to the general public</li>
<li><a href="http://www.mathpages.com/home/kmath109/kmath109.htm">MathPages – The Speed of Sound</a></li>
<li><a href="http://www.makeitlouder.com/Decibel%20Level%20Chart.txt">Supersonic sound pressure levels</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"Does the Tip of a Snapped Towel Travel Faster Than Sound?". <a href="https://www.hiviz.com/projects/towel/towel.htm" target="_blank">https://www.hiviz.com/projects/towel/towel.htm</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Mike May (2002). "Crackin' Good Mathematics". American Scientist. 90 (5). Archived from the original on 2016-03-22. Retrieved 2015-08-26. <a href="https://web.archive.org/web/20160322062952/http://www.americanscientist.org/issues/pub/2002/9/crackin-good-mathematics" target="_blank">https://web.archive.org/web/20160322062952/http://www.americanscientist.org/issues/pub/2002/9/crackin-good-mathematics</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>"Hypography – Science for everyone – Whip Cracking Mystery Explained". Archived from the original on 2012-02-17. Retrieved 2008-02-06. <a href="https://web.archive.org/web/20120217002832/http://www.hypography.com/article.cfm?id=32479" target="_blank">https://web.archive.org/web/20120217002832/http://www.hypography.com/article.cfm?id=32479</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>"Hornady Ammunition Charts" (PDF). Archived from the original (PDF) on 2007-09-27. Retrieved 2011-11-04. <a href="https://web.archive.org/web/20070927043455/http://www.hornady.com/images/ballistics/ballistics_charts.pdf" target="_blank">https://web.archive.org/web/20070927043455/http://www.hornady.com/images/ballistics/ballistics_charts.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
</ol>

Supersonic speed open-in-new

Supersonic speed