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{{Short description|A tool used to measure projectile speed}}
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A '''ballistic chronograph''' or '''gun chronograph''' is a [[measuring instrument]] used to [[measurement|measure]] the [[velocity]] of a [[projectile]] in [[flight]], typically fired from a [[gun]] or other [[firearm]]. The instrument is often useful for tasks such as gauging the utility of a [[firearm]] or safety of non-lethal projectiles fired from items such as a [[Paintball marker|paintball gun]] or [[BB gun]].
==History==
[[Benjamin Robins]] (
[[Alessandro Vittorio Papacino d'Antoni]] published results in 1765 using a wheel chronometer. This used a horizontal spinning wheel with a vertical paper mounted on the rim. The bullet was fired across the diameter of the wheel so that it pierced the paper on both sides, and the angular difference along with the rotation speed of the wheel was used to compute the bullet velocity.<ref>{{Citation |last=d'Antoni |first=Alessandro Vittorio Papacino |title=Esame Della Polvere |year=1765 |location=Torino |publisher=Nella Stamperia Reale}}</ref>
An early chronograph that measures velocity directly was built in 1804 by [[Grobert]], a colonel in the French Army. This used a rapidly rotating axle with two disks mounted on it about 13 feet apart. The bullet was fired parallel to the axle, and the angular displacement of the holes in the two disks, together with the rotational speed of the axle, yielded the bullet velocity.<ref>{{Citation |last=Prony |contribution=Report of a method of measuring the initial Velocity of Projectiles discharged from Fire-arms, both horizontally and with different Elevations, made to the Physical and Mathematical Class of the National Institute |title=A Journal of Natural Philosophy, Chemistry and the Arts |editor-first=William |editor-last=Nicholson |volume=XI |year=1805 |location=London |url=http://books.google.com/books?id=uwkAAAAAMAAJ&pg=RA1-PA42&hl=en&sa=X&f=false}} at page 42<br/> abridged from ''Journal des Mines'' No 92 p. 117, May 1804.</ref>▼
▲An early chronograph that measures velocity directly was built in 1804 by [[Grobert]], a colonel in the French Army. This used a rapidly rotating axle with two disks mounted on it about 13 feet apart. The bullet was fired parallel to the axle, and the angular displacement of the holes in the two disks, together with the rotational speed of the axle, yielded the bullet velocity.<ref>{{Citation |last=Prony |contribution=Report of a method of measuring the initial Velocity of Projectiles discharged from Fire-arms, both horizontally and with different Elevations, made to the Physical and Mathematical Class of the National Institute |title=A Journal of Natural Philosophy, Chemistry and the Arts |editor-first=William |editor-last=Nicholson |volume=XI |year=1805 |location=London |url=
{{Harvtxt|Ingalls|1882|p=18}} describes Bashforth's chronograph:<ref>{{citation |last=Ingalls |first=James M. |publisher=D. van Nostrand |location=New York |year=1886 |title=Exterior Ballistics in the Plane of Fire }}</ref>▼
{{Harvtxt|Ingalls|1886|p=18}} describes Bashforth's chronograph that could make many measurements over long distances:
: In 1865 the Rev. [[Francis Bashforth]], M. A., who had then been recently appointed Professor of Applied Mathematics to the advanced class of artillery officers at [[Royal Military Academy, Woolwich|Woolwich]], began a series of experiments for determining the resistance of the air to the
[[File:Girl Gunners- the work of the Auxiliary Territorial Service at An Experimental Station, Shoeburyness, Essex, England, 1943 D12697.jpg|thumb|right|The velocity of [[Ordnance QF 25-pounder]] shells being measured in the United Kingdom, 1943]]
The Bashforth screens were made with several threads and series connected switches. A projectile passing through a screen would break one or more threads, the broken thread caused a switch to momentarily (about 20 ms) interrupt a current as the switch arm moved from its weighted position to its unweighted position, and the momentary interruption would be recorded on a paper chart.<ref>{{Harvnb|Bashforth|1866|pp=12–13}}</ref>
The first electronic ballistic chronograph was invented by Kiryako ("Jerry") Arvanetakis in the 1950s.{{Citation needed|date=May 2011}} As consulting engineer under contract by NACA (later [[NASA]]), he was asked to find a way to accurately measure the velocity of various projectiles fired at [[hypersonic|hyper-velocities]] into a variety of engineered materials in anticipation of
==Modern chronograph==
The modern chronograph consists of two sensing areas
Advanced ballistic chronographs include a type employing [[Doppler radar]] to measure bullets in free flight at various distances; another is a device mounted at the end of a barrel, which uses magnetic field sensors for the measurement of a bullet's velocity as it exits the muzzle.<ref>{{Cite web|url=https://outdoorworld.reviews/best-shooting-chronograph/|title = 15 Best Shooting Chronographs|date = 22 November 2020}}</ref>
▲The first electronic ballistic chronograph was invented by Kiryako ("Jerry") Arvanetakis in the 1950s.{{Citation needed|date=May 2011}} As consulting engineer under contract by NACA (later [[NASA]]), he was asked to find a way to accurately measure the velocity of various projectiles fired at [[hypersonic|hyper-velocities]] into a variety of engineered materials in anticipation of manned space flight. His first design was an open rectangular frame of square [[aluminum]] tubing with a screen of fine copper wire at both ends. Breaking the first wire started charging a [[capacitor]], breaking the second wire stopped it. Measuring the accumulated voltage and knowing the rate of charge the elapsed time could be accurately calculated.
== See also ==
▲[[File:Prochrono2.jpg|thumb|Down Range Chronograph with storage and statistical tools.]]
* [[Aberdeen chronograph]]
==References==
{{reflist|30em}}
* {{Citation |last=Bashforth |first=Francis |authorlink=Francis Bashforth |title=Description of a Chronograph adapted for measuring the varying velocity of a body in motion through the air and for other purposes |location=London |publisher=Bell and Daldy |year=1866 |url=https://books.google.com/books?id=tBxWAAAAcAAJ}}
▲
==Further reading==
* {{Citation |last=Bashforth |first=Francis |authorlink=Francis Bashforth |title=A mathematical treatise on the motion of Projectiles founded chiefly on the results of experiments made with the author's chronograph |location=London |publisher=Asher and Company |year=1873 |url=https://archive.org/details/amathematicaltr00bashgoog |ref=none}}
* {{Citation |last=Bashforth |first=Francis |authorlink=Francis Bashforth |url=https://archive.org/details/ballisticexperim00bashrich |title=
* {{Citation |last=Bashforth |first=Francis |authorlink=Francis Bashforth |title=
* {{Citation |last=Bashforth |first=Francis |authorlink=Francis Bashforth |url=
{{Firearms}}
[[Category:Horology]]
[[Category:Firearm terminology]]
[[Category:Ballistics]]
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