Airborne Interception radar, Mark IV, was the first successful air-to- air radar system, used in Britain's Bristol Beaufighter heavy fighters by early 1941 in the Second World War. Early development of the Mk. IV was prompted by a 1936 memo from the inventor Henry Tizard to Robert Watt, director of the radar research efforts, who agreed to allow physicist Taffy Bowen to form a team to study the problem of air interception. The team had a test bed system in flights later that year, but progress was delayed for four years by emergency relocations, three abandoned production designs, and Bowen's increasingly adversarial relationship with Watt's replacement, Albert Percival Rowe. The Mk. IV had many limitations, including displays that were difficult to interpret, a maximum range that decreased with the aircraft's altitude, and a minimum range that was barely close enough to allow the pilot to see the target. Nevertheless, the Mk. IV played a role in the Royal Air Force's increasingly effective response to The Blitz, the Luftwaffe‍‍ '​‍s night bombing campaign. The Mk. VIII largely relegated the Mk. IV to second-line duties by 1943.

Read more: https://en.wikipedia.org/wiki/AI_Mk._IV_radar

_______________________________ Today's selected anniversaries:

1201:

John Komnenos the Fat briefly seized the throne of the Byzantine Empire from Alexios III Angelos, but he was soon caught and executed. https://en.wikipedia.org/wiki/John_Komnenos_the_Fat

1703:

English writer Daniel Defoe was placed in a pillory for seditious libel after publishing a pamphlet politically satirising the High Church Tories. https://en.wikipedia.org/wiki/Daniel_Defoe

1777:

The Second Continental Congress passed a resolution allowing French nobleman Marquis de Lafayette to enter the American revolutionary forces as a Major General. https://en.wikipedia.org/wiki/Gilbert_du_Motier,_Marquis_de_Lafayette

1975:

The Troubles: In a botched paramilitary attack, three members of the popular Miami Showband and two Ulster Volunteer Force gunmen were killed in County Down, Northern Ireland. https://en.wikipedia.org/wiki/Miami_Showband_killings

1991:

The Soviet Union and the United States signed the bilateral START I treaty (signing pictured), the largest and most complex arms control treaty in history, which eventually removed 80% of all strategic nuclear weapons then in existence. https://en.wikipedia.org/wiki/START_I

_____________________________ Wiktionary's word of the day:

coppice: A grove of small growth; a thicket of brushwood; a wood cut at certain times for fuel or other purposes, typically managed to promote growth and ensure a reliable supply of timber. https://en.wiktionary.org/wiki/coppice

___________________________ Wikiquote quote of the day:

We do not need magic to transform our world. We carry all the power we need inside ourselves already. We have the power to imagine better.   --J. K. Rowling https://en.wikiquote.org/wiki/J._K._Rowling