Editing Flight recorder (section)

=== Early designs ===
One of the earliest and proven attempts was made by [[François Hussenot]] and Paul Beaudouin in 1939 at the [[Marignane]] flight test center, France, with their "type HB" flight recorder; they were essentially photograph-based flight recorders, because the record was made on a scrolling [[photographic film]] {{convert|8|m|yd}} long by {{convert|88|mm}} wide. The [[latent image]] was made by a thin ray of light deviated by a mirror tilted according to the magnitude of the data to be recorded (altitude, speed, etc.).<ref name="Fayer"/> A pre-production run of 25 "HB" recorders was ordered in 1941 and HB recorders remained in use in French flight test centers well into the 1970s.<ref name="Beaudouin-2"/><ref>{{Cite web|title=Black Box History|date=May 22, 2020|website=Native Khabar|url=https://www.nativekhabar.com/india/black-box-plane-flight-data-recorder-aeroplane/5731|access-date=May 22, 2020|archive-date=January 25, 2022|archive-url=https://web.archive.org/web/20220125123838/http://nativekhabar.com/|url-status=live}}</ref>

In 1947, Hussenot founded the Société Française des Instruments de Mesure with Beaudouin and another associate, so as to market his invention, which was also known as the "hussenograph". This company went on to become a major supplier of data recorders, used not only aboard aircraft but also trains and other vehicles. SFIM is today part of the [[Safran]] group and is still present in the flight recorder market. The advantage of the film technology was that it could be easily developed afterwards and provides a durable, visual feedback of the flight parameters without needing any playback device. On the other hand, unlike magnetic tapes or later flash memory-based technology, a photographic film cannot be erased and reused, and so must be changed periodically. The technology was reserved for one-shot uses, mostly during planned test flights: it was not mounted aboard civilian aircraft during routine commercial flights. Also, cockpit conversation was not recorded.

Another form of flight data recorder was developed in the UK during World War II. Len Harrison and Vic Husband developed a unit that could withstand a crash and fire to keep the flight data intact.  The unit was the forerunner of today's recorders, in being able to withstand conditions that aircrew could not.  It used copper foil as the recording medium, with various styli, corresponding to various instruments or aircraft controls, indenting the foil. The foil was periodically advanced at set time intervals, giving a history of the aircraft's instrument readings and control settings. The unit was developed at [[Farnborough, Hampshire|Farnborough]] for the [[Ministry of Aircraft Production]]. At the war's end the Ministry got Harrison and Husband to sign over their invention to it and the Ministry patented it under British patent 19330/45.

[[File:Lentokoneen_musta_laatikko._Ollut_käytössä_1940-70._Valtion_lentokonetehdas,_1940-luku._Tampereen_museot._Kuva_Marika_Tamminen,_Vapriikin_kuva-arkisto._(16271443869).jpg|thumb|right|"Mata-Hari" flight data recorder]]

The first modern flight data recorder, called "Mata-Hari", was created in 1942 by Finnish aviation engineer Veijo Hietala. This black high-tech mechanical box was able to record all required data during test flights of [[fighter aircraft]] that the [[Finnish Air Force]] repaired or built in its main [[Valtion lentokonetehdas|aviation factory]] in [[Tampere]], Finland.<ref>{{cite web|url=http://siiri.tampere.fi/displayObject.do?uri=http://www.profium.com/archive/ArchivedObject-8077CE76-2B43-6FAA-D11C-77AAFD6C72E8|trans-title=State aircraft factory: Mata-Hari or black box|title= Valtion lentokonetehdas: Mata-Hari eli musta laatikko |date=1946| website=Museums of Tampere |archive-url=https://web.archive.org/web/20171019110346/http://siiri.tampere.fi/displayObject.do?uri=http%3A%2F%2Fwww.profium.com%2Farchive%2FArchivedObject-8077CE76-2B43-6FAA-D11C-77AAFD6C72E8 |archive-date=October 19, 2017 |url-status=dead|access-date=October 19, 2017|language=fi}}</ref>

During World War II both British and American air forces successfully experimented with aircraft voice recorders.<ref>{{Cite AV media|last=Chuck Owl|title=Audio From the Past [E01] - WW2 - Avro Lancaster Crew Radio|date=February 4, 2015|url=https://www.youtube.com/watch?v=MF5_hvE4WEA|access-date=February 13, 2019|via=[[YouTube]]|archive-date=November 16, 2018|archive-url=https://web.archive.org/web/20181116214517/https://www.youtube.com/watch?v=MF5_hvE4WEA&feature=youtu.be|url-status=live}}</ref> In August 1943 the [[USAAF]] conducted an experiment with a [[Wire recording|magnetic wire recorder]] to capture the inter-phone conversations of a B-17 bomber flight crew on a combat mission over Nazi-occupied France.<ref>{{Cite web|url=https://www.americanradiohistory.com/Archive-Radio-News/40s/Radio-News-1944-01-R.pdf|title=Radio News, 'Radio - On a Flying Fortress' |page=21|last=Porter|first=Kenneth|date=January 1944|website=www.americanradiohistory.com|access-date=February 13, 2019|archive-date=January 25, 2022|archive-url=https://web.archive.org/web/20220125123836/https://worldradiohistory.com/Archive-Radio-News/40s/Radio-News-1944-01-R.pdf|url-status=live}}</ref> The recording was broadcast back to the United States by radio two days afterwards.