{{Short description|Biplane flying boat produced in Yugoslavia}} <!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout. --> {{Infobox aircraft | name = Ikarus IO | logo = | logo_size = | image = | alt = | caption = Airplane Ikarus IO 2 | long_caption = | other_names = | aircraft_type = Reconnaissance flying boat | aim = | outcome = | related = | national_origin = Yugoslavia | manufacturer = [[Ikarbus|Ikarus]] | design_group = | designer = [[Josip Mikl]] | builder = | issuer = | status = retired | owners = | primary_user = [[Yugoslav Royal Navy]] | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = 38 | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = 1927 | retired = | first_flight = September 1926 | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }} The '''Ikarus IO''' ([[Serbian Cyrillic]]:'''Икарус ИО''' – Извиђач Обални) was a [[biplane]] [[flying boat]] produced in [[Yugoslavia]] in the late 1920s. It was a conventional flying boat design for its day, featuring a large single-bay wing cellule, the staggered wings of slightly uneven span braced with N-struts. The pilot and observer sat side by side in an open cockpit, and a gunner sat in an open position ahead of them, in the bow. The pusher engine and frontal radiator were carried on struts in the inter-plane gap.
==Development== [[File:Liberty L-12-1.jpg|thumb|A Liberty L-12, as installed in the Ikarus IO]]
After the crash of the [[Ikarus IM]] prototype reconnaissance seaplane ([[Serbian Cyrillic]]:'''Икарус ИМ''' – Извиђач Морнарички) with {{convert|260|hp|abbr=on}} [[BMW IV]] engine, on 31 May 1926, Ikarus immediately started development of a second reconnaissance seaplane prototype powered by a {{convert|4-00|hp|abbr=on}} Liberty L-12 engine, also designed by Josef Mikl, the Ikarus Technical Manager. The new prototype was named Ikarus IO (Coastal Reconnaissance) and the first test flight took place from the [[Danube]] at [[Novi Sad]] in September 1926.
After all-round tests, the aircraft was given a positive assessment and the Naval Air Force ordered the first series of 12 aircraft, which were delivered during 1927, serialled 101 to 112. Based on observations arising from the operational use of the aircraft, certain modifications were applied and another 24 modified IOs were ordered, receiving serials 113 to 136. In parallel with the development of the second IO series, Ikarus built prototype aircraft powered by a Loren engine.<ref>Петровић, Огњан М. (2/2000.). "Војни аероплани Краљевине СХС/Југославије (Део I: 1918 – 1930.)" (in (Serbian)). Лет – Flight (YU-Београд: Музеј југословенског ваздухопловства) 2: стр. 21–84. {{ISSN|1450-684X}}</ref>
The Ikarus IO was a flying boat with completely wooden structure, with wings rounded at the edges and covered with canvas. Auxiliary floats increased the stability of water-borne navigation. The two flight crew members, scout and pilot were seated side by side in parallel and the gunner sat in front of them in an open position with a [[Scarff ring]] gun mounting. Painted light gray, the aircraft were used in coastal reconnaissance and bombing roles and could carry about {{convert|250|kg|abbr=on}} of bombs and were armed with a {{convert|7.7|mm|in|abbr=on|3}} [[Darne machine gun]] mounted on the gunner's Scarff ring.
==Variants== Markings subtypes of these aircraft were fitted with engines, according to [1]:
;IO/Li: Coastal Reconnaissance seaplane with {{convert|400|hp|abbr=on}} [[Liberty L-12]], (36 copies + 1 prototype built the 1927th and 1928 when available). ;IO/Lo :Coastal Reconnaissance seaplane with {{convert|450|hp|abbr=on}} [[Lorraine-Dietrich 12Eb]], (1 copy – a prototype conversion 1929th year) ;IO/Re :Coastal Reconnaissance seaplane with {{convert|500|hp|abbr=on}} [[Renault 12Ke]](1 copy – the prototype of the 1930th year 1937), ;IO/Lo :Coastal Reconnaissance seaplane with {{convert|400|hp|abbr=on}} [[Lorraine Dietrich-12Db]], (20 copies – Conversion 1934th year).
==Operational history== The IO was used by the Kingdom of SHS / Yugoslavia Navy as a coastal reconnaissance seaplane and light bomber from 1927 until 1941. The aircraft were deployed and served at [[Divulje]], [[Vodice, Croatia|Vodice]] and [[Kumbor]]. Initially the IO suffered a high accident rate and by 1932 only 29 of the 37 production aircraft were still in service. Because of intensive use the Liberty engines were worn out and difficult to support necessitating substitution with Lorraine-Dietrich engines. In January 1941, 4 aircraft remained in service, of which two were airworthy, which were not used in operations before being withdrawn.
==Operators== ;{{flag|Kingdom of Yugoslavia}} *[[Yugoslav Royal Navy]] <!-- ==Units using this aircraft/Operators (choose)== -->
==Specifications== {{Aircraft specs |ref=<!-- reference --> |prime units?=met <!-- General characteristics --> |genhide=
|crew=3 |capacity= |length m=10.4 |length ft= |length in= |length note= |span m=15.2 |span ft= |span in= |span note= |upper span m= |upper span ft= |upper span in= |upper span note= |mid span m= |mid span ft= |mid span in= |mid span note= |lower span m= |lower span ft= |lower span in= |lower span note= |height m=3.52 |height ft= |height in= |height note= |wing area sqm=47.5 |wing area sqft= |wing area note= |aspect ratio=<!-- sailplanes --> |airfoil= |empty weight kg=1520 |empty weight lb= |empty weight note= |gross weight kg=2450 |gross weight lb= |gross weight note= |max takeoff weight kg= |max takeoff weight lb= |max takeoff weight note= |fuel capacity= |more general= <!-- Powerplant --> |eng1 number=1 |eng1 name=[[Liberty L-12]] |eng1 type=45° V-12 water-cooled piston engine |eng1 kw=<!-- prop engines --> |eng1 hp=400 |eng1 shp=<!-- prop engines --> |eng1 kn=<!-- jet/rocket engines --> |eng1 lbf=<!-- jet/rocket engines --> |eng1 note= |power original= |thrust original= |eng1 kn-ab=<!-- afterburners --> |eng1 lbf-ab=<!-- afterburners -->
|prop blade number=<!-- propeller aircraft --> |prop name= |prop dia m=<!-- propeller aircraft --> |prop dia ft=<!-- propeller aircraft --> |prop dia in=<!-- propeller aircraft --> |prop dia note= <!-- Performance --> |perfhide=
|max speed kmh=170 |max speed mph= |max speed kts= |max speed note= |max speed mach=<!-- supersonic aircraft --> |cruise speed kmh=145 |cruise speed mph= |cruise speed kts= |cruise speed note= |stall speed kmh= |stall speed mph= |stall speed kts= |stall speed note= |never exceed speed kmh= |never exceed speed mph= |never exceed speed kts= |never exceed speed note= |range km=600 |range miles= |range nmi= |range note= |combat range km= |combat range miles= |combat range nmi= |combat range note= |ferry range km= |ferry range miles= |ferry range nmi= |ferry range note= |endurance=<!-- if range unknown --> |ceiling m=4500 |ceiling ft= |ceiling note= |g limits=<!-- aerobatic --> |roll rate=<!-- aerobatic --> |climb rate ms= |climb rate ftmin= |climb rate note= |time to altitude= |lift to drag= |wing loading kg/m2= |wing loading lb/sqft= |wing loading note= |fuel consumption kg/km= |fuel consumption lb/mi= |power/mass= |thrust/weight=
|more performance= <!-- Armament --> |armament=<!-- add bulletted list here or if you want to use the following specific parameters, remove this parameter--> |guns= 1x {{convert|7.7|mm|in|abbr=on|3}} [[Darne machine gun]] in the bow gunners position |bombs= {{convert|250|kg|abbr=on}} |rockets= |missiles= |hardpoints= |hardpoint capacity= |hardpoint rockets= |hardpoint missiles= |hardpoint bombs= |hardpoint other=
|avionics= }}
==See also== {{aircontent <!-- include as many lines are appropriate. additional lines/entries with carriage return. --> |see also= * [[Ikarus ŠM]] |related=<!-- related developments --> |similar aircraft=<!-- similar or comparable aircraft --> |lists= * [[List of aircraft of World War II]] }}
==Notes== {{reflist}}
==References== # {{cite book |last= Taylor |first= Michael J. H. |title=Jane's Encyclopedia of Aviation |year=1989 |publisher=Studio Editions |location=London |pages=528 }} # {{cite book | last = Лучић | first = Душан | script-title=sr:Основи практичне аеродинамике са описима аероплана | year = 1936 | publisher = Ваздухопловни Гласник | location = YU-Нови Сад | language = sr | id = | pages = | chapter = }} # {{cite book | last = Микић | first = Сава Ј. | script-title=sr:Историја југословенског ваздухопловства | year = 1933 | publisher = Штампарија Д. Грегорић | location = YU-Београд | language = sr | id = | pages = | chapter = }} # {{cite book | last = Оштрић | first = Шиме |author2=М. Мицевски | script-title=sr:Летећи Чунови: Чамци који лете – летјелице које плове | date = 2007 | publisher = Гал��рија '73 | location = SRB-Београд | language = sr | id = | pages = | chapter = }} # {{cite book | last = Isaić | first = Vladimir |author2=Danijel Frka | title = Pomorsko zrakoplovstvo na istočnoj obali Jadrana 1918–1941. (prvi dio) | year = 2010 | publisher = Tko zna zna d.o.o. | location = Zagreb | language = hr | isbn = 978-953-97564-6-6 | pages = | chapter = }} #{{cite journal | last = Петровић | first = Огњан М. | date = 2000 | title = Војни аероплани Краљевине СХС/Југославије (Део I: 1918–1930.) | journal = Лет – Flight | volume = 2 | publisher = Музеј југословенског ваздухопловства | location = YU-Београд | language = sr | issn = 1450-684X | pages = стр. 21–84 }} # {{cite book | last = Јанић | first = Чедомир |author2=Петровић, Огњан | script-title=sr:Век авијације у Србији 1910–2010, 225 значајних летелица | year = 2010 | publisher = Аерокомуникације | location = Београд | language = sr | isbn = 978-86-913973-0-2 }}
==External links==
*https://web.archive.org/web/20100113150445/http://www.paluba.info/smf/mornaricka-avijacija/ikarus-io-izvidac-obalni/ *http://www.pouke.org/forum/index.php?topic=5559.5;wap2 {{Webarchive|url=https://web.archive.org/web/20211203055027/https://pouke.org/forum/index.php?topic=5559.5;wap2 |date=2021-12-03 }}
{{Ikarus aircraft}}
[[Category:1920s Yugoslav military reconnaissance aircraft]] [[Category:Flying boats]] [[Category:Ikarus aircraft|IO]] [[Category:Biplanes]] [[Category:Single-engined pusher aircraft]] [[Category:Aircraft first flown in 1926]]