Caudron C.860

{{Short description|Single engine, single seat monoplane}}  {{Infobox aircraft | name = Caudron C.860 | logo = | logo_size = | image = | alt = | caption = | long_caption = | other_names = | aircraft_type = Long range communication aircraft | aim = | outcome = | related = | national_origin = France | manufacturer = Société des Avions Caudron | design_group = | designer = Marcel Riffard | builder = | issuer = | status = | owners = | primary_user = Air Ministry | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = 1 | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = | first_flight = 6–10 September 1938 | initiated = | in_service = | last_flight = | expected = | developed_from = Caudron Simoun and Rafale | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }}

The '''Caudron C.860''' was a single engine, single seat monoplane ordered by the French government as a long-distance communications aircraft. First flown in 1938, it was also expected to set speed and altitude records but the outbreak of World War II ended developments.

==Design==

The C.860 was ordered by the French Air Ministry who planned to use it, piloted by André Japy, for rapid long-distance communications. Powered by a {{convert|9.5|L|cuin|abbr=on}} Renault 6Q-03 engine, it had a range of up to {{convert|8000|km|mi nmi|abbr=on}} when cruising at {{convert|290|km/h|mph kn|abbr=on}}. It was also expected to set distance and altitude records in Category 1 with a {{convert|8.0|L|cuin|abbr=on}} Renault engine and in Category 2 with a {{convert|6.5|L|cuin|abbr=on}} Renault,<ref name=LailesM/> but war intervened.

Its wing and empennage were aerodynamically similar to those of the Caudron Simoun, though the single-piece wing was structurally closer to that of the record-setting Rafale racer. The wing was tetragonal in plan, with more sweep on the trailing edge than on the leading edge, though the tips were semi-elliptical. It had an all-wood structure with a single box spar which incorporated an upper flange of gumbo-limbo, a Central and South American wood of particularly high bulk modulus, together with spruce and plywood ribs. The ply skin was finished with a fabric overlay. Its ailerons were carried on auxiliary spars.<ref name=LailesM/>

The C.860's fuselage was slender, with a maximum width of only {{convert|850|mm|in|abbr=on}} and about one third of it ahead of the wing leading edge. Its {{convert|240|hp|kW|abbr=on|order=flip}} {{convert|9.5|L|cuin|abbr=on}} air-cooled six-cylinder Renault 6Q-03 inverted in-line engine, supercharged to {{convert|2000|m|ft|abbr=on}}, was in the nose with its main and collector fuel tanks behind it over the centre of gravity. Together with four smaller wing tanks, these gave a fuel capacity of {{convert|1500|L|Impgal USgal|abbr=on}}. The pilot had an enclosed cockpit with his head raised only slightly above the fuselage under a shallow canopy with a horizontal strip of plexiglas for forwards and sideways vision, a solid top and an extended fairing aft. There were also windows in the fuselage sides for downward views.<ref name=LailesM/>

The fuselage had a wooden frame with canvas covered sides and curved magnesium sheet top and bottom. The empennage of the C.860 was conventional, with a straight-tapered, blunt-tipped horizontal tail carrying separate elevators. The tall vertical tail had a similar shape though, unlike the elevators, the rudder was balanced. The aircraft had a fixed, tailwheel undercarriage with a {{convert|2|m|ftin|abbr=on}} track. Messier oleo strut landing legs were mounted on the wing spar. Legs, mainwheels and the steerable tailwheel, also on an oleo strut, were enclosed in fairings.<ref name=LailesM/>

==Development==

By 5 September 1938 the C.860 had been brought, still not quite complete, from the Caudron factory at Issy-les-Moulineaux to the airfield at Guyancourt.<ref name=Fig1/> The first flight had been made, piloted by Delmotte, by 10 September.<ref name=Fig2/> Its initial tests had been completed by the end of September, when the C.860 entered the Centre d'Essais de Matériels Aériens (CEMA), the French official testing centre at Villacoublay.<ref name=Lailes1/> These tests temporarily finished at the beginning of January 1939<ref name=Lailes2/> but the C.860 returned to CEMA at the end of the month.<ref name=Lailes3/>

With certification complete, the Air Ministry took the C.860 to Istres to determine the take-off run required with the heavy fuel load needed to achieve the desired long range.<ref name=Lailes4/> A 24.5 hour flight at {{convert|290|km/h|mph|abbr=on}}, covering {{convert|7100|km|mi|abbr=on}}, consumed {{convert|1340|L|impgal USgal|abbr=on}} of petrol and {{convert|80|L|Impgal USgal|abbr=on}} of oil. The resulting take-off weight of {{convert|2300|kg|lb|abbr=on}}, required a take-off run of {{convert|650|m|ft|abbr=on}}, well within the Air Ministry's {{convert|1000|m|ft|abbr=on}} specification limit.<ref name=LailesM/>

==Specifications== {{Aircraft specs |ref=Les Ailes 8 June 1939<ref name=LailesM/> |prime units?=met  |genhide=

|crew=One |length m=8.60 |length note= |span m=10.40 |span note= |height m=3.28 |height note= |wing area sqm=16 |wing area note= |aspect ratio= |airfoil= |empty weight kg=1160 |empty weight lb= |empty weight note= |gross weight kg=1650 |gross weight lb= |gross weight note=for certification tests, up to {{convert|2400|kg|lb|abbr=on}} for distance records |max takeoff weight kg= |max takeoff weight lb= |max takeoff weight note= |fuel capacity={{convert|1500|L|Impgal USgal|abbr=on}} |more general=  |eng1 number=1 |eng1 name=Renault 6Q-03<ref name=avfr1/> |eng1 type={{convert|9.5|L|cuin|abbr=on}} air-cooled six-cylinder, inverted in-line piston engine, supercharged to {{convert|2000|m|ft|abbr=on}} |eng1 hp=240 |eng1 note= |power original=

|perfhide=

|max speed kmh=340 |max speed mph= |max speed kts= |max speed note= at {{convert|2500|m|ft|abbr=on}} |cruise speed kmh=290 |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= |minimum control speed kmh= |minimum control speed mph= |minimum control speed kts= |minimum control speed note= |range km=7100 |range note= at a weight of {{convert|2300|kg|lb|abbr=on}} |endurance= |ceiling m= |ceiling ft= |ceiling note= |g limits= |roll rate= |glide ratio= |climb rate ms= |climb rate ftmin= |climb rate note= |time to altitude= |sink rate ms= |sink rate ftmin= |sink rate note= |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= *'''Take-off distance:''' {{convert|340|m|ft|abbr=on}} at {{convert|1650|kg|lb|abbr=on}}; {{convert|650|m|ft|abbr=on}} at {{convert|2300|kg|lb|abbr=on}}

}}

==References== {{reflist|2|refs=

<ref name=LailesM>{{cite journal |last=Frachet |first=André |date=8 June 1939|title=L'avion de performance Caudron "C-860"|journal=Les Ailes|issue=938 |pages=9|url=http://gallica.bnf.fr/ark:/12148/bpt6k6554698t/f9 }}</ref>

<ref name=Lailes1>{{cite journal |date=29 September 1938|title=Les avions en essais|journal=Les Ailes|issue=902 |pages=10|url=http://gallica.bnf.fr/ark:/12148/bpt6k6555906x/f10 }}</ref>

<ref name=Lailes2>{{cite journal |date=5 January 1939|title=Les avions en essais|journal=Les Ailes|issue=919 |pages=8|url=http://gallica.bnf.fr/ark:/12148/bpt6k65546767/f12 }}</ref>

<ref name=Lailes3>{{cite journal |date=6 February 1939|title=Les avions en essais|journal=Les Ailes|issue=922 |pages=9|url=http://gallica.bnf.fr/ark:/12148/bpt6k65546767/f12 }}</ref>

<ref name=Lailes4>{{cite journal |date=6 April 1939|title=Les avions en essais|journal=Les Ailes|issue=929 |pages=9|url=http://gallica.bnf.fr/ark:/12148/bpt6k6554689v/f9 }}</ref>

<ref name=Fig1>{{cite news |author=Phillipe Roland |title=AVIATION |url= http://gallica.bnf.fr/ark:/12148/bpt6k409970g/f5|newspaper=Le Figaro |date=5 September 1938 }}</ref>

<ref name=Fig2>{{cite news |author=Phillipe Roland |title=AVIATION |url=http://gallica.bnf.fr/ark:/12148/bpt6k409976r/f4 |newspaper=Le Figaro |date=11 September 1938 }}</ref>

<ref name=avfr1>{{cite web |url=https://www.aviafrance.com/aviafrance1.php?ID=10225&ID_CONSTRUCTEUR=313&ANNEE=0&ID_MISSION=0&MOTCLEF=|title=Caudron C.860 |author=Bruno Parmentier |date= |accessdate=30 May 2016}}</ref>

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Category:1930s French civil aircraft C. Category:Aircraft first flown in 1938