CLW Curlew

{{Short description|Training aircraft}}  {{Use dmy dates|date=March 2018}} {{Use British English|date=March 2018}} {{Infobox aircraft | name = Curlew | logo = | logo_size = | image = | alt = | caption = ''Flight Global archive''<ref name="FlightA"/> | long_caption = | other_names = | aircraft_type = Demonstrator and trainer | aim = | outcome = | related = | national_origin = United Kingdom | manufacturer = CLW Aviation Co.Ltd. | design_group = | designer = Arthur Levell and Francis Welman | builder = | issuer = | status = | owners = | primary_user = | 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 = 3 September 1936 | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }} The '''CLW Curlew''' was a two-seat, single-engined training aircraft built partly to demonstrate a new wing structure. It flew successfully in the UK in 1936, but the company went bankrupt and only one Curlew flew.

==Design and development==

In the early 1930s Francis Welham and Arthur Levell conceived a new single spar duralumin wing structure that promised weight savings without loss of strength. It was quite different from the already established Monospar design.<ref name="OH2587-9">{{harvnb|Ord-Hume|2000|pp=299–300}}</ref> The wing was built around a cross braced, girder-like box, with the front and rear members attached to it with cantilever ribs.<ref name="FlightA">{{cite magazine |title=Primarily for Training |magazine=Flight |date=17 September 1936 |volume=XXX |issue=1447 |page=296 |url=http://www.flightglobal.com/pdfarchive/view/1936/1936%20-%202539.html |access-date=16 March 2019}}</ref><ref name="OH2587-9"/> With financial support from S.W. Cole of EKCO radio, they set up a company known by their initials as CLW Aviation, based at Gravesend, Kent and built a wing for testing.<ref name="OH2587-9"/> This performed to the calculations even under destructive testing, and the company decided to produce a small aeroplane using it.<ref name="OH2587-9"/> The CLW Curlew was intended both as a demonstrator and as a trainer for those pilots going on to modern, fast monoplanes.<ref name="OH2587-9"/> It was also seen as a contender in the open two-seater market, particularly for the richer buyer after a machine with "snappier" performance.<ref name="FlightB">{{harvnb|''Flight'' 23 April 1936|p=417}}</ref> It made its first flight on 3 September 1936 at Gravesend, flown by the ex-Beardmore pilot A.N. Kingwill.<ref name="OH2587-9"/>

The Curlew was an all-metal aeroplane, apart from the fabric covering of its elliptical, cantilever wing, and so an unusual light plane for its time. The wing carried short span Frise ailerons outboard. The rest of the trailing edge carried manually operated split flaps. The fuselage was a monocoque structure, built on duralumin ovals and stringers, covered with stress bearing Alclad sheet.<ref name="FlightA"/> The engine installation was particularly neat for a radial. The 7-cylinder 26.5 in (673 mm)<ref>{{harvnb|Lumsden|2003|p=179}}</ref> diameter 90 hp (67 kW) Pobjoy Niagara came as a "power-egg" complete with all accessories and its own long chord cowling, plus Pobjoy's characteristic "smiley" front baffle. The similarity to inline installations was enhanced by the upward off-set of the drive shaft of the two-bladed propeller, caused by the gearbox.<ref name="OH2587-9"/> The two generous open cockpits were in tandem, the front one at mid wing and the other at the trailing edge. The empennage was conventional: a slender fin carried a rounded, unbalanced rudder which extended down the bottom of the fuselage, and the tapered, mid-fuselage tailplane carried separate elevators so the rudder could move between them.<ref name="OH2587-9"/> The undercarriage had vertical (in flying position) legs from the wings with a large (3 in or 76 mm) movement, each sloping outwards slightly to increase the track and braced inwards by struts from halfway down the legs to the wing roots.<ref name="FlightA"/>

Sqn Ldr F.W.H.Lervill (another CLW director) had clear ideas on training aircraft and the Curlew was intended to place the pupil at the front to familiarise him or her with the sensation of flying alone. He also chose not to fit wheel brakes, for he thought they were likely to confuse the novice.<ref name="FlightA"/>

After its first flight, the Curlew successfully completed its initial trials, which include a terminal velocity dive at 305 mph (491 km/h) and a maximum loaded weight producing a wing loading of 14 lb/sq ft (68 kg/m<sup>2</sup>). Landing speed with flaps down was 38 mph (61 km/h). The machine was advertised as suitable for other engines up to powers of 130 hp (97 kW) and the de Havilland Gipsy Major was specifically mentioned. Though Cole had by this time withdrawn his financial support, things for a short while looked bright for CLW, with talk of an Australian order for 50 Curlews, but they were over extended and went bankrupt. Plans for a twin-engined light transport using a similar wing structure were abandoned. The sole Curlew, registered ''G-ADYU'' and built at a cost of £10,000 went to Essex Aero, also of Gravesend, in the asset sale.<ref name="OH2587-9"/><ref>[https://cwsprduksumbraco.blob.core.windows.net/g-info/HistoricalLedger/G-ADYU.pdf "Registration Certificate for ''G-ADYU''"]</ref><ref name="aerop101">{{Harvnb|Dunnell|2019|p=101}}</ref> It then went to Martlesham Heath and gained its Certificate of Airworthiness on 19 November 1936. It seems to have done little flying after that, and was put up for sale in July 1938. Stored during the war, it was broken up in 1948.<ref name="OH2587-9"/><ref name="aerop101"/>

==Specifications== thumb|right|General arrangement drawing of the Curlew. ''Flight Global archive''<ref>{{Harvnb|''Flight'' 19 March 1936|p=305}}</ref> {{Aircraft specs |ref={{harvnb|Ord-Hume|2000|pp=299–300}} |prime units?=imp  |genhide= |crew=2 |capacity= |length m= |length ft=21 |length in=6 |length note= |span m= |span ft=27 |span in=0 |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= |swept m= |swept ft= |swept in= |swept note= |dia m= |dia ft= |dia in= |dia note= |width m= |width ft= |width in= |width note= |height m= |height ft=9 |height in=0 |height note= |wing area sqm= |wing area sqft=116 |wing area note= |swept area sqm= |swept area sqft= |swept area note= |volume m3= |volume ft3= |volume note= |aspect ratio= |airfoil= |empty weight kg= |empty weight lb=970 |empty weight note= |gross weight kg= |gross weight lb=1500 |gross weight note= |max takeoff weight kg= |max takeoff weight lb= |max takeoff weight note= |fuel capacity= |lift kg= |lift lb= |lift note= |more general=  |eng1 number=1 |eng1 name=Pobjoy Niagara III |eng1 type=7-cylinder radial engine, geared down by 0.47:1 |eng1 kw= |eng1 hp=90 |eng1 kn= |eng1 lbf= |eng1 note= |power original= |thrust original= |eng1 kn-ab= |eng1 lbf-ab= |eng2 number= |eng2 name= |eng2 type= |eng2 kw= |eng2 hp= |eng2 kn= |eng2 lbf= |eng2 note= |eng2 kn-ab= |eng2 lbf-ab= |eng3 number= |eng3 name= |eng3 type= |eng3 kw= |eng3 hp= |eng3 kn= |eng3 lbf= |eng3 note= |eng3 kn-ab= |eng3 lbf-ab= |more power= |prop blade number= |prop name= |prop dia m= |prop dia ft= |prop dia in= |prop note= |rot number= |rot dia m= |rot dia ft= |rot dia in= |rot area sqm= |rot area sqft= |rot area note=  |perfhide= |max speed kmh= |max speed mph=120 |max speed kts= |max speed note= |max speed mach= |cruise speed kmh= |cruise speed mph=110 |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= |range miles=380 |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= |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= |disk loading kg/m2= |disk loading lb/sqft= |disk loading note= |power/mass= |thrust/weight= |more performance=  |armament= |guns= |bombs= |rockets= |missiles= |hardpoints= |hardpoint capacity= |hardpoint rockets= |hardpoint missiles= |hardpoint bombs= |hardpoint other= |avionics= }}  {{aircontent  |see also= |related= |similar aircraft= |lists= }}

==References==

===Citations=== {{reflist|3}}

===Cited sources=== {{refbegin}} *{{cite magazine |last=Dunnell |first=Ben |title=Aeroplane Archive: Call of the Curlew |magazine=Aeroplane |date=April 2019 |volume=47 |issue=4 |pages=99–101 |issn=0143-7240 }} *{{cite book |title=British Piston Engines and their Aircraft|last=Lumsden|first=Alec|year=2003|location=Marlborough, Wiltshire|publisher=Airlife Publishing| isbn=978-1-85310-294-3}} *{{cite book |title= British Light Aeroplanes|last=Ord-Hume|first=Arthur W.J.G.| year=2000|publisher=GMS Enterprises |location=Peterborough |isbn=978-1-870384-76-6}} *{{cite magazine |title=Modern Light Aircraft Reviewed |magazine=Flight |date=23 April 1936 |volume= XXIX |issue=1426 |pages=414–425 |url=https://www.flightglobal.com/pdfarchive/view/1936/1936%20-%200995.html |access-date=16 March 2019 |ref={{Harvid|''Flight'' 23 April 1936}} }} *{{cite magazine |title=Two British Newcomers |magazine=Flight |date=19 March 1936 |volume=XXIX |issue=1421 |pages=305–306 |url=https://www.flightglobal.com/pdfarchive/view/1936/1936%20-%200700.html |access-date=16 March 2019 |ref={{Harvid|''Flight'' 19 March 1936}} }} {{refend}}

Category:1930s British aircraft Category:Aircraft first flown in 1936 Category:Low-wing aircraft Category:Single-engined tractor aircraft