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Aviation History
1925
1925 - 0484.PDF
JULY 30, 1925 THE CRANWELL C.L.A.3 LIGHT MONOPLANE ' \ i - Bristol "Cherub" Engine As the only new machine entered for1 the Royal Aero Clubrace meeting at Lympne, very considerable interest attaches to the little monoplane produced by the Cranwell LightAeroplane Club for the August races. This club occupies a somewhat unique position in that it is coii\p.osed of RoyalAir Force officers, and, up to the present, has the distinc- tion of having twice entered amateur-built m2.ch.ines foropen competitions. It may be of interest to menton that the President of the Club is Squadron-Leader W. Thomas,M.C., while Flight-Lieutenant E. P. Mackay is Treasurer, and also acts in the capacity of reserve pilot. The Club's designeris Flight-Lieutenant N. Comper, who will also pilot the *">•.,- wood construction. Although an attempt has been made togive the machine as clean lines as possible, the cantilever principle has not been adopted for the wing construction ;it probably being considered by the designer that any slight extra resistance caused by wing bracing struts would be morethan made up for by the lighter structure which could be achieved when bracing was employed. The rear portion ofthe fuselage has flat sides and bottom, but there is a deep deck faring on top. In front, however, very great care hasbeen taken to obtain as smooth a contour as possible, this being formed by light formers and stringers passing on theoutside of ihe main fuselage structure, which in itself is of o o o o o o o o o o o o o o o o o o o o Cranwell C.L.A.3: Three - quarter front view. Note the caref u:l streamlining of the nose. O O O O O O O machine in the Lympne races. It may be mentioned thatFlight-Lieutenant G. T. H. Pack is in charge of wood con- struction, while engine installation, cowling, etc., is in theable hands of Flying-Officer F. H. Cashmore. It may be recollected that in last year's Lympne competitionthe Cranwell Light Aeroplane Club was represented by a biplane, the C.L.A.2, with Bristol " Cherub " engine, whichwon the reliability prize of ;£300, with a total mileage of 762 J, and a total number of hours flying of 17 hours 53 mins. 18 sees.The biplane was a somewhat slow machine, what with the Ride- by-side arrangement of pilot and passenger, and this greatnumber of hours had to be put in in order to cover the mileage in the reliability trials. The Cranwell Club thoroughly well considerably smaller cross-sectional area. Streamline formis maintained right up to the nose, a large beaten cowl sur- rounding the Bristol " Cherub " engine, of which only thecylinder heads project. The monoplane parasol wing is of constant chord but has the tips rounded off. The sectionused is known as Eiffel No. 371. This section has given very good results in model tests, but the full size performanceof it is, we believe, somewhat of an untried quantity. This section is a fairly deep one, with flat bottom camber, but havinga slight rise to the leading edge. The conventional under- carriage and normal tail planes complete the aerodynamicdesign, which altogether may be characterised as very clean, but bv no means freakish. o o O O O O O The Cranwell C.L qu 0 O .A .3 : a r t er view O O Three- rear O O O O O O O o r\ \J o oo o o deserved this encouragement, and everyone will be glad tolearn that last year's success has induced the Club to have another try this year. The C.L.A.3 is, however, a verydifferent kind of machine, and is expected to be one of the fastest for its power in the race. • All will wish the CranwellClub every success again this year, as theirs is a spirit much too rare in this country, where amateur designing and con-struction has never attained the popularity with which it is regarded abroad, particularly in Germany. The Cranwell C.L.A.3, designed by Flight-LieutenantComper, A.F.R.Ae.S., is shown in the accompanying general arrangement drawings. It is a parasol monoplane of normal Constructional featuresGenerally speaking the Cranwell C.L.A.3, is of fairly normal construction, and naturally forms have been chosen whichlend themselves to amateur construction, the whole of the work of building the machine having been carried out bymembers of the Club, who, it must be admitted, have made a very creditable job of it. The rear portion of the fuselageis built up as a Warren girder comprising four longerons braced by diagonal struts so as to provide perfect triangulation.This form of construction extends from the stern post to the cockpit, but from here to the engine plate wire bracing hasbeen employed. The struts in the triangulated portion of 484
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