Volume 16 No 1 Feb 1965.pdf - Lakes Gliding Club

as the squall struck us, about half thebirds settled 'on the water and the otherhalf attempted to continue to soar buthad to resort to a lot of flapping. Nota single one, as far as I could see, continuedpure soaring flight. The reasonfor this, I believe, was that the windblowing parallel to the waves had tbesame speed in tbe hollows as on thecrests, was not deflected upwards by thecrests, and that the frictional sLowing-upon the water was insufficient for puredynamic soaring. The fact that none ofthe birds attempted to soar in the newup-current to windward of the ship Ido not think in any way extraordinary,becaUse in a strong wind a bird's wingswould have to be retracted to such anextent for it to keep pace, that it wQuldbe in danger of colliding with the sideof the ship. This statement is borne outby the fact that I have seen birds soaringin this manner only in Light tomoderate winds.I might describe one more incidentwhich demonstrates a method of soaringin a dead calm which is sometimes usedby tbe albatross. One morning, therebeing no wind but an occasional veryheavy roll, I noticed six albatrossesflapping behind the ship on the lookoutfor refuse. Suddenly one birdstarted flying off to one side and wasalmost immediately followed by the fiveothers. I watched and, at first, wonderedwhy, but soon realised that thefirst one had seen an extra large rollercoming towards us, crest parallel toour direction, the others had followed,and that they were now Usitting" on theadvancing front and soaring with aboutsix inches to spare! On reaching theship they discarded the roller at theprospect of food, but a short time laterthe performance was repeated.From the above remarks one mightconclude that the particular method ofsoaring used by an ocean bird dependsmore on the wind strength than anyother factor. In a dead calm the albatrosssoars in front of an advancingroller; in a light to moderate wind anysea-bird will soar over a ship or acliff; while in a strong wind the combinationof wind deflection and dynamicsoaring appears to be the only methodused.F. M. HAMILTONEDITORIAL NOTE.-This letter wasaccompanied by another from Dr. J. CMottram, a less experienced member ofthe London Club, who bad been onmarine scientific ex.peditions. He wrotethat albatrosses "take a zig-zag course,Row to get "SAD.PJ.ANE AND GJ.lDING""Sailplane and Gliding" can be obtained in the U.K. at all Glidjng Clubs. or send24s. (post incl.) for an Annual Subscription to: The British Gliding Association. 75Victoria StTf:Ct. London. S.W.1. SingJe c,opic!i and most back issues arc aJso available.price 4s. (post incl.). Enquiries regarding bulk orders of 12 or more eopies. at wholesaleprices, should be made to The British Gliding Association.OVERSEAS AGENTSAUSTRALiA: D. Row. Waikerie, South AustraEa.1'IEWHOLLAND ::l.EALAND:u.S..... .IOTHER COUNTRIES:S. RHODESIA:DENMARK:SWEDEN:Plea.., apply direct to British Gliding Association. Single copies4s. or 24s. annually.J. van Eck, Tijgerstraat 203, Nijmcgen, Posltckcniflg 1007247,Abonncmcntsptijs FJ. 12.50.Please apply direct to British Glidinll Association. Single copies4•. (post incl.) or 24s. annually (60 cents or $3.50 annually)'.Enterpri.., Bookshop. 13 Munndy Sq., HillhJands. Salisbury,S. Rhbdeaia.Knud RaslnUSscn, EFPT, 60 Vesterbropde, Copenballen.V.Flyg-Biblioteket, Box 121, Falsterbo.Red Lealher Clolh BiAder .ekia. 11 I.aea (1 yunlr IS•• 6cI. po..... b. 3d. froJII B_G.A.Will ell.O biD' your ••G.A. P__I PilM IAcbooka.51