THE ROTOR SHIP

Hokitika Guardian, 19 February 1925, Page 3

THE ROTOR SHIP

ARRIVES IN SCOTLAND. Australian and n.z. cable association LONDON, February 17. Flettncrs’ rotorship lias arrived in tlie Firth of Fortli from the Elbe. It experienced bad weather throughout its 460 miles journey and it was i eoessary frequently to revert to its Diesel engine. The “Daily Telegraph” consi ics the vessel would make a similar passage with the old canvas rig and an auxiliary engine. THE IDEA. 75 YEARS OLD. The correspondent of a Home pi per writing from Berlin on December 2“,; 1924, had the following to say about Flottner’s rotor ship: The rotor ship, the ship which sails without sails, is going on a trial H’p on Wednesday. ' When the ship was first talked a-mut it was -stated by the inventor, lirri Flcttner, that the basis of his invention was the Magnus principle. 1 discovered that at the chief physical laboratory of Berlin the question was being asked: What is the Magnus principle? ft was known that Dr Magnus had taught at the Uuivers.ly of Gottingen more than had a century ago, and the German dictionary of national biography gives ' ini a i< r.g notice; but what exactly Tie had discovered nobody could remember. I sought the help of a learned friend, Dr Gregor Much, and by rummaging in the public library he found the neg- 1 lectcd book in which the Gottingen professor had described the priii'iplo which bears his name. Dr Magnus was at the time employed in studying the erratic movements of bullets and shells. In his labe'.etory ho made experiments to find out the effect of the wind on revolving bodies. Eor this purpose he constricted a simple apparatus. It consisted of an upright cylinder which could he i'".' veil by turning a wheel and a hci'uvs for blowing air into it. Littleflags were used to show the action of the current of air when the - vPiuler was still and when it was revolving. It was found that when the e'linder was still the (lags on either side of it behaved exactly the same in the current of air, but that when the cylinder was revolved one was blown .lose to it and the other away from it. 'lnis showed that on one side there was a rarefaction of the air between the hag I and the cylinder and on the other sde 1 a condensation. Consequently a pics- 1 sure was exerted on the cylinder at I right angles to the current of air dir- < cc-ted on it. '

Dr Magnus then placed his revolving cylinder on a movable arm and observed the effect of a current of air directed against it at various angles. This apparatus is nothing less Ilian a model of Dr Flettner’s revolving lovers on the rotor ship, but it struck neither Dr Magnus nor his contemporaries to make technical use of the discovery. They were interested only in the movements of shot and shell, and when they had solved that question interest in the experiments was lost and the discovery, was forgotten, except at Gottingen, where use lias been made of it by Herr Flettner three-quarters of a century after Dr Magnus had nude his apparatus. Supposing there is no wind, when the cylinder rotates it causes a whirling of the air round it, and the irea oAvhirling air is wider according to the rapidity of the rotations. It a wind springs up, it meets the whirling air round the cylinder. On the one side, where wind and whirling air arc in the same direction, thore is a low pressure, and on the other side, where the currents clash, there is a high pressure. Thus cn one side of the cylinder there is a suction •action and on the other ft push, and tho ship, to speak of Herr Flettner s ship, with two 60ft high revolving cylinders, will move at right angles to tho wind. , Dr 'IN Ifagnus * recognised • that too greatest force was obtained when there was a certain relation between tho rapid!tv of the cylinder’s rotations and of the wind. The art of sailing a rotor ship consists in conserving this relation by regulating the rapidity with which the ship’s cylinders rotate.