Account of some experiments on a vessel called the "Liverpool screw," fitted with Grantham's engines, and Woodcroft's screw propeller
1844
Journal of the Franklin Institute
The Liverpool Screw, upon which the experiments, described in this paper, were trie, d, is a small iron vessel 65 ft. long by 12 ft. 6 ins. beam, and 3 ft. 9 ins. draught of water. She is propelled by two high pressure oscillating engines, with cylinders of 13 ins. diameter, and 18 ins. length of stroke. The steam, which varies from 5(i ibs, to (;0 lbs. pressure in the boiler, is admitted to the piston tbr one-fourth the le, ngth of the stroke, the remainder working by expansion. The nominal
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... er was 20 horses, but the effective power rarely, exceeded 18~ horses. The cylinders are placed diagonally, at right angles to each olher, and work to one crank upon the main driving shaft, which runs direct to the propeller without gearing, or bands. The propeller, which makes 95 revolutions per minute, is on Wooderoft's plan, with a pitch exl?amli~g li'om 10 ~o 11 ft.; after being enlarged at three several times, l?'~)m .3 ft. 10 ins. diameter, it is now 5 ft. ,t ins. diameter by 2o ins. tong; it is of wrought-iron, and consists of fbur short arms, whose united area is equal to 16 square feet i of this o~flg about 13 ft. are immersed, a portion of the upper side being const'autly above the water; the angle of the centre of the floats is 45 ° . and about 40 o at the peril)hery. The author then gives the details o[ a mm~ber oI" experiments, and he states, that, although the proportions of the vessel were llot ikvorable tbr speed, her length being only five tim~s the beam, and the sectional dispiaeement 28 feet, the speed was greater than that of ail the steamers on the Mersey, except the large sea goiHg steam vessels. That the "slip" of the propeller, when tried by 5Iassey's log, was less titan five per cent. That the action of the screw across the way of the vessel, did not appear to a/ibet ~he steerhG, or have the slightest tendency to turn the head of the vessel. The author is of' opinion, that engineers, ia get~eral, fearing a loss might take place ti'om lateral action, with a long pitch, and that Ih~? steering would be a fleeted if tim propeller was not immersed, have made the propellers too small, and that the short pitch, which had ~'endcred a higil vetoeity necessary, was detrimentak Several satisfactory experiments, in towing vessels, are a}so mentioned, and, i~ i~ stated, that m a heavy sea, the superiority of the sere~" propeller was very visible, The dimensions are then given ibr vessels of war and eonlnlerce, \vorkiitg with screw propellers, driven direct by oseiilating engines, which, the author anticipates, would prove much more s~,rviecablc aud sea worthy, than any of the paddle-wheel steamers now in use. The papc,.,' is ilJuslrated by a diagram of the propeller ot ~ the Li,'e~'pool 5Z.rew, and by plans of the machinery and general arrangements of ttae propos~'.d ii'igafc and steamers. Remarks.~Mr. Rennie observed, that the Institution was much indebted to Mr. Grantham, tbr bringing forward the subject of screw E.vperimenls on Screw Propellers. 8~ propellers; tile lnore particularly as it had now become of natiomd importance, and that every aUempt at perfecting the sub-marine p.ro. pellet merited encottragement. It was ditficltlt correctly to assign the merit of Ihc first itivention of this species of propeller, as it had been tried at various periods, and with as varied results, on the Con. tinent, in tim United States of America, and in this country; * but it appeared certain that Mr. Samuel Brown, the inventor of the gas vacuuln engine, was among the first who applied the sub-marine pro. pellet wilh any practical ell'oct. The propeller used by him was on the principle of a regular screw, and consisted of two blades, which were atlixed at an angle of 45 ° to a horizontal shaft, which was placed in the bow of the vessel, and he believed that it [tad also been usec in the sterl:. 'l'ilis l)ropeller was driven by a gas vactmm engine, o the rlominat power of 12 horses, and actually caused a vessel of 6( feet iu hmgth, to move at the rate of six, or seven, miles per hour M. Sauvage, of Boulogne-sur-Mer, had also nmde several attempts a pl.opelih~g vesse!s by the same means, and it was very gratifying tt find tiler his :qerviees had recently been acknowledged and rewarder by the I;.il~/of the French. It was, however, Mr. F. P. Smith, w]l~ tii'st rendered lho screw propeller practically useful; for his perseve ranec, b~il~g :~ided by sph'ited capita]isis, induced the bui'lding of th~ 1889 Rennie, .
doi:10.1016/s0016-0032(44)90634-4
fatcat:aj6ti2ojxveypdxxqqngcz6f6q