Page:Popular Science Monthly Volume 90.djvu/712

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��Popular Science Monthly

��You Can Rock This Boat but You Can't Turn It Over or Sink It

THE several hull sections of the collaps- ible boat illustrated are tapered so that they telescope. Packing rings between the joints prevent leakage. The sections are distended by pressure on three tubes and then locked. To prevent tilting boat the inventor, Yves And- re Bouget, "of Philadel- phia; has ' attached to the hull of the boat stabilizing casings or shells. These shells have remov- able plugs in their tops, but ordinarily the tops are closed and the bottoms opened to admit water.

���A rod and transverse bar lock the hull sections after they have been distended

��A New Twelve-Cylinder Aeroplane Engine Makes Its Debut

THE aeroplane engine is the lightest motor made, for the power it gives. Although its use in driving the propeller of an aeroplane is well established by this time, it is now attracting the attention of automobile owners. At least one car owner in the United States has a twelve- cylinder aeroplane engine under his motor hood. The illustration at right shows a new type of aeroplane engine mounted for testing purposes on a motor truck. The engine turned the propeller fast enough to move the truck through the snow.

While the engine operates at more than two thousand revolutions per minute, the propeller is geared down to give a rotation of from looo to 1400 per minute. The arch enemy of lightweight motors is vibration. In the new motor vibration has been avoided. Every moving part is held secure and rigid. The camshaft is located next to the valves, situated on top of the cylinders, and with the rocker arms is enclosed in an oilbearing casing, thus granting it the same benefit that the crankshaft and connecting rods have from their casing.

��Through an oil-tight joint the other ends of the rocker arms stick out into the open where the valve springs are best protected from heat. Every three of the twelve cylinders form a solid block, within which nothing can shake loose. The crankshaft is stout and short, owing to this "twin-six," V-shaped arrangement and to the con- necting rod having forked wrists.

Lubrication by power (forced feed) insures an ample supply of oil. There is an angle of only forty degrees be- tween the two sets of cylin- ders, thus insuring compact- ness and elim- inating vibration. The cooling waterjackets are made extra long. The pistons have three rings to utilize every fraction of pressure. An electric starter makes it unnecessary to crank the motor by turning the propeller by hand, and gives full power control in the air. The motor furnishes two hundred horsepower. Yet the individual cylinders are only four by six inches, and a block of three weighs only forty pounds.

���The truck was driven through heavy snow by the aeroplane motor and the propeller

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