Windjammer ACTION 4What helps drive a windjammer forward at speed
Imagine the force of the wind as it was stopped or jammed by the huge sails of the merchant ship a ship that sped over the ocean carrying its cargo from land to land This is where these great ships got their name windjammer These three to five-masted ships were heavy vessels with hulls or frames made of steel Designed to carry heavy cargo over long distances they relied on the wind power caught in up to 20 large square canvas sails to drive them forward Although popular in the late 1800s these mighty ships were still in use in the 1950s And there are even plans to bring them back into use After all wind is a cheap and environmentally safe form of power even if an engine might be needed for those calm days at sea ANSWER SAIL SHAPE It’s the shape of the windjammer’s sail that helps drive the craft forward The sail is curved with a slight bulge in the middle This means that the side on the outside of the curve is slightly longer than the side on the inside The wind moving along the longer side has to travel faster to meet up with the wind moving along the short side Faster-moving air means less pressure or push Slower-moving air means more pressure So the slower-moving air on the inside of the sail has more pressure and pushes the sail forward The 6-masted Preussen was the largest windjammer ever built wind slower moving air higher pressure push forward 5
The earliest steam engines were very large and relied on lots of work They needed large quantities of coal on board This was burned to heat the water in the boiler Then the hot burst of steam that was given off pushed against rods called pistons to drive the wheels 6 When the engine was placed in front of a series of carriages or rail cars it could carry loads or people from place to place connecting cities everywhere An engine joined to carriages was known as a locomotive Steam train ACTION What is used to power the locomotive
7 ANSWER STEAM ENGINE WORKING PARTS Steam locomotives ran on iron rails which made the ride fast and smooth But the steam engine could also be used for other work A traction engine was used to supply power to other farm machines coal is burned in the furnace water heats in the boiler smoke piston driving wheels steam When steam pushes against a piston in a cylinder it causes the piston to move backwards and forwards This rocking action is what drives the wheels A powerful steam engine could pull about 50 carriages Traction engines were like steam-powered farm tractors chimney headlamp boiler smoke box driver’s cab safety valve cylinder
