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Message: <blockquote data-quote="riggerrob" data-source="post: 371269" data-attributes="member: 8794">"<blockquote data-quote="CaseyKnight" data-source="post: 302647" data-attributes="member: 7844">I'm replying on behalf of someone elsecharleybarley<ul> <li data-xf-list-type="ul">Steam-turbines often ran with their turbines in a stalled condition: This had to do with the pitch of the turbine blades and the geometry of the blades, which meant they'd extract the energy to spin a turbine, but leave no surplus left over to continue to push the plane.  If I recall, Alan Griffith realized this back in the late 1920's (I'm not sure if this was known in the United States).</li> <li data-xf-list-type="ul"> </li> <li data-xf-list-type="ul">Proponents of gas-turbines were concerned about the excessive weight of the engine: Indicating that they did seem to understand that thrust could be produced, just that it would be too heavy (it would appear that there were a multitude of reasons excessive weight were expected, of which I may not know all of them, but one might have been that steam-turbines were big and heavy).</li> </ul></blockquote>"First generation gas turbines were developed from lessons already learned from steam turbines.First generation steam turbines were Pelton wheels that deliberately run with stalled buckets or blades because their goal was to extract all the energy to turn a propeller. They were designed more like water wheels than windmills.In 1894 Mr. Parson's ship "Turbinia" was faster than any other ship afloat, but only 20 percent as efficient at converting fuel to energy. "Turbinia" also suffered problems with propeller cavitation in sea water. "Cavitation" is another way to describe "stall."Eventually "Turbinia" got three, direct-drive steam turbines turning three propellers each, for a total of 9 propellers!Steam turbine fuel efficiency rapidly improved until (1906) HMS Dreadnaught was the first battleship with steam turbines. All subsequent British battleships had steam turbines.Similarly, when (1906) Birger and Fredrick   Ljunstrom invented  centrifugal flow  steam turbines to generate electricity, they tried to extract all the energy to drive the shaft and did not care about exhaust velocity.  Ljungstrom  turbines are based on a pair of counter-rotating discs studded with axial blades. These axial blades are parallel to the drive shaft and extract energy from radial (outwards) steam flow. Ljungstrom. turbines were primarily used to generate electricity in Sweden and Switzerland (Brown Boverie) and powered a few ships, but were not as efficient as axial flow steam turbines.Now the Segata Sherpa helicopter company is developing a Ljungstrom   Turbine to power their counter-rotating rotor blades.</blockquote>

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