NIKOLA TESLA'S DISK TURBINE

Tomorrow's Gas Engine Is At Our Doorstep

Since its invention more than 100 years ago the reciprocating explosive gas engine has handily served mankind as we have sought to replace raw muscle power with that of the machine. In this type of motor a linear motion is given to one or more pistons by the compression and explosion of a combustible mixture of vaporized fuel and air. The energy released by the explosion is transmitted to a crank shaft which converts the reciprocating movement into rotation. With the passage of time the primitive device of the 1860s has evolved into a complex marvel of machinery capable of propelling an automobile at speeds in excess of 300 mph and yet it still bears the same basic configuration and the same mode of operation as that of its earliest ancestor.

An alternative to the reciprocating engine is the rotary engine. The most common form of these machines, the conventional bladed turbine, is used for everything from the propulsion of aircraft and large ships to stationary power generation. While working in a somewhat different manner as the machine described above, the end result of its operation is still the same - the creation of torque. Among the advantages to be gained from this design option is a reduction in the number of moving parts. In the rotary engine the piston, connecting rod, crankshaft, and flywheel are replaced by a single moving component known as a rotor. In direct contrast to the typical reciprocating engine, a well balanced rotary engine will operate virtually without vibration. Other advantages include an increase in power to weight ratio and better fuel economy. On the other side of the coin, bladed turbines are highly precision machines built to very close tolerances, and thus are much more expensive.

Nikola Tesla's disk turbine, the Tesla Turbine , which is said to approach the ideal rotary heat engine, can be viewed as an inexpensive alternative to the bladed turbine. It consists simply of multiple shaft mounted disks suspended upon bearings which position the rotor system within a cylindrical casing. In operation high velocity gases enter tangentially at the periphery of the disks, flow between them in free spiral paths to exit, depleted of energy, through central exhaust ports. The slight viscosity of the moving gas along with its adhesion to the disks' faces combine to drag them along, efficiently transferring the fuel's energy to the disks and on to the shaft.

The central component of this unique engine, the rotor, is built up using eight basic components: ported disks, star washer spacers, ring washer spacers and rivets, all of which constitute the runner subassembly, and the rotor shaft with its shaft keys, bearings and lock nuts. Fabrication of the runner is fairly straight forward. The parts are assembled with the aid of a stub shaft that has three key ways machined in it to line up with three complimentary key ways machined in the center hole of each disk. The stub shaft's length should be about three times the intended width of the runner. One end of the shaft is threaded and a shoulder ring is fastened just over a third of the way in from that end.

Assembly begins by slipping one of the thicker end disks on to the shaft. With the rivets inserted the first set of spacers are installed followed by the first thin disk. Additional spacers and disks are added in sequence with the second end disk going on last. (An operational note: In addition to providing spacing and support to the disks, each ring spacer also adds a small amount of lift that helps to propel the runner around.) At this point half a dozen or more "C" clamps are used to compress the subassembly so the rivets can be tightly peened down. The next step is truing up of the runner's width with a surface cut across the faces of the two end disks.

While it is not as critical, the runner's outside circumference can also be trued up at this point. Care should be exercised here to reduce the chance of damage. Any burrs and irregularities can next be removed with a narrow cutting tool. Now that the runner subassembly is nearly completed all that remains to be done is to remount it on the actual motor shaft for dynamic balancing. This is done with the aid of sophisticated machinery through the removal metal from appropriate locations around the runner's perimeter by the drilling of shallow holes near or directly into the outer edges of the end disks.

As a starting point, the thickness of the spacers and thus the dimension of the intra-discular space can be approximated using the depth of boundary layer of air adjacent to the disks' surfaces. The boundary layer's true depth will depend somewhat upon the temperature and density of the propelling gas. Drawing on the science of aerodynamics we learn that the boundary layer on the skin of an aircraft in flight is approximately .020 of an inch in depth.

So, it can be assumed the layer on each side of the disks is nearly .020" thick also. If the disk spacing were to exceed .040" there would be a space through which some of the propelling fluid could flow and fail to effectively interact with the gas molecules making up the boundary layer. Reduce the spacing to .040" and the two layers could be said to come in contact with each other. This sets the maximum limit of spacing. With a spacing of .030", a standard thickness of 304 stainless sheet stock, the two layers would overlap by .010". The practical experience of at least one disk turbine builder lends support to the use of .030" for the thickness of the spacers and the disks as well.

The engine rotor housing or casing as described in Tesla's turbine patent consists of two basic elements, not counting seals. These are a central ring casting and two end plate castings to which the flange pillow block bearing assemblies are bolted. As can be seen from the figure an alternative configuration involves the use of an upper and lower casting. A third option incorporates four castings, both left and right, top and bottom.

Many independent builders choose the first option, preferring to bypass the casting process and mill all of their housing components from commercially available stock. Another important element associated with the casing is the inlet nozzle through which the propelling fluid is introduced. If reversibility is desired, a second nozzle can be installed for the introduction of fluid in the opposite direction. Using compressed air or even steam to operate such a motor as described here is fairly straight forward. All that is needed is a compressor or a conventional boiler as the source of pressurized fluid. If, however, this motor is to be run on gasoline or some other explosive fuel it needs an accessory apparatus or fluid pressure generator into which the fuel and air are injected, to mix and than be ignited. The products of combustion that are developed, along with steam, if water is also injected, are then directed through a nozzle into the rotor housing.

Such pressure generating appliances that are used in conjunction with upstream compressor stages already exist. In them an ignited fuel air mixture is continuously burned to provide a nearly uniform flame front. Another important creation of Nikola Tesla's, called the valvular conduit, simplifies the design even further by reducing the need for a compressor while also making possible the introduction of a modified combustion regime. When incorporated at the combustion chamber inlets the valvular action of this device makes the turbine more like an internal combustion engine. While introduction of fuel and air proceeds as usual, immediately upon the point of ignition all of the inlets are effectively closed. This is due to the action of the valvular conduit which, without moving parts, has the singular property of permitting free flow to occur in one direction only.

After the hot gases enter into the turbine, natural venting working in combination with an optional compressor or downstream ventilator clears the combustion chamber and promotes the introduction of another charge. In such a manner successive explosions of the fuel air mixture occur and are projected through the nozzle. The rapidity of these pulses depends primarily upon the volume of the combustion chamber and the degree of ventilation. In speaking of their frequency Tesla said, "I have been able to speed up the rate of such explosions until the sound of exploding gasses produced a musical note."

What improvements might be made to the basic disk turbine design? Between 1906 and 1927 Tesla made real progress optimizing the engine. Nevertheless, it is reasonable to expect that some further work could have a positive effect on the machine's performance. A first step might be to evaluate the properties of the propelling fluid as it exists while inside the engine casing. In this way the intra-discular spacing might be modified in response to the actual boundary layer depth and physical conditions at and near the disk surfaces. Another possibility lies in working with the number, size and distribution of the rivets and more importantly the ring washer spacers that are positioned between the turbine disks. A third area warranting serious investigation relates to the materials used in construction of the runner subassembly.

It is well known that any increase in the allowable turbine operating temperature results in higher engine efficiency. Turbine engineers have long sought exotic materials out of which to fabricate their turbine blades, the most heat sensitive component. These efforts have resulted in the development of a variety of suitable materials. One of the best that is presently being used is a complex super alloy known as Inconel. Its three principal constituents are: nickel (60%), chromium (16%), and cobalt (8.5%), with lesser amounts of aluminum, titanium, tungsten, molybdenum, tantalum and cadmium. Inconel has proven capable of sustaining turbine inlet temperatures of 1,832 F. It is interesting to note that some of Tesla's turbine disks were fabricated out of a material known as German Silver. This hard alloy, once commonly used for tableware, also contains nickel along with copper and zinc in varying proportions.

No doubt the super high performance heat engines of the future will be constructed of even more advanced temperature resistant, high strength materials. There are a number of promising possibilities in this regard. One prospect is injection-molded silicon nitride (Si3N4) strengthened with silicon carbide (SiC) whiskers. Components formed out of this ceramic composite are processed using a technique known as Hot Isostatic Pressing (HIP).

Another candidate is a metal matrix composite of niobium (Nb) combined with tungsten mesh, or refractory fibers of Nicalon or FP-Al2O3 for reinforcement. Components made of niobium matrix composites require an iridium coating for oxidation protection. A third promising contestant that has been identified is a reaction milled composite called AlN dispersoid-reinforced NiAl. This nickel-aluminum alloy based material is produced by milling NiAl powder in liquid nitrogen. While actual performance data are not yet available for the NiAl/AlN composite, tests show that it compares very favorably with other super alloys that are presently being used.

A related material known as single crystal NiAl has already been formed into turbine blades and could be adopted immediately. A near term benefit to be derived from the use of this material, as with the other NiAl compounds, would be a substantial reduction in weight. In this case weight savings in a conventional rotor blade and disk system would be about 40%. Furthermore, it is expected that techniques will be developed to control high temperature deformation of these oxidation resistant materials. This will result in heat engines with further reduced cooling requirements and even higher operating temperatures.

Dr. Tesla's engineering legacy when placed in context with recent developments in the areas of conventional turbine engine design, tooling, materials processing and electronics establishes a secure platform for the development of a radically new type of automobile engine and drive train. By adopting an interdisciplinary approach that incorporates new light weight carbon fiber composite materials, advanced power electronics and microprocessors in combination with hydraulics and our best electric motors we can have a form of personal transportation such as the world has never seen. The vehicles of the twenty-first century promise to be more efficient, economical, durable, better performing and easy on the environment than anything we have on the road today!

compliments: Gary Peterson - 21st Century Books, http://www.tfcbooks.com used by permission.

WHEN his World Wireless System project crashed, Tesla turned again to a project to which he had given considerable thought at the time he was developing his poly phase alternating-current system: that of developing a rotary engine which would be as far in advance of existing steam engines as his alternating-current system was ahead of the direct-current system, and which could be used for driving his dynamos. All of the steam engines in use in powerhouses at that time were of the reciprocating type; essentially the same as those developed by Newcomer and Watt, but larger in size, better in construction and more efficient in operation. Tesla's engine was of a different type--a turbine in which jets of steam injected between a series of disks produced rotary motion at high velocity in the cylinder on which these disks were mounted. The steam entered at the outer edge of the disks, pursued a spiral path of a dozen or more convolutions, and left the engine near the central shaft.

When Tesla informed a friend in 1902 that he was working on an engine project, he declared he would produce an engine so small, simple and powerful that it would be a ''powerhouse in a hat.'' The first model, which he made about 1906, fulfilled this promise. It was small enough to fit into the dome of a derby hat, measured a little more than six inches in its largest dimension, and developed thirty horsepower. The power-producing performance of this little engine vastly exceeded that of every known kind of prime mover in use at that time.

The engine weighed a little less than ten pounds. Its output was therefore three horsepower per pound. The rotor weighed only a pound and a half, and its light weight and high power yield gave Tesla a slogan which he used on his letterheads and envelopes--''Twenty horsepower per pound.'' There was nothing new, of course, in the basic idea of obtaining circular motion directly from a stream of moving fluid. Windmills and water wheels, devices as old as history, performed this feat. Hero, the Alexandrian writer, about 200 bc, described, but he did not invent, the first turbine. It consisted of a hollow sphere of metal mounted on an axle, with two tubes sticking out of the sphere at a tangent to its surface. When water was placed in the sphere and the device was suspended in a fire, the reaction of the steam coming out of the tubes caused the device to rotate.

Tesla's ingenious and original development of the turbine idea probably had its origin in that amusing and unsuccessful experiment he made when, as a boy, he tried to build a vacuum motor and observed its wooden cylinder turn slightly by the drag of the air leaking into the vacuum chamber. Later, too, when as a youth he fled to the mountains to escape military service and played with the idea of transporting mail across the ocean through an underwater tube, through which a hollow sphere was to be carried by a rapidly moving stream of water, he had discovered that the friction of the water on the walls of the tube made the idea impracticable. The friction would slow down the velocity of the stream of water so that excessive amounts of power would be required to move the water at a desired speed and pressure. Conversely, if the water moved at this speed, the friction caused it to try to drag the enclosing tube along with it.

It was this friction which Tesla now utilized in his turbine. A jet of steam rushing at high velocity between disks with a very small distance separating them was slowed down by the friction--but the disks, being capable of rotation, moved with increasing velocity until it was almost equal to that of the steam. In addition to the friction factor, there exists a peculiar attraction between gases and metal surfaces; and this made it possible for the moving steam to grip the metal of the disks more effectively and drag them around at high velocities. The first model which Tesla made in 1906 had twelve disks five inches in diameter. It was operated by compressed air, instead of steam, and attained a speed of 20,000 revolutions per minute. It was Tesla's intention eventually to use oil as fuel, burning it in a nozzle and taking advantage of the tremendous increase in volume, in the change from a liquid to burned highly expanded gases, to turn the rotor. This would eliminate the use of boilers for generating steam and give the direct process proportional increased efficiency.

Had Tesla proceeded with the development of his turbine in 1889 when he returned from the Westinghouse plant, his turbine might perhaps have been the one eventually developed to replace the slow, big, lumbering reciprocating engines then in use. The fifteen years, however, which he devoted to the development of currents of high potential and high frequency, had entailed a delay which gave opportunity for developers of other turbine ideas to advance their work to a stage which now was effective in putting Tesla in the status of a very late starter. In the meantime, turbines had been developed which were virtually windmills in a box. They consisted of rotors with small buckets or vanes around the circumference which were struck by the incoming steam jet. They lacked the simplicity of the Tesla turbine; but by the time Tesla introduced his type, the others were well entrenched in the development stage. Tesla's first tiny motor was built in 1906 by Julius C. Czito, who operated at Astoria, Long Island, a machine shop for making inventor's models. He also built the subsequent 1911 and 1925 models of the turbine, and many other devices on which Tesla worked up to 1929. Mr. Czito's father had been a member of Tesla's staff in the Houston Street laboratories, from 1892 to 1899, and at Colorado Springs.

Mr. Czito's description of the first model is as follows: "The rotor consisted of a stack of very thin disks six inches in diameter, made of German silver. The disks were one thirty-second of an inch thick and were separated by spacers of the same metal and same thickness but of much smaller diameter which were cut in the form of a cross with a circular center section. The extended arms served as ribs to brace the disks...There were eight disks and the edgewise face of the stack was only one-half inch across. They were mounted on the center of a shaft about six inches long. The shaft was nearly an inch in diameter in the mid section and was tapered in steps to less than half an inch at the ends. The rotor was set in a casing made in four parts bolted together.

The circular chamber where the rotor turned was accurately machined to allow a clearance of one sixty-fourth of an inch between the casing and the face of the rotor. Mr. Tesla desired an almost touching fit between the rotor face and the casing when the latter was turning. The large clearance was necessary because the rotor attained tremendously high speeds, averaging 35,000 revolutions per minute. At this speed the centrifugal force generated by the turning movement was so great it appreciably stretched the metal in the rotating disks. Their diameter when turning at top speed was one thirty-second of an inch greater than when they were standing still." A larger model was built by Tesla in 1910. It had disks twelve inches in diameter, and with a speed of 10,000 revolutions per minute it developed 100 horsepower, indicating a greatly improved efficiency over the first model. It developed more than three times as much power at half the speed. During the following year, 1911, still further improvements were made. The disks were reduced to a diameter of 9.75 inches and the speed of operation was cut down by ten per cent, to 9,000 revolutions per minute--and the power output increased by ten per cent, to 110 horsepower!

Following this test, Tesla issued a statement in which he declared: I have developed 110 horsepower with disks nine and three quarter inches in diameter and making a thickness of about two inches. Under proper conditions the performance might have been as much as 1,000 horsepower. In fact there is almost no limit to the mechanical performance of such a machine. This engine will work with gas, as in the usual type of explosion engine used in automobiles and airplanes, even better than it did with steam. Tests which I have conducted have shown that the rotary effort with gas is greater than with steam. Enthusiastic over the success of his smaller models of the turbine, operated on compressed air, and to a more limited extent by direct combustion of gasoline, Tesla designed and built a larger, double unit, which he planned to test with steam in the Waterside Station, the main powerhouse of the New York Edison Company.

This was a station which had originally been designed to operate on the direct-current system developed by Edison--but it was now operating throughout on Tesla's poly phase alternating-current system. Now Tesla, invading the Edison sanctum to test a new type of turbine which he hoped would replace the types in use, was definitely in enemy territory. The fact that he had Morgan backing, and that the Edison Company was a ``Morgan company,'' had no nullifying effect on the Edison-Tesla feud. This situation was not softened in any way by Tesla's method of carrying on his tests. Tesla was a confirmed ''sun dodger''; he preferred to work at night rather than in the daytime.

Powerhouses, not from choice but from necessity, have their heaviest demands for current after sunset. The day load would be relatively light; but as darkness approached, the dynamos started to groan under the increasing night load. The services of the workers at the Waterside Station were made available to Tesla for the setting up and tests of his turbine with the expectation that the work would be done during the day when the tasks of the workers were easiest. Tesla, however, would rarely show up until five o'clock in the afternoon, or later, and would turn a deaf ear to the pleas of workers that he arrive earlier. He insisted that certain of the workers whom he favored remain after their five-o'clock quitting time on the day shift to work with him on an overtime basis. Nor did he maintain a conciliatory attitude toward the engineering staff or the officials of the company. The attitudes, naturally, were mutual.

The turbine Nikola Tesla built for this test had a rotor 18 inches in diameter which turned at a speed of 9,000 revolutions per minute. It developed 200 horsepower. The overall dimensions of the engine were--three feet long, two feet wide and two feet high. It weighed 400 pounds. Two such turbines were built and installed in a line on a single base. The shafts of both were connected to a torque rod. Steam was fed to both engines so that, if they were free to rotate, they would turn in opposite directions. The power developed was measured by the torque rod connected to the two opposing shafts. At a formal test, to which Tesla invited a great many guests, he issued a statement in which he said, as reported, in part:

"It should be noted that although the experimental plant develops 200 horsepower with 125 pounds at the supply pipe and free exhaust it could show an output of 300 horsepower with full pressure of the supply circuit. If the turbine were compounded and the exhaust were led to a low pressure unit carrying about three times the number of disks contained in the high pressure element, with connection to a condenser affording 28.5 to 29.0 inches of vacuum the results obtained in the present high pressure machine indicate that the compounded unit would give an output of 600 horsepower without great increase of dimensions. This estimate is very conservative."

Tests have shown that when the turbine is running at 9,000 revolutions per minute under an inlet pressure of 125 pounds to the square inch and with free exhaust 200 brake horsepower are developed. The consumption under these conditions of maximum output is 38 pounds of saturated steam per horsepower per hour, a very high efficiency when we consider that the heat drop, measured by thermometers, is only 130 B.T.U. and that the energy transformation is effected in one stage. Since three times the number of heat units are available in a modern plant with superheat and high vacuum the utilization of these facilities would mean a consumption of less than 12 pounds per horsepower hour in such turbines adapted to take the full drop.

Under certain conditions very high thermal efficiencies have been obtained which demonstrate that in large machines based on this principle steam consumption will be much lower and should approximate the theoretical minimum thus resulting in the nearly frictionless turbine transmitting almost the entire expansive energy of the steam to the shaft. It should be kept in mind that all of the turbines which Tesla built and tested were single-stage engines, using about one-third of the energy of the steam. In practical use, they were intended to be installed with a second stage which would employ the remaining energy and increase the power output about two or three fold. (The two types of turbines in common use each have a dozen and more stages within a single shell.)

Some of the Edison electric camp, observing the torque-rod tests and apparently not understanding that in such a test the two rotors remain stationary--their opposed pressures staging a tug of war measured as torque--circulated the story that the turbine was a complete failure; that this turbine would not be practical if its efficiency had been increased a thousand fold. It was stories such as these that contributed to the imputation that Tesla was an impractical visionary. The Tesla turbine, however, used as a single-stage engine, functioning as a pygmy power producer, in the form in which it was actually tested, anticipated by more than twenty five years a type of turbine which has been installed in recent years in the Waterside Station. This is a very small engine, with blades on its rotor, known as a ''topping turbine,'' which is inserted in the steam line between the boilers and the ordinary turbines. Steam of increased pressure is supplied, and the topping turbine skims this ``cream'' from the steam and exhausts steam that runs the other turbines in their normal way. The General Electric Company was developing the Curtis turbine at that time, and the Westinghouse Electric and Manufacturing Company was developing the Parsons turbine; and neither company showed the slightest interest in Tesla's demonstration.

Further development of his turbine on a larger scale would have required a large amount of money--and Tesla did not possess even a small amount. Finally he succeeded in interesting the Allis Chalmers Manufacturing Company of Milwaukee, builders of reciprocating engines and turbines, and other heavy machinery. In typical Tesla fashion, though, he manifested in his negotiations such a lack of diplomacy and insight into human nature that he would have been better of if he had completely failed to make any arrangements for exploiting the turbine.

Tesla, an engineer, ignored the engineers on the Allis Chalmers staff and went directly to the president. While an engineering report was being prepared on his proposal, he went to the Board of Directors and ''sold'' that body on his project before the engineers had a chance to be heard. Three turbines were built. Two of them had twenty disks eighteen inches in diameter and were tested with steam at eighty pounds pressure. They developed at speeds of 12,000 and 10,000 revolutions per minute, respectively, 200 horsepower. This was exactly the same power output as had been achieved by Tesla's 1911 model, which had disks of half this diameter and was operated at 9,000 revolutions under 125 pounds pressure. A much larger engine was tackled next. It had fifteen disks sixty inches in diameter, was designed to operate at 3,600 revolutions per minute, and was rated at 500 kilowatts capacity, or about 675 horsepower. Hans Dahlstrand, Consulting Engineer of the Steam Turbine Department, reports, in part:

We also built a 500 kw steam turbine to operate at 3,600 revolutions. The turbine rotor consisted of fifteen disks 60 inches in diameter and one eighth inch thick. The disks were placed approximately one eighth inch apart. The unit was tested by connecting to a generator. The maximum mechanical efficiency obtained on this unit was approximately 38 per cent when operating at steam pressure of approximately 80 pounds absolute and a back pressure of approximately 3 pounds absolute and 100 degrees F superheat at the inlet. When the steam pressure was increased above that given the mechanical efficiency dropped, consequently the design of these turbines was of such a nature that in order to obtain maximum efficiency at high pressure, it would have been necessary to have more than one turbine in series.

The efficiency of the small turbine units compares with the efficiency obtainable on small impulse turbines running at speeds where they can be directly connected to pumps and other machinery. It is obvious, therefore, that the small unit in order to obtain the same efficiency had to operate at from 10,000 to 12,000 revolutions and it would have been necessary to provide reduction gears between the steam turbine and the driven unit. Furthermore, the design of the Tesla turbine could not compete as far as manufacturing costs with the smaller type of impulse units. It is also questionable whether the rotor disks, because of light construction and high stress, would have lasted any length of time if operating continuously. The above remarks apply equally to the large turbine running at 3,600 revolutions. It was found when this unit was dismantled that the disks had distorted to a great extent and the opinion was that these disks would ultimately have failed if the unit had been operated for any length of time.

The gas turbine was never constructed for the reason that the company was unable to obtain sufficient engineering information from Mr. Tesla indicating even an approximate design that he had in mind. Tesla appears to have walked out on the tests at this stage. In Milwaukee, however, there was no George Westinghouse to save the situation. Later, during the twenties, the author asked Tesla why he had terminated his work with the Allis Chalmers Company. He replied: ''They would not build the turbines as I wished''; and he would not amplify the statement further. The Allis Chalmers Company later became the pioneer manufacturers of another type of gas turbine that has been in successful operation for years.

While the Dahlstrand report may appear to be severely critical of the Tesla turbine and to reveal fundamental weaknesses in it not found in other turbines, such is not the case. The report is, in general, a fair presentation of the results; and the description of apparent weaknesses merely offers from another viewpoint the facts which Tesla himself stated about the turbine in his earlier test--that when employed as a single-stage engine it uses only about a third of the energy of the steam, and that to utilize the remainder, it would have to be compounded with a second turbine. The reference to a centrifugal force of 70,000 pounds resulting from the high speed of rotation of the rotor, causing damage to the disks, refers to a common experience with all types of turbines. This is made clear in a booklet on ''The Story of the Turbine,'' issued during the past year by the General Electric Company, in which it is stated: It [the turbine] had to wait until engineers and scientists could develop materials to withstand these pressures and speeds. For example, a single bucket in a modern turbine traveling at 600 miles per hour has a centrifugal force of 90,000 pounds trying to pull it from its attachment on the bucket wheel and shaft. . . .

In this raging inferno the high pressure buckets at one end of the turbine run red hot while a few feet away the large buckets in the last stages run at 600 miles per hour through a storm of tepid rain--so fast that the drops of condensed steam cut like a sand blast. Dahlstrand reported that difficulties were encountered in the Tesla turbine from vibration, making it necessary to re-enforce the disks. That this difficulty is common to all turbines is further indicated by the General Electric booklet, which states:

Vibration cracked buckets and wheels and wrecked turbines, sometimes within a few hours and sometimes after years of operation. This vibration was caused by taking such terrific amounts of power from relatively light machinery--it some cases as much as 400 horsepower out of a bucket weighing but a pound or two. . . .

The major problems of the turbine are four--high temperatures, high pressures, high speeds and internal vibration. And their solution lies in engineering, research and manufacturing skill. These problems are still awaiting their final solution, even with the manufacturers who have been building turbines for forty years; and the fact that they were encountered in the Tesla turbine, and so reported, is not a final criticism of Tesla's invention in the earliest stages of its development.

The development of new alloys, which can now almost be made to order with desired qualities of mechanical stability under conditions of high temperature and great stresses, is largely responsible for this turn of events. It is a possibility that if the Tesla turbine were constructed with the benefit of two or more stages, thus giving it the full operating range of either the Curtis or the Parsons turbine, and were built with the same benefits of engineering skill and modern metallurgical developments as have been lavished on these two turbines, the vastly greater simplicity of the Tesla turbine would enable it to manifest greater efficiencies of operation and economies of construction.

Most people remember Nikola Tesla for his work and revelations in the field of electrical energy and the invention of radio. However, Tesla had a life long interest in developing a flying machine. Tesla had envisioned himself as the first man that would fly. He had planned to build an aircraft that would operate on electric motors. However, the first men who successfully flew an aircraft used the reciprocating internal combustion engine. Though successful in achieving flight, aircraft using these engines were dangerous and unpredictable, due to the engine's lack of adequate power. Tesla turned his attention to revamping the internal combustion engine so as to make flying safe for all and minimize its environmental impact. Documented in this text is the result of Tesla's endeavors and the resulting marvel of machines called the Bladeless Boundary- Layer Turbine.

Although Tesla's dream for his engines application in aircraft was not realized in his life time, if allowed to be used in aircraft today, it would provide a quiet, safe, simple and efficient alternative to our supposedly advanced bladed turbine aircraft engines. It has been estimated that an increase in fuel efficiency of a factor of three could be realized in aircraft and thus substantially reduce pollution. Not only this, the Bladeless Tesla Turbine Engine can turn at much higher speeds with total safety. If a conventional bladed turbine engine goes critical or fails, watch out, you have exploding parts slicing through hydraulic lines, control surfaces and maybe even you. With the Bladeless Tesla Turbine this is not a danger because it will not explode. If it does go critical, as has been documented in tests at 85,000 rpm, the failed component will not explode but implode into tiny pieces which are ejected through the exhaust while the undamaged components continue to provide thrust to keep you airborne. We. can only speculate on the human suffering that could and should be averted.

The application of this amazing engine was not to be limited to aircraft. Tesla was setting up plans to replace what he considered the wasteful, polluting, inefficient and complicated reciprocating engine in all its applications, including the automobile. Tesla's small but powerful engine has only one moving part and is 95% efficient, which means tremendous mileage. It runs vibration free and doesn't even require a muffler. Not only is this engine 95% efficient, as compared to 25% efficiency or less of the conventional gas engine, it can run efficiently on any fuel from sawdust to hydrogen with no wear on the internal engine components. This engine's speed-torque characteristic allows full torque at the bottom of the speed range eliminating the conventional shifting gear transmission. This provides additional economy as the expensive, complicated and wear prone transmission is eliminated.

Unlike most people of the time, Tesla was very concerned about the long range environmental damage the reciprocating engines would create. He stressed over and over how we must take the long range view and not step out of harmony with our life support systems. Today the widening concern for Spaceship Earth and the renewal of an old ethic "We don't inherit the Earth from our ancestors, we borrow it from our children" is slowly beginning to awaken people to the concerns of Tesla.

Although the existence of the automobile on city streets dates back to the first years of the century, its role as a contributor to air contamination did not receive wide acceptance among scientists until the 60's. Factual evidence that urban area smog was chemically related to automobile emissions had been produced and acknowledged by scientific groups in the 1950's. Despite vehement disagreement which ensued between government and the automotive industry on this volatile issue, research and development programs were initiated by both groups in an effort to identify the reciprocating internal combustion engine's sources of pollution and determine what corrective action might be taken. Obviously Tesla's ounce of prevention was not heeded, leaving us with well over the pound required for a cure with nearly half of all air pollution caused by the reciprocating internal combustion engine.

The Boundary Layer Turbine is not only an engine that is hard to comprehend by our currently imposed standards, but can also be used as a pump with slight modification. And like its cousin the engine, it has Herculean power. Unlike conventional pumps that are easily damaged by contaminants, the Bladeless Tesla Pump can handle particles and corrosives in stride as well as gases with no cavitation effect that destroys, in short order, conventional type pumps.

These pumps and engines, though unknown to most, are available for commercial sale. If large scale commercial production was implemented, these engines and pumps would be extremely affordable due to their simplicity of manufacture, longevity, almost total lack of maintenance and the added bonus that they require no crank case oil.

Almost a quarter of the air pollution today comes from the coal being burned to generate electricity. Fuel consumption, resulting in air pollution and acid rain, could be significantly reduced simply by replacing the conventional blade steam turbines currently used by utilities with the Bladeless Tesla Steam Turbine. This also would have the added bonus of drastically reducing maintenance. But the real solution lies in using low temperature wet steam occurring naturally from the ground in the form of geothermal energy. This energy would destroy a conventional bladed steam turbine, unless expensive steam drying is employed. However, the Bladeless Tesla Steam Turbine requires no drying and can be connected directly to the geothermal source. It has been estimated that the geothermal potential in just Southern California alone, could power the entire North American Continent with NO POLLUTION! Large oil companies have comprehended the potential of geothermal energy and have purchased many of these large tracks of prime geothermal land.

Due to the revolutionary concepts embodied in this engine, we can easily end the so called energy crisis and dramatically reduce pollution. Even the vested energy interests are beginning to understand that now is the time for change, realizing their future health and wealth is directly linked to that of the environment. You can't hide or buy your way out of a devastated planet. There must also be a move forward for the many misinformed environmentalists who see our future as one of regression from technology instead of its proper usage.

Tesla from his 1919 autobiography, My Inventions: "My alternating system of power transmission came at a psychological moment, as a long-sought answer to pressing industrial questions, and although considerable resistance had to be overcome and opposing interests reconciled, as usual, the commercial introduction could not be long delayed. Now, compare this situation with that confronting my turbine, for example. One should think that so simple and beautiful an invention, possessing many features of an ideal motor, should be adopted at once and, undoubtedly, it would under similar conditions. But the prospective effect of the rotating field was not to render worthless existing machinery; on the contrary, it was to give it additional value. The system lent itself to new enterprise as well as to improvement of the old. My turbine is an advance of a character entirely different. It is a radical departure in the sense that its success would mean the abandonment of the antiquated types of prime movers on which billions of dollars have been spent. Under such circumstances the progress must needs be slow and perhaps the greatest impediment is encountered in the prejudicial opinions created in the minds of experts by organized opposition."

H.G. Wells once said that future history will be a race between education and catastrophe. This book is dedicated to the race for education. Reprinted from: Boundary-Layer Breakthrough - The Tesla Bladeless Turbine pages 114-118.

A MARKED step was taken in the simplification of prime movers when Watt's cumbersome beam engine, with its ingenious but elaborate parallel motion, gave way to the present standard reciprocating type, with only piston rod, cross head and connecting rod interposed between piston and crank. An even greater advance toward ideal simplicity occurred when, after years of effort by inventors to produce a practical rotary, Parsons brought out his compact, though costly, turbine, in which the energy of the steam is developed on a zig-zag path through multitudinous rows of fixed and moving blades.

And now comes Mr. Tesla with a motor which bids fair to carry the steam engine another long step toward the ideally simple prime mover - a motor in which the fixed and revolving blades of the turbine give place to a set of steel disks of simple and cheap construction. If the flow of steam in spiral curves between the adjoining faces of flat disks is an efficient method of developing the energy of the steam, the prime mover would certainly appear to have been at last reduced to its simplest terms.

The further development of the unique turbine which we describe elsewhere will be followed with close attention by the technical world. The results attained with this small high-pressure unit are certainly flattering, and give reason to believe that the addition of a low pressure turbine and a condenser would make this type of turbine as highly efficient as it is simple and cheap in construction and maintenance.

It will interest the readers of the Scientific American to that Nikola Tesla, whose reputation must, naturally, stand upon the contribution he made to electrical engineering when the art was yet in its comparative infancy, is by training and choice a mechanical engineer, with a strong leaning to that branch of it which is covered by the term "steam engineering." For several years past he has devoted much of his attention to improvements in thermo-dynamic conversion, and the result of his theories and practical experiments is to be found in an entirely new form of prime movers shown in operation at the waterside station of the New York Edison Company, who kindly placed the facilities of their great plant at his disposal for carrying on experimental work.

By the courtesy of the inventor, we are enabled to publish the accompanying views, representing the testing plant at the Waterside station, which are the first photographs of this interesting motor that have yet been made public. The basic principle which determined Tesla's investigations was the well-known fact that when a fluid (steam, gas or water) is used as a vehicle of energy, the highest possible economy can be obtained only when the changes in velocity and direction of the movement of the fluid are made as gradual and easy as possible. In the present forms of turbines in which the energy is transmitted by pressure, reaction or impact, as in the De Laval, Parsons, and Curtiss types, more or less sudden changes both of speed and direction are involved, with consequent shocks, vibration and destructive eddies. Furthermore, the introduction of pistons, blades, buckets, and intercepting devices of this general class, into the path of the fluid involves much delicate and difficult mechanical construction which adds greatly to the cost both of production and maintenance.

The desiderata in an ideal turbine group themselves under the heads of the theoretical and the mechanical. The theoretically perfect turbine would be one in which the fluid was so controlled from the inlet to the exhaust that its energy was delivered to the driving shaft with the least possible losses due to the mechanical means employed. The mechanically perfect turbine would be one which combined simplicity and cheapness of construction, durability, ease and rapidity of repairs, and a small ratio of weight and space occupied to the power delivered on the shaft. Mr. Tesla maintains that in the turbine which forms the subject of this article, he has carried the steam and gas motor a long step forward toward the maximum attainable efficiency, both theoretical and mechanical. That these claims are well founded is shown by the fact that in the plant at the Edison station, he is securing an output of 200 horse-power from a single-stage steam turbine with atmospheric exhaust, weighing less than 2 pounds per horse-power, which is contained within a space measuring 2 feet by 3 feet, by 2 feet in height, and which accomplishes these results with a thermal fall of only 130 B.T.U., that is, about one-third of the total drop available. Furthermore, considered from the mechanical standpoint, the turbine is astonishingly simple and economical in construction, and by the very nature of its construction, should prove to possess such a durability and freedom from wear and breakdown as to place it, in these respects, far in advance of any type of steam or gas motor of the present day.

Briefly stated, Tesla's steam motor consists of a set of flat steel disks mounted on a shaft and rotating within a casing, the steam entering with high velocity at the periphery of the disks, flowing between them in free spiral paths, and finally escaping through exhaust ports at their center. Instead of developing the energy of the steam by pressure, reaction, or impact, on a series of blades or vanes, Tesla depends upon the fluid properties of adhesion and viscosity--the attraction of the steam to the faces of the disks and the resistance of its particles to molecular separation combining in transmitting the velocity energy of the motive fluid to the plates and the shaft.

By reference to the accompanying photographs and line drawings, it will be seen that the turbine has a rotor A which in the present case consists of 25 flat steel disks, one thirty-second of an inch in thickness, of hardened and carefully tempered steel. The rotor as assembled is 3 1/2 inches wide on the face, by 18 inches in diameter, and when the turbine is running at its maximum working velocity, the material is never under a tensile stress exceeding 50,000 pounds per square inch. The rotor is mounted in a casing D, which is provided with two inlet nozzles, B for use in running direct and B' for reversing. Openings C are cut out at the central portion of the disks and these communicate directly with exhaust ports formed in the side of the casing.

In operation, the steam, or gas, as the case may be is directed on the periphery of the disks through the nozzle B (which may be diverging, straight or converging), where more or less of its expansive energy is converted into velocity energy. When the machine is at rest, the radial and tangential forces due to the pressure and velocity of the steam cause it to travel in a rather short curved path toward the central exhaust opening, as indicated by the full black line in the accompanying diagram; but as the disks commence to rotate and their speed increases, the steam travels in spiral paths the length of which increases until, as in the case of the present turbine, the particles of the fluid complete a number of turns around the shaft before reaching the exhaust, covering in the meantime a lineal path some 12 to 16 feet in length. During its progress from inlet to exhaust, the velocity and pressure of the steam are reduced until it leaves the exhaust at 1 or 2 pounds gage pressure.

The resistance to the passage of the steam or gas between adjoining plates is approximately proportionate to the square of the relative speed, which is at a maximum toward the center of the disks and is equal to the tangential velocity of the steam. Hence the resistance to radial escape is very great, being furthermore enhanced by the centrifugal force acting outwardly. One of the most desirable elements in a perfected turbine is that of reversibility, and we are all familiar with the many and frequently cumbersome means which have been employed to secure this end. It will be seen that this turbine is admirably adapted for reversing, since this effect can be secured by merely closing the right-hand valve and opening that on the left.

It is evident that the principles of this turbine are equally applicable, by slight modifications of design, for its use as a pump, and we present a photograph of a demonstration model which is in operation in Mr. Tesla's office. This little pump, driven by an electric motor of 1/12 horse-power, delivers 40 gallons per minute against a head of 9 feet. The discharge pipe leads up to a horizontal tube provided with a wire mesh for screening the water and checking the eddies. The water falls through a slot in the bottom of this tube and after passing below a baffle plate flows in a steady stream about 3/4 inch thick by 18 inches in width, to a trough from which it returns to the pump. Pumps of this character show an efficiency favorably comparing with that of centrifugal pumps and they have the advantage that great heads are obtainable economically in a single stage. The runner is mounted in a two-part volute casing and except for the fact that the place of the buckets, vanes, etc., of the ordinary centrifugal pump is taken by a set of disks, the construction is generally similar to that of pumps of the standard kind.

In conclusion, it should be noted that although the experimental plant at the Waterside station develops 200 horse-power with 125 pounds at the supply pipe and free exhaust, it could show an output of 300 horse-power with the full pressure of the Edison supply circuit. Furthermore, Mr. Tesla states that if it were compounded and the exhaust were led to a low pressure unit, carrying about three times the number of disks contained in the high pressure element, with connection to a condenser affording 28 1/2 to 29 inches of vacuum, the results obtained in the present high-pressure machine indicate that the compound unit would give an output of 600 horse-power, without great increase of dimensions. This estimate is conservative.

The testing plant consists of two identical turbines connected by a carefully calibrated torsion spring, the machine to the left being the driving element, the other the brake. In the brake element, the steam is delivered to the blades in a direction opposite to that of the rotation of the disks. Fastened to the shaft of the brake turbine is a hollow pulley provided with two diametrically opposite narrow slots, and an incandescent lamp placed inside close to the rim. As the pulley rotates, two flashes of light pass out of the same, and by means of reflecting mirrors and lenses, they are carried around the plant and fall upon two rotating glass mirrors placed back to back on the shaft of the driving turbine so that the center line of the silver coatings coincides with the axis of the shaft. The mirrors are so set that when there is no torsion on the spring, the light beams produce a luminous spot stationary at the zero of the scale. But as soon as load is put on, the beam is deflected through an angle which indicates directly the torsion. The scale and spring are so proportioned and adjusted that the horse-power can be read directly from the deflections noted. The indications of this device are very accurate and have shown that when the turbine is running at 9,000 revolutions under an inlet pressure of 125 pounds to the square inch, and with free exhaust, 200 brake horse-power are developed. The consumption under these conditions of maximum output is 38 pounds of saturated steam per horse-power per hour - a very high efficiency when we consider that the heat-drop, measured by thermometers, is only 130 B.T.U., and that the energy transformation is effected in one stage. Since about three times this number of heat units are available in a modern plant with super-heat and high vacuum, the above means a consumption of less than 12 pounds per horse-power hour in such turbines adapted to take up the full drop. Under certain conditions, however, very high thermal efficiencies have been obtained which demonstrate that in large machines based on this principle, in which a very small slip can be secured, the steam consumption will be much lower and should, Mr. Tesla states, approximate the theoretical minimum, thus resulting in nearly frictionless turbine transmitting almost the entire expansive energy of the steam to the shaft.

Journey back to the future and discover the fascinating secret behind the most powerful and economic internal or external combustion engine of all time: Tesla's Bladeless Boundary-Layer Turbine. You will experience the excitement of understanding as Tesla's mechanical breakthrough is explored, shattering the boundaries of our current mechanical standard. You will be swept into the awareness of discovery as the simplicity of this whirl wind machine of natural harmony is revealed. Unveiled here today how it is possible to convert the normally undesired energy of drag into the tremendous vortex energy of Tesla's perfectly controlled mechanical tornado. The real answer to energy.

The history of Tesla's monarch of machines is then followed into the present day work of researchers and inventors C.R. "Jake" Possell [1]. and Frank Germano (President of International Turbine And Power, LLC)[2]. You will learn how modern day applications of the bladeless turbine could improve all aspects of our mechanical life. Today's applications range from indestructible pumps and Freon free air conditioning to speed boats and supersonic aircraft.

Conventional pumps and engines pale in comparison. This jewel of mechanics has no equal. It stands alone above all others. No other pump or engine can match the longevity, economy, size, safety, silence and vibration free Herculean power of this truly elegant machine. It waits patiently to solve the efficiency and pollution problems of today and could literally usher in A NEW WORLD. Fully Illustrated

[1] Mr. C. R. "Jake" Possell Is President of a Public Company - QUADRATECH, Inc., 1417 South Gage Street, San Bernardino, CA 92408

[2] Mr. Frank Germano is President of a Private Company - International Turbine And Power, LLC, 931 Rumsey Avenue, Cody, Wyoming 82414, and Founder and CEO of Global Energy Technologies, Inc., 11th Street, Blakely, PA 18447.

[3] BOUNDARY-LAYER BREAKTHROUGH - THE BLADELESS TESLA TURBINE Volume II. The Tesla Technology Series, ISBN 1-882137-01-9

The Tesla Turbine "Yahoo Groups" List:
this list has grown substantially since its initial creation in 1999. The list is used to keep members informed of important updates, new ideas on turbine construction, and for a general forum and outlet on new and innovative concepts in the construction of the Tesla Turbine. The list is moderated by founder and creator of International Turbine And Power, LLC - Mr. Frank Germano. There are at any time approximately 1000 interested individuals on this list. If you would like to join this exciting Tesla Turbine List, use the link(s) below and follow the instructions.

Compliments & Acknowledgements: Gary Peterson, "Twenty First Century Books"...if you are interested in learning more about the Tesla bladeless boundary disk turbine, or the Tesla Pump, check out Gary's web site. Besides carrying a complete listing of excellent books pertaining to Nikola Tesla (honestly: it's probably THE most comprehensive collection of Nikola Tesla books, articles and information We've ever seen...!), he also has written the book , "The Tesla Bladeless Turbine and Related Turbo Machinery", which goes into great detail and depth, on the turbine/pump itself. The web site definitely is worth the time to check out...it's a pretty large site. Great info !

Books I highly recommend

"This book describes the concept of the Disc Turbine as originally patented by Nicola Tesla, and provides concept designs for modern versions of the engine, incorporating the Disc Turbine as a power unit for applications in Automobiles and Light Aircraft, and also give descriptions of the original Turbines and the prototype machines. It also provides designs for other machines operating on the principle of a disc turbine: an Air Compressor, an Air Motor, and a Vacuum Exhauster. The facility of the principle to operate in either a clockwise or anti-clockwise direction of rotation, in a single machine, using only a two-way valve, is described, and applications where this feature can be applied to advantage are suggested.

Data is given on the performances attained by the original engines, together with stress and performance information. Finally, we give a design for a modernized version of the original turbine, to one half scale, complete with working drawings and manufacturing instructions to enable the model or experimental engineer to construct a fully operational engine, using such tools and equipment as are usually available to model makers.

It should be apparent that this dry foreword written by the author sounds like the abstract of a paper published in a professional engineering journal. That's because the author IS an engineer who has a number of published papers. Cairns is no novice. He knows what he's talking about. Chapters include: Tesla's original machine * The Disc Turbine Operating Principle * The first experimental Turbine * The 9.75 in. Disc Prototype Turbine * Larger Turbines to 60 in. disc diameter * Future developments * Other Rotary Engines * The Automotive Disc Turbine * Air Compressor, Vacuum Pump, Air Motor, Light Aircraft Engines * The Dual Direction Facility * Stresses in the discs and performance calculations * Building a model Disc Turbine * Drawings for a model Disc Turbine* Since this is a 36 page "booklet" each "chapter" is necessarily short. But what you DO get is loaded with valuable information. Remember this is written by an engineer who is interested in getting results. The last nine pages are dedicated to the model with six pages of detailed, dimensioned drawings. The model described is approximately one half the size of the original Tesla unit, but uses present-day materials and techniques... Required machine tools are a lathe, with a 3.5" centre height, ideally with a milling attachment, and circular table, a bench drill, micrometer or vernier, and conventional hand tools (metric dimensions are used). From the testing section: "Run for no more than two minutes, stop, check the housing temperature. If cool to slightly warm, re-open the valve and continue running. At around 1.75 bar and 1.5 cfm, the turbine will attain a shaft speed of 20,000 R.P.M. At all times ensure a supply of oil to the bearings, and continually monitor the housing temperature. It should be noted that the prototype attained a speed of approximately 50,000 R.P.M. under no-load conditions; hence it is advised that a brake or dynometer be provided on the shaft."

So...you've read through this page; now what? How about some HELP from YOU?!
HELP FRANK GERMANO in making this technology available, commercially.

Frank D Germano,
Founder and President,
International Turbine And Power
931 Rumsey Avenue, PO Box 550
Cody, Wyoming 82414