68-GT-54
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Governing Gas Turbine Engines for Marine Propulsion Power Versus Speed Control
D. A. O'NEIL Senior Gas Turbine Engineer, Turbo-Power & Marine Department Pratt & Whitney Aircraft Division, United Aircraft Corporation, East Hartford, Conn.
This paper _examines typical shipboard operational requirements, conventional marine propulsion control methodology, and the related merits of power and speed governing for the a·ircraft derived marine gas turbine engine applications of the future.
Contributed by the Gas Turbine Division of The American Society of Mechanical Engineers for presentation at the Gas Turbine Conference & Products Show, Washington, D. C., March 17-21, 1968. Manuscript received at ASME Headquarters, January 26, 1968. Copies will be available until January 1, 1969.
THE AMERICAN SOCIETY Of MECHANICAL ENGINEERS, UNITED ENGINEERING CENTER, 345 EAST t7th STREET, NEW YORK, N.Y. 10017 r
Governing Gas Turbine Engines for Marine Propulsion Power Versus Speed Control
D. A. O'NEIL Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1968/79870/V001T01A054/2389859/v001t01a054-68-gt-54.pdf by guest on 30 September 2021
In 1765 James Watt, of Scotland, produced an Today's aircraft type gas turbine engine effective steam engine which was improved upon by promises the marine industry the capabilities of Pickard's connecting rod and crank system in 1780. quicker starts, more rapid propulsion response, Watt is also credited for an early patent on a de lower machinery weights, less on-board maintenance, vice that could maintain constant shaft speed re documented reliability, space-savings, and a power gardless of changes in boiler pressure or load. plant that is inherently more suitable for control The device regulated steam flow based on the dif from remote locations. Each ship's specific re ference between the actual and the demanded shaft quirements for maneuvering and steady-state opera speeds. tions, as well as special operational requirements, Later, men like Fitch, Symington, .Hull, must be integrated with that specific type of en Stevens, and Livingston first applied the steam gine1 s ability to respond to a given order for engine to marine propulsion. Then in 1807, Ful power or speed. ton's North River Steamship, better known today as This paper discusses common shipboard opera the Clermont, paved the way to commercial steam tional requirements and how they are met on con ship operation with its journey up the Hudson ventionally powered vessels in order to later re River. late some views on controlling and governing gas There was little information at hand to en turbine powered vessels. able the pioneers of steamship propulsion to math ematically evaluate their engine's governing sys GENERAL tem as it related to peculiar shipboard operations, because it was not until the latter part of the The prime considerations associated with the nineteenth century that scientists like Maxwell control of combatant vessels will naturally vary developed techniques for analyzing Watt 1 s regu from those associated with commercial or special lator and other control devices. What is indis purpose vessels. Similarly, there is a wide varia putable, however, is that "they must have done tion in the priority one would assign to certain something right, 11 because 11 Fulton 1 s Folly" was in control system design parameters associated with a deed more success than folly. Today, marine engi twin-screw vessel, as opposed to a single-screw neers are able to select from a multitude of en vessel, or for manned machinery versus fully auto gines and heat cycles for marine propulsion. Just mated or bridge controlled machinery. as important as the selection of the prime mover The various Maritime Administration, Amer is the selection of the method by which the engine ican Bureau of Shipping, Coast Guard, Navy, and responds to the orders given on the bridge, and other military specifications or rules and regula the way in which the engine governs itself when tions will be of little or negative value. Those unattended. directed to gas turbines are still in their infancy, Fundamental shipboard operational require and more than likely will evolve slowly, being pat ments are steadily becoming more critical due to terned after the earliest gas turbine applications. increases in vessel sizes, speeds, and the pres These may or may not have proven to be optimal in sure to remain competitive or to maintain military the area of controls. supremacy. Traditionally, orders for ship speed and directional control have been transmitted from CONVENTIONAL SHIP CONTROL the bridge to the engine room by some communica tion media, usually the engine order telegraph. A brief analysis of the major ship control The operator would then manipulate a variety of requirements and how these requirements are met on propulsion plant devices to cause the engine to conventionally propelled vessels should be useful respond to the order. as an aid in the evaluation of control for gas
1 turbine propelled vessels. hold constant speed regardless of load. Horsepower, The pioneer of fuel burning mechanized ship under these circumstances, following fuel metering, board propulsion was, as mentioned in the Introduc varies in order to maintain near constant speed. tion, the steam reciprocating engine. Maneuvering The high mass of' diesel engine rotating components control for this type of engine was generally ac and the relatively slow action of the diesel type complished by the throttling of steam from the speed governors tend to minimize potential gross boiler. The main throttle valve was positioned variations of either power or speed, and this pro manually to set cylinder admission pressure at cess of control is quite adequate for the marine
~uch a value as to adjust engine speed to meet the diesel, under steady-state operation, normal and Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1968/79870/V001T01A054/2389859/v001t01a054-68-gt-54.pdf by guest on 30 September 2021 speed ordered by the bridge. Once near steady gross transients. Maneuvering is easily handled state operation was achieved, boiler pressure and by setting the speed ordered by adjusting governor firing rate was established and the throttle valve spring pressure via a speed set lever. fully opened to reduce throttling losses leaving Steam turbines are controlled in much the the steam reciprocating engine essentially under same manner as steam reciprocating engines. Dur constant steam flow "control." This was essen ing maneuvers, the main steam throttle is opened tially constant "power control," even though the until the turbine steam chest pressure required to language used to relay the order was in terms of produce an ordered shaft rpm is reached. Slight 11 speed 11 and the "check" instrument was a tach corrections in setting the throttle are made as ometer. "vernier adjustments" to compensate for the effect As normal fluctuations in propeller loading of off-design sea water injection temperature on occurred, either from the effects of the seaway,. main condenser vacuum. Normal variations in pro turning, or rudder movement, steam admission pres peller loading result in slight changes in turbine sure remained constant, and the propeller "found speed, while power remains essentially constant. its own way" continually and adjusted its speed to Gross variations in speed are protected against the instantaneous "power applied." Shaft horse- automatically either by hydraulic or mechanical power, on the other hand, remained very nearly overspeed governors which quickly throttle or shut constant. off steam flow on commercial vessels. Naval ves- The only engine speed or power limits imposed sels are not usually so equipped, because addi- on the system by additional hardware were intro- tional manpower is available. duced to prevent mechanical damage in the event of For steady-state steaming, the throttle is an overspeed during a broached propeller situation, opened fully and steam admission pressure is set considered here as a gross transient rather than by varying turbine inlet nozzles. normal transient. In the early days of the steam reciprocating engine, a quick closing manual valve GAS TURBINE CONTROL - SPEED GOVERNING was manned constantly in heavy weather, and was closed to reduce overspeed by a perceptive aper- Speed control is achieved by setting a pbwer ator. This. form of protection was eventually auto- turbine output shaft speed sensing governor (quite mated by means of the mechanical overspeed gover- similar to those found on diesels), which in turn nor. Speed, in this case, was the "control param- causes the gas generator fuel control (metering eter" sensed to govern against mechanical damage. system) to regulate fuel flow to maintain the de- The larger main propulsion marine diesel en- sired power turbine speed. Fluctuations in load- gines, basically, are controlled by metering the ing cause slight power turbine speed changes which fuel admitted to each cylinder. The operating produce a governor error signal. This signal is speed range of diesels is comparatively lower than amplified and is used to reposition the gas gener- for turbine engines (600 to 1200 rpm versus 3000 ator fuel metering system to reschedule the fuel to 10,000 rpm). Because a diesel has a minimum to air ratio within the gas generator. This in operating speed and a very critical structural max- turn changes the gas generator mass flow and gas imum speed limitation, speed governing becomes far temperature to produce the effect of returning the more applicable than on steam turbines or recipro- power turbine to its governed speed. eating engines. We find, therefore, that most diesels are usually controlled by speed governors GAS TURBINE CONTROL - POWER GOVERNING which mechanically regulate engine output by sens ing and maintaining engine speed by closed loop Power control is basically near constant fuel speed error proportioning. metering, and output power.is virtually unchanged As variations in propeller loading occur, regardless of the changes in power turbine speed diesel governors attempt to maintain the speed that will occur due to load fluctuations. It is setting by varying the injector rack position to comparable to the steam turbine method of governing
2 control where constant s_team flow is established governing best meets operational requirements. The by setting steam chest pressure. familiar, 'near cubic relationship between engine A typical fuel control system does not di power and ship's speed (shp versus propeller speed) rectly establish a particular fuel flow schedule under steady state conditions, appears to minimize but does so indirectly through a "computer." Addi the problem of ideal control selection, because tionally, it_ can be of the electronic or hydrome under those rarely achieved conditions, the valid chanical type and programs fuel flow for starting, ity of that finite relationship leads one to be acceleration, deceleration, and steady state by lieve that either power or speed control would suf sensing power lever angle, high pressure compres fice. Handling transient performance more closely Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1968/79870/V001T01A054/2389859/v001t01a054-68-gt-54.pdf by guest on 30 September 2021 sor rotor speed, and compressor pressure. represents the fundamental reason for automated control, and provides the basis for ultimately GAS TURBINE OVERSPEED PROTECTION adopting speed, power or torque governing or a combination of these. These transient conditions Power turbine overspeed protection on the are related to fluctuations in propeller loading Pratt & Whitney Aircraft FT4A-2 and FT12A-3 is pro- caused either by changes in engine output or by vided by three independent methods. hydrodynamic changes external to the machinery With power control, the speed governor is re- proper such as changes in propeller submergence tained as a power turbine overspeed limiter, nor due to heave, roll, pitch, or interaction of rud mally set at rated turbine speed, similar to the der and ship maneuvering. steam turbine overspeed limiter. It acts as a An order for a shaft speed during maneuver speed topping governor, limiting the speed of the ing can be expected to represent more widely dif power turbine by controlling gas generator fuel ferent power levels than indicated on the ships
·\ flow. An electrical overspeed trip mechanism, set hull curve for steady state. For example, an order at 115 percent rated rpm, controls a solenoid for 2/3 ahead in shaft revolutions with sternway operated, quick closing, fuel shutoff valve. In on, often produces propeller cavitation. The re addition, there is another solenoid valve which is sultant power versus speed relationship is far dif controlled by a mechanically actuated overspeed ferent than that indicated for 2/3 ahead on the a trip, which is also set at 115 percent rated rpm. forementioned curve of ship resistance. Similarly, Normally, upon an overspeed condition, both trips the bollard condition, the shaft drag mode, shal and their shutoff valves will be actuated. How low water operations, or the towing situation all ever, ei~her trip mechanism will close its valve produce power versus speed relationships which are even if the other fails. The probability of a not usually predictable by the operator. An order power turbine overspeed trip occurring is extreme for a change in either speed or power can be ly low because the speed limiting governor has a thought of as a command for a certain vectoral very rapid response and will cut fuel flow when force to be exerted by the propulsion system to power turbine speed exceeds its rated speed. Trip move the ship in a predictable manner. out normally will occur in less than one-tenth of The worth of the power plant's response is one second when 100 percent load i's dropped. greatest when the predictability of the force value is reliable and repeatable within quite a low tol GENERAL SHIPBOARD CONSIDERATIONS erance band. Since this vectoral force, propeller thrust, is more closely related to the power ap The most fundamental functions of ship con plied by the propeller than its speed alone during trol as they relate to engine governing include transients, the following argument is offered. the following: 1 Setting of engine output during maneuvers POWER GOVERNING VERSUS SPEED GOVERNING (response to Engine Orders) • 2 Protection against damage from excessive Thrust Control for Maneuvering powers or speeds (torque and overspeed protection). Power governing should perform the engine's 3 Governing under normal transients (rudder role in maneuvering the vessel more consistently action, turning, and seaway operation). than speed governing. To illustrate this the fol 4 Governing under gross transients (heavy lowing example is presented. seas, drop load, and high speed turns). Thrust (T) is a function of power applied 5 Precise maintenance of steady state when (F), propulsive efficiency (E) and ship velocity set (station keeping, formation steaming, and (r) (propulsive efficiency can be neglected for fueling at sea). the example presented). The basic selection of any engine control in T = 326 P E volves the evaluation of whether power or speed v
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portion. Like the steam turbine, the gas turbine or operates most efficiently at high constant speed. T = f {P, E, v) Acceleration and deceleration naturally increase fuel consumption through losses in efficiency in Control of thrust by power governing then can be the areas of the gas generator compressors and reduced to: burners. Thus it is desirable to run the gas gen T = f (P) erator at a steady output rate and allow power turbine speed to 11 find its own way. 11 That is, (When one considers that the ship inertia will the power turbine should be allowed to change maintain nearly constant ship speed during load ,-._.. speed with changes in propeller torque, while
changes.) Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1968/79870/V001T01A054/2389859/v001t01a054-68-gt-54.pdf by guest on 30 September 2021 maintaining a constant power turbine inlet gas Power is a function of torque (Q) and shaft ' flow and temperature similar to the power setting speed (N) method of the steam turbine previously described.
Effect of Governor Cycling and Drop Load or Experience has shown that a speed sensing governor will cause the gas generator output to P = f (Q, N) cycle unnecessarily in a seaway as it attempts to Control of thrust by speed governing can similarly correct for changes in propeller revolutions. be reduced to: Should the engine's and the governor's natural response times be phased with the ship's natural T = f (N, Q) pitching period, the speed excursions could be What is significant here is that to perform even amplified by a speed governor. Additionally, the most basic order, to accurately synchronize governor "dither" usually accompanies speed govern the thrust on each of two shafts, two parameters ing and is detrimental. De-tuning the sensitivity must be measured when speed control is used, as of the speed governor has been suggested as a ~1"" compared to one parameter, power, when power con means of minimizing these phenomena. It is highly I trol is used. unlikely that a ship would operate at high powers ''!:'-; "'( On a steam vessel, horsepower measurement is when broaching could occur requiring quick gover derived from torque measurement and is normally nor response; however, a 100 percent drop load performed only on trials, with the costly equip could occur if a clutch disengaged at power. The ment removed shortly afterwards. On a gas turbine speed topping effect will effectively prevent an vessel, however, horsepower can be read on an in overspeed, thus the requirement to trip on over strument no more costly nor complex than a cali speed above 115 percent rated rpm can be obviated brated Bourdon tube pressure gage which will be by a rapidly responding speed topping governor. discussed later. In addition to the earlier exam- The author can think of no more stringent test for ple, speed control is much more sensitive to diZ- any topping governor than a full drop load with a ferences in actual pitch setting where controllable relatively low inertia gas turbine engine. Top- pitch propellers are used. ping governors are capable of holding speed below It is unfortunate that the method of order- the trip out setting when 100 percent load is
ing an engine response is generally in terms of dropped in an increment of time as low as 0.5 to -.4\ ) speed rather than thrust. What the author would 1. 0 sec. "De-tuning" speed governors in heavy • like to suggest here is that power terminology seas would render them useless for heavy seaway should be used to more closely represent the de- operations, sacrificing safety for expediency. ,. - ~- ., sired end result. In addition to the maneuvering situation, the Effects of Turning and Load Sharing effects of the ship upon the engine require less When the rudder is moved in a ship employing of the governor when power control is used for gas speed control, an effect is immediately sensed by turbines than when speed control is used for regu the speed governor as the power turbine speed lating the engine during most normal transients. drops due to the increase in the load on the pro Gross transients, on the other hand, present a peller. The speed governor immediately acts to different picture which will be discussed shortly. increase power turbine speed and causes the gas generator to accelerate and develop more power, Effect on Specific Fuel Consumption restoring power turbine set speed. Not only is The jet or gas generator portion of the gas this unnecessary increase in power over set steady """'~ turbine engine is more directly responsible for state power to be considered a fuel penalty, but .J, •. /, specific fuel consumption than the power turbine also an effective increase in thrust and torque, "'-4.J,
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TIME IN SECONDS Fig.l Effect of rudder movement on shp IO 15 shp versus time TIME IN SECONDS Fig.2 Changes in speed settings Effect on shp with time generally not ordered or anticipated. Torque limiting is often required to prevent the outboard (i.e., relative to the turn) shafting from becom in a speed control system. The ensuing changes in ing damaged, Furthermore, it is not a readily pre speed would be slight by comparison and would not dictable change in thrust even after an operator alter thrust output significantly. with the "con" understands that the phenomena may occur. A military turn in formation or a turn in Effect on Split Plant Operation a narrow passage is further complicated by trying Power control also permits the military ves to judge just what change in thrust will result. sel to operate in a split plant mode with a cruise The rudder angle, depth of channel, draft, trim, engine at full power (lowest specific fuel con and vessel speed, as well as the usual effects of sumption) on one shaft, and one boost gas turbine current and wind, must be considered. A power con at a higher power on the other (as opposed to run trolled ship under these same situations would see ning two boost engines at equal power). This a smaller increase in torque as rpm decreases, but ability increases the vessells range considerably not enough to require torque limiting nor an appre and gives the ship speeds beyond the reach of the ·>-- '"'· ciable change in thrust. cruise plant alone. The desired "thrusts" (powers) Another important factor is that of the com- can be set regardless of hydrodynamic effects men plex hydrodynamic load sharing situation of a twin- tioned earlier that would preclude speed control screw vessel when operating on speed control. An from being useful in this mode. analogy of this condition is that of two constant It was determined on one gas turbine powered speed electric generators operating in parallel. vessel that it was practical to run a cruise en The transfer of propulsive power from one shaft to gine at full power on one shaft and run a larger the other occurs during ship turns, rudder move bqost gas turbine on the other at 150 percent the ment, and ship motions without being ordered, just power of the former without carrying corrective as load is transferred from one electric generator rudder. Interestingly enough, the factor that to the other with no perceptible change in speed precluded running at higher power differentials occurring, when their governor droops are too was not the detriment of drag due to carrying cor similar or flat. In the case of one gas turbine rective rudder but was the potential of overspeed powered vessel, 50 percent variations in power ing the cruise engines. were observed with propeller speed set equally, as near as conventional marine readout instrumen- Effect of Overshoot tation would allow. The most straightforward way to change gas .· l·c\ ., An example of the load sharing effect caused turbine engine output level with "speed control" by vessel turning from one gas turbine powered ship is to move the speed set lever to a semicalibrated is presented in Fig.l. position and make vernier adjustments as necessary . .... ;,.,.. Power control on the other hand would allow When the lever is moved too quickly or through a the operator to set and maintain constant power on large percentage of total travel, the speed gover ·'··:+:. each shaft with far less excursions in power than nor sees a large speed differential and causes the 5 I : CONTROL GAGES ·- 1 .,, ~ / F ' 'v l-
gas generator to accelerate or decelerate rapidly, overshooting the desired power setting until the ator outlet pressure and brake horsepower at a power turbine has responded. The gas generator given ambient temperature gives rise to using this then returns to the desired steady-state values. relationship for a readout of engine power deliv- With a noncalibrated system, speed control requires ered when maneuvering. In this way the hazards of more "hunting around" to adjust power turbine or lever calibration are eliminated because with such shaft revolutions to the desired rate. a gage, the importance of. where the lever is for a The following was observed and is typical of given response is minimal. one speed governed gas turbine powered vessel con- The gage could look quite similar to the cerning overshoot. conventional engine order telegraph for either The power governing method should produce commercial or military vessels as depicted, Fig.4. the profiles as superimposed on the curves, Fig.2, Gas generator outlet pressure responds imme- during maneuvering. System torque during acceler diately to changes in power lever setting and is ations would be considerably lower without speed independent of power turbine response so that the governing. lever can be set instantaneously (less than 2 sec lag) for normal changes in power settiDgs. The REPEATABILITY OF ENGINE RESPONSE operator could leave the console after making the It does not appear to be economically feasi setting and be certain that power would not change. ble to attempt to calibrate operating lever posi Furthermore, there would be no need for him to re tions, particularly on multiengine installations. main at the console to read the slower responding This is due to the costs involved in minimizing shaft tachometer to close the feedback loop. the stackup of tolerances, f'!qualizing hysteresis If it were desired for record purposes or effects, reproducing the precise governor droop, determining fault after a collision, for example, or matching actuator trim and linkage friction a simple data logger could record basic lever forces throughout their entire operating range. movement and the gas generator pressure transducer This applies to both power and speed governing. output signal. These data would provide a legal The following is representative of an attempt to record and ·Show discrepancies in engine order ver synchronize shaft speed outputs while operating sus engine response should some part of the pro from a remote location. Constant horsepower for pulsion machinery cause the plant to fail to re periods greater than 5 min indicates an attempt to spond to an ordered signal. synchronize both shaft speed outputs. The addi tion of more accurate feedback either automatic POWER DETERMINATION USING GAS GENERATOR ally or manually, such as a large dial tachometer OUTLET PRESSURE or gas generator output gage, would close the loop Engine pressure ratio (ratio of gas gener- - , somewhat, but some "lever hunting" would still ator exhaust pressure to inlet pressure) is the exist, Fig.3. most commonly used parameter for measuring power output on turbo-Jet engines. This same argument SHIP SPEED READOUT/GAS GENERATOR OUTPUT can be used for use of gas generator outlet pres GAGE FOR BRIDGE READOUT sure. The equation relating power to engine pres- •.., The unique relationship between gas gener- sure ratio
6 where wg = gas generator mass flow = gas generator outlet temp Ttout Pt in gas generator inlet pressure gas generator outlet pressure Pt out Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1968/79870/V001T01A054/2389859/v001t01a054-68-gt-54.pdf by guest on 30 September 2021 If ratio of specific heat cp /c v YJ. is the isentropic efficiency and is a function of the enthalpy drop across the power turbine and its rotational speed. There also exists a unique relationship be tween Pt t/Pt. and the power turbine inlet flow OU in parameter W~/Pg out tout such that the bhp equation can be rewritten as
w~ bhp _ g out ~ c p 1 Pt out~ - ti] 'I\ p tout p tout [ - ptin y tout t Then for a particular Pt /Pt· 4-in. H 0 inlet duct pressure loss out in 2 6-in. H20 exhaust duct pressure loss bhp = K~ "11. Pbarometer = 29.92 in. Hg out Prop load curve through 25,500 bhp at 3600 N N.L. 3 where the constant K Fig,5 Pratt & Whitney Aircraft FT4A-2 gas turbine engine .. Estimated variation of brake horsepower w~ g out C and gas generator exhaust pressure p p Ptout tout Because the variation in Pt. is a function of the barometric pressure only, tfi~ relationship holds T amb deg R for Pt alone. out For a known load characteristic, the rela- 4.59· 7 deg R tionship between Pt t/Pt. and 1't is unique. Con- ou in Fig.5 reflects the relationship between bhp sidering propeller load curves (bhp-power turbine and gas generator outlet pressure (Pt ) at vari speed), large variations in power'turbine speed ous gas generator inlet temperatures ?¥~. (± 10 percent) result in small variations in bhp in ). ( <2 percent) for a specific Pt • out Additionally, the variations in Ttout (at CONCLUSIONS Ptout = C) are negligible for the normal range of In light of the preceding data and general inlet temperatures experienced. The result is that there exists a reasonably discussion, it would appear that typical ships unique relationship between bhp and Pt which have control requirements for maneuvering and for . . . . out justifies its use as a power determining parameter. normal engine loading variations that are best handled on gas turbine propulsion plants by a con stant power setting type of control. The over bhJ2 f speed protection provided by a speed topping gover J(J s (>ut) nor is just as necessary and also should be incor amb amb amb porated on gas turbine powered ships for protection where against machinery speeds in excess of those for p s = amb in. Hg abs which the machinery was designed. In addition, amb 29.92 in. Hg abs engine orders can be met with greater precision
7 and repeatability by means of a noncalibrated Shipping, 1966. power setting lever, used in conjunction with a Peschon, Disciplines and Techniques of Sys gage which reflects gas generator outlet pressure tems Control, Blaisdell, 1965. calibrated in terms of vessel speed similar to the Baker, Introduction to Steel Shipbuilding, conventional engine order telegraph. McGraw-Hill, 1953, Marks, Mechanical Engineer's Handbook, Mc ACKNOWLEDGMENTS Graw-Hill, 1941. Kosow, Servomechanism Fundamentals and Ex The author wishes to acknowledge the assist periments, Prentice-Hall, 1964. Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1968/79870/V001T01A054/2389859/v001t01a054-68-gt-54.pdf by guest on 30 September 2021 ance in the preparation of this paper given by E. Second Annual NASA University Conference on P. Worthen, Marine Consultant, United Aircraft Manual Control Corporation; Captain H. O. Travis Engineering Seward, "Marine Engineering," Society of Dept., United States Merchant Marine Academy; P. Naval Architects & Marine Engineers, 1960. J. Kiene, Senior Performance Engineer, Pratt and D. W. Taylor, "The Speed and Power of Ships," Whitney Aircraft; G. A. Singer and the other mem U.S. Government Printing Office, 1943. bers of the Turbo-Power and Marine Dept. of Pratt G. H. Nolte, "PWA Marine Gas Turbine: Their and Whitney Aircraft, Division of United Aircraft Development and Capabilities, 11 Paper No. ASME 66- Corporation. GT/M- 35, 1966. G. H. Nolte, "Sea Experience with PWA FT12 BIBLIOGRAPHY Gas Turbine in LCM-8," Paper No. ASME 65-GTP-26, 1965. Braynard, Famous American Ships, Hasting W. A. Brockett, "U.S. Navy's Marine Gas Tur House, 1956. bines, 11 Paper No. ASME 66-GT/M-28, 1966. Villiers, "Men, Ships and the Sea, 11 National C. L. Carlson, "FT4A Gas Turbine Engine for Geographic Society, 1962. Marine and Industrial Applications, 11 ASME 64-GTP-8, Osbourne, Modern Marine Engineer's Manual, 1964. Cornell Maritime Press, 1941 and 1943. D. B. Carpenter, 11 The Light Weight Gas Tur R, R. Donnelley & Sons, "Rules for Building bine and Merchant Vessels, 11 ASME - 1966 National and Classing Steel Vessels," American Bureau of Transportation Symposium, 1966.
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