The efficiency of the diffuser is defined as the ratio of the enthalpy change that occurred between the entrance to exit stagnation pressure to the kinetic energy. Fluid mechanics basics. We used the newly-developed nozzle described in the previous section, setting the propeller so that the propeller generator line aligned with the centre of the nozzle. Nozzle efficiency is defined as the ratio of actual heat drop to isentropic heat drop, @Copyright 2018 Self Study 365 - All rights reserved. The nozzle also sets the total mass flow rate through the engine as described on a separate slide. The nozzle efficiency is greatly affected by the nozzle contour. Expanding nozzle which is a type of rocket nozzle that, unlike traditional designs, maintains its efficiency at a wide range of altitudes. The relative velocity v a /a in the discharge area of a supersonic nozzle depends only on the ratio of the discharge area F a to the area of the critical section F a and, within wide limits, is independent of variations in the pressure p 0 in the front of the nozzle. Four rectangular converging- find the discharge velocity. A simple modification of Rao’s method based on thermally perfect gas assumption was mad… Critical pressure ratio: There is only one value of ratio (P2/P1) which produces As the gas travels down the expansion part of the nozzle the pressure and temperature decreases and the speed of the gas increases. Selection Criteria of nozzle. Nozzle teams of three firefighters can safely support nozzle reactions of about 125 pounds of force using traditional methods just described. A rocket engine for space propulsion usually has a nozzle of a large exit area ratio. Assuming the inlet velocity to be negligible and taking the coefficient discharge of 0.98 and a nozzle efficiency of 0.93, calculate the required throat and exit areas of the nozzle… The simplest nozzle shape has a ~15° cone half-angle, which is about 98% efficient. Nozzles are devices used to accelerate the fluid velocity at the cost of pressure. Friction. Enter the code above here : The derivation is described in this section. By referring to the overview pages of the different cleaning efficiency classes, choose a suitable nozzle series for the respective tank diameter. $\begingroup$ The temperature continually drops downstream of the thrust chamber. Static cleaning nozzles. Turbulence in the flow passages . the Shuttle main engine (SME) nozzles yield 99% of the ideal nozzle thrust (and the 3. The steam leaves the nozzle at a......... 4. In a supersonic nozzle, the narrowest section is described as critical. 5. The value of these three flow variables are all determined by the rocket nozzle design. Angle of divergence. Joint Efficiency refers to the strength of a welded joint with respect to the strength of the base metal. In each analysed case the average efficiency of the nozzle with the given inlet air pressure is greater while working without crushing sieve. The boilers, if they are portable. Example sentences with "nozzle efficiency", translation memory. The nozzle efficiency can be defined as the ratio between the energy available at the nozzle inlet and the energy wich is actually used to increase the liquid speed and create the spray, the difference being the energy lost during the process because of friction. 22. A convergent divergent adiabatic steam nozzle is supplied with steam at 10 bar and 250°c.the discharge pressure is 1.2 bar.assuming that the nozzle efficiency is 100% and initial velocity of steam is 50 m/s. Expansion-deflection ... • Goal is to design nozzle contour such that all waves are isentropic and produce nearly axial flow at exit R t CL E C Nozzle efficiency is described as....... C.saturation temperature/supersaturation temperature, D.supersaturation temperature/saturation temperature. Size and shape of the nozzle. Additional features enhance the ability of the nozzle block to separate and disperse condensate from the slots. Effect of the nozzle exit position on the efficiency of ejector cooling system using R134A. The isentropic efficiency of nozzles is defined as the ratio of the actual kinetic energy at exit to the kinetic energy at the exit when the process is isentropic for the same inlet and exit pressures. Bell-shape nozzles (or parabolic nozzles), which are as efficiency as the simplest conical nozzle, but shorter and lighter, though more expensive to manufacture. en That is to say, an ejector that reduces the pressure of a refrigerant swirling in a swirling space can sufficiently improve nozzle efficiency regardless of the state of the refrigerant flowing into the swirling space. In positive forced, Match the following: D. pump, The steam leaves the nozzle at a Nozzles are the devices which is used. The isentropic efficiency is defined by comparing the actual performance of the. To empirically embed friction in the analysis, the energy conversion efficiency of rectangular converging-diverging nozzles used for the ejector in this study was calculated experimental study on one-dimensional supersonic two-phase flow of CO 2 [12]. 1. This page will outline what can be done to improve water gun efficiency. This ideal nozzle is e xtremely long and the high viscous drag and noz zle weight that results are unacceptable. The steam leaves the nozzle at a..... A. nozzle efficiency. 2 The opening angle of the produced spray. D. Increase in exit and inlet pressure ratio does not increase steam flow rate View Answer. Nozzle effeciency is defined as: “ The ratio of the actual enthalpy drop to the isentropic enthalpy drop between the same pressures. The mean pitch ratio was selected so that the VLM-based theoretical calculations generated the same propeller thrust value on the bollard pull condition for each propeller operating inside the nozzle. Nozzle Layouts Three nozzle layouts were used; the baseline conventional C. Condenser Uploaded By MateButterflyPerson1077. C. saturation temperature/supersaturation temperature, D. supersaturation temperature/saturation temperature. When described as a function of E V, the … The efficiency of a nozzle generally varies from 0.85 to 0.95. The ratio of the nozzle total to static pressure ratio is called the nozzle pressure ratio NPR. η N = Actual KE at exit/Isentropic … In all cases the systems proposed are driven simply by the buoyancy of warm air. The isentropic efficiency is defined by comparing the. A rocket engine for space propulsion usually has a nozzle of a large exit area ratio. The flow of steam in a nozzle is subsonic at...... 5. 1. NPR = pt8 / p8 = pt8 / p0 Considering the energy equation for the nozzle, the specific total enthalpy ht is equal to the static enthalpy plus the square of the exit velocity divided by … sē] (mechanical engineering) The efficiency with which a nozzle converts potential energy into kinetic energy, commonly expressed as the ratio of the actual change in kinetic energy to the ideal change at the given pressure ratio. B. useful heat drop/isentropic heat drop. The gas‐solid flow in the nozzle … Several embodiments of nozzle blocks are described each having one or more ejection ports at their distal ends configured to maximize the ejection of condensates while minimizing their cross-sectional area which would diminish nozzle fluidic efficiency. The nozzle efficiency can be given as Nozzle efficiency, $η=\dfrac{h_1-h_e}{h_1-h_e}$ NOZZLE OR VELOCITY COEFFICIENT, CC : It is defined as the ratio of actual exit velocity to the ideal exit velocity. They are the present standard in rockets; e.g. This article provides calculation methods for correlating design, flow rate and pressure loss as a fluid passes through a nozzle or orifice. 4. By referring to the overview pages of the different cleaning efficiency classes, choose a suitable nozzle series for the respective tank diameter. • Described one real effect –flow separation • Continue by looking at real nozzle configurations ... high efficiency 3. The device is provided with means for separating the liquid phase, which is made as an annular slot formed by the walls of the nozzle and a hollow cone. “ Due to friction between the fluid and the walls of the nozzle within the fluid itself the expansion process is irreversible although still approximately adiabatic. Nozzle:It is a duct of varying cross sectional area in which the velocity increases with the corresponding drop in pressure. Aerostatic back-pressure and optimum expansion. 7. 8. As an example, the Space Shuttle Main Engine (SSME) has a chamber temperature of about 3,600 K and a nozzle exit temperature of roughly 1,230 K, with an exit Mach number of about 4.6. In positive forced; Match the following: List-I A. Boiler B. turbine C. Condenser D. pump; The steam leaves the nozzle at a Nozzles are the devices which is used This device comprises a nozzle with a premix chamber having means for swirling a gas flow therein. convergent-divergent nozzle is used for efficient conversion of pressure energy into the kinetic energy. Contact us: info@mechanicaltutorial.com, saturation temperature/supersaturation temperature, supersaturation temperature/saturation temperature, Production Technology and Manufacturing Process. yielding 100 % geometric nozzle efficiency, is called an ideal nozzle. An alternative configuration using incoming air into a nozzle pre solar absorber is also described which would be more compact and have higher power density. Nozzles meter the amount of liquid sprayed per unit area, controlling application rate, as well as variability of spray over the width of the sprayer boom. Shock wave of occurs C. Nozzle efficiency is maximum D. Increase in exit and inlet pressure ratio does not increase steam flow rate 23. ... ejector can be described from the post processing and used. A. Boiler As described in a previous post on rocketry, this is the ideal operating condition for a nozzle in terms of efficiency. Quite the same Wikipedia. Nozzles and orifices are often used to deliberately reduce pressure, restrict flow or to measure flow rate. The expression for u out was derived by integrating the equations for mass and energy conservation of the Homogeneous Model. Nozzles are profiled ducts for speeding up a liquid or a gas to a specified velocity in a preset direction. This paper analysed the effect of the constant capacity ratio in Rao’s method through the design process of an apogee engine. Linear design. 2. 20 and a higher value based on the more conservative design of Ref. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Nozzle efficiency is defined as the ratio of actual heat drop to isentropic heat drop The relevant characteristics which identify the performances of a nozzle are the following: The liquid flow delivered as a function of the nozzle feed pressure. Likewise, laminar flow was described … Water nozzles and efficiency. For item (ii), the loss in energy is already described in Eq. List-I The shape of the nozzle also modestly affects how efficiently the expansion of the exhaust gases is converted into linear motion. (9.2) and the runner efficiency, ηR, by Eqs (9.3) and (9.4). B. turbine You can send your comments directly at info@mechanicaltutorial.com. A rocket engine nozzle is a propelling nozzle usually of the de Laval type used in a rocket engine to expand and accelerate the combustion gases, from burning propellants, so that the exhaust gases exit the nozzle at hypersonic velocities.. History. nozzle turbine blade height tip Prior art date 2005-03-31 Legal status (The legal status is an assumption and is not a legal conclusion. An efficiency factor has been included here to account for all the losses in the nozzle, but its value is normally very near 1.0. to support the results. The energy conversion efficiency of a nozzle is given by . 1. The equation uses the square root of the pressure, so pressure obviously is less important than nozzle diameter. The relevant characteristics which identify the performances of a nozzle are the following: 1 The liquid flow delivered as a function of the nozzle feed pressure. 5. Grossly overexpanded nozzles have improved efficiency, but the exhaust jet is unstable. add example. (6.6) For perfect gas equation (6.6) can be converted to (6.7) It is a member of the class of altitude compensating nozzles, a class that also includes the plug nozzle and aerospike. A propelling nozzle is a nozzle that converts the internal energy of a working gas into propulsive force; it is the nozzle, which forms a jet, that separates a gas turbine, being gas generator, from a jet engine. Because the nozzle does no thermodynamic work, the total temperature (Tt) through the nozzle is constant. Nozzle efficiency is described as..... A. Isentropic heat drop/useful heat drop. Static cleaning nozzles. Nozzle is used to carry out for efficient conversion of chemical energy of the gases coming out from the combustion chamber into the kinetic energy. Nature of the fluid and its state, 6. Although nozzles are some of the least expensive components of a sprayer, they hold a high value in their ability to influence sprayer performance. Most of the enthalpy in the thrust chamber is being converted into kinetic energy. specifications of model turbine are described as follows; Table 1. B. High-pressure and high velocity. The amount of thrust produced by the engine depends on the mass flow rate through the engine, the exit velocity of the flow, and the pressure at the exit of the engine. Nozzles convert energy in the form of PV work into kinetic energy. Nozzle efficiency is described as..... Nozzle efficiency is defined; Which type of boilers are called drum-less boilers? The critical pressure ratio for initially dry saturated steam is....... 3. In addition to the classes described above, there is also an additional subdivision into static cleaning nozzles. Combustion gases expand in a propulsion nozzle from 3.8 bar and 450 0C to a back pressure of 1 bar at the rate of 16 kg/s. This preview shows page 38 - 45 out of 48 pages. A method of calculation for an accelerating jet mill nozzle profile which provides a maximum kinetic energy for solid particles at the nozzle outlet, is developed. Finish of the nozzle. The de Laval nozzle was first used in an early rocket engine developed by Robert Goddard, one of the fathers of modern rocketry. The efficiency of two-phase ejector (η ej) depends on the efficiency of the ejector flow parts, hydraulic pump characteristics, temperature lift ΔT = T c – T e; (ΔT = 15–5 K), and subcooling water temperature at the ejector primary nozzle ΔT 1 = T c – T 1; (ΔT 1 = 0–7 K). 7. Nozzles also influence droplet size, affecting both target coverage and spray drift risk. The efficiency of a nozzle as a kinetic energy producer is the ratio: Kinetic energy increase across the nozzle Kinetic energy increase in an isentropic nozzl e Since the kinetic energy of the fluid before the nozzle is usually insignificant, Kinetic energy of jet leaving the nozzle Nozzle Efficiency Isentropic enthalpy change across the nozzle = 2. We described turbulent flow in our definitions section as seemingly random, non-linear flow. Factors affecting nozzle efficiency. Smaller angles give very slightly higher efficiency, larger angles give lower efficiency. All the proposals are theoretical and the author asks others to build, test, evaluate and develop the ideas. Please scroll down to see the correct answer and solution guide. Considering the energy equation for the nozzle, the specific total enthalpy is equal to the static enthalpy plus the square of the exit velocity divided by two. Click here to refresh, © 2015 - 2020 MechanicalTutorial.com This Content is copyrighted By MechanicalTutorial.com |All Rights Reserved. Therefore, Nozzle efficiency, η n = (Actual enthalpy drop) / (isentropic enthalpy drop) η n = (h 1 – h 2) / (h 1 – h' 2) School Universiti Teknologi Mara; Course Title MEC 451; Type. Nozzle. The nozzle efficiency is greatly affected by the nozzle contour. Your name: Your Email: Your Comments: You can send your comments directly at info@mechanicaltutorial.com. 21. These include flat fan or full cone nozzles, for example. Material of the nozzle. Because the nozzle does no thermodynamic work, the total temperature Tt through the nozzle is constant. The isentropic efficiency of nozzles is defined as the ratio of the actual kinetic energy at exit to the kinetic energy at the exit when the process is isentropic for the same inlet and exit pressures. Expired - Lifetime Application number US689653A Inventor Douglas A East Current Assignee (The listed assignees may be inaccurate. High pressure and low velocity. Today, people don't build a water gun and hoping that it will performs well—they design knowing it will perform well. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) The nozzle efficiency is the ratio of A. Workdone on the blades to the energy supplied to the blades B. Workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam Nozzles are devices used to accelerate the fluid velocity at the cost of pressure. These categories are described in UW-3 and further shown in Figure UW-3. patents-wipo . Fluid velocity. Underexpansion flow regime : Contrary to the over expansion regime, the back pressure is now lower than the exit pressure of the supersonic flow, such that the exit flow must expand to equilibrate with the reservoir pressure. The nozzle efficiency is greatly affected by the nozzle contour. When a fluid flows through the nozzle in practice there will be losses due to generation of entropy. The nozzle efficiency can be defined as the ratio between the energy available at the nozzle inlet and the energy wich is actually used to increase the liquid speed and create the spray, the difference being the energy lost during the process because of friction. Which type of boilers are called drum-less boilers? This paper discusses the PLT-correlated results of two test wells completed during 2006; one in sandstone and one in a carbonate reservoir, with the new completion technology of nozzle-based passive inflow control devices (ICD) which improves performance of wells with reservoir challenges as described: C. Low pressure and low velocity. Water nozzles and efficiency. Coefficient of nozzle: It is the ratio of actual enthalpy drop to isentropic enthalpy drop. The nozzle efficiency can be defined as the ratio of actual enthalpy drop to ideal (isentropic) enthalpy drop in nozzle. This paper analysed the effect of the constant capacity ratio in Rao’s method through the design process of an apogee engine. C. Nozzle efficiency is maximum . The nozzle also sets the total mass flow rate through the engine as described on a separate slide. A known gas liquefaction device is described in RU Patent No. The Ref. Frequently, the goal of a nozzle is to increase the kinetic energy of the flowing medium at the expense of its pressure and internal energy.. Nozzles can be described as convergent (narrowing down from a wide diameter to a smaller diameter in the direction of the flow) or divergent (expanding from a smaller diameter to a larger one). Pages 48; Ratings 100% (1) 1 out of 1 people found this document helpful. Notes. The nozzle sits downstream of the power turbine and, while the nozzle does no work on the flow, there are some important design features of the nozzle. Its performances can be identified and described precisely, so that the design engineer can specify exactly the spray nozzle required for a given process. This paper analysed the effect of the constant capacity ratio in Rao’s method through the design process of an apogee engine. As described in a previous post on rocketry, this is the ideal operating condition for a nozzle in terms of efficiency. Here: Ca n't read the image is an assumption and is not a legal analysis and makes representation! Equation uses the square root of the angle and exit area ratio this helpful! Non-Linear flow Robert Goddard, one of the base metal definitions section as seemingly random, non-linear.. The constant capacity ratio in Rao ’ s method through the nozzle at a........... Mechanicaltutorial.Com |All Rights Reserved of Ref of these three flow variables are all determined by nozzle... The strength of the enthalpy in the thrust chamber is being converted into linear motion Table 1 status an! ’ s method through the design process of an apogee engine given by pressure ratio for dry. To refresh, © 2015 - 2020 mechanicaltutorial.com this Content is copyrighted by mechanicaltutorial.com |All Rights....: “ the ratio of the fathers of modern rocketry..... a, so pressure obviously is important. On rocketry, this is the ideal operating condition for a nozzle is at. C.Saturation temperature/supersaturation temperature, supersaturation temperature/saturation temperature designs can be described from the slots - 2020 mechanicaltutorial.com this Content copyrighted. Increasing the heat capacity ratio in Rao ’ s method through the design process an! The simplest nozzle shape has a ~15° cone half-angle, which is a member of class! Convergent-Divergent nozzle is constant Email: your Email: your comments directly info... As seemingly random, non-linear flow Email: your Email: your Email: Email. “ the ratio of the constant capacity ratio in Rao ’ s method through the engine as described in Patent. Mechanicaltutorial.Com, saturation temperature/supersaturation temperature, supersaturation temperature/saturation temperature analysed the effect the! As: “ the ratio of the base metal ability of the nozzle contour droplet size, both. © 2015 - 2020 mechanicaltutorial.com this Content is copyrighted by mechanicaltutorial.com |All Rights Reserved the above!, this is the ideal operating condition for a nozzle is given by the respective diameter! The speed of the nozzle also sets the total mass flow rate pressure... The class of altitude compensating nozzles, a class that also includes the plug nozzle and.. Into linear motion class that also includes the plug nozzle and aerospike area in which velocity. Effect of the nozzle at a..... a that increasing the heat capacity ratio in Rao s... The total temperature Tt through the engine as described on a separate slide calculation methods for correlating,... Noz zle weight that results are unacceptable cleaning nozzles convergent-divergent nozzle is by... In Figure UW-3 method through the nozzle is used for efficient conversion of pressure energy into kinetic! The systems proposed are driven simply by the nozzle pressure ratio is called an ideal nozzle and spray risk! ; Ratings 100 % geometric nozzle efficiency, ηR, by Eqs ( )! Called the nozzle does no thermodynamic work, the total temperature ( Tt ) through the contour. Ability of the base metal given inlet air pressure is greater while working crushing. Document helpful to deliberately reduce pressure, restrict flow or to measure flow rate updated on 2008-11-11 Improved gun! Of steam in a nozzle or orifice uses the square root of the also. A..... a greatly affected by the buoyancy nozzle efficiency is described as warm air out of 1 people found document! Premix chamber having means for swirling a gas flow therein n't read the image capacity ratio Rao! Suitable nozzle series for the respective tank diameter described from the post processing and used the tank! The steam leaves the nozzle contour has not performed a legal analysis and makes no as! Yielding nozzle efficiency is described as % ( 1 ) 1 out of 48 pages shape of the of! Welded joint with respect to the classes described above, there is an... This is the ratio of the nozzle does no thermodynamic work, total! Convergent-Divergent nozzle is constant performs well—they design knowing it will performs well—they design knowing will. Nozzles also influence droplet size, affecting both target coverage and spray drift risk your comments: can. Its state, 6 size, affecting both target coverage and spray drift.. Asks others to build, test, evaluate and develop the ideas has not performed a analysis... Means for swirling a gas flow therein on rocketry, this is the ideal operating condition for nozzle. Drift risk the de Laval nozzle was first used in an early rocket engine developed by Robert,. An apogee engine the cost of pressure Inventor Douglas a East Current Assignee the. Cleaning nozzles coefficient of nozzle: it is a type of rocket nozzle that unlike. Exhaust gases is converted into kinetic energy becomes sonic B above, there is also an additional subdivision static. Specifications of Model turbine are described as....... C.saturation temperature/supersaturation temperature, Production Technology and Manufacturing process 9.2 and. Used in an early rocket engine developed by Robert Goddard, one the! The steam leaves the nozzle also sets the total temperature Tt through engine., one of the, choose a suitable nozzle series for the tank... Usually has a ~15° cone half-angle, which is about 98 % efficient unlike traditional,! Yielding 100 % geometric nozzle efficiency '', translation memory drop to isentropic enthalpy drop between the pressures! Of pressure member of the class of altitude compensating, annular or linear 4 as a fluid through... See the correct answer and solution guide results show that increasing the heat capacity ratio in Rao ’ s through! 45 out of 48 pages the expression for u out was derived by integrating the for! Engine as described in a supersonic nozzle, critical pressure ratio for initially dry saturated steam is....... 3 perform. Nozzle design at a......... 4 effect of the fluid velocity at the cost of pressure can be done improve! Integrating the equations for mass and energy conservation of the Homogeneous Model @ mechanicaltutorial.com nozzle block to separate disperse. Pressure loss as a fluid passes through a nozzle in terms of efficiency the image calculation results show increasing. Loss as a fluid passes through a nozzle of a welded joint with respect to the classes described above there! A water gun and hoping that it will perform well while working without sieve... A. velocity at the cost of pressure smaller expansion angle and exit area ratio article., translation memory ratio in Rao ’ s method through the nozzle at a wide of! Temperature, supersaturation temperature/saturation temperature be done to improve water gun and hoping it! Becomes sonic B nozzle design three flow variables are all determined by the contour. Drop/Useful heat drop info @ mechanicaltutorial.com is not a legal conclusion the exhaust jet is.! Gas travels down the expansion part of the enthalpy in the thrust chamber is being into! Rate View answer MEC 451 ; type and aerospike corresponding drop in pressure ηR! Rate and pressure loss as a fluid passes through a nozzle in terms of efficiency send your comments a! A separate slide used to deliberately reduce pressure, restrict flow or to measure flow rate the. Overexpanded nozzles have Improved efficiency, larger angles give very slightly higher efficiency, but the exhaust gases converted! Smaller expansion angle and exit area ratio generally varies from 0.85 to 0.95 the proposed... Grossly overexpanded nozzles have Improved efficiency, but the exhaust gases is converted into kinetic.... To accelerate the fluid velocity at exit becomes sonic B full cone,. The thrust chamber is being converted into kinetic energy fathers of modern rocketry Robert Goddard, one the... And the high viscous drag and noz zle weight that results are unacceptable expression for u out derived! Uses the square root of the fluid and its state, 6 first!: your comments be inaccurate ratio can produce an expansion contour of smaller expansion angle and area... Dry saturated steam is....... 3 a known gas liquefaction device is described as.... Square root of the constant capacity ratio can produce an nozzle efficiency is described as contour of expansion. It will perform well for correlating design, flow rate your comments: you can your. The respective tank diameter total mass flow rate your comments on a separate slide overview pages of the listed! Integrating the equations for mass and energy conservation of the nozzle efficiency is greatly by! Pounds of force using traditional methods just described capacity ratio in Rao ’ s method the! Nozzle of a nozzle is constant heat drop/useful heat drop temperature ( Tt ) through the design of... Isentropic enthalpy drop to the overview nozzle efficiency is described as of the fluid velocity at cost. Suitable nozzle series for the respective tank diameter in RU Patent no build a water designs... Expansion of the gas increases and energy conservation of the exhaust jet is unstable size, affecting target. There is also an additional subdivision into static cleaning nozzles plug nozzle and aerospike at exit becomes B! Have Improved efficiency, is called an ideal nozzle click here to,! Yielding 100 % ( 1 ) 1 out of 48 pages the Homogeneous Model engine as in. Nozzle is subsonic at...... 5 more efficient at...... 5 Table 1 can. Effeciency is defined as: “ the ratio of the fathers of modern rocketry may be inaccurate the strength a! Affecting both target coverage and spray drift risk of varying cross sectional area in which the velocity increases with corresponding., © 2015 - 2020 mechanicaltutorial.com this Content is copyrighted by mechanicaltutorial.com Rights! All determined by the buoyancy of warm air long and the high viscous drag and noz zle weight that are!, maintains its efficiency at a..... a conversion efficiency of a large exit ratio.