OpenLLM-France/wikimedia huggingface dataset:
# Jet Propulsion/Nozzles

The exhaust gases (and the bypass air in turbofans) are expanded and accelerated through nozzles, accelerating the flow, by reducing the static pressure of the stream, and provides propulsive force. Convergent nozzles have a progressive reduction in flow area and are used to accelerate flows to subsonic velocities. Convergent-divergent nozzle enable supersonic exit velocities provided a sufficient pressure differential exists.
The common view is that nozzles provide most of the thrust in practice there is often significant thrust provided by the pressure differentials across other components of the engine such as intakes.
Thrust vectoring nozzles direct the exhaust laterally to provide lateral thrust. Thrust reversers redirect the exhaust forwards to provide braking.

## Gas Turbines

A gas turbine (GT) engine or jet engine is used not only in aircraft but also in various other contrivances power generation, ships and even battle tanks (the US M1A2 Abrams tank uses a 1000 hp gas turbine). In these cases, the nozzle design isn't of much importance because the engine is not used for providing any thrust. In fact, these GT engines are replacements to the usual piston engine because of the high power to weight ratio. Hence the shaft of the GT is coupled to the required contivace, say a generator or a propeller or a gearbox.The exhaust gases from a GT engine in these scenarios get the same treatment that the exhaust gases from the piston engine.
But when the same GT engine is used in an aircraft a nozzle is used because the hot exhaust gases coming out of the GT will have very high pressure which will in turn propel the aircraft forward in accordance to Newton's 3rd Law of motion which states that "EVERY ACTION HAS AN EQUAL AND OPPOSITE REACTION" .
    Action----> Hot gases at high pressure from nozzle.
    Reaction--> The aircraft being propelled forward.
Nozzles were, until recently, only used for proving thrust but now modified nozzles are being used for changing the course of the aircraft which was traditionally done only using aileron and tail fins.
# Jet Propulsion/Rotors

The moving parts of the jet engine. The turbomachinery blades are mounted on a number of Rotors.

## disks

The disks provide structural fixing and resist the radial and axial forces generated by the airfoils in the fans. compressors, turbines.

### Clearance control
## shafts

Shafts connect the functional parts and transfer forces from turbines to fans and compressors and to bearings.

### Materials, Manufacturing and Assembly
## bearings

The rotors are supported on bearings.

### Functional requirements

Loading, Overloading, service life, lubrication

### Bearing lubrication and cooling
## Seals

The pressure differentials between different rotating parts are maintained by seals.
# Jet Propulsion/Materials
### Jet propulsion

Jet Propulsion is a type of propulsion used in aircraft, spacecraft, and other vehicles that involves the expulsion of high-speed gases to generate thrust. Jet propulsion systems are critical to modern aerospace engineering and require the use of advanced materials to withstand high temperatures, stresses, and corrosive environments.
Materials used in jet propulsion systems must exhibit a range of properties, including high strength, low weight, good thermal conductivity, and durability. Common materials used in jet propulsion systems include high-temperature alloys such as titanium and nickel-based super-alloys, which exhibit excellent high-temperature performance and resistance to wear and corrosion.
Ceramic matrix composites (CMCs) are another type of material commonly used in jet propulsion systems. CMCs offer high-temperature performance, excellent wear resistance, and low thermal expansion, making them ideal for use in hot sections of jet engines.
In addition to materials selection, manufacturing processes are also crucial in the development of jet propulsion components. Advanced manufacturing techniques such as 3D printing and additive manufacturing have become increasingly important in the production of jet propulsion components, allowing for the creation of complex geometries and reducing production time and cost.
The use of advanced materials and manufacturing techniques has enabled significant advancements in jet propulsion technology. For example, the development of high-thrust, high-efficiency turbofan engines has revolutionized air travel, allowing for longer flights with reduced fuel consumption and emissions.
As technology continues to evolve, new materials and manufacturing techniques will undoubtedly play a critical role in the ongoing development of jet propulsion systems. The use of advanced materials and manufacturing techniques will enable the creation of even more efficient and reliable jet propulsion systems, further advancing the field of aerospace engineering.
Some examples of sources that discuss the use of advanced materials in jet propulsion systems include:
* Materials for High-Temperature Aerospace Propulsion Systems, by R. A. Miller and E. W. Lee
* High-Temperature Materials and Processes in Jet Propulsion, by C. T. Liu
* Ceramic Matrix Composites in Aerospace Propulsion, by P. Portella and C. H. Kuo
Additional sources on jet propulsion and materials science can be found in academic journals such as The Journal of Propulsion and Power, The Journal of Aerospace Engineering, and The Journal of Materials Science.
# Jet Propulsion/Propulsive efficiency

The propulsive efficiency is defined as:
$\eta _{p}={\frac {PropulsiveWorkDeliveredToVehicle}{MechanicalWorkGeneratedByEngine}}$
The mechanical work generated by the engine is crudely split between the work difference between the input and exit mass flows from the engine as well as to the work imparted to the vehicle. For a jet engine in the air frame of reference the input mass flow has zero kinetic energy. Thus for a jet engine with a constant relative exit velocity (a close approximation of a turbojet) the propulsive efficiency increases with aircraft velocity.
Mathematically the propulsive efficiency :
$\eta _{p}={\frac {2u_{0}}{u_{e}+u_{0}}}$
where
$u_{0}=$ velocity of the vehicle
$u_{e}=$ velocity of the exhaust
Thus reducing the exhaust velocity will give a higher propulsive efficiency. The thrust of the engine is given by
$F={\dot {m}}(u_{e}-u_{0})$
where ${\dot {m}}$ is the mass flow through the engine. Thus to for a given thrust the exhaust velocity can be decreased if the mass flow is increased. This is usually done by adding a fan or a propeller to the turbojet, resulting in a turbofan or turboprop engine. The reduction in exhaust velocity also reduces the exhaust noise, but has the disadvantage that the thrust reduces more markedly with speed than for a turbojet.
# Jet Propulsion/Ramjet

A ramjet uses the open Brayton cycle. In the above diagram a 2D supersonic intake is shown downstream of which is a divergent subsonic diffuser.
Ramjets are inefficient at subsonic speeds and their efficiency improves at supersonic speeds.
At hypersonic speeds the compression and dissociation processes make full diffusion unattractive and supersonic combustion is being researched. Scramjet slow the air down to low supersonic speeds and then burn high flame velocity fuels such as hydrogen or methane to try to get net thrust.
# Jet Propulsion/Mach number

Mach number (Ma) is defined as a ratio of velocity to the velocity of sound in the Free stream.
# Jet Propulsion/Propellants

Jet fuel which is a type of kerosene is the most commonly used fuel. Gas turbines can burn almost any liquid or gas fuel and have been operated on diesel fuels, avgas, methane and hydrogen. Any energy source that can heat the compressed gas can theoretically be used, including nuclear reactors.

## Fuel requirements

ignition

### temperature stability
## Fuel Characteristics
### flash point

Is the temperature at wich the fuel will combust in the presence of oxygen

### Relight
## Fuel Standards
### JP6
## Non standard fuels
### Methane
## Nuclear propulsion
## Hybrid fuels
### Nitrous

Jet fuels in wikipedia

## Refrences

* Jet Fuel - Kerosene
# History of wireless telegraphy and broadcasting in Australia/Topical/Publications/Australasian Radio World/Issues/1944 06
## P.03 - Contents Banner

The Australasian Radio World
Devoted entirely to Technical Radio
and incorporating
All-Wave All-World DX News
Vol. 9 - JUNE, 1944 - No. 1

## P.03 - Publication Notes

Proprietor - A. G. HULL
Manager - Dudley L. Walter
Secretary - Miss E. M. Vincent
Short-wave Editor - L. J. Keast
For all correspondence: City Office - 243 Elizabeth St., Sydney - Phone MA2325
Office Hours - Week-days: 10 a.m. - 5 p.m., Saturdays: 10 a.m. - 12 noon
Editorial Office - 117 Reservoir Street, Sydney
Subscription Rates - 6 issues 5/3, 12 issues 10/6, 24 issues £1, Post free to any address
Service Departments - Back Numbers, 1/- ea., post free; Reply-by-mail Queries, 1/- each
Printed by Bridge Printery Pty. Ltd., 117 Reservoir Street, Sydney, N.S.W., for the proprietor of the "Australasian Radio World," 117 Reservoir St., Sydney (Footnote P.28)

## P.03 - Contents

CONTENTS:
CONSTRUCTIONAL -
Utility Battery-Operated Set . . . . 6
A Long-Range Utility Receiver . . . . 8
Direct-Coupled Utility Design . . . . 10
TECHNICAL -
Details of Victorian Amplifier Contest . . . . 5
Some New Ideas from Modern Circuits . . . . 11
Output Transformer Construction . . . . 13
Adjustable I.F. Selectivity . . . . 16
A.B.C. of Frequency Modulation . . . . 19
U.S. Claims Invention of Radar . . . . 20
Signal Officers in the Making . . . . 21
SHORTWAVE REVIEW -
Notes From My Diary . . . . 23
New Stations . . . . 23
Shortwave Notes and Observations . . . . 24
THE SERVICE PAGES -
Answers . . . . 26

## P.03 - Editorial Notes

Editorial
Every now and then a new reader takes me to task for my rough and ready way of sketching out circuit diagrams without paying due attention to indicating suppressor grids, for example. Often enough I leave out the symbol for the heater, and my neglect of such things as iron cores in coils, or using the same condenser symbol for even electrolytics, is becoming almost notorious. I can only plead "guilty" to these crimes, but I would point out to my critics that there are several extenuating circumstances to be considered. I consider that "Australasian Radio World" is not the same as a text book, so there is not so much need to be pedantic. Most of our readers are men with a working knowledge of theory, and most of them are busy, so that they want simple circuits, easy to read at a glance, and with all essential details and values clearly shown but not cluttered up with intricacies. I consider, too, that the placing of capacity and resistance values right at the symbol is far more effective than giving each one a letter and then tabulating values, even if it doesn't look quite so professional. Not that it would make much difference if my style was all wrong, for it is now just as much a part of me as my handwriting and my signature. It would be a most difficult task to change either after all these years. - A. G. HULL.
# History of wireless telegraphy and broadcasting in Australia/Topical/Publications/Australasian Radio World/Issues/1944 07
## P.03 - Contents Banner

The Australasian Radio World
Devoted entirely to Technical Radio
and incorporating
All-Wave All-World DX News
Vol. 9 - JULY, 1944 - No. 2

## P.03 - Publication Notes

Proprietor - A. G. HULL
Manager - Dudley L. Walter
Secretary - Miss E. M. Vincent
Tech. Editor - J. W. Straede, B.Sc.
Short-wave Editor - L. J. Keast
For all correspondence: City Office - 243 Elizabeth St., Sydney - Phone MA2325
Office Hours - Week-days: 10 a.m. - 5 p.m., Saturdays: 10 a.m. - 12 noon
Editorial Office - 117 Reservoir Street, Sydney
Subscription Rates - 6 issues 5/3, 12 issues 10/6, 24 issues £1, Post free to any address
Service Departments - Back Numbers, 1/- ea., post free; Reply-by-mail Queries, 1/- each
Printed by Bridge Printery Pty. Ltd., 117 Reservoir Street, Sydney, N.S.W., for the proprietor of the "Australasian Radio World," 117 Reservoir St., Sydney (Footnote P.28)

## P.03 - Contents

CONTENTS:
CONSTRUCTIONAL -
Simple Vacuum Voltmeter . . . . 7
Home Built Communications Set . . . . 14
TECHNICAL -
R.A.A.F. Jungle Broadcaster . . . . 5
Winning Essay . . . . 8
Design Considerations for Amplifiers . . . . 10
Finer Points About Pick-ups . . . . 19
Distortion - Its Cause and Cure . . . . 20
SHORTWAVE REVIEW -
Notes From My Diary . . . . 23
New Stations . . . . 23
Short Wave Notes and Observations . . . . 24
THE SERVICE PAGES -
Answers . . . . 26

## P.03 - Editorial Notes

Editorial
With the invasion going well and the war news very bright at the moment of writing, it is perhaps natural to find that thoughts are turning more and more to the post-war problems and prospects. All over the world there will be huge stores of war material to be disposed, and the old parable of the "ill-wind" may be repeated. Here in Australia it has been estimated that when the war finishes there will be radio components in store to the value of about ten million pounds. Amongst these parts will be lots of transmitting valves, condensers and other parts which will not be suitable for use in broadcast receivers. They will be a wonderful windfall for those who operate experimental transmitters. There will be great stocks of components suitable for use in building the thousands upon thousands of receivers which ·will be required to satisfy the overdue demands of the ordinary listeners, and the whole of the radio trade will need to handle things carefully to ensure that these parts are put to good use without upsetting factory production or affecting normal trading. Some radio traders are apprehensive about the possible effects of the release of war surplus stocks, but others are quite confident that the matter can be easily handled by the trade, in close co-operation with the technical press, bringing about a boom in technical radio, with all-round benefits to the radio trade as a whole. - A. G. HULL.
# History of wireless telegraphy and broadcasting in Australia/Topical/Publications/Australasian Radio World/Issues/1944 10
## P.03 - Contents Banner

The Australasian Radio World
Devoted entirely to Technical Radio
and incorporating
All-Wave All-World DX News
Vol. 9 - OCTOBER, 1944 - No. 5

## P.03 - Publication Notes

Proprietor - A. G. HULL
Manager - Dudley L. Walter
Secretary - Miss E. M. Vincent
Short-wave Editor - L. J. Keast
For all correspondence: City Office - 243 Elizabeth St., Sydney - Phone MA2325
Office Hours - Week-days: 10 a.m. - 5 p.m., Saturdays: 10 a.m. - 12 noon
Editorial Office - 117 Reservoir Street, Sydney
Subscription Rates - 6 issues 5/3, 12 issues 10/6, 24 issues £1, Post free to any address
Service Departments - Back Numbers, 1/- ea., post free; Reply-by-mail Queries, 1/- each
Printed by Bridge Printery Pty. Ltd., 117 Reservoir Street, Sydney, N.S.W., for the proprietor of the "Australasian Radio World," 117 Reservoir St., Sydney (Footnote P.28)

## P.03 - Contents

CONTENTS:
CONSTRUCTIONAL -
Something Fresh in Amplifiers . . . . 5
"Novochord" is Electronic Piano . . . . 7
Pick-Up Principles and Practice . . . . 13
Cathode-Follower Amplifier Design . . . . 16
Inductance and Capacity Meter . . . . 17
TECHNICAL -
Cathode Follower Output Stage . . . . 11
Iconoscope - The Electron "Gun" . . . . 21
SHORTWAVE REVIEW -
Notes of My Diary . . . . 23
Shortwave Notes and Observations . . . . 24
New Stations . . . . 24
THE SERVICE PAGES -
Answers . . . . 26

## P.03 - Editorial Notes

Editorial
Frequency modulation is headline news in the papers these days, following on statements which have emanated from Canberra. Following the usual routine, these statements have in due course been denied, and counter-statements have been issued. But where there is smoke you usually find fire, and so people gain the impression that there must be something to this frequency modulation business. The talk about frequency modulation has caught many radio engineers "on the hop", and we have been inundated for the back numbers in which the subject was dealt with, but these are no longer available. We have not had time to get a full story ready for this issue, but we plan to cover the whole subject in detail in next month's issue, including the possibilities which the scheme may open up. We do not under-estimate these possibilities, but at the same time we feel sure that they will take a considerable time to reach fruition and there is not quite as much need for a rush as some of our readers seem to feel. First the war has to be completely cleaned up, then the plans have to be laid, and we cannot imagine that frequency modulation will be a completely established service until at least a couple of years after the cessation of hostilities. In the meantime, radio technicians will have ample time to become thoroughly acquainted with the new technique.
# History of wireless telegraphy and broadcasting in Australia/Topical/Publications/Australasian Radio World/Issues/1944 12
## P.03 - Contents Banner

The Australasian Radio World
Devoted entirely to Technical Radio
and incorporating
All-Wave All-World DX News
Vol. 9. - DECEMBER, 1944 - No. 7.

## P.03 - Publication Notes

Proprietor - A. G. HULL
Manager - Dudley L. Walter
Secretary - Miss E. M. Vincent
Short-wave Editor - L. J. Keast
For all correspondence: City Office - 243 Elizabeth St., Sydney - Phone MA2325
Office Hours - Week-days: 10 a.m. - 5 p.m., Saturdays: 10 a.m. - 12 noon
Editorial Office - 117 Reservoir Street, Sydney
Subscription Rates - 6 issues 5/3, 12 issues 10/6, 24 issues £1, Post free to any address
Service Departments - Back Numbers, 1/- ea., post free; Reply-by-mail Queries, 1/- each
Printed by Bridge Printery Pty. Ltd., 117 Reservoir Street, Sydney, N.S.W., for the proprietor of the "Australasian Radio World," Elizabeth St., Sydney (Footnote P.36)

## P.03 - Contents

CONTENTS:
CONSTRUCTIONAL -
Contest Was Keen . . . . 5
Pick-up Principles . . . . 13
Victorian Championship . . . . 17
TECHNICAL -
Aesthetics of Reproduction . . . . 19
Music While You Work . . . . 26
SHORTWAVE REVIEW -
Shortwave Notes and Observations . . . . 29
Notes From My Diary . . . . 31
New Stations . . . . 33
THE SERVICE PAGES -
Answers . . . . 34

## P.03 - Editorial Notes

Editorial
Those of our readers who are enthusiasts on the subject of quality reproduction must be a little bewildered at the moment. We had hardly finished publishing an amplifier circuit "to end all amplifier circuits" when along came the cathode-follower scare. To add to the confusion, then came the results of the Victorian Amplifier Championship, indicating that beam power valves, even with inverse feedback, do not give the practical results which can be calculated for them by theory. Even direct-coupled enthusiasts were disappointed. In fact, it might be said that the Victorian contest puts us all back about fifteen years in our theories. To cap it all, along comes the latest issue of the famous Wireless World from London, with an article by well-known quality exponent H. A. Hartley, who now confesses that high fidelity reproduction is not desirable. The article is so complete in its coverage and so full of interest in every way that we feel bound to reprint it for the benefit of our many readers who are unable to obtain a copy of the English publication. At the same time we feel that some sort of explanation is needed to clarify our policy in these matters. Some letters have been received from irate readers who claim that we seem to be deliberately misleading them by publishing contradictory stories in quick succession. Briefly, our policy at the moment is to present all these theories as they come to hand. We leave it to you to use your own discrimination as to what you decide to follow.
# History of wireless telegraphy and broadcasting in Australia/Topical/Publications/Australasian Radio World/Issues/1944 04
## P.03 - Contents Banner

The Australasian Radio World
Devoted entirely to Technical Radio
and incorporating
All-Wave All-World DX News
Vol. 8 - APRIL, 1944 - No. 11

## P.03 - Publication Notes

Proprietor - A. G. HULL
Manager - Dudley L. Walter
Secretary - Miss E. M. Vincent
Short-wave Editor - L. J. Keast
For all correspondence: City Office - 243 Elizabeth St., Sydney - Phone MA2325
Office Hours - Week-days: 10 a.m. - 5 p.m., Saturdays: 10 a.m. - 12 noon
Editorial Office - 117 Reservoir Street, Sydney
Subscription Rates - 6 issues 5/3, 12 issues 10/6, 24 issues £1, Post free to any address
Service Departments - Back Numbers, 1/- ea., post free; Reply-by-mail Queries, 1/- each
Printed by Bridge Printery Pty. Ltd., 117 Reservoir Street, Sydney, N.S.W., for the proprietor of the "Australasian Radio World," 117 Reservoir St., Sydney (Footnote P.28)

## P.03 - Contents

CONTENTS:
CONSTRUCTIONAL -
Standard Features for Utility . . . . 6
Avoiding the H.T. Transformer . . . . 7
Electronics in Modern Music . . . . 9
"Mystery" Crystal Set . . . . 17
TECHNICAL -
Ideals in DX Sets . . . . 5
Simple Volume Expander Circuit . . . . 11
Reviving Dry Batteries Electrically . . . . 13
Pentodes and Similar Power Valves . . . . 14
SHORTWAVE SECTION -
Shortwave Review . . . . 20
New Stations . . . . 20
Shortwave Notes and Observations . . . . 21
Loggings . . . . 23
THE SERVICE PAGES -
Answers . . . . 26

## P.03 - Editorial Notes

Editorial
We would not like to suggest that any of our readers could be unreasonable, but it is very apparent that a few of them are inclined to be completely carried away by their enthusiasm. They seem to get so carried away, in fact, that they completely overlook the problems of the times and expect to find that "Radio World" has an unlimited staff of technicians with plenty of time to spare to go into the most elaborate details of component design in order to maintain the queries service. Now, in case you are not aware, practically every radio magazine in the world has been forced to abandon its query service; we have stuck to ours so far in the hope that what little time we can afford will be duly appreciated. There are one or two points we would like to suggest, as they will make it possible for us to give better results for the time made available. Firstly, please write plainly, on one side of the paper, as briefly as possible, yet giving all the necessary facts, and attaching diagrams on a separate sheet of paper, so that they can be studied at the same time as the letter itself. Try and put yourself in our position and remember that the amount of time devoted to each query cannot possibly exceed ten minutes. Therefore it is quite useless to expect to have special power or output transformers designed to order. It is equally useless to ask to have a special set designed to use the junk or odd valves which you have on hand. - A. G. HULL.