Aeronautical definitions

Wing geometry 
The planform of a wing is the shape of the wing seen on a plan view of the aircraft. Figure 1.4 illustrates this and includes the names of symbols of the various para- meters of the planform geometry. Note that the root ends of the leading and trailing edges have been connected across the fuselage by straight lines. An alternative to this
convention is that the leading and trailing edges, if straight, are produced to the aircraft centre-line.

An internal gearbox,Direct drive

Fig. 7-3 An internal gearbox.

Direct drive

11. In some early engines, a radial driveshaft was used to drive each, or in some instances a pair, of

accessory units. Although this allowed each accessory unit to be located in any desirable location

around the engine and decreased the power transmitted through individual gears, it necessitated

a large internal gearbox. Additionally, numerous radial driveshafts had to be incorporated within the

design. This led to an excessive amount of time required for disassembly and assembly of the engine

for maintenance purposes.

ENERGY TRANSFER FROM GAS FLOW TO TURBINE

Fig. 5-6 A typical turbine blade showing
twisted contour.

ENERGY TRANSFER FROM GAS FLOW TO TURBINE
6. From the description contained in para. 1, it will be seen that the turbine depends for its operation on the transfer of energy between the combustion gases and the turbine. This transfer is never 100 per cent because of thermodynamic and mechanicallosses, (para. 11). 

Fig. 5-7 Gas flow pattern through nozzle and blade

  7.when the gas is expanded by the combustion process (Part 4), it forces its way into the discharge nozzles of the turbine where, because of theirconvergent shape, it is accelerated to about the speed of sound which, at the gas temperature, isabout 2,500 feet per second. At the same time thgas flow is given a ’spin’ or ’whirl’ in the direction o rotation of the turbine blades by the nozzle guid vanes. On impact with the blades and during th subsequent reaction through the blades, energy is absorbed, causing the turbine to rotate at high speed and so provide the power for driving the turbine shaft and compressor.

Turbines

Fig. 5-1 A triple-stage turbine with single shaft system.

Fig. 5-2 A twin turbine and shaft arrangement.

INTRODUCTION
1. The turbine has the task of providing the power to drive the compressor and accessories and, in the case of engines which do not make use solely of a jet for propulsion, of providing shaft power for a propeller or rotor. It does this by extracting energy from the hot gases released from the combustion system and expanding them to a lower pressure and temperature. High stresses are involved in this process, and for efficient operation, the turbine blade tips may rotate at speeds over 1,500 feet per second, The continuous flow of gas to which the turbine is exposed may have an entry temperature between 850 and 1,700 deg. C. and may reach a velocity of over 2,500 feet per second in parts of the turbine.
2. To produce the driving torque, the turbine may consist of several stages each employing one row of stationary nozzle guide vanes and one row of moving blades (fig. 5-1). The number of stages depends upon the relationship between the power required from the gas flow, the rotational speed at which it must be produced and the diameter of turbine permitted.
3. The number of shafts, and therefore turbines, varies with the type of engine; high compression ratio engines usually have two shafts, driving high and low pressure compressors (fig, 5-2). On high by-pass ratio fan engines that feature an intermediate pressure system, another turbine may be interposed between the high and low pressure turbines, thus forming a triple-spool system (fig, 5-3). On some engines, driving torque is derived from a free-power turbine (fig. 5-4). This method allows the turbine to run at its optimum speed because it is mechanically independent of other turbine and compressor shafts.

Rolls-Royce Turbomeca Adour Mk102 | Rolls-Royce RB37 Derwent V

Rolls-Royce RB37 Derwent V

Rolls-Royce Turbomeca Adour Mk102

Work commenced in January 1945 on a 0.855 scale Nene, reduced to fit the engine nacelle of a Gloster Meteor. Known as the Derwent V the engine passed a 100 hr test at 2600 lb thrust in June 1945 and in September went into production with a service rating of 3500 lb. Two world speed records were set by Meteor IV’s powered by special Derwent V’s in November 1945 and September 1946.

Combustion stability

Fig. 4-11 Combustion stability limits.

28. Combustion stability means smooth burning and the ability of the flame to remain alight over awide operating range.
29. For any particular type of combustion chamber there is both a rich and weak limit to the air/fuel ratio, beyond which the flame is extinguished. An extinction is most likely to occur in flight during a glide or dive with the engine idling, when there is ahigh airflow and only a small fuel flow, i.e. a veryweak mixture strength.
30. The range of air/fuel ratio between the rich and weak limits is reduced with an increase of air velocity, and if the air mass flow is increased beyond a certain value, flame extinction occurs. A typical stability loopis illustrated in fig. 4-11

COMBUSTION CHAMBER PERFORMANCE

Fig. 4-9 Annular combustion chamber.

COMBUSTION CHAMBER PERFORMANCE
23. A combustion chamber must be capable of allowing fuel to burn efficiently over a wide range of operating conditions without incurring a large pressure loss. In addition, if flame extinction occurs, then it must be possible to relight. In performing these functions, the flame tube and spray nozzleatomizer components must be mechanically reliable.
24. The gas turbine engine operates on a constant pressure cycle, therefore any loss of pressure during the process of combustion must be kept to a minimum. In providing adequate turbulence and mixing, a total pressure loss varying from about 3 to 8 per cent of the air pressure at entry to the chamber is incurred.

INTRODUCTION - An early combustion chamber.

INTRODUCTION

Fig. 4-1 An early combustion chamber.

1. The combustion chamber (fig. 4-1) has the difficult task of burning large quantities of fuel, supplied through the fuel spray nozzles (Part 10), with extensive volumes of air, supplied by the compressor (Part 3), and releasing the heat in such a manner that the air is expanded and accelerated to give a smooth stream of uniformly heated gas at all conditions required by the turbine (Part 5). This task must be accomplished with the minimum loss in pressure and with the maximum heat release for the limited space available.

A turbo/ram jet engine.

Fig. 1-10 Comparative propulsive efficiencies

16. At aircraft speeds below approximately 450 miles per hour, the pure jet engine is less efficient than a propeller-type engine, since its propulsive efficiency depends largely on its forward speed; the pure turbo-jet engine is, therefore, most suitable for high forward speeds. The propeller efficiency does, however, decrease rapidly above 350 miles per hour due to the disturbance of the airflow caused by the high blade-tip speeds of the propeller. These characteristics have led to some departure from the use of pure turbo-jet propulsion where aircraft operate at medium speeds by the introduction of a combination of propeller and gas turbine engine.
17. The advantages of the propeller/turbine combination have to some extent been offset by the introduction of the by-pass, ducted fan and propfan engines. These engines deal with larger comparative airflows and lower jet velocities than the pure jet engine, thus giving a propulsive efficiency (Part 21) which is comparable to that of the turbo-prop and exceeds that of the pure jet engine (fig. 1-10).

Mechanical arrangement of gas turbine engines.

Fig. 1-9-2

Basic mechanics

 

Fig. 1-9-1

Mechanical arrangement of gas turbine engines.

PRINCIPLES OF JET PROPULSION

Fig. 1-4 Hero’s engine - probably the earliest
form of jet reaction.

6. Jet propulsion is a practical application of Sir Isaac Newton’s third law of motion which states that, ’for every force acting on a body there is an opposite and equal reaction’. For aircraft propulsion, the ’body’ is atmospheric air that is caused to accelerate as it passes through the engine. The force required to give this acceleration has an equal effect in the opposite direction acting on the apparatus producing the acceleration. A jet engine produces thrust in a similar way to the engine/propeller combination. Both propel the aircraft by thrusting a large weight of air backwards (fig. 1-3), one in the form of a large air slipstream at comparatively low speed and the other in the form of a jet of gas at very high speed.
7. This same principle of reaction occurs in all forms of movement and has been usefully applied in many ways. The earliest known example of jet reaction is that of Hero’s engine (fig. 1-4) produced as a toy in 120 B.C. This toy showed how the momentum of steam issuing from a number of jets could impart an equal and opposite reaction to the jets themselves, thus causing the engine to revolve.

Fig. 1-5 A garden sprinkler rotated by the
reaction of the water jets.

8. The familiar whirling garden sprinkler (fig. 1-5) isa more practical example of this principle, for themechanism rotates by virtue of the reaction to thewater jets. The high pressure jets of modern

Basic mechanics for JET ENGIN

INTRODUCTION
1. The development of the gas turbine engine as an aircraft power plant has been so rapid that it is difficult to appreciate that prior to the 1950s very few people had heard of this method of aircraft propulsion. The possibility of using a reaction jet had interested aircraft designers for a long time, but initially the low speeds of early aircraft and the unsuitably of a piston engine for producing the large high velocity airflow necessary for the ‘jet’ presented many obstacles.

2. A French engineer, René Lorin, patented a jet propulsion engine (fig. 1-1) in 1913, but this was an athodyd (para. 11) and was at that period impossible to manufacture or use, since suitable heat resisting materials had not then been developed and, in the second place, jet propulsion would have been extremely inefficient at the low speeds of the aircraft of those days. However, today the modern ram jet is very similar to Lorin’s conception.

3. In 1930 Frank Whittle was granted his first patent for using a gas turbine to produce a propulsive jet, but it was eleven years before his engine completed its first flight. The Whittle engine formed the basis of the modern gas turbine engine, and from it was developed the Rolls-Royce Welland, Derwent, Nene and Dart engines. The Derwent and Nene turbo-jet engines had world-wide military applications; the Dart turbo-propeller engine became world famous as the power plant for the Vickers Viscount aircraft. Although other aircraft may be fitted; with later engines termed twin-spool, triple-spool, by-pass, ducted fan, unducted fan and propfan, these are inevitable developments of Whittle’s early engine.

Boomerang plans Pattern

DESIGN AND DEVELOPMENT OF THE SWIFT: A FOOT-LAUNCHED SAILPLANE

 Abstract

This paper describes the development of what might be considered the first successful ultralight sailplane.The SWIFT is a high performance foot-launched glider, designed to combine some of the convenience of hang gliders with the soaring performance of sailplanes. It takes off and lands like a hang glider, yet maintains exceptional performance at high speeds, achieving a lift-to-drag ratio of about 25:1. Although it is a fullycantilevered rigid wing with aerodynamic controls and flaps, it is light enough to launch by running from a hillside and is easily transported on the top of a car. This paper describes the design, development, and flying of this unique aircraft. Introduction and Background

 Introduction and Background

Pioneers of heavier-than-air flight were inspired with the idea of being able to fly like birds – not for the purpose of efficient, high-speed transportation, but for the shear freedom that such a capability would permit. This was the motivation for, and is the appeal of,modern soaring aircraft such as paragliders, hang gliders, and sailplanes. Although the performance of sailplanes has increased dramatically over many decades  so that lift-to-drag ratios of 60:1 have been achieved and 1000 km flights are possible, certain aspects of high performance sailplanes seem counter to the vision espoused by Lilienthal and others [1]. Especially for a group of graduate students in the San Francisco Bay Area, the cost of sailplane flying, along with the long drive to an airport that supported such activities, meant that achieving the goal of bird-like flight was only somewhat more realizable than it was 100 years ago.

How To Make Traditional Boomerangs

Construction of traditional Australian boomerang (for right hand)

Instructions how to make traditional boomerang
1. Take plywood sheet of 12mm thickness. Draw boomerang contour pattern as shown in picture above. The 107 degree angle size is not critical, just optimum. It can be more or less than 107deg. Chord length near the center of boomerang = 80 mm, and 60 mm near tips. Make wing chord length few millimeters wider as is required, because it necessarily reduces during sanding process. Also make some access length at boomerang wings tips, as it possible, that you will have to cut them during tune procedure of the boomerang.
Note:
If you make angle >>107, consider that rotation plate becomes small and it can be difficult to keep the
boomerang spinning.
If you make angle of about 90 degrees, the boomerang flight trajectory circle radius is minimum. Angles
<90 deg and >90 degrees increase circle radius.
2. First what you have to do is to sand dihedrals of wings. You have to make decision were is top and
bottom. Put plywood boomerang on flat table and see if the tips are up or down. The traditional Australian boomerang has positive dihedral. The best choice is to find position in which the boomerang wings tips are up. (Do not care about that if your plywood is absolutely flat).
Remove some material from boomerang bottom at distance of about D=70...90 mm from both tips. It can
be asymmetrical, but condition A+B = 14 mm should be satisfied.
Note:

The Clark Y Airfoil is Ideal for RC Model Aircraft

Complete instructions on how to plot out a Clark Y airfoil Outline of a Clark Y airfoil

Clark Y is the name of an airfoil that is widely used in aircraft design. With its predictable and gentle stall characteristics and flat bottom outline, the Clark Y airfoil is an ideal choice for sport RC model aircraft. I have used the Clark Y airfoil for all my model airplane designs, from the Electro Aviator to the Finch.

See later on in this article for complete instructions on how to plot out a Clark Y airfoil from tabulated ordinates. Drawing up your own airfoil shape is very easy to do. You can use the tabulated ordinate method to draw a Clark Y airfoil by hand, or use TurboCAD for the drafting task. You can then use TurboCAD to draw additional versions of the finished Clark Y wing rib shape for any length wing rib your model aircraft design requires.

 

Table 1: Ordinates to draw a Clark Y airfoil. All figures are a percentage of rib chord (top line), with percentage of chord upper and lower airfoil points on next two lines

principles Of Flight

Lesson Plan: Paper Glider Measurement

Grade Level:  5-6
Subject Area: Math
Time Required: 

1.  Preparation: 1 hour
2. Activity: 2-3 hours

National Standards Correlation: Math (grade 3-5)

Measurement Standard:

Apply appropriate techniques, tools, and formulas to determine measurements.

1. • Data Analysis and Probability Standard: Understand and apply basic concepts of probability.
2. • Data Analysis and Probability Standard: Select and use appropriate statistic methods to analyze data.
3. • Representation Standard: Use representation to model and interpret physical, social, and mathematical phenomena. Math (grades 6-8)
4. • Measurement Standard: Apply appropriate techniques, tools, and formulas to determine measurements.
5. • Data Analysis and Probability Standard: Understand and apply basic concepts of probability.
6. • Data Analysis and Probability Standard: Select and use appropriate statistic methods to analyze data.
7. • Representation Standard: Create and use representations to organize, record, and communicate mathematical ideas.

757 Glider Kit-GLIDER CHALLENGE EVENTS

DIRECTIONS: Divide class into flight squadrons (3 to 4 students per squadron). Have each student construct a 757 glider and write their name on the wing. Present glider challenges to squadrons. Explain to students the object of each event and how it is scored. Extra points can be obtained by completing a glider extension activity. Students should be encouraged to conduct some experimentation (i.e., add weight; reshape wing or tail) on their gliders in order to maximize the performance for the different objectives of each challenge. Rotate squadrons through the challenges keeping score on a squadron’s scoresheet. Debrief afterwards to discuss glider designs, experimentations, and outcomes.
CHALLENGE #1 -- 
Spot Landing Set-up: Tape off a large circle, 7 meters in diameter. Create a bull’s-eye ring with 3 circles, equally spaced from each other, inside the circle (5, 3, and 1 meter). Label circles (A, B, C, D) with A being the center ring. Give a point value to each circle with A being the largest point value and D being the smallest point value. Indicate the launching zone with another piece of masking tape 4 meters from the edge of outer circle. (You may wish to try a glider unmodified to see how far it can go and use the distance as a baseline for making adjustments.)
Playing rules: Object is to make modifications to the glider to improve its performance with the goal of launching the glider towards the circle and touching down inside circle A (the bull’s-eye).
Scoring: Points are determined by the spot the glider first “touches down” in the target area, not where it finally comes to rest. After each squadron member has landed their glider and determined the point score, the squadron’s combined points are entered on the score sheet.

757 Glider Kit

A Boeing 757-200 (B-757) was acquired in 1994 by the National Aeronautics and Space Administration (NASA) for aeronautical research. Given the call sign NASA 557, this aircraft is used for conducting research on increasing aircraft safety, operating efficiency, and compatibility with future air traffic management systems, benefiting the U.S. aviation industry and commercial airline customers. Part of the Transport Research Facilities (TRF) project, this twinengine commercial aircraft was modified extensively to create a “flying laboratory.” Most of the seats were removed to make room for a large test area capable of carrying over 5100 kg (10,700 lb) of experiment equipment. It is outfitted with electronics for extremely precise instrumentation and data gathering capabilities, and a flexible interior configuration allows future upgrades to be incorporated. The B-757 is continuing the work begun by NASA’s Boeing 737-100, which has been in service for over 20 years. The B-757 retains the experimental approach of the B-737, but offers newer technology and improved capability.

“Airborne Trailblazer” by Lane Wallace is an excellent history of NASA’s B-737 research aircraft. <see: http://www.dfrc.nasa.gov/History/Publications/SP-4216/> One of the basic working philosophies of the TRF project is the concept of “simulation to flight.” The main objective is to develop technical or operational concepts (e.g., electronic cockpit displays, flight management systems, airborne windshear detection sensors) and take them from ground-based simulation testing to flight testing in an easy and straightforward manner. The TRF project includes the B-757 aircraft as well as several ground-based simulators and a Research Systems Integration Laboratory (RSIL). Increasing the effectiveness of conducting experiments from simulation to flight will better meet the needs for bringing advances in safety, operations, and capacity into the ever-changing national airspace system. The NASA 557 will be maintained and flown by NASA’s Langley Research Center (LARC) in Hampton, VA. Listed below are some experiments that have used the NASA 557.