H o m e

Index of all pages

- Airfoils - - Other Topics -
[Pylon Racing]
[Flying Wings] [Model Aerodynamics] [F3D Pylon Racing]
[Sailplanes] [Other Objects] [Other Topics]
[Airfoil Index] [Global Index]

Glossary

AAC
Aluminum Aluminum Chrome: aluminum piston, running in a chrome plated aluminum sleeve. Typically used in pylon racing engines. Advantages: low friction and tight fit, when properly run. Disadvantage: more expensive and more sensitive to foreign object damage. see also: ABC.
 
ABC
Aluminum Brass Chrome: aluminum piston, running in a chrome plated brass sleeve. see also: AAC.
 
Angle of Attack
Angle between the reference axis (x-axis) of an airfoil and the onset flow direction. Variable, depending of flow direction and flight condition.
 
Angle of Incidence
Angle between the reference axis (x-axis) of an airfoil and the reference axis of the aircraft (e.g. fuselage center line). Constant, built into the aircraft.
 
Bernoulli, Daniel (1700-1782)
Is credited for Bernoulli's equation, although it seems to be Euler, who really derived this equation (see [8]).
 
Drag Coefficient
Normalized drag force, makes the comparison of the aerodynamic properties of different sized objects possible; Definition.
 
Euler, Leonhard (1701-1783)
Well known for the Euler differential equations. Probably also origin of Bernoulli's equation, which relates pressure and velocity of a fluid:

where: v ... velocity, p ... pressure, and rho ... density.
This equation can be applied to transform pressure distributions into velocity distributions and vice versa.
 
FAI
Féderation Aeronautique Internationale (french): International Aeronautics Society
 
F1
FAI class prefix for uncontrolled models (free flight):
F1A FAI class for outdoor, free flight glider models.
F1B FAI class for outdoor, free flight rubber powered glider models.
F1C FAI class for outdoor, free flight combustion engine powered glider models.
F1D FAI class for indoor, free flight rubber powered glider models.
F2
FAI class prefix for control line models:
F2A FAI class for control line speed models.
F2B FAI class for control line aerobatic models.
F2C FAI class for control line team racing models.
F2D FAI class for control line fox hunt models.
F3
FAI class prefix for radio controlled models:
F3A FAI class for acrobatic models with combustion engines.
F3B FAI class for allround sailplanes.
F3C FAI class for helicopter models.
F3D FAI class for piston engine pylon racing models.
F4
FAI class prefix for scale models:
F4B FAI class for control line scale models with combustion engines.
F4C FAI class for radio controlled scale models with combustion engines.
F5
FAI class prefix for models powered by electric motors.
F5A FAI class for electric powered acrobatic models.
F5B FAI class for electric powered sailplanes.
F5D FAI class for electric powered pylon racing models.
 
Laminar Flow
State of fluid flow, where the particles move along parallel, ordered paths. Results in low friction on submerged surfaces, but has problems to follow retreating shapes (e.g. fuselage tails, airfoil behind location of maximum thickness). see also: Turbulent Flow.
Lift Coefficient
Normalized lift force, makes the comparison of the aerodynamic properties of different sized objects possible; Definition.
Mach, Ernst (1838-1916)
Born in Austria, he became became a professor in Prague in 1867. There he worked as a Physicist and Philosopher for 28 years. He was one of the first who made supersonic flow visible and who understood the importance of the speed of sound for supersonic flows.
In honor of him, the ratio v/a is called Mach number (where a is the speed of sound, which is about 340 m/s at sea level).
 
Moment Coefficient
Normalized torque moment, makes the comparison of the aerodynamic properties of different sized objects possible; Definition.
 
PEF
Abbreviation for Polar Exchange Format. Look here for a description.
 
Pitot Tube
An L-shaped, open tube, one end connected to a pressure measuring device, the other end placed in a flow with the opening facing the wind. Can be used to measure the total pressure of a flow (stagnation pressure). In conjunction with a static pressure measurement the flow velocity can be calculated, if the density of the fluid is known. A device, which combines both pressure measurements is a pitot-static tube (at least in Germany also called a Prandtl-tube).
Named after a Frenchman, Henri Pitot (1695-1771).
 
Pylon
A sign, marking the corner of the racing course. May be a tripod like structure or a simple pole with an oil drum on top of it.
 
Reynolds, Osborne (1842-1912)
Worked for 37 years as a professor of engineering at the university of Manchester, Great Britain. In 1883 his experiments lead him to the definition of a dimensionless parameter, which indicated transition from laminar to turbulent flow in pipes. This parameter was later known as Reynolds number.
For the flow inside a tube of diameter l he determined the critical value of this parameter to be 2300.
Reynold's number is a very important parameter in fluid dynamics. Flows at the same Reynolds number are similar, which make it possible to use smaller models (length l) for tests at higher velocities (velocity v) to achieve the same Reynolds number as the full scale airplane.
 
Turbulent Flow
State of fluid flow, where the particles move in irregular, wavy paths. Results in high friction on submerged surfaces, but can more easy follow retreating shapes (e.g. fuselage tails, airfoil behind location of maximum thickness). see also: Laminar Flow.
 
Wake
A region of a flow field located behind a body, which is moving through the air. The velocity and the pressure in the wake region can be very different from the external flow field. The wake contains information about the lift and the drag of the body that generated it. Usually the pressure in the wake behind a body is lower than the pressure in the surrounding flow field. The pressure difference corresponds to the drag of the body. Lift forces can create strong vortices in a wake, which can make the wake exist for a long time, until it gets dissolved through friction effects.
 

Last modification of this page: 09.06.02

[Back to Home Page] [Index of all Pages] Suggestions? Corrections? Remarks? e-mail Martin Hepperle.
As I get quite a number of messages, it might take some time until you receive an answer and in some cases I get lost in the flood and you may even receive no answer at all. I apologize for this, and if you have not lost patience, you might want to send me a copy of your e-mail after a month or so.
Copyright 1986-2002 Martin Hepperle
You may use the data given in this document for your personal use. If you use this document for a publication, you have to cite the source. A publication of a recompilation of the given material is not allowed, if the resulting product is sold for more than the production costs. Some names appearing on this web are trademarks or registered names whose rights belong to their owners, even if not explicitely stated. This document can be found by navigating from the Web site http://www.MH-AeroTools.de/
.
Weitere rechtliche Hinweise für Deutschland
.