Fiber Optics in Commercial Aerospace
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Fiber Optics in Commercial Aerospace
Does anyone have an idea as to whether Fiber optics is being used in commercial aviation as such, if it is, then where does it find its application. I have come to know that Fiber optics is likely to be used for cabin lighting. Fiber optics being a much lighter and more reliable medium can also be used for on-board communication purposes, but that remains to be seen. Any inputs !!
phoenix28,
Fiber optics are not by definition lighter than conventional lighting. First of all, the fiber cable is not able to produce light it can only transport light from a light source to another place. So you still need a light source. I personally think that LED (Light emitting diodes) are more interesting. They produce a lot of light and have a low weight and dimension.
Fiber optics are used to transport a mass of data (light) trough high distances of cable . On the start and the end you need some electronics to translate light into electrical signals. You can say when you use standard serial data communicating systems that you also need it, but this system is more used and so more known. And do you need to transport so mutch data in an aircraft?.
Greetz,
Dave
Fiber optics are not by definition lighter than conventional lighting. First of all, the fiber cable is not able to produce light it can only transport light from a light source to another place. So you still need a light source. I personally think that LED (Light emitting diodes) are more interesting. They produce a lot of light and have a low weight and dimension.
Fiber optics are used to transport a mass of data (light) trough high distances of cable . On the start and the end you need some electronics to translate light into electrical signals. You can say when you use standard serial data communicating systems that you also need it, but this system is more used and so more known. And do you need to transport so mutch data in an aircraft?.
Greetz,
Dave
Hi!
Optical fibers are also used in new types of gyroscope. But I don't know how and what for...
It is also used in what we called "fly-by-light". You probably know the "fly-by-wire" (on Airbus and also Boeing 777). In fly-by-light technology, the wires are replaced by optical fibers and the signal is transmit from the yoke or joystick to the elevators etc... through the optical fibers.
The problem is, when the optical fiber is curved, a non negligible part of the signal is lost, outside the fiber. Using such technology implies using light amplifier. But you also need a LASER to produce the light you will inject into the fiber. So it's a bit complicated to introduce this technology in a plane.
The only think I know, is that an helicopter has been build with fly-by-light in germany...
Karl
Optical fibers are also used in new types of gyroscope. But I don't know how and what for...
It is also used in what we called "fly-by-light". You probably know the "fly-by-wire" (on Airbus and also Boeing 777). In fly-by-light technology, the wires are replaced by optical fibers and the signal is transmit from the yoke or joystick to the elevators etc... through the optical fibers.
The problem is, when the optical fiber is curved, a non negligible part of the signal is lost, outside the fiber. Using such technology implies using light amplifier. But you also need a LASER to produce the light you will inject into the fiber. So it's a bit complicated to introduce this technology in a plane.
The only think I know, is that an helicopter has been build with fly-by-light in germany...
Karl
jan_olieslagers wrote:
Allow me to express some doubts. Fibre optic is being used more and more for connecting computers in (Ethernet) networks. Where I work there are bundles of fibre-optic cables connecting two building approx. 2 km apart with no problems - so your story of amplifiers sounds a bit doubtful to me. But there is a difference between so-called mono-mode and multi-mode fibre-optics, I should have to look up what it all exactly comes down to.
Indeed you have two kinds od OF : monomode (only one mode circulates in the fiber) and multimode.
A mode is link to stationary waves in the perpendicular direction of the propagation of the main wave. In a monomode fiber, you have only one wave. This is the best fiber to transmit informations. In a multimode fiber, you have more than one wave because stationary waves are produced.
You have to consider two thinks :
- the fading of the signal due the fiber itself which are the absorption in the material (IR and UV), the Raylegh diffusion and the intrinsic absorption (due to the OH- peaks).
Note that for a typical multimode fiber "à gradient d'indice", the decresing of the signal is about 0.5dBm per kilometer wich means that if you have -10dBm at the entrance and if you need -35dBm (typical sensibility of an optical detector) at the exit, you can use a fiber of maximum 50km.... So this is less then your 2 km... If you need more than 50km you need an emplifier.
- the fading of the signal due to connection between fibers or due to a curved fiber. These kinds of fading are higher.
Here is a nice site (but in French): http://perso.wanadoo.fr/michel.hubin/physique/phys.htm
Karl
Fiber optic gyros (FOGs) may be constructed as resonators (much as RLG's = Ring Laser Gyro's) or interferometers. Resonator FOGs have been attempted but suffered from a high lossto-gain ratio and excessive scatter. Therefore most operational FOGs are interferometrs.sn53E wrote:
Optical fibers are also used in new types of gyroscope. But I don't know how and what for...
The interferometric fibre optic gyro (IFOG) consists of a light source, a coupler, a fiber coil, and a detector. Light is launched from a broadband laser source and coupled through a fiber optic coil in both the clockwise and counterclockwise directions. The optical paths seen by the two beams differ in proportion to the angular rate applied to the gyro. After recombination, the two beams interfere and the intensity measures the phase difference between the beams. Asyou can see the principle ressembles thus to the principle used in RLGs.
Optical fibers are thus used to transport the laser light. in RLGs we sued an ionized gas which will produce two beams. Then we calculate the rate of rotation of the plane with the help of an interferometer device as well.
Chris
Wasn't there a BAC 1-11 converted to test Fly-By-Light?
Indeed vc-10,
There is an article about it in my Hydraulics course about the evolution of servo hydraulics. There was a BAC1-11 with spoilers that were controlled by light in 1993.
Some photo's
An article about it
More articles by google
Greetz,
Dave