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rjbrown89

Easy Fly By Wire

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Hi all,

 

I'm really interested in adding some sort of fly by wire / attitude hold to my flight sim. I've been trying to use easyFBW and have just been running into lots of trouble with it. I was wondering if anyone else on here had tried using it, or anything like it?

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My understanding of Fly By Wire is that instead of cables and pulleys operating the various control surfaces electronic signals are directed through wires to achieve this.  Isn't this what the sim controls already available to us do?  My CH Products yoke and throttle certainly send electronic signals to the sim via their wires attached to USB ports.  I don't see any cables and pulleys!

 

Dijvid

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"Fly by wire" is a syatem which is far more complex than you seem to think Dijvid. Via this system, any manual flight control inputs by the pilot, do not go directly to exterior control surfaces via hydraulic or electrical systems but go indirectly via an onboard computer.

Think of it in this extremely simplified way:

 

When flying in normal autopilot mode the pilot only needs to turn, e.g. the autopilot heading knob, for his aircraft to turn to the new selected heading. The same for the altitude knob, etc.

 

In manual and non-autopilot flight mode the "Fly by wire" system does the same but now via yolk, joystick and/or rudder inputs, while the onboard computer sees to it that e.g. airframe limits, are not exceded. You should see it as a kind of indirect manual flight control, as though you are flying via manual autopilot inputs only. However, the normal autopilot function as a separate system, remains available, if and when activated.

 

I hope that my extremely basic explanation of this very complex and multi sided safety system, helps in giving you a basic understanding.

 

Regards

 

Hans

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"Fly by wire" is a syatem which is far more complex than you seem to think Dijvid. Via this system, any manual flight control inputs by the pilot, do not go directly to exterior control surfaces via hydraulic or electrical systems but go indirectly via an onboard computer.

 

Regards

 

Hans

 

Thanks for the information, Hans.

 

So are we saying that we want to create a virtual onboard computer inside our computers/PCs so as to operate the various exterior control surfaces?  If so then I'm not sure that I understand how this is going to improve either our flying or our perceived enjoyment of the sim.  I dread to think what overhead that would add to something like the iFly 737 or PMDG B747!!

 

David 

 

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Dijvid,

 

When you would manually be real world flying via the "Fly By Wire" system, you will not notice anything under any normal flying conditions, even although it's an indirect way of flying as opposed to the direct "seat of your pants" type of flying. Even when applying, e.g. sudden full power at, e.g. take off, the "Fly By Wire" system will perform this gradually so as to not over stress the engines/airframe and also to save some fuel. However, for the real cowboy pilots the system can be switched off but it's my opinion that the airline concerned will not be too happy with such pilots, nor will the manufacturer.

 

However, programming all these types of things into FS would, as you say, create a lot of extra overhead and be very difficult indeed to do but not impossible, unless of cause you would like to perform aerobatics in an Airbus A-340/Boeing B-747 to see exactly where, when and how the "Fly By Wire" system would intervene.

 

Another example is the very different "Fly By Wire" system in, e.g. an F-16 jet fighter, in which the system remains absolutely necessary because the wing/fuselage configuration of the plane itself makes it very unstable in flight, so much so that the pilot would not be able to control it, much less during offensive/defensive manouvers.

 

I therefore agree with you that any form of "Flying By Wire" is purely for safety reasons in real world flying and would not be really feasable in FS, although technically possible.

 

Hans

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Hi Hans

 

Thanks for the further info and educating me a bit more!!

 

Dijvid

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FBW is not "purely for safety reasons", it can provide operational benefits to civil operations as well as military. 

 

Like the F-16, the Boeing 777 (as well as some Airbus models) have "relaxed longitudinal stability", in this case not to increase manoeuvrability but to improve fuel economy.  In a conventional aircraft, longitudinal stability is achieved by having the centre of gravity forward of the centre of lift of the wings.  To stop the nose dropping, the tail has to provide a downward force which increases the lift that the wings must produce, and hence increases drag.  Moving the COG closer to the COL reduces the drag, but makes the aircraft harder to control in pitch.  The smaller balancing force needed from the tail surfaces means that these can also be smaller, further reducing drag.

 

Having a computer between the control stick and the flying surfaces means that all sorts of other functions can be incorporated, such as auto-trimming and the various protections. But the protections are not the main reason for FBW.   I believe  that the reason people associate FBW with "protections" is due to the Airbus philosophy of using a side-stick without force feedback, making it possible to overstress the aircraft which a conventional yoke with an "artificial feel" system would make much less likely because of the sheer force required.

 

And yes, the various B777 and Airbus offerings for FSX do simulate the FBW of the real-world aircraft with varying degrees of accuracy, generally in proportion to their price.

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But of course none of the above answers the OP's question regarding easyfbw.  So out of curiosity I downloaded it from the Avsim library and fired up my trusty FS9 for the first time in many months.

 

After a few minutes playing around I can confirm it doesn't work, at least on my system.  The pop-up window reads out the joystick X and Y coordinates with the FBW off, but on clicking the FBW on the joystick data freezes and the aircraft controls lock.  Clicking off the FBW restores control but the joystick data still doesn't show up in the pop-up, so it seems likely that the program's joystick input routine is hanging up.

 

The library entry is dated 2005, and Windows has moved on quite a bit since those days.   The program is probably doing some nifty stuff to intercept the joystick commands before FS9 gets them, and there may be some incompatibility somewhere that stops it working.

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At the end of the day the variables used by the sim to move the control surfaces are the same whether you move your control column or not. So the only way to have a FBW in the sim is to create your own variables that evaluate your control inputs and then create a system around those variables that only send inputs to the sim variables if certain conditions are met.

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