Question: Your take on Fly-By-Wire, Power-By-Wire etc. in Light aircraft

[facthunter]

I don't agree with your conclusion TJ. It doesn't have to be resistance to change etc. It's really not appropriate to our part of flying which is essentiallly simple, basic and to do with manipulating an aircraft. I like the challenge of starting a big radial or using a hand primer and getting the engine to fire up ever so gently> Hydraulic controls are necessary on the larger aircraft as the effort needed is of a large order to overcome the aerodynamic loads. Fly by wire is appropriate to the fighters that can't be manually flown because they are designed unstable in order to be highly manoueverable. Modern jet transports are using fly by wire because it reduces the number of people required to manage a large complicated aeroplane. None of the last three apply to us. That's the point. It woudn't be progress to go down that road, unless you don't actually like flying a plane. Model helicopters are almost unflyable without gyro stabilisation. U/L's should not be unstable and should be nice to fly, if they are built right. Nev

 

 

[Guest Andys@coffs]

A few points for consideration:-

 

1) so the biggest issue in our aircraft is weight. Im not convinced that DFBW will reduce weight in our aircraft, rather its likely to increase it. Im my J230 control is by a few sheathed push/pull cables (Bowden) just a bit bigger than push bike brake cables. any form of encoder (synchro) and servo motor(artifical feedback) at the stick and then encoder and motor at the control surface is very likely to weigh significantly more.

 

2) Exactly what problem does this advance solve for us. In our aircraft class control surfaces arent too heavy, or dynamically unstable. complexity rises orders of magnitude (F111's I used to work on had 3 flight computers, so that you could build in voting logic between all 3 in case one hard failed or worse comanded incorrectly, in which case the other 2 agreeing with each other could vote and boot out the failed device) In itherwords given criticality redundancy is required...there goes more weight

 

3) Our DC power systems are pretty agricultural and again for reasons of weight cant deliver too much power. The ignition systems, knowing power is a commodity thats good, but not always guarenteed, operate independent of power and duplicated for redundancy. If FBW requires gurenteed electircal power then introduce complexity and redundancy into that system.

 

4) We dont do hydraulics when our planes grow into something bigger maybe, but we dont want or need that complexity

 

5) Computer power is not the important aspect here, the fact that I can build a computer for 20gms where it used to be 200gms is irrelevant when the actuator motors are still 5kg plus and for us in the worst possible location as far away from the COG as we can get.

 

6) In your original post you seemed to infer that a common feel to flying a DFBW would be a good thing. In the big end that may be so, but at our end its the differences between each model and manufacturer that we celibrate. If a Jab230 and a sportstar ended up feeling the same to fly what on earth would we argue about on places like here.People like Tomo for example seem to get great joy telling us that theyve added another type to their belt and more power to them.

 

As an ex avionics tech, I wouldnt touch DFBW on primary flight controls with a barge pole at present. To get it to the point where I was satisfied that it was safe and foolproof would mean the aircraft couldnt lift my heavy A$$ and be under MTOW. Synchros (lesser extent) and Servos (greater extent) cost heaps of weight if they are able to exert the same flight control surface forces as I can through the cable systems I have on my aircraft.

 

Andy

 

 

[Guest Andys@coffs]

Oh great. every time you get swept by radar, you lose control, due to the interference with the signal. or someone jams it with the microwave!

Yeah I can just see me briefing the passenger..

 

"Mobile phones can interfere with our navigation and anger management systems causing us to beat you to death with your 3G handset, with some luck the beating will turn off the phone before we test the what happens when an immeasurable force is applied to an immovable earth"

 

 

[Powerin]

[Litespeed]

And it adds a new dimension to a "computer crashing"

 

There is a old joke about why pilots would not use windows in a aircraft, been around since the early 90's- still holds true.

 

As a side issue- what happens in a fully computer controlled plane if some one gives you a virus?

 

Or decides they want to take control mid flight for safety or malicious reasons?

 

Or its inbuilt safeguards on flight performance ban you from doing whats needed to stay alive?

 

Think about all those Toyota recalls and unintended acceleration - would you trust such a system?

 

Even such a simple things as a car GPS is completely wacko sometimes and takes you the opposite direction to what you ask for.

 

The only computer a light plane needs is the brain of the pilot- 6 billion made and counting.

 

 

[Guest davidh10]

...Or its inbuilt safeguards on flight performance ban you from doing whats needed to stay alive?

or worse, it takes a dislike to the pilot and decides to kill you...

For those old enough to remember.... the words of HAL in 2001 a Space Odyssey.

 

Open the pod bay door HAL.

 

I'm sorry, Dave. I can't do that. This mission is too important....

 

 

https://www.youtube.com/watch?v=ukeHdiszZmE

 

"No; Dave; Don't do it; Dave; Stop; Dave; Will you stop Dave; I'm afraid; My mind is going...

 

 

[rdarby]

I don't think it's resistance to change. Actually I think resistance to change stops a lot of good ideas, but in this case are we not really talking about us becoming more than recreational again? If you do FBW, why not get something to control you in controlled airspace, and then go above 10000ft, and while you are at it, register you new plane as GA.

 

I want to keep the little home mades alive.