Fly-by-wire and gliders

One thing to consider is what will happen when the FBW will fail from some reason and you end up with pilots who don't know how to fly manually as happened to AF447.

Ramy

On 10/31/2014 3:22 PM, Ramy wrote:
One thing to consider is what will happen when the FBW will fail from
some reason and you end up with pilots who don't know how to fly
manually as happened to AF447.

Ramy

Are you saying that simply pushing the "Return to Gliderport" button
might not always be an option?

Vaughn

I have worked with "Freedom's Wings International" for a few years now...(Flying for Pilots with Disabilities.)

Our gliders are fitted with "hand control" for rudder. The problem arises that the pilot must let go of the rudder control, to deploy the spoilers.....the spoilers are "notched" so they stay put, and the pilot goes back to rudder quickly....but a change in spoiler setting repeats the process...

After seeing a Duckhawk with electric flaps, and electric landing gear...I figured it would be nice to configure a glider with electric spoilers....Then there would be no need to take the hand off the rudder control....just push a button, or slide switch or whatever!

Of course radio controlled model gliders have everything fly by wire!


Cookie

One of the main issues with FBW is that there is relatively little in the way of off-the-shelf components of the right size and power to build the control systems out of. What OTS components are available from the world of sailplane-sized UAVs tend to be priced commensurately the low volume and specialized applications for which they were designed--which is to say, really freakin' expensive.

If somebody wants to jump into the market and make a line of high-reliability, low-power, servos and sensors and such, along with a networked FMS to run it all, I'm sure they could build it into quite a business in ten or twenty years or so.

FBW is the only reasonable way to get rid of the tail surfaces. That's easily 20% of the total drag and an easy 10% of the weight. All in all, I would think a 35-50% increase in performance is possible, once one can deal with the huge issues of implementing a FBW.

20+ years ago, I flew this Speed Canard ( http://en.wikipedia.org/wiki/Gyroflug_Speed_Canard ) . No tail stabilizer, no FBW, and flying it didn't require any special skill (I've never had any ;-) ). Nice to fly. It actually even wouldn't stall.
I guess this proves that instability is actually not a problem. Indeed, if the speeds unwillingly increases, we don't wait for stability to correct, we pitch up ourself well before !
Or do I get it wrong ?

On Tue, 04 Nov 2014 01:53:34 -0800, Francois VG wrote:

20+ years ago, I flew this Speed Canard (
http://en.wikipedia.org/wiki/Gyroflug_Speed_Canard ) . No tail
stabilizer, no FBW, and flying it didn't require any special skill (I've
never had any ;-) ). Nice to fly. It actually even wouldn't stall.
I guess this proves that instability is actually not a problem. Indeed,
if the speeds unwillingly increases, we don't wait for stability to
correct, we pitch up ourself well before !
Or do I get it wrong ?

As I understand it, the main problem with flying wings is that, contrary
to popular superstition, they are not particularly efficient due to the
reflexed wing sections that are often used on flying plank designs, i.e.
no or minimal sweepback, and the often extreme amounts of wash-out that
many swept wing designs need to be stable.

In the competition free flight model world, which requires models to be
auto-stable since they are not remotely controlled, you never see flying
wings in competition with conventional layouts and the designs flown in
specialist tailless competition classes have clearly inferior performance.

Its also noticeable that contemporary 'tailless' high performance gliders
and light aircraft such as the Genesis II, Gyroflug Speed Canard and
VariEZE are *not* tailless designs.

If anybody on the list has flown a true tailless glider, such as the
Hortens or the French Fauvel designs, it would be interesting to hear how
they rate their performance against similar conventional designs.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

"...no tail stabilizer..."

What do you call that canard? ...And those vertical thingies on the
wing tips...

Dan Marotta

On 11/4/2014 2:53 AM, Francois VG wrote:
20+ years ago, I flew this Speed Canard ( http://en.wikipedia.org/wiki/Gyroflug_Speed_Canard ) . No tail stabilizer, no FBW, and flying it didn't require any special skill (I've never had any ;-) ). Nice to fly. It actually even wouldn't stall.
I guess this proves that instability is actually not a problem. Indeed, if the speeds unwillingly increases, we don't wait for stability to correct, we pitch up ourself well before !
Or do I get it wrong ?

I've been intrigued by the no horizontal stab idea for that reason. A clever fellow implemented a simple control system on a model sailplane and was able to achieve this. He explains the design problem really well too. Here's the page for those interested.
http://www.charlesriverrc.org/articl...lke_asfwpp.htm

I wonder what performance hits there may be while thermalling? This is a problem that the Genesis I/II faces.

I'd love to try it on a model glider, but not on full-scale. Too easy to imagine what happens if the angle of attack sensor vane fails... aka the X-31 crash and so on...

On Saturday, November 1, 2014 7:17:12 AM UTC-4, J. Nieuwenhuize wrote:
FBW is the only reasonable way to get rid of the tail surfaces. That's easily 20% of the total drag and an easy 10% of the weight. All in all, I would think a 35-50% increase in performance is possible, once one can deal with the huge issues of implementing a FBW.

Show me a soaring bird without movable tail surfaces, then I might consider it!

Mike