Fly-by-wire and gliders

We have not seen much performance increase with new gliders for couple of decades, other than increased wingloading. I wonder if anyone has run the numbers for glider with FBW steering. I'm thinking of flapped glider with multiple moving segments of flaps (independent servos) and very small rear fuselage/tail, possibly with only minimal elevator (like Genesis2). Designed stability would not be issues as FBW brain would keep nose pointed to where you want all the time, glider could be aerodynamically unstable like modern fighter. Rudder authority would not be issue as yaw could be partly controlled with outboard flaps acting as spoilers, possibly airbrakes could be done with flaps only, FBW would adjust for configuration changes. Probably rudder pedals could be "optional" as FBW could keep "yaw string" centered. No need for control lines or flap mixers. Power for FBW and servos would need few bigger lithium batteries.

I'm visioning glider flying into thermal, where you just press "auto-thermal" and enjoy scenery.

Auto-Thermal scenery would have been enjoyable yesterday, where the strongest lift was frequently towards the wall of granite.
Jim

On Thursday, October 30, 2014 12:20:10 PM UTC-5, krasw wrote:
We have not seen much performance increase with new gliders for couple of decades, other than increased wingloading. I wonder if anyone has run the numbers for glider with FBW steering. I'm thinking of flapped glider with multiple moving segments of flaps (independent servos) and very small rear fuselage/tail, possibly with only minimal elevator (like Genesis2). Designed stability would not be issues as FBW brain would keep nose pointed to where you want all the time, glider could be aerodynamically unstable like modern fighter. Rudder authority would not be issue as yaw could be partly controlled with outboard flaps acting as spoilers, possibly airbrakes could be done with flaps only, FBW would adjust for configuration changes. Probably rudder pedals could be "optional" as FBW could keep "yaw string" centered. No need for control lines or flap mixers. Power for FBW and servos would need few bigger lithium batteries.

I'm visioning glider flying into thermal, where you just press "auto-thermal" and enjoy scenery.

I would hazard a guess that you haven't flown an older ship against a newer ship if you believe that the only difference is wing loading. The older airfoils "went to worms" with rain or bugs, or if you pulled a wee bit too hard in the thermal.

FBW is not going to boost glider performance. Glider performance comes from laminar flow and lack of separated flow much more than from reduced stability and a computer working to keep you pointed where you think you want to go.

And, there are certain sailplanes that already let you sit back and enjoy the scenery while thermalling. And they don't require FBW. Unless you consider the 7 x 19 cables that are hooked from the control surfaces to the pilot input devices. :-)

Just my two cents worth.

Steve

On 10/30/2014 1:20 PM, krasw wrote:

I'm visioning glider flying into thermal, where you just press "auto-thermal" and enjoy scenery.


Is that what you really want? Whats the point? Why not just pop in a
National Geographic blu-ray on your 80" plasma and enjoy the scenery on
the couch?

Luke

On Thursday, October 30, 2014 12:20:10 PM UTC-5, krasw wrote:
We have not seen much performance increase with new gliders for couple of decades, other than increased wingloading. I wonder if anyone has run the numbers for glider with FBW steering. I'm thinking of flapped glider with multiple moving segments of flaps (independent servos) and very small rear fuselage/tail, possibly with only minimal elevator (like Genesis2). Designed stability would not be issues as FBW brain would keep nose pointed to where you want all the time, glider could be aerodynamically unstable like modern fighter. Rudder authority would not be issue as yaw could be partly controlled with outboard flaps acting as spoilers, possibly airbrakes could be done with flaps only, FBW would adjust for configuration changes. Probably rudder pedals could be "optional" as FBW could keep "yaw string" centered. No need for control lines or flap mixers. Power for FBW and servos would need few bigger lithium batteries.

I'm visioning glider flying into thermal, where you just press "auto-thermal" and enjoy scenery.

Windward has at least one Duckhawk flying with auto-flaps...

Condor?

Ernst

While I am not looking forward for any automatic controls, I agree with the OP that FBW will significant improve performance. I believe the lost of performance due to inaccurate pilot input, un centered yaw string (heavy foot), non optimal flap position (I estimate I am flying in non optimal flap position maybe 30% of the time especially when doing a lot of transitions), flying too slow/too fast etc hurts performance more than the difference in glide performance between modern gliders.

Ramy

so... You want to eliminate all the things that make soaring challenging?

Dan Marotta

On 10/30/2014 6:04 PM, Ramy wrote:
While I am not looking forward for any automatic controls, I agree with the OP that FBW will significant improve performance. I believe the lost of performance due to inaccurate pilot input, un centered yaw string (heavy foot), non optimal flap position (I estimate I am flying in non optimal flap position maybe 30% of the time especially when doing a lot of transitions), flying too slow/too fast etc hurts performance more than the difference in glide performance between modern gliders.

Ramy

On Thursday, October 30, 2014 6:13:41 PM UTC-7, Dan Marotta wrote:
so...* You want to eliminate all the
things that make soaring challenging?

Dan Marotta
On 10/30/2014 6:04 PM, Ramy wrote:



While I am not looking forward for any automatic controls, I agree with the OP that FBW will significant improve performance. I believe the lost of performance due to inaccurate pilot input, un centered yaw string (heavy foot), non optimal flap position (I estimate I am flying in non optimal flap position maybe 30% of the time especially when doing a lot of transitions), flying too slow/too fast etc hurts performance more than the difference in glide performance between modern gliders.

Ramy

No no, I don't want this, just agreeing with the OP that this will indeed improve performance, but in the account of fun and challenge.

Ramy

On Friday, 31 October 2014 02:04:10 UTC+2, Ramy wrote:
While I am not looking forward for any automatic controls, I agree with the OP that FBW will significant improve performance. I believe the lost of performance due to inaccurate pilot input, un centered yaw string (heavy foot), non optimal flap position (I estimate I am flying in non optimal flap position maybe 30% of the time especially when doing a lot of transitions), flying too slow/too fast etc hurts performance more than the difference in glide performance between modern gliders.

Ramy

Yes and we have to remember that whole concept of conventional glider with tail has built-in-drag as elevator pushes the tail down all the time instead of giving only occasional control inputs. I bet there is several extra % of drag right there, as is in the large wetted area of long rear fuselage and rudder, which is only needed to counteract the yaw created by aileron drag. Flight controls have to be designed to have nice feel and harmony. Would there be more aerodynamically optimal geometries if this would be a non-issue? You could program any control feel you wish to joystick.

New wingprofiles (current are from nineties BTW, Ventus 2 & ASW 27 etc.) could be used with more narrow area of optimum angle-of-attack as FBW could nail it indefinetly while thermalling.

One could speculate with safety aspects as well. FBW would be easily programmed with unability to stall. Think about it, only coordinated turns, if you pull the stick while thermalling low, nose would go up until close to stalling angle of attack but not an inch more.

I believe hardware is coming cheaper and easily available as this is all stuff that UAVs use right now. You probably got most of the required sensors in your pocket right now. And I bet that at least some Akaflieg have studied this concept already.

Would we want FBW controlled glider? Did we want glider made from glassfibre instead of wood during 60s? Electrical varios during 70s? Or GPS in 90s? PW5? (No wait, no-one wanted that.)

THEY ALL RUINED THE SPORT when introduced, remember?