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Why are side sticks unpopular in sailplanes



 
 
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  #11  
Old February 19th 17, 07:44 PM posted to rec.aviation.soaring
Martin Gregorie[_5_]
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Default Why are side sticks unpopular in sailplanes

On Sun, 19 Feb 2017 08:02:38 -0800, Tango Eight wrote:

On Sunday, February 19, 2017 at 9:59:27 AM UTC-5, Martin Gregorie wrote:
On Sun, 19 Feb 2017 05:08:07 -0800, Tango Eight wrote:


Had a side stick for a decade. Center stick is just better.

Can you expand a bit, please?


Sure. I think the irreducible issue is simply one of leverage and
limited motion options. There's only one way to grip the stick, there's
only one way to interact with it.

All of the side stick designs I've seen for direct mechanical actuation
of controls require a sliding fore/aft motion for elevator (elbow +
shoulder) and a rolling motion of the wrist for aileron. Blending those
motions with finesse is just more work (more fatigue) than a
conventional gimballed stick. I landed out a couple of times in my side
stick glider simply because I got tired and sloppy after 4+ hours and
couldn't climb well. Coordination never became unconscious in that
ship.

The other things that I don't like about side stick equipped gliders
tend to be the *reasons* designers opted for side sticks, not the sticks
themselves: supine seating position, lousy forward visibility, tiny
instrument pods, cockpits with no extra space for anything.

That said, I have always had a desire to fly (but not own!) a Diana2,
just because the thing was so radical.

Thanks for the additional detail. Like you I'd like to check out a Diana
2 for comfort and forward visibility and wonder if cricked necks could be
a problem. I entirely understand your point about about panel space.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
  #12  
Old February 19th 17, 08:04 PM posted to rec.aviation.soaring
Martin Gregorie[_5_]
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Default Why are side sticks unpopular in sailplanes

On Sun, 19 Feb 2017 09:46:35 -0700, Bob Whelan wrote:

As a natural right-hander, I've often imagined adapting to a left-side
stick (think many powerplanes) would require far more "mental
adaptation" on my part than did adapting to my Zuni's right-side-stick.
Maybe some Airbus-driving glider pilots will chime in?

As a natural left-hander, I do most things left-handed. Yes, I built Free
Flight models with the timer on the left but the start trigger on the
right and I start engines left-handed. However, I had no problem learning
to fly gliders right-handed: that was a non-issue. These days I normally
fly right-handed and use my left for fiddling with instruments. I only
swap hands in the Libelle to raise or lower the wheel.

The only other thing I'm exclusively right-handed for is using cameras,
which all seem to be designed by right-handers for right-handers.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
  #13  
Old February 19th 17, 10:06 PM posted to rec.aviation.soaring
Del Jensen
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Default Why are side sticks unpopular in sailplanes

How does a side stick compare to a parallelogram stick (e.g. Glasflugel)?

  #14  
Old February 19th 17, 10:22 PM posted to rec.aviation.soaring
Dan Marotta
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Default Why are side sticks unpopular in sailplanes

Again, I've never flown a side stick, though if you think about it, a
simple Cessna with a yoke is flown with the left hand, ala side stick.

The parallelogram stick in the Mosquito feels better than a floor
gimballed center stick. It's very smooth operating and the throw is
small enough that you can fly with wrist motion. Very nice.

On 2/19/2017 2:06 PM, Del Jensen wrote:
How does a side stick compare to a parallelogram stick (e.g. Glasflugel)?


--
Dan, 5J
  #15  
Old February 19th 17, 11:45 PM posted to rec.aviation.soaring
Martin Gregorie[_5_]
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Default Why are side sticks unpopular in sailplanes

On Sun, 19 Feb 2017 13:06:04 -0800, Del Jensen wrote:

How does a side stick compare to a parallelogram stick (e.g.
Glasflugel)?


DG-300 is also a parallelogram stick AFAIK. I've not flown a Glasflugel
Mosquito but I have sat in one I was considering buying and handled the
stick. The Mossy and the DG-300 sticks seemed pretty similar except that
the Mossy's trim worked a lot better. From what others have said, it
sounds as though the side stick is less 'natural' because centralised
ailerons mean the handle sticks out horizontally from the cockpit wall
but in the DG-300/Mossy its vertical like a conventional stick. Both side
and parallelogram sticks require you to rotate your wrist to operate the
ailerons, though with a parallelogram stick that would depend on just how
you hold the stick.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
  #16  
Old February 20th 17, 07:12 AM posted to rec.aviation.soaring
[email protected]
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Default Why are side sticks unpopular in sailplanes

Are the differences in jets documented? The Saab Gripen has a center stick for example, despite being newer than an F-16.
Russians also standardized center stick.
  #17  
Old February 20th 17, 04:07 PM posted to rec.aviation.soaring
Michael Opitz
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Posts: 318
Default Why are side sticks unpopular in sailplanes

At 06:12 20 February 2017, wrote:
Are the differences in jets documented? The Saab Gripen has a

center stick
for example, despite being newer than an F-16.
Russians also standardized center stick.

Sure, they are documented. You can Google it. Stick location comes
down to manufacturer, engineer, and pilot preferences. Like I said, if a
fighter pilot takes combat hits and has injuries, then a center stick is
more accessible by either hand. On the flip side, if you are flying close

formation and maneuvering, the inflating and deflating g-suit on your
legs can cause one to bobble the stick if one uses one's thigh as a
forearm brace. (allows one to make very small corrections using the
wrists and fingers alone without moving the entire arm) That's why
the Blue Angels don't use g-suits. The side stick in this case has a
retractable forearm brace that is attached to the side of the cockpit,
which provides a rock-solid platform for one's forearm... Lockheed
products (F-16, F-22, F-35) have side sticks. Boeing / MD products
favor center sticks. As far as I know, all of the fighter side sticks
are mounted vertically with a center-up neutral point. Most (if not all)
are "fly by wire" and thus have pressure sensors embedded to sense
forces applied. This translates to maybe only 1 cm of actual stick
movement compared to a glider with manual controls (thus big control
stick deflections to incorporate into the cockpit design) and a stick that

has a neutral point laying on it's side ~50-90° to it's left. In a glider

cockpit, one would lose all of the space saving benefits of a side stick if

one mounted it vertically.
RO

  #18  
Old February 21st 17, 10:10 PM posted to rec.aviation.soaring
Bob Kuykendall
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Default Why are side sticks unpopular in sailplanes

I finally got a few minutes to respond in the long form. Here are a bunch of points in no particular order:

* For a human factors class towards my psych minor, my semester project was comparing a sliding side stick with a pivoting center stick for a simple tracking task. The results suggested that tracking was improved when it involved angular displacement of the wrist. Tracking was also improved with greater linear and angular travel.

* Because of their size and general characteristics, sailplanes tend to have long control system paths and also a lot of roll and yaw inertia. Flying a sailplane is definitely work in the technical sense of a force applied over a distance (control stick travel). The shorter the travel, the greater the force required to do the necessary work of defecting a control surface. But when you crowd the control stick up against the cockpit rail, you tend to run out of travel.

* From a practical perspective, if you're going to have a side stick, you improve its chances of working well if you:
-Maximize control stick travel
-Reduce control system friction
-Reduce control system slop and lost motion
-Increase control system stiffness (reduce "springiness")
-Reduce control system and surface inertia

To this end, some of the side stick implementations we've seen in the soaring world have been disappointing. In the HP-18, you get 4.3" of horizontal travel between full nose up and nose down. In that travel, you move two relatively large ruddervators that are sized and counterweighted more for their effect as rudders than as elevators. To move them, you slide 24 feet (!) of 5/8" aluminum tubing through a dozen raw nylon guides. The ailerons aren't much better, again using simple plastic guides. In both dimensions there tends to be a lot of slop and friction that effectively masks what little stability the ship has.

In the Zuni, the side stick is connected to an all-flying tailplane, which regardless of its demand for fine touch has a lot of inertia of its own.

* I flew an HP-18 once with the side stick, and converted it to center stick before I flew it again.

* I anticipate that we might see a resurgence in side stick adoption once fly by wire becomes more common. I figure we'll see a hybrid approach in which the control stick has a limited direct mechanical connection, say to the outboard flaperons and half of the elevator. That will be supplemented by electronic connections to inboard flaperons, spanwise camber control, and the other elevator half. Such a system would offer advanced control features including auto flaps, auto speed-to-fly, and perhaps even auto thermal centering, but still have enough control for a safe landing if the electronic stuff fails.

Thanks, Bob Kuykendall
https://www.facebook.com/HP-24-Sailp...t-200931354951
www.hpaircraft.com
  #19  
Old February 22nd 17, 04:52 PM posted to rec.aviation.soaring
[email protected]
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Posts: 15
Default Why are side sticks unpopular in sailplanes

I transitioned to Diana SZD-56 (identical side-stick to Diana 2) with 1500 hours. Gimbaled stick: no slide. It’s all in the wrist. Everyone asks how long does it take to get used to it? Answer: No time: it’s completely natural. Nobody believes me. But the stick is where my hand is. Central stick would be perfect if one’s hand came out of his fly.
“I like flying with a side stick. It feels natural.“ -Mike Opitz Feb 19
Switching hands? I’m not ambidextrous, but I have no trouble twiddling knobs with my left hand (or operating gear, spoilers or flapperons). And without a central stick, the closer instrument panel is very handy, so to speak.
Left-handers? While sitting, rest your right hand on your right thigh, and left on left. Now pretend you’re flying with a gimbaled side-stick on your right. Ask your left hand to mimic the motions of your right. It’s as if your hands were connected by a parallelogram.
“…no big deal with the stick in my left hand. -Mike Opitz Feb 19
“…I'd like to check out a Diana 2 for comfort and forward visibility and wonder if cricked necks could be a problem.” -Martin Gregorie Feb 19
Diana’s seating is almost too comfortable! Isn’t there an FAR against napping at altitude? Diana’s transparent canopy goes nearly to the nose, so forward visibility is as good as it can be. I never had a cricked neck, but looking up was a bit awkward. So I spring-loaded the headrest pivot. Now when I look up at clouds (or the rare glider temporarily above me) the headrest swivels down and then pops back up for cruising. Perfect!
-Jack Wyman


  #20  
Old February 23rd 17, 12:00 AM posted to rec.aviation.soaring
Soartech
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Posts: 268
Default Why are side sticks unpopular in sailplanes

I also flew a gimbaled side-stick for 8 years in a Millennium ultralight sailplane. It was so smooth, natural and comfortable I looked for a sailplane with the same arrangement. But alas, all I could find were clunky setups with sliding sticks. No wonder side sticks get a bad rap in our little world.. The center stick is OK, side stick is better, more natural.
 




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