Sidestick control vs control yoke vs panel-mounted control wheel

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SVSUSteve

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What are everyone's thoughts on each of the common control interfaces? I would honestly like to use a side stick control in my larger design (as I did in the Vireo LSA) because such a design minimizes obstructing the pilot's view of the instrument panel and also increases the distance between the pilot and the structures in front of him in the event of a crash.

At the same time, I have reservations about it with regards to making sure I can impart sufficient force with that approach at the extremes of the performance envelope (not that I plan to go there, but it is something I need to think about). It would seem to be much easier to impart some form of mechanical advantage through the use of a control yoke like is seen on airliners and some turboprops. Since I don't have the money for a fly-by-wire system and I like the "feel" of being directly connected to the control surfaces, I figured it would be worthwhile to get everyone's input on this.

Comments, questions, concerns and good natured ribbing are welcomed.
 

fly2kads

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One of the things that impressed me when sitting in a Cirrus was the feeling of spaciousness in the cockpit. Getting the stick off to the side made a big difference in how the cockpit "felt," in addition to the other factors you mentioned. Alas, I didn't get to actually fly the thing and try it out.

The FARs have guidance on permissible forces for control sticks and yokes, but I haven't seen anything comparable for side controllers. I'd like to see it if there is something out there.
 

SVSUSteve

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One of the things that impressed me when sitting in a Cirrus was the feeling of spaciousness in the cockpit. Getting the stick off to the side made a big difference in how the cockpit "felt," in addition to the other factors you mentioned. Alas, I didn't get to actually fly the thing and try it out.
Yeah, the spaciousness of the front seats is one of the few aspects of the Cirrus concept that I actually want to emulate.

The FARs have guidance on permissible forces for control sticks and yokes, but I haven't seen anything comparable for side controllers. I'd like to see it if there is something out there.
Here are the control stick and yokes.... http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/8c81806b17ac08e685256687006c07aa!OpenDocument&ExpandSection=-3

I'll go looking to see if I can find anything specific about sidesticks and report back.
 

Topaz

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I've flown panel-mounted yoke, center stick, and side stick. The yoke was in the Cessnas and Pipers, the center stick is in all the gliders I fly, and the side stick was in a LongEZE, from the back seat. My personal order of preference, best to worst:

1) Center stick
2) Side stick
3) Yoke

You'll note that all of my time is in aircraft much lighter than what you're designing. That may have influenced the order of #2 & #3. In a heavier airplane, I might switch those; I don't know.

I like a center stick best because, for me, it gives me the best stick-and-rudder feel for the aircraft. I feel closest to the aircraft with that arrangement. There's the added benefit that I can also clamp the stick with my knees if I need to look at a chart or something.

Side sticks are neat, but my experience in the LongEZE was that they were a little twitchy. I suppose that may be an individual design thing. I like them, and may use one in my own aircraft. I'm not that far yet.

Yokes feel like driving a car for me, and that takes some of the fun out of flying. I feel "separated" from the aircraft somehow. Completely a subjective thing.

Because it is so subjective, my best recommendation is to get some time with each type. A yoke and center stick shouldn't be hard to find, and with all the Cirrus flying around these days, side-stick time shouldn't be too terribly difficult either.
 

Rick McWilliams

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The control yoke is a complex system. There is usually considerable slop and friction between the yoke and the control surface. It is complicated; frequently having universal joints, cables, chains, torque tubes and fittings. I would guess that the yoke system adds about 15 pounds for a small 2 place dual control airplane. You can fly aerobatics with a yoke control airplane. It is kind of like moving the couch it only takes one person.

I am a fan of the between the legs stick. It is light and convenient. You can fly with either hand, with several grip positons. You can fly with you knees while eating a sandwich or folding a map. It provides simple friction free mechanical advantage to a pushrod type control system. It does make getting aboard a little more acrobatic. You need to learn how to get into any small airplane.

When I am flying acrobatics, I change hand for rolls in each direction. It is traditional to fly aerobatics with the right hand on the stick, left on the trottle. I usually land flying with the left hand on the stick and right on throttle. My Zlin has two throttles for ambidexterous control.
 

bmcj

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Ditto to everything Topaz said. For me, yokes feel unnatural, and center sticks seem very intuitive. Side sticks are great for space and OK for control, but like you said, they may lack some leverage. The other issue I have with side sticks is that you must always fly with the hand on the stick side, and there can be a tendency to pull toward you (a roll input) when you pull back for flare.
 

SVSUSteve

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Not FAA but I found this for the Europeans....

http://www.easa.europa.eu/rulemaking/docs/npa/2011/NPA 2011-09.pdf

14. Side stick controls
Structure item
For aeroplanes equipped with a side stick instead of a conventional control stick, the
current requirement of CS 25.397, which defines limit pilot forces and torques for
conventional wheel or stick control, is not adequate. Therefore a new subparagraph (d) of CS 25.397 is proposed to define the limit pilot forces for side stick controls. This proposal is based on several (generic) CRIs raised in the past for such installations.


Flight test/flight controls item
The introduction of side stick controllers notably associated with electronic flight control systems has required the consistent application of additional requirements to CS 25 to accommodate their features. The following changes to CS-25 are proposed:
(1) CS 25.143 Controllability and Manoeuvrability
A new subparagraph CS 25.143(k) is proposed to address the following items:
a) CS 25.143(d) prescribes for conventional wheel type controls the maximum control forces permitted during the associated controllability and manoeuvrability testing. In addition, there are also specific pitch control force limits prescribed by CS 25.145(b) and 25.175(d). These standards are not applicable to side stick controllers which have different stick force-deflection characteristics and are intended to be controlled with one hand. A new paragraph is proposed which replaces the prescribed stick force limits by requiring suitable side stick control forces for the expected the operating conditions.

b) It was recognised that piloting interaction with a side stick control device may be
adversely affected in turbulence conditions and consequently a new paragraph is
proposed requiring a test assessment in these conditions.

c) The use of side stick controllers together with electronic flight control systems
which provide control augmentation and control deflection limiting systems could affect piloting awareness that the aircraft is approaching a control limited flight condition. It may be that return to normal flight condition and/or continuing of safe flight needs a specific crew action. In these circumstances a suitable flight control position annunciation is required to be provided to the crew, unless other existing indications are found adequate or sufficient to prompt that action.
(2) CS 25.777 Cockpit controls
Side stick controller force-deflection characteristics in pitch and roll together with
displacement sensitivity and gains need to be evaluated. The intention is to show that normal inputs on one control axis will not cause significant unintentional inputs on the other. Consequently a new paragraph CS 25.777(i) is proposed requiring a suitable assessment.
This part of the FAR seems pertinent as well:
[SIZE=+1]Sec. 23.397 Limit control forces and torques.[/SIZE]
(a) In the control surface flight loading condition, the airloads on movable surfaces and the corresponding deflections need not exceed those that would result in flight from the application of any pilot force within the ranges specified in paragraph (b) of this section. In applying this criterion, the effects of control system boost and servo-mechanisms, and the effects of tabs must be considered. The automatic pilot effort must be used for design if it alone can produce higher control surface loads than the human pilot.
(b) The limit pilot forces and torques are as follows:
Maximum forces or torques for design weight, weight equal to or less than Minimum forces Control 5,000 pounds /1/ or torques /2/
Aileron: Stick 67 lbs 40 lbs. Wheel /3/ 50 D in.-lbs /4/ 40 D in.-lbs./4/ Elevator: Stick 167 lbs 100 lbs. Wheel (symmetrical) 200 lbs 100 lbs. Wheel (unsymmetrical) /5/ 100 lbs. Rudder 200 lbs 150 lbs.
/1/ For design weight (W) more than 5,000 pounds, the specified maximum values must be increased linearly with weight to 1.18 times the specified values at a design weight of 12,500 pounds and for commuter category airplanes, the specified values must be increased linearly with weight to 1.35 times the specified values at a design weight of 19,000 pounds.
/2/ If the design of any individual set of control systems or surfaces makes these specified minimum forces or torques inapplicable, values corresponding to the present hinge moments obtained under Sec. 23.415, but not less than 0.6 of the specified minimum forces or torques, may be used.
/3/ The critical parts of the aileron control system must also be designed for a single tangential force with a limit value of 1.25 times the couple force determined from the above criteria.
/4/ Dwheel diameter (inches).
/5/ The unsymmetrical force must be applied at one of the normal handgrip points on the control wheel.
[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as amended by Amdt. 23-7, 34 FR 13089, Aug. 13, 1969; Amdt. 23-17, 41 FR 55464, Dec. 20, 1976; Amdt. 23-34, 52 FR 1829, Jan. 15, 1987; Amdt. No. 23-45, 58 FR 42160, Aug. 6, 1993]
[SIZE=+1]Sec. 23.399 Dual control system.[/SIZE]
(a) Each dual control system must be designed to withstand the force of the pilots operating in opposition, using individual pilot forces not less than the greater of--
(1) 0.75 times those obtained under Sec. 23.395; or
(2) The minimum forces specified in Sec. 23.397(b).
(b) Each dual control system must be designed to withstand the force of the pilots applied together, in the same direction, using individual pilot forces not less than 0.75 times those obtained under Sec. 23.395.
[Amdt. 23-48, 61 FR 5145, Feb. 9, 1996]
[SIZE=+1]Sec. 23.405 Secondary control system.[/SIZE]
Secondary controls, such as wheel brakes, spoilers, and tab controls, must be designed for the maximum forces that a pilot is likely to apply to those controls.


Because it is so subjective, my best recommendation is to get some time with each type. A yoke and center stick shouldn't be hard to find, and with all the Cirrus flying around these days, side-stick time shouldn't be too terribly difficult either.
I have time in all three (well...."true" yoke time only in simulators) and I really dislike/distrust the Cirrus series (not because of the sidestick but for other reasons not germane to this discussion) so I'll never fly in one again.


ou can fly with you knees while eating a sandwich or folding a map.
That's what an autopilot and/or copilot is for. ;)

Center stick (as in just the metal pole between the knees) is not a consideration.

You can fly aerobatics with a yoke control airplane.
I'm not really looking to fly aerobatics but rather to just have sufficient mechanical advantage to allow for an upset recovery.

This post also has a good set of PDFs from the European perspective.

Yokes feel like driving a car for me, and that takes some of the fun out of flying.
How so?
 

Topaz

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Because a car is a car and an airplane is an airplane. It's all about feel. A wheel is very sensitive for control inputs in one plane of movement. I couldn't imagine heading into a turn in my 914 with anything but a wheel. But on an airplane, you have two planes of motion for a pitch/roll controller. Moving the same type of motion in two planes (as with a center stick) is smooth and intuitive - you're making the same type of motion throughout the control "volume". A yoke has you making automotive-style inputs (turning) for one axis, and airplane-style inputs (push-pull) for the other. Some part of me feels that dichotomy and it just doesn't feel natural to me.

Some of this may be because I have a lot of time driving cars fast, and some of it on tracks. I may simply have enough muscle memory there that a yoke, in the roll axis, is always going to jolt me out of "airplane" mindset into "car" mindset. And that's not fun for me.
 

Topaz

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Yes. The Money Pit. ;)

1973 2.0L Original stock with all the options except the automatic and the air conditioning (thank God!). The only thing that's been done to it is add 5-point racing harness mounts and a little more open exhaust. Handles (and rides) like a go-kart with license plates.


img182.jpg
 

bmcj

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A yoke has you making automotive-style inputs (turning) for one axis, and airplane-style inputs (push-pull) for the other. Some part of me feels that dichotomy and it just doesn't feel natural to me.
Very good point and very true. Obtaining a "balanced" feel between the two control axes is non sequitur because the two motions are so dissimilar.
 

Jay Kempf

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Yes. The Money Pit. ;)

1973 2.0L Original stock with all the options except the automatic and the air conditioning (thank God!). The only thing that's been done to it is add 5-point racing harness mounts and a little more open exhaust. Handles (and rides) like a go-kart with license plates.


View attachment 17025
I'm a 928er. One of my closest colleagues has a bumble bee 72 all stock and restored to death with the original Fuchs. What a great car although my head sticks out the top :).

Back to sticks.
 

Hot Wings

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I'll go looking to see if I can find anything specific about sidesticks and report back.

Unless you are considering a control setup like in the Cirrus a side stick, don't bother thinking about one for an LSA. Right now the required control forces (70 N) are WAY too high for a glider/EZ/BD-5 style side control. It's alleged that this is scheduled to get debated/changed but at the pace F-37 moves it may be a decade.
 

SVSUSteve

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Unless you are considering a control setup like in the Cirrus a side stick, don't bother thinking about one for an LSA.
Already done with the LSA design and yes, the design of the sidestick is like the Cirrus. I've never seen the sidestick in a glider (at least not the part that isn't plainly visible when the plane is ready to fly). What I'm working on now is the high-performance turboprop.
 

Topaz

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...I've never seen the sidestick in a glider (at least not the part that isn't plainly visible when the plane is ready to fly)...
Quite a large number (if not the majority) of high-performance gliders have a side-stick. The forces from the very narrow-chord control surfaces at the relatively low speeds (compared to a high-performance turboprop) mean that most of the usual problems with a side-stick go away.
 

SVSUSteve

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Quite a large number (if not the majority) of high-performance gliders have a side-stick. The forces from the very narrow-chord control surfaces at the relatively low speeds (compared to a high-performance turboprop) mean that most of the usual problems with a side-stick go away.
That's what I figured he was getting at but I just wasn't sure if there was something specific about the control mechanisms themselves or if it was simply a matter of the difference in speed and control surface area.
 

bmcj

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I want to reiterate one of my points about a sidestick which I think should concern SVSUSteve given the role of his design...

Unless you put a stick on both sides of the pilot's seat, sidestick must always be flown by the same hand... no swapping back and forth. This becomes a little bit of an issue with comfort and a big issue for doing other stuff (adjusting instruments and radios, eating a sandwich or taking a drink, copying clearances, etc).
 

SVSUSteve

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I want to reiterate one of my points about a sidestick which I think should concern SVSUSteve given the role of his design..
That's a very good point, although I would think that the aircraft being flown dual pilot for the most part would to most persons seem to be a solution. However, I do see the need to keep in mind the potential to have this aircraft being operated single pilot so perhaps this is the best argument against the sidestick. Thanks for point that out. I owe you one for that.

I may just have to utilize a yoke and figure out how to overcomes it's limitations.
 

Jay Kempf

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Unless you put a stick on both sides of the pilot's seat, sidestick must always be flown by the same hand... no swapping back and forth. This becomes a little bit of an issue with comfort and a big issue for doing other stuff (adjusting instruments and radios, eating a sandwich or taking a drink, copying clearances, etc).
I think two sticks/throttles/trims make a lot of sense for a single seater assuming the complexity and weight aren't an issue.
 

bmcj

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I may just have to utilize a yoke and figure out how to overcomes it's limitations.
Or a center stick. I've seen some nice center sticks contoured so that they are mostly out of the way or short ones mounted on a pylon on the front of the seat pan. Both are fairly unobtrusive and out of the way.

My preference though is still a stick (side or center) over a yoke. Yokes always seem to be in the way and block panel view. If you go with a left-side sidesticks, you can position the passenger's stick in the center console such that it is accessible by the pilot too... problem solved.
 
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