Rudder Pedal Spacing - How Far Apart Should They Be?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by wsimpso1, Mar 3, 2019.

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  1. Mar 5, 2019 #21

    pictsidhe

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    I don't like the idea of adjusting your rudder to stretch your legs. In unexpected events, you may lack time or coordination to wind them back into reach. My cockpit will be snug. I am hoping I can have tubular pedals that I can tuck my feet underneath. If they are ground adjustable for height and reach, that would work for anyone. In unexpectedly bumpy air, I can reposition my feet quickly, or even pull on the pedals. Later spitfires had "two step" pedals. The lower step for comfort during the long boring parts of flight, the upper step for combat. This idea may be adaptable for us too. During cruise, we won't need much rudder.
     
  2. Mar 5, 2019 #22

    Toobuilder

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    Have to agree with NOT having the pedals adjust in flight "for comfort". Move your feet to the side, sure. But fiddling with a lever/knob at a critical time is not a great plan IMHO.

    Also, I have a hard time justifying a left side throttle on a side by side. Would like to hear about the circumstances that drove that choice.
     
  3. Mar 5, 2019 #23

    BJC

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    I learned to fly with the stick in my right hand (7AC, J-3, PA-12 & -18, 7 & 8KCAB, etc.). Then flew serious aerobatics for many hours with the stick in my right hand. Had 30 minutes flight time with the stick in my left hand before making the initial flight in my then new Sportsman2+2 with the stick in my left hand. It never seemed un-natural or awkward.

    Bill, I predict that it will be the same for you if you elect to place the engine controls in the center.


    BJC
     
    Last edited: Mar 5, 2019
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  4. Mar 5, 2019 #24

    wsimpso1

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    Go ahead.
     
  5. Mar 5, 2019 #25

    BJC

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    Bill:

    I’m guessing that your airplane is intended more for cross country than for maneuvering, so the stability will allow for steady hands-off flight.

    Also assuming that you will have a two axis autopilot.


    BJC
     
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  6. Mar 5, 2019 #26

    Toobuilder

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    Without hearing your reasons (I hope you share), I think one gives up a bunch of utility by having a throttle restricted to only one pilot. Especially with a pilot spouse. I also share the opinion that left stick/right throttle is not hard to get used to. My Hiperbipe was so equipped and I would frequently jump back and forth between it and the conventionally configured RV-8 and Rocket without a thought. Finally. If you must have the throttle in the left hand, fly PIC from the right seat.

    Also, as this is a cross country ship, I expect that you will spend the vast majority of your time on autopilot. This further removes the need to have fighter pilot ergonomics.
     
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  7. Mar 5, 2019 #27

    wsimpso1

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    I usually go the duration of the cruise phase of a flight without pushing on either rudder pedal, even when hand flying. The closest I have had in 2100 hours and a lot of long trips is speedy disengagement of the autopilot and pitch/roll away from a King Air that looked like it was on a high deflection angle gunnery pass at me.

    Please detail events that actually occur in high altitude cruise that require immediate access to full travel of the rudder.

    Billski
     
  8. Mar 5, 2019 #28

    wsimpso1

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    Byron, I am not married to using the stick or throttle with one hand or the other. I was just trying to fit everything necessary in the airplane. Billski
     
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  9. Mar 5, 2019 #29

    wsimpso1

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    The issue is not one of preferred hand, just of fitting the needed stuff inside the cockpit.
     
  10. Mar 5, 2019 #30

    wsimpso1

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    Now what the heck? I had written a post about my mission, design and layout decisions... Sigh.

    Mission is cross country with lots of people and baggage room, plus gentlemen's aerobatics. The large baggage bay drives more fuselage length forward and aft of the wing than is typical to keep the airplane flyable over the range of weight and CG. This ends up putting the seat bottom pans over the spar set.

    Elevator and flap (Johnson bar) mechanisms pass over the aft spar between the seats, and pretty well fill the console.

    I like quadrants, so it could easily go on the left wall with good ergonomics, but it appears to be pretty badly positioned hanging off the panel and out of the way of other stuff there.

    Wife and I split flying duties by having the pilot flying sit left seat, so everything is set up around left seat PIC.

    If I just had to have throttle quadrants available to both pilots, I could run a quadrant on the right wall with paired cables linking each lever of the two quadrants together. Right side might be a tad mushy, but it would work.

    The other option is push-pull with Vernier on the panel near centerline.

    Now I gotta go out to the shop and see how that might all fit.

    Billski
     
    Last edited: Mar 5, 2019
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  11. Mar 5, 2019 #31

    Topaz

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    I keep forgetting that you guys are always flying in smooth air. :gig:
     
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  12. Mar 5, 2019 #32

    BJC

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    Well, I've never been able to react to rough air with the stick between my knees.

    BTW, I do not often fly with the autopilot engaged, but I do like it when in class B with heavy traffic or other heavy traffic areas.


    BJC
     
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  13. Mar 5, 2019 #33

    davidb

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    No need to route mixture and prop controls to the right side. Just having a second throttle control in the center or right side would give the right seater the ability to land or go around. Might that simplify installation a bit?
     
  14. Mar 5, 2019 #34

    BoKu

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    This pretty much covers what I came here to add. The ergonomics of sailplane cockpits is a 3D concern that is to a surprising degree constrained by the 2D nature of knee joints. At issue is that most modern sailplanes have a center stick and an instrument pedestal or column between the pilot's legs that enforce a certain amount of what subway commuters call "manspreading." With the knees held apart by the cockpit infrastructure and the heels constrained by the tapering of the fuselage nose, the optimal angle for the pedal platform or crossbar, or for the pedal pivot, is not necessarily parallel to the aircraft lateral axis. Most modern sailplanes, mine included, have about a 15-degree angle between the pivot axes of the two pedals. The pedals themselves are relatively planar, so the 15-degree angle is reflected at the pedal crossbar as well. The result is a low-fatigue system in which the rudder is operated essentially by the ankles alone, and in which the pivoting of the ankle involves only the very natural deflections used during normal activities such as walking.

    Bottom line, I'd locate the bottom of the pedals wherever convenient, but then I'd do a round of sit-ins to play around with the pedal and pivot angles to make them relatively neutral to the alignment of the lower leg. If you don't use the rudder a lot, it might be acceptable to have the pedal crossbars at a slight angle, but with pivots parallel to the lateral axis.

    --Bob K.
     
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  15. Mar 5, 2019 #35

    Pops

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    I understand completely. My left ankle has a bone graft and pins to lock one joint and very limited and marginal movement for the amount of movement required to operate toe brakes in the other joint. I have to adjust the toe brake angle to get it just right or I have to lift my leg and use my heel on the toe brake.
     
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  16. Mar 5, 2019 #36

    don january

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    Pops looks like we need to tap and drill your ankles for a grease Zerk. :) Stiff ankles is one reason I went heel brakes on mine.
     
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  17. Mar 5, 2019 #37

    Pops

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    Grease will not help bone grafts and pins :) I fell about 16'-18' and landed on concrete with my left leg straight down. Lots of broken bones in my left leg and damage to my hip and back. Concrete is HARD.
    Cast from toes to hip for 6 months two times.
     
  18. Mar 5, 2019 #38

    wsimpso1

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    I thought I was simplifying by skipping mixture and alternate air...
     
  19. Mar 5, 2019 #39

    Daleandee

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    In my Cleanex (Corvair/Sonex) sitting in the left seat gets a comfortable set of pedals to use that are about shoulder width apart. Because I have a single center stick I have the option to change up and sit in the center using the outside rudder pedals which are obviously wider but still quite comfortable. Makes for a wide cabin single seater ... and much easier to watch your six.

    I see you are building a center console with dual sticks so this option isn't something that would work ...

    Dale
    N319WF
     
  20. Mar 5, 2019 #40

    Pops

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    My Falconar F-12 had rudder pedals on both sides ( 2 place , side by side) with a single center stick and flap handle and a Piper style overhead elevator trim crank. Engine controls on the left side. I liked everything, I could set towards the center and use the outside rudder pedals except having to use the flap handle that was down between the seats. No problem in cruise on a long trip. Could also put both feet in between the rudder pedals and extend my legs towards the firewall to stretch out. Lot of room to move around. Lots of long trips in this airplane.
     
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