Van's Air Force
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A/P disconnect - stick or panel?
- Thread starter Tbone
- Start date
Rosie
Well Known Member
Here's a panel suggestion. I typically use the autopilot for long, cross-country trips; A/P engaged, both hands in my lap, eyes-outside with an occassional check of the instruments. When I'm ready to 'take control', left hand moves to the stick, right hand middle finger pushes the red A/P disconnect button then hand continues to the throttle (a very natural movement for me) 
Rosie
Rosie
flyvans.com
Well Known Member
a/p disconnect definitely on the stick!
especially when there is also a CWS (control wheel steering) function on the same knob to engage the autopilot.
especially when there is also a CWS (control wheel steering) function on the same knob to engage the autopilot.
N941WR
Legacy Member
Exactly what I did. My PTT is on top of my stick and the AP disconnect is in the trigger position. BTW, I have the teak grips and bought a couple of different size momentary push switches from McMaster Carr and used the one I thought would work best. Turned out to be the smallest one. Sorry, I don't recall the part number.
When I drilled the hole I did it in two stages. A small hole first, all the way through for the wires. Then using a slightly larger drill bit I enlarged the hole about 3/4 of the way through so the switch would be a snug fit.
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I also vote for the stick to utilize the CWS function. Keep in mind however it's not really CWS. It disconnects the AP for the time the switch is held down and reengages in a attitude hold when released. Still I like the function and use it more then I thought.
George
George
N941WR
Legacy Member
This depends on the AP installed. Press and releasing the button on the Dynon disengaged the AP. If you hold it down, it disengages it until you release the button. Another reason to put it on the stick.
pauldan181
Well Known Member
Stick is better
I have my TT disconnect/CWS button on the panel and don't like it there. I'm going to move it to the stick at the next condition inspection.
I have my TT disconnect/CWS button on the panel and don't like it there. I'm going to move it to the stick at the next condition inspection.
Definitely on the stick, if you feel like giving yourself a present there a some great vendors here that sell multifunction stick grips.
I am using the Tosten grip and really like it.
I chose to use the button on the front of stick under the press to talk, the button is recessed so it's harder to accidentally press.
Cheers
I am using the Tosten grip and really like it.
I chose to use the button on the front of stick under the press to talk, the button is recessed so it's harder to accidentally press.
Cheers
At least with the TT A/P you would need to keep pressing the GPSS button for a few seconds to get the A/P engagud. It is not a matter of a one push and the A/P turning to tracking.
Fair enough. Though, I can easily see myself unknowingly pushing it for more than a few seconds, e.g. when pulling for a loop, or vertical for hammerhead or flying inverted. It was a risk not worth taking for me. One less thing to worry about.
I vote for the stick. When you are half asleep and the auto-pilot starts going bananas you will naturally grab the stick. In such a scenario it is really difficult to put your finger on the button on the panel. Most autopilots I've flown the button turns off the A/P completely. I also like that.
Sam Buchanan
been here awhile
Red AP disconnect switch for the Trio Pro Pilot is located just above the throttle:
Very intuitive to find and can be pushed with my hand on the throttle either for disconnect or CWS.
Very intuitive to find and can be pushed with my hand on the throttle either for disconnect or CWS.
Why not go all the way?
Why not install a multi-button grip, Infinity or similar, and put the ptt, trim, AP disc/CWS, fuel pump, flaps, landing light/wigwag, and anything else you want on it. You can then run your whole pre-landing checklist without removing your hand from the stick. You would have to do some rewiring, from the panel location to the base of the stick.
Why not install a multi-button grip, Infinity or similar, and put the ptt, trim, AP disc/CWS, fuel pump, flaps, landing light/wigwag, and anything else you want on it. You can then run your whole pre-landing checklist without removing your hand from the stick. You would have to do some rewiring, from the panel location to the base of the stick.
And don't forget, master, starter, ignition, radio volume, OnStar, and cruise control!
Mine is on the panel
Since I like simplicity, I just use the one button stick grip, and put the A/P switch on the panel, close to the throttle control.
Since I like simplicity, I just use the one button stick grip, and put the A/P switch on the panel, close to the throttle control.
This is one of those areas where personal preference is really the determining factor, but I would make a general point on the autopilot disconnect switch: long ago, I was taught to always have your hand on the stick (yoke) when disconnecting the autopilot, for obvious reasons (at least to me). One way to be sure is to have the disconnect on the stick--that's why I am a proponent.
HOTAS
Exactly, Pat,
There is a practice used in some military flight programs called HOTAS, hands on throttle and stick. The idea is to keep your hands on the throttle and stick as much as possible, particularly during takeoff and landing, hence the concept of having much of the pre-landing checklist items on the grip, such as APD, landing light, trim, ptt, fuel pump, flaps, etc.
Exactly, Pat,
There is a practice used in some military flight programs called HOTAS, hands on throttle and stick. The idea is to keep your hands on the throttle and stick as much as possible, particularly during takeoff and landing, hence the concept of having much of the pre-landing checklist items on the grip, such as APD, landing light, trim, ptt, fuel pump, flaps, etc.
Sam Buchanan
been here awhile
This is one of those areas where personal preference is really the determining factor, but I would make a general point on the autopilot disconnect switch: long ago, I was taught to always have your hand on the stick (yoke) when disconnecting the autopilot, for obvious reasons (at least to me). One way to be sure is to have the disconnect on the stick--that's why I am a proponent.
That is why my panel mounted switch works very nicely--left hand on stick, right hand on throttle, right index finger on switch.
RV7Guy
Well Known Member
Clarification
I'm am wiring my panel on the new 7. My AP disconnect will be on the grip as it was with my first 7. Also, there is no reason you can wire in 2 switches for the same purpose, one on the stick and one on the panel.
After reading the posts, I was a little confused about what the CWS actually accomplishes. I want to be able to disconnect quickly. After reading some of the posts I thought that the CWS would re-engage as soon as you let off the switch/button. I shot an email to Lucas at TT and got the following response.
"It serves both functions. If you press and hold it, the AP will go into CWS mode. Upon release the AP will re-engage. But if you just press and release the switch the AP will disengage. I hope that clears it up."
Cleared it up for me
I'm am wiring my panel on the new 7. My AP disconnect will be on the grip as it was with my first 7. Also, there is no reason you can wire in 2 switches for the same purpose, one on the stick and one on the panel.
After reading the posts, I was a little confused about what the CWS actually accomplishes. I want to be able to disconnect quickly. After reading some of the posts I thought that the CWS would re-engage as soon as you let off the switch/button. I shot an email to Lucas at TT and got the following response.
"It serves both functions. If you press and hold it, the AP will go into CWS mode. Upon release the AP will re-engage. But if you just press and release the switch the AP will disengage. I hope that clears it up."
Cleared it up for me
Which is yet another reason why I would make the case for having the CWS/disconnect switch on the stick. If you use the Control Wheel Steering function, then it would make sense that it should be on the "control wheel." Typically you would use the CWS function when on autopilot and you momentarily want to take control, such as to deviate around traffic, then give it back to the autopilot.
Also, I would argue that anytime you would encounter a situation that would require an immediate control input (such as a bird, etc.), it would probably be faster to have the disconnect on the stick. Just food for thought.
Also, I would argue that anytime you would encounter a situation that would require an immediate control input (such as a bird, etc.), it would probably be faster to have the disconnect on the stick. Just food for thought.
I'm am wiring my panel on the new 7. My AP disconnect will be on the grip as it was with my first 7. Also, there is no reason you can wire in 2 switches for the same purpose, one on the stick and one on the panel.
After reading the posts, I was a little confused about what the CWS actually accomplishes. I want to be able to disconnect quickly. After reading some of the posts I thought that the CWS would re-engage as soon as you let off the switch/button. I shot an email to Lucas at TT and got the following response.
"It serves both functions. If you press and hold it, the AP will go into CWS mode. Upon release the AP will re-engage. But if you just press and release the switch the AP will disengage. I hope that clears it up."
Cleared it up for me
Unless I have a different version of the TT that is not correct. If you push and release the autopilot switch it disengages. No issue there. If you push and hold the button down it does the exact same thing. The autopilot disengages. The difference is that when you have held the button down the autopilot will reengage when the button is released. It never goes into a CWS mode. I am not sure why they even call it that. A CWS mode leaves the autopilot engaged and the autopilot and servos are still flying the aircraft. Inputs to the autopilot are made with the stick rather then the EFIS or control head. There is a vastly different feel to a aircraft using a CWS system when engaged and it requires a different control technique.
This is not a slam on the TT autopilot. Initially I did not really want the button on the stick. My partner wanted it there so I agreed. It turns out he is much smarter then me and I find both functions of the button very useful on the stick and would not switch back. I dodged a bird just last week with the button on the stick. Had it been on the panel as in our prior setup my only option would have been to duck. Both the disconnect and poor mans CWS have been getting far more use then I imagined.
George
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Gee thanks. Now buy me dinner.
Regarding dodging birds & other emergency maneuvers with autopilot on, every autopilot I have ever used could easily be overpowered with the control stick/yoke without disengaging the autopilot. I believe there is a requirement for that to be possible, with the force to overpower the autopilot being not in excess of (some number I don't remember) pounds.
cfiidon
Well Known Member
I cannot speak for TT, but on my Dynon AP it works like this:
Press and hold button, engages autopilot, syncs heading and altitude. Release.
Press and hold: CWS mode, hand fly but does not change the prior selected heading and altitude. Release and it goes back to AP at former heading and altitude.
Press and hold to engage as above. Press and release to disengage. Subsequent press and hold establishes NEW heading and altitude.
So for me it is Control Wheel Steering .... Perhaps the TT works similarly?
Don
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Mike S
Senior Curmudgeon
CWS TruTrak
Here is a copy/paste from the TruTrak website, explaining CWS.
BTW, my button is on the stick, and mine works exactly as described.
Q - What is Control Wheel Steering?
A - The control wheel switch is a momentary low contact switch mounted on the control wheel/stick. When the switch is held down for 1.5 seconds or more, the autopilot enters the control wheel steering mode. During the time that the switch is held down, the servo/servos will be disengaged and the pilot can manually fly to the new desired track. Upon release of the switch, the unit will synchronize to the track being flown at the time. All of the multi-axis with vertical speed capability will also synchronize to the vertical speed being flown at the time of control wheel switch release. A momentary push and release of the control wheel switch will disengage the autopilot.
http://www.trutrakflightsystems.com/faq.html
Here is a copy/paste from the TruTrak website, explaining CWS.
BTW, my button is on the stick, and mine works exactly as described.
Q - What is Control Wheel Steering?
A - The control wheel switch is a momentary low contact switch mounted on the control wheel/stick. When the switch is held down for 1.5 seconds or more, the autopilot enters the control wheel steering mode. During the time that the switch is held down, the servo/servos will be disengaged and the pilot can manually fly to the new desired track. Upon release of the switch, the unit will synchronize to the track being flown at the time. All of the multi-axis with vertical speed capability will also synchronize to the vertical speed being flown at the time of control wheel switch release. A momentary push and release of the control wheel switch will disengage the autopilot.
http://www.trutrakflightsystems.com/faq.html
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R. Daniels
Well Known Member
It's up to the builder to program the servos for the lightest torque value that will allow the A/P to fly the plane. RV's have light control forces and only need a low torque value. Trial and error here. All the A/P's I've installed in RV's are set really low. It's very easy to control the A/C with the A/P engaged. That said, I have mounted the disengage button in all cases on the stick. My personal A/C (RV-8) has infinity grips. I use the "pinky" finger button for my A/P disengage. When I fully grip the stick and squeeze I automatically hit the switch.
Mike, I suspect I have not made myself clear. That is how my TT works. It's not however how a true CWS system works. In a true CWS system the servos remain engaged. You supply the input to the autopilot to run the servos from the stick. The aircraft will maintain the exact attitude it's at if the stick is released. It's a expensive system to install because you have to have stick sensors to feed the autopilot inputs. In all the expermental systems I have seen pushing CWS disconnects the servos and your hand flying until you release the button and the servos engage again. With a true CWS system you are not hand flying. Very different feel to the stick in CWS also.
George
Like the autopilot function on the EFIS?
A/P momentary switch on the stick, plus A/P functionality via the EFIS (Dynon Skyview) here.
az_gila
Well Known Member
And the alternative method can simply be a pullable breaker on the circuit that provides power to the servos.
Simply bypass all of the software and hardware in the loop.
Norman CYYJ
Well Known Member
All autopilots that I have worked on over the last fifty years have a master power switch to the entire system. You must have a way of turning them off that cannot fail in the event that it fails, whether it is on an aircraft, boat or ship.
A/P Disconnect
I have the GRT Sport in my 7A project with the GRT A/P servos. I have DPST momentary on switch on the panel. This switch when depressed will either engage or disengage the A/P. This system also has a disconnect only switch will be on the stick. This gives me the safety of having to reach to the panel to turn the A/P on so as to not accidently engage it at the stick. But I have the ability to disengage the A/P from either position with the stick switch being closer for an emergency disconnect.
I have the GRT Sport in my 7A project with the GRT A/P servos. I have DPST momentary on switch on the panel. This switch when depressed will either engage or disengage the A/P. This system also has a disconnect only switch will be on the stick. This gives me the safety of having to reach to the panel to turn the A/P on so as to not accidently engage it at the stick. But I have the ability to disengage the A/P from either position with the stick switch being closer for an emergency disconnect.
