If I wanted Trim in the Stick (RV-12):

[txaviator]

I have been thinking it may be much more comfortable to install a trim buttom in the stick grip, along with the mic button (Ray Allen, etc.)

Wouldn't this be as simple as installing the new grip/buttons, and running the trim wires in SERIES with the existing trim wires going from the panel to the trim servo? Or would I tie them in via a parallel connection? In other words, where the panel trim switch would still operate, along with the stick trim switch.

My electrical mind isn't working yet this morning. Thanks for any advice!

 

[Mike S]

Not knowing for sure how your plane is wired, this is a bit of a guess, but I am pretty sure you would have to do a parallel setup, maybe even use a relay deck.

 

[txaviator]

Not knowing for sure how your plane is wired, this is a bit of a guess, but I am pretty sure you would have to do a parallel setup, maybe even use a relay deck.

Mike, I just ordered the grips and yep, the folks at RA told me I also needed the relay deck. Thanks for the info! Ordered that too. I'm with you, I'm thinking parallel?

It's just standard RV-12 trim wiring now...momentary trim switch in the panel, and basically the trim wires / servo power wires run thru the tunnel back to the trim servo under the stabilator.

 

[f1rocket]

Parallel. You can run the wires either to the servo or to the momentary switch in the panel (one to each side).

I wanted to do that as well when I bought my stick grips but since I'm strictly ELSA, no joy. Not sure I will go back and redo it once I'm flying.

One note, I had that setup in my Rocket and as was my custom, I'd read a book while travelling cross country. I once rested the book on the stick and it disconnected my autopilot by mistake. That was a little surprise.

 

[BobTurner]

Be careful here. The standard Ray Allen rocker switch shorts the wires to the motor together when the switch is in neutral (this helps stop the motor from coasting). If you just parallel the new wires from the stick to the motor wires then you will trip the CB if you use the stick switch.
You can "undo" the shorting feature (or perhaps you just have an ordinary double pole double throw switch in the panel without the shorting function) and then it (paralleling) will work, AS long as no one pushes both switches at the same time, and in opposite directions (e.g., copilot pushes panel switch for trim up, pilot pushes stick switch for trim down). If that happens you again will blow the CB.
There are various isolation schemes to prevent this from happening, the most common being the "relay deck". But there is no need to buy an expensive one from Allen, you can build your own. Another solution is to put in a switch which selects either the panel switch or the stick switch but never both.

 

[f1rocket]

Good explanation Bob. Thanks for that.

 

[txaviator]

Be careful here. The standard Ray Allen rocker switch shorts the wires to the motor together when the switch is in neutral (this helps stop the motor from coasting). If you just parallel the new wires from the stick to the motor wires then you will trip the CB if you use the stick switch.
You can "undo" the shorting feature (or perhaps you just have an ordinary double pole double throw switch in the panel without the shorting function) and then it (paralleling) will work, AS long as no one pushes both switches at the same time, and in opposite directions (e.g., copilot pushes panel switch for trim up, pilot pushes stick switch for trim down). If that happens you again will blow the CB.
There are various isolation schemes to prevent this from happening, the most common being the "relay deck". But there is no need to buy an expensive one from Allen, you can build your own. Another solution is to put in a switch which selects either the panel switch or the stick switch but never both.

Yes, thanks Bob! So, since I've already bought the RA relay deck, I should be able to wire it up so that I won't have fuse blowing problems- under the scenarios you mentioned? All I'm really wanting to accomplish is to have the sticks with trim in them, but also be able to use the panel trim just in case the stick switch went bad, etc. And it will be much easier to do my interconnect wiring at the momentary switch already in the panel. It's a much closer run, versus snaking a new wire all the way back to the tail/servo. Further thoughts? Thanks again!

 

[BobTurner]

I cannot remember exactly where - either they come with the Ray Allen trim deck, or they are on their web site - there are instructions on how to modify the rocker switch and how to wire it, and other switches, up to the relay deck. All the switch wires will go into the relay deck. Locate that wherever you like.

 

[rvbuilder2002]

Keep in mind that when a person starts modifying from an original design, there can be a lot of design aspects to consider... (seems like I write that a lot)

The standard RV-12 build has a PWM speed reduction for the pitch trim control system. If one is not used (don't know if your are using the Van's electrical system parts or not) the pitch trim will be extremely sensitive.

Any changes in the pitch trim control switch should include considerations for having (or not defeating what you have now) speed reduction of the pitch trim servo motor.

 

[txaviator]

Keep in mind that when a person starts modifying from an original design, there can be a lot of design aspects to consider... (seems like I write that a lot)

The standard RV-12 build has a PWM speed reduction for the pitch trim control system. If one is not used (don't know if your are using the Van's electrical system parts or not) the pitch trim will be extremely sensitive.

Any changes in the pitch trim control switch should include considerations for having (or not defeating what you have now) speed reduction of the pitch trim servo motor.

Scott,
I appreciate the input. On the trim system, I am using stock Van's/RV-12 everything- other than the Ray Allen grips with trim in them. I plan to integrate the grip trim switches into the existing Van's harness, probably making the wiring connections somewhere in the tunnel up front, rather than at the back of the panel mounted trim switch. Ideally I'll have trim up/down in the stick grips, and ALSO still have the operating trim switch in the panel from Van's.

It is my hopes that this does NOT interfere with the PWM speed reduction system that you mention? I'm thinking it will not, since I am simply adding another manually activated source to tell the trim servo to move one way or the other. I know it's tough for you to comment when people deviate from the factory plans, so again, I appreciate any further input. ?

 

[BobTurner]

This should all work okay. Just be sure to follow the directions on the Ray Allen web page:
If you are using the stock RA rocker switch in the panel, take it apart and re-wire it as shown on the web page.
The output of the speed control goes to the blue wire on the relay deck. You need to provide 12 volts to the red wire.

 

[rvbuilder2002]

Scott,
I appreciate the input. On the trim system, I am using stock Van's/RV-12 everything- other than the Ray Allen grips with trim in them. I plan to integrate the grip trim switches into the existing Van's harness, probably making the wiring connections somewhere in the tunnel up front, rather than at the back of the panel mounted trim switch. Ideally I'll have trim up/down in the stick grips, and ALSO still have the operating trim switch in the panel from Van's.

It is my hopes that this does NOT interfere with the PWM speed reduction system that you mention? I'm thinking it will not, since I am simply adding another manually activated source to tell the trim servo to move one way or the other. I know it's tough for you to comment when people deviate from the factory plans, so again, I appreciate any further input. ?

On the standard RV-12 wiring architecture, the only wires in the tunnel related to pitch trim are the ones going aft that connect teh circuitry in the box (speed control) to the servo mtr. If you make a connection here you will have bypassed the PWM speed control.

The only way you could make your plan work, and still maintain functionality as designed, is to tie in to the harness between the Switch module and the AV50000 box.