GaryHou

Hello to all from Houston !

help if you can. I have purchased a Great planes PT17 which has dual elevator servos. I thought of using a servo reverser but I have a brand new Futaba 6EX FASST system that I want to install and it has 2 mixable channels. I've been reading posts everywhere and there seems to be several ways to do this - but it seems that the overall best way would be to use the built in mix.... but the instructions aren't clear to me AT ALL on how to do this.... If any of you have mixed on the 6EX for dual elevators - I would really appreciate your help and instructions.

Many thanks,
Gary
Bomberfield USA

bruce88123

Can't help with the 6EX but know it isn't simple or a great radio for THAT function. Ya should have sprung for the 7C which easily supports the Dual elevator functions.

Hopefully someone will come up with a satisfactory answer for you.

beau0090_99

Hello from the Twin Cities!

OK, I have not done it on my 6EXAP, but it seems simple enough and I do it with Industrial servos all of the time, so i might have a better understanding than most noobs. Effectively, you are setting a master/slave relationship between two channels. In this case the Master is your main elevator(channel 2), and your slave is the channel you have your other elevator plugged into (maybe 5?). So if that is the case, then you enter the programming mode by pressing both buttons together and let the screen flash. Then select the Mode button until you see the PMIX flash. Then press the up button to make it turn on. Now press the select key twice to see the MAS setting. Now choose CH2 by pressing the up button. Now press the Select button to see the SLV, press the up button until you see CH5. Press the Select button twice again to see the % sign and select from -100% to +100% to choose how much the slave will follow the master and the +/- is the direction it will follow.
After this is done, press both buttons and the programming screen will go back to normal.

I hope this helps,
Curtis

beau0090_99

Oh, and by the way, they should have programmed it so you turn the function on, or Inhibit it, then choose your Master, then Slave, then your follower rate, that is why I had you hit the select button twice those two times, because to me it makes a lot more sense to set it up that way.
Try it out and let me know how it works.
Curtis

bruce88123

BUT, you will only be able to trim one servo. I think.

GaryHou

Thanks Curtis !!! And I should have probably bought the 7C like the other fellow suggested but I was buying on impulse and have the 6EX to show for it.... I really think it will be an okay 2.4 system for where I'm at right now.

Thanks again and I will let you know how it goes... may be able to try it tonight.

MasterAlex

Yep, you are correct Bruce. You can mix, em - but the trim is less than ideal for the situation. [:@]

-MA

JohnBuckner

My Feedback: (1)

Gary if your airplane is the Great Planes PT-17 ARF then there are a couple of things you need to know.

First this airplane is not setup for two elevator servos (However they do give you that option) it is set up out of the box for one elevator servo. If you will look at page twenty four of the assemblty manual it is well illustrated. With dual elevator pushrods all the way forward to the servo tray The two pushrods are wheel collored together just behind the tray and extend forward to the front most servo on the left for elevator function. This system works beautifully with all the adjustability one could want.

Now if you insist on dual servos then you still have options that require no mixing, and no reversed servo or a reversing y chord. You do need a plain ordinary Y. If you look at page 24 there is an extra position for a fourth servo. The assembly manuel offers no info on how to do the forth one for elevator. This servo is positioned on the right side so if you are using a reversed servo or a reversing Y then both servo arms should be pointing toward the middle of the airplane pretty simple OR if you are not using a reversed servo or a reversing Y then the servo arm on the right side of the tray will need to point to the right side and the second pushrod will need to be moving toward the right side and nothing more is needed. Mixes or reversers.

To date we have had four of them local and they are an elegant flyer I maidened one of them. One of the others messed his up on the first flight and I ended up with it doing the rebuild not done yet. All were using a single elevator servo as will mine when it remaidens.

John

GaryHou

John,
I bought this one already built from a chap at a fly-in this weekend. Nice plane! He built it with the dual elevator servos but I tried the mix last night on my 6EX and even though I got it mixed okay - I just don't like the way it works. The servos are mounted with the control arms to the middle so I'm gonna try a reversing Y and if that doesn't work well - then I'm gonna go back to the original design with one servo. Doesn't seem like this plane needs twin servos back there for the kind of flying I'm doing anyway.

My next issue is the figure out the engine. It has an OS 1.20 and it started fine last night but did not run up to full power. I'm using 10% fuel and the guy I bought it from was using 5% so that is likely the difference. I'm hoping it will run okay on 10% so I can stay with one fuel. This one has installed the fuel valve which I have not used before but it seemed to fuel up fine with the valve full open... full open is correct for normal flying ????

This is a WONDERFUL web site - I wish I had joined long ago !

bruce88123

Fuel valve??

GaryHou

There is a valve - cutoff valve ??? - inline between the fuel filler line and the tank. It's down in the cowling so there is a small diameter adjustment wire similar to a very small allen key which is make into the valve so that it can be opened and closed. I've seen it as an option listed on some larger models but can't find it to give you the part or name.... now that I think of it, I bet this is a remote needle mixture valve.... Don't ya just love newbies :-)

bruce88123

That is what I thought you MIGHT be talking about but wanted to be sure of.

Newbies? We need you guys to keep the hobby growing. Keep asking questions and post pics if you can and can't describe a problem like this one well.

GaryHou

Thanks for the encouragement. Okay - back to the mix. I tried what Curtis suggested which follows the manual exactly. And it worked - I got CH 2 and 5 to mix with 2 being master and 5 slave. What happens though is that the servo on CH5 doesn't seem to get the same "throw" as the master. No amount of adjustments on the EPA seem to match up until I get to wher Ch2 matches CH5 and the throw one direction is so small as to be unuseable in flight. I know it's not the servo cause I put that over on CH4 for a second and threw the "rudder" each way and the servo travels full travel on that channel. Likewise, I happened to have a straight through "Y" and that same servo gives full defliction (opposite direction) on the "Y". Only in the mixed configuration does the travel get limited in one direction....

Anyone experienced this on the 6EXA? Any fixes? I'm about to buy a reversed "Y" and end it all with the push rod adjustments like the old days :-)

alfredbmor

Which type of OS 120?
The Ax and four strokers have not a remote mixture valve, can you post a picture?

alfredbmor

Use the "Y" and also use the other side of the servo arm to attach the pushrod in one of the servos (then you do not need a servo reverser), there should not be any difference.

GaryHou

I can tell that the valve is after market and I talked to the previous owner today who confirmed that... silly me.... 2 3/4 turns out seems to be the setting for this engine. As to swapping arms, I tried that but the throw is not the same in both directions due to the slight difference in angle of the rod to the arm, etc....

bruce88123

You can add a remote mixture needle valve to any engine by simply opening the needle on the carb further than normal and then using the remote needle for the actual tuning. It would look odd IMO on an exposed engine area but under a cowl nobody would notice.

JohnBuckner

My Feedback: (1)

Bingo - two elevator servos with this airplane buys you nothing but perhaps some vague sense of redundancy thats unlikely to make any differance in a real world failure of a an elevator servo.

Now if you simply insist then: looking in the servo compartment from the bottom wing side:

If the front/left servo and the right/rear servo have both output arms pointing towards each other then either a reversing (Y) cord will be required-OR-two channels mixed on the Tx will be required.

If the front/left output arm is pointing to the right-and-the right/rear servo output arm is also pointing to the right then only an ordinary (Y) cord is needed! It will be neccessary to move the front pushrod housing of the right pushrod over to the right a bit to accomplish.

Do yourself a favor pull that second servo and set things up as intended on page 24 of the assembly manual. This is a great flying airplane with none of these added hassels needed or wanted. If you don,t have the assembly manual I suspect it is avaliable on line.

John

fieldy73

Here's another way. Plug one elevator servo into ch2 as usual, the other into ch6. Then, go into the FLPR menu and make sure it is inhibited or "INH". This is because if FLPR (flaperon) is on the elevator servo that is plugged into ch6 will move with your ailerons, and you don't want that. Next, go to the FLTR menu (flap trim) and make sure it is turned ON. The FLTR menu is where you will adjust the trim of the elevator servo that is plugged into ch6. Next, use programmable mix 1 or 2 (doesn't matter which). Make ch2 the master, ch6 the slave, SW to ON, 100% (+ or -, depending on servo direction) and the elevator plugged into ch6 will move with the one plugged into ch2. If the one plugged into ch6 is moving opposite of the way you want it to you can also reverse ch6. Here is the cool part. You also get the ability to adjust both trim and end points for each elvator half independently! This makes final adjustments a breeze. You can adjust trim and end points of the one plugged into ch2 just as you always do. You can adjust the trim of the one plugged into ch6 by going into the FLTR menu and using the data input lever to the right of the display, and you can adjust the end points for ch6 in the EPA menu.

Note - Trim only works on one elevator half, so mechanical trim is required on the ground.