Anybody a pro with JR Matchboxes & running dual elevators on their airplane?

Any tips on setting them up so the end points are the same on any rate.


I've heard that at times guys have had issues with the high rates and or the low rates not matching on end points like this was a big issue.

Anybody else here this?

Anybody have any tricks and or tips on setting them up ?


Thanks,


Van [8D]

Van,
Matchbox's shine when you need to match two or more servos that are on a single surface.

What radio are you using? Typically, dual elev servos are mixed in a program in the radio.
It certainly can be done with a Matchbox but there may be an easier way thats just under your fingertips.

Assuming you are using JR equipment 8103, 9303, or 10X... you would use channels 3 and 7. Plug the right elevator into the ELEV (Channel 3). Plug the left elevator into Channel 7 or (SPOI). Use Mix 5 or 6 as they are "including" mixes...meaning the elevator trim will operate both channels (important). In the Mix setup....you mix ELEV to SPOI (Channel 7) and make sure the percentages in both directions are 100%. Make it "ON" instead of switch activated.

You will still be able to move the SPOI surface with the AUX 2 Channel. You can use another mix to "turn off" AUX2

mwarren400:
Guess I am ignorant regarding matchboxes and our computer radios in general. Just what does a matchbox do that the radio using end pont adjustments do not do? Useing a JR matchbox and dual elevators, I positioned two lazer pens on each side. locateing them to converge on a + on a wall about 8' away. Useing the matchbox, I then matched the servo travel to identical endpoints projected on the wall. The projected wall locations are about 2,000% more accurate than just measuring at the control surface due to angles and distance of the projection. With the elevators centered at nutural, the end points were adjusted to the same location on a stickup on the wall with a + mark. So, at this time, I assumed the elevator positions at any point from nutural to the end would travel the same. They did NOT, by a bunch. Why, the geometry of the servo arms, control surface horns and angles were not identical. The only way I could get the control surfaces moving in the same manner at any point through the travel was to make templates of the servo location on one side, make the other side identical from the template, relocate one of the horns on the elevator halfs from a template made from one side. Once the geometry of servo location and elevator horns , and pushrods were made the same, and mechanically centered, the elevators traveled through the servo stroke equally with the match box removed. In looking at the overall value of the matchbox and transmitter programs provided by my 10 X, the matchbox was worthless. Assumeing you use 3 or 4 servos on the same control surface, the geometric setup must be identical, otherwise the servos will be fighting each other through the stroke, negateing the value of the system. Other than a convenient connection location that could have been acomplished with a Y harness, what is the real value of the matchboxes, or have I missed something here?

The "JR Matchbox" with my limited knowledge allows us to save channels by coordinating multiple servos that perform one function. I have dual elevators on my Giles 202, but I need 2 channels to operate the elevator. In my case...one channel is mixed so that the "elevator" movement operates the other servo to the same extents. The "matchbox" (which I've never used by the way) is supposed to allow you to dial in symmetry between mutliple servos and operate them on the same channel...like flaps, spoilers, or on those 35% planes that use 3 servos on the ailerons. It appears the advantage is only when more than two servos are needed.

I am not an expert by any means...I figured out how to use a mix to operate dual elevators...then found documentation on the 8103 that confirmed how to do it. Fortunately there were some special considerations that I was enlightened to such as an "including mix" ...a mix that allows both servos to be operated by the trim button.

I don't understand what RMENKE is talking about. Actually, I think I DO understand the problem, and I'll explain why you'll ALWAYS have this problem with a Matchbox or even mixing the servos in your TX. Not slamming RMENKE--not at all. Just trying to help out.

Lets use dual elevators as an example:

Your horns and linkages MUST be exactly the same. Both control horns must be measured and placed identical to each other. Same distance from the hingeline. Same distance from the CL of the servo output shaft. This means---you gotta glue the tail on straight.

The pushrods must be the same exact length. Not within 1mm of each other. EXACTLY the same length.

The servos must be mounted EXACTLY the same distance from the hingeline and control horn. Not within 1/8" of each other or 1/16". They must be EXACTLY the same distance from the horn and hingeline.

If your going to use dual elevators, they BOTH must have the horn coming off the same side. Both horns facing UP or both facing DOWN. You can't cheat and put 1 servo with the horn coming off the top and then stagger the other servo up higher on the other side of the fuse and have that horn coming off the bottom. That won't work.

BOTH servos have to be mounted exactly straight across from each other. BOTH servo horns have to come off EITHER the top or the bottom. Not 1 off the top on the left servo and 1 off the bottom on the right servo.

If you just follow these simple rules of good installation technique--you will LOVE the Matchbox. I've never had resolution problems. Never had differential throws between neutral and endpoints. My elevators track uniformly throughout the entire range of travel.

I don't use the Matchboxes much anymore. I bought a JR8103 and it will mix my dual elevator servos. I'm using a Matchbox on a 1/3 scale Pitts with 4 aileron servos. It works fine. Plug all the aileron servos in the Matchbox and set up all the center points. Reverse any servos that need it. Set all the end points and go flying. Works great.

Matchoxes will definately work for dual elev servos but in almost all cases, its not needed if your using a computer radio.
You Mix the elev to the channel your second elev servo is in. Now you have subtrim and epa on both sides independant of eachother.

The real use for a matchbox is when you have two or more servos on a single surface. This allows you to subtrim each servo and epa each servo independant of eachother and have the whole thing plugged into one channel.
You need this even if the geometry is perfect because the output splines on servos are not always the same. This prevents the servo arms from matching eachother.
Think of it as a multi channel, individual servo adjuster, Y harness.

To further confuse you --
some radios -older ones do NOT match the outgoing signals to the elev and the aux channel - bad setups
these will never match.
the best newer setups such as the 9303JR have a built in elev/aux setup you select the radio to kill any switch involvement then select active elev and extra channel - NOW the radio shows a left elev channel and a right elev channel.
IF you do your geometry exactly the same for each side (as noted above)- you will get things as good as possible allowing for slop/ internal component differences etc.
So - the matchbox can really help if you have a radio which is a less than perfect setup -- but it will never correct for lousy geometry.

I'm using a 10X.

Any suggestions?

Thanks.

[8D]

That makes dual elev SIMPLE.

Go to function 22. Hit next page and then select D-Elev
Plug the right elev into the elev channel and the left into Aux 3.

Thats it. Your done.


One more thing to add... (you should do this with any plane on a 10X)
Go to function 17 and inhibit everything there.
This deactivates the sliders and switches you wont be using like aux 3 when you set up your dual elevators.

SOME computer radios won't have the trim include function as the 8103, 9303, 10X have.

My JR652 is a 6ch 5model radio. You can mix the elevators together, but only the master servo (elevator) will respond to trim inputs. The slave servo (gear) will not trim up and down with the trim tabs.

Thats why I moved up to the 8103. Run a mix on PMix5 or PMix6 and you automatically have trim included on both servos.

I'll use my 8103 for dual elevators and 2 rudder servos. Run them on PMix5 for the elevators and PMix6 for the rudder servos. Works great. Simple. Let the computer do the work. Thats what it's for. I don't use Matchboxes unless I have too--like on the Pitts with 4 aileron servos.

Your horns and linkages MUST be exactly the same. Both control horns must be measured and placed identical to each other. Same distance from the hingeline. Same distance from the CL of the servo output shaft. This means---you gotta glue the tail on straight.

Sorry Rcpilet but the bold part of the statement above is wrong.
As long as the servo is the same distance (vertically) from the stabilizer and the pushrod is at 90 deg to the servo horn and the control horn is identical on each half of the elevator it will work fine.

Whatever. Do it your way. I'm just posting what I know works.

I'm not saying your wrong. I'm just saying, that if you make sure everything is equal. All servos and linkages are the same distances--you won't have problems.

Maybe you know some way to do it where the CL of the output shaft on the servo doesn't have to be the same distance on each servo. Maybe it works.

I KNOW that if you put the CL of the output shafts equal distance and make all the linkages and horns the same--it will work right. I DON'T know if placing the servos at different distances from the hingeline will work or not. I quit trying stuff like that years ago when I discovered that your better off to just make everything the same distance.

rcpilet
yes but thats not possible in many cases, ie artf. Your post was very "you must" do etc etc

to stress again the impotant bit is to get the servo horn at 90 deg to the push rod and contro horns equal distancefrom the hinge line.