I would like to use a DEPS system instead of dual elevator
servo's in my BRIO.

Besides having to relocate the hard points on the elevators
does anyone see a problem with this?

I am also considering removing the stock rudder and doing a built
up one, not only to save weight, but to benefit from the wider
trailing edge.

Thank you for the help.

IMO, the Brio is not a good platform for DEPS. I built the standard kit, and I'm not sure where you would put the servo. The balsa tunnel floor isn't really structural and may be too high. Going aft of the tunnel would be difficult to access.

I’ve done three roaches with DEPS and the Brio with duel servos in the tail. The DEPS always requires trim changes each time out where I haven’t touched the elevator trim on the Brio since the initial flights.

I kept the stock rudder and used 3421SA’s in the tail and did not have any balance issues with an OS140RX up front.

For the horns, I made some from 3/32 ply and laminated with CF. A slot was cut in the elevator using a Dremel cutoff wheel just catching the hard point (this would have been inboard enough for DEPS.) The horn was epoxied in after covering. The main reason I did this was to get the pushrod attach point over the hinge line…it’s a long reach with the top hinge! The whole process worked out so well that this is how I will do all horns in the future. No more MK horns for me.

What do you hope to gain with DEPS?

Scott,
Some good ideas!
I am just now starting to assemble an Impact.
I like to use Rocket City ball links with stainless steel balls.
In the instructions CA virtually guarantees this will cause flutter if you use "single sided" ball links and their phenolic horns.
By single sided they mean does not have the ball of the link sandwiched between two horns.
I don't want to double up the horns.
On the Impact thread an Impact owner suggested and showed how he lamenated the stock horns with CF.
You are using ply.
In your experience does the carbon fiber eliminate any flexing on your horns?
I may go that route...or I may still laminate the supplied phenolic.
Your thoughts?
Thanks!
JLK

I installed the DEPS in my Brio and did not move the hard points on the elevator.

The exit holes came out slightly further forward than I would have liked, but it works just fine. Just for peace of mind I added a 1/8" CF rod over top of the .007 rod between the exit hole and the elevator horn since it was about 10 or so inches.

I'm very happy with he system and I think it provides excellent even control.

The primary reason I went with the DEPS was to move the CG forward because I built my Brio electric.

Keith B

I forgot to mention:

1. Swapping out the rudder is a very good idea, the stock one is way too heavy and I've heard of cases where the hinge has cracked. It also makes it much easier setting up the DEPS system and a tail former if you choose to add one.

2. Two of the pictures included above show the technique I use to help find the exit holes for the DEPS system (also works for pull-pull).

I've attached some pics of my ruder build.

Keith B

The main reasons I would like to use a DEPS is true elevator
matching.

I find it frustrating to spend hours trying to get the dual elevator
servo's to track precisely the same on my larger planes. Even
with the use of a Hitec programmer I spend many hours working
it out.

I could mount the servo (side mount) inverted under the
rudder servo tray.

The side benefits would be 1 less servo, no servo extentions,
a little less hardware, and a really clean looking installation
without servo's hanging out in the rear.

Someone on this forum compared IMAC and Pattern planes
like Nascar and formula 1.... The DEPS system just seems
more like a formula 1 solution.

I like your idea of the control horns, how tall did you make them?

Thank you for the pictures Keith!

What did you install inside the rudder post on the fuse?
Also how wide did you make the trailing edge on the new rudder?

I would hate to add the DEPS and create a problem with balance,
unfortunately I have not decided on an engine. I am leaning
toward a ZDZ40 FAI engine, but they are not available yet.

I have pretty much ruled out a YS, so if the ZDZ engine
does not work out, then a 2 stroke OS 140 or 160 would
be my next choice.

Now I have done it!
Just cut the rudder off..... 2.8 oz.

Kelly,

If you go with the ZDZ or any of the glow motors then you'll certainly have no issues with the plane being tail heavy even with servos in the rear. In fact, you might be a bit nose heavy w/o the servos in the rear. But I'm sure you could be creative and move some weight back if that happens. The "true" elevator matching that you speak of is probably the best (and maybe only) reason to go with the DEPS.

I've put dual elevator servos on two pattern planes and had absolutely no problem getting them to track the same. I have a trick that I use in measuring the elevator throw. First turn the radio on and get the two halves so that they are perfectly level with each other. This is easy to do by using the tips of the stab as a guide. I then tape two laser pointers (the lightest you can find) to the elevator, one on each half, and aim them at my white refrigerator about 6 feet away. Shim the laser pointers until the dots are exactly next to each other horizontally. Now using the radio move the elevator up and down. Any difference in throw will be EASILY spotted when projected six or more feet away. I personally have never had much trouble getting the halves to track right with each other after I set the end points of each elevator half the same (JR 10X). NOTE: Your control horn lengths, angles, etc. need to be the same, but this is fairly easy.

Using the JR DS3421sa mini digitals I get many fights out of the plane before having to worry about it. My experience is that this approach is rock solid.

FWIW, I know numerous NATS FAI finalists (Quique, Andrew Jesky, Don Szczur all flying the Brio) that have the servos in the stab. I know in theory it can't be as exact as the DEPS system, but many people use the stab servos with great success.

I say this only because the DEPS system is more trouble than stab servos and I'd hate for you to think that it's a requirement to have an acceptable flying plane.

Best of luck,
Keith B

Even with DEPS, this is an extremely difficult task because you must get the pushrod attach point at exactly the same position on both elevator halves. Another difficulty I had with the Central setup was the installation had to be dead on straight or the push rods would bind. The CST sheathing was a little more forgiving but it looks like they have something new, which I haven't tried.

The attach point is 17mm below the stab. To JLK, yes these are very stiff once the CF is applied. I used 2 layers of 2.8oz cloth on both sides.

You may want to consider the Sullivan Composite Rod over DEPS. I understand it will allow for some bend in the installation and is less susceptible to temperature changes. See the Prestige thread [link=http://image.rcuniverse.com/forum/upfiles/118400/Pk31601.jpg](Ed Alts's plane)[/link] for reference.

Thanks for the help guys....

Maybe I am making a mountain out of a mole hill!
Most of my dual elevator troubles have been with large
planes and extreme throws on dual rates.

Setting up dual elevators to work perfectly at 45 degrees
and also work perfectly at 15 degree's is a challenge.
On top of that I like to keep all my radio endpoints at zero,
all my ATV's at 130 or 140, and all my rate numbers the same
in both directions. Basicly I work with the linkage and the
Hitec programmer until everything is perfect.

Right now I use carbon fiber sticks taped to the elevator half's,
some home made throw meters, a level table, a level aircraft,
and a lot of measuring.

Your laser pointer idea sounds great!

I imagine that setting up this plane should be a little easier
if I go with dual elevator servo's.

Another advantage of the dual servo solution: redundancy.

With DEPS, every component that can fail can bring the airplane down: servo, cf rod, cf rod end, servo clevis, servo - receiver plug, receiver port, servo wire, ...

I know that many of those components are very reliable, but from a design point of view this system is LESS reliable than dual servo.

Now let's analyze the dual servo approach. Here all is replicated: two servos, two receiver plugs, two wires, two links, two clevis...

And if either one fails, the other one is enough to safely land the plane - I can witness that, I've seen exactly that situation happening

The bigger disadvantage I see of the dual servo solution could be the weight in the tail.

I really hate it when I can't make up my mind!

All valid points on the dual elevator servo's. Let me
ask this...

I have seen 3 variations on the dual servo installation,
One picture I saw had them in the fuse, another picture
had them mounted in the stabs but laying flat, the other
option is to build it per the instructions.

What to do????

I like the setup in picture #2

And one other question. When you do dual elevator servo's
are you using a Y connector or 2 channels on the Rx.

Personally I like the servos mounted on the stab, that way taking the stab off is simple and does not require unhooking the control linkage.

Second point, I see in your pic you have what looks like a JR DS9411sa. In my opinion that's WAY overkill for the rudder on a pattern plane. Also way too much weight. I'd suggest going with the [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=JRPS3421SA]JR DS3421sa servos [/link] which will save you 1/2 oz. They're about the same speed as the 9411s, actually .01 sec/60° faster

I've used these on two different planes with excellent results.

These smaller servos may also give you additional mounting options given their small size. I mounted both of my stab servos with the servo on its side, but I've found that this limits the throw that can be used since the arm will drop into the servo recess when throwing to the extremes. Because of this the next time I do this I'll probably mount the servo perpendicular to the stab (like is normally done with the aileron servo). This allows more throw without bumping into the wing surface.

Keith

And I on the other hand mounted them in the fuse because I didn't want to deal with the servo wires. I used the shortest extensions possible and had both pairs neatly twisted and running through a 1/2 in paper tube. It would have been more work to disconnect the leads from the receiver (2 channels on the receiver to your earlier question) and feed the extensions back through than remove a couple of <easy to get> bolts at the back end.

We’re not making this any easier for you are we?!

Picture #1 looks like my photo. I have 165 flights on this setup so far and have no complaints. Elevator trim is rarely touched. I just made sure I had two servos that were closely matched on centering. Lickily I didn't have to go beyond the handful I had laying around. I used the JR9411SA digitals which I also use on ailerons in my Brio and other planes. Just set end points equal and checked at various points and saw no need for multipoint mixing or anything like a matchbox.

Keith:

I just grabbed those pictures from another Brio build thread.

These are what I use on my throttles for the big planes,
http://www.servocity.com/html/hs-524...ital_mini.html

They look like a good match to the JR's you use.

Scott:
No, you aren't making this any easier!

Did you install some plywood backer or a bulkhead behind
the servo's in the fuse?

My truck is large enough that I would rarely have to remove the
stabs, so the fuse mount might be the better solution for me.

jlachow:

Yes, your picture. I grabbed it from you web site i think.
If I use a Hitec digital I can program them to match.

At least 50% of your elevator troubles will be caaused by not having the controll horns 100% identical in every plain, on both elevator halfs.
It's a real pain. At least the MK's have some screw thread at the top so you're able to do some seriously A' retentive adjustment to match 'em up.
Mind you, you could be making a bigger deal out of this beause of your IMAC (who mentioned Freestyle) experience.
You'll only be needin' very small throws for F3A. If you're used to *****g out the ATVs, you'll be needing the inner most hole at the servo and the outermost hole at the horn. Even then you'll be dialing it down considerably.
Forget about removing the stabs on a F3A plane... thas not the idea. They're in separate halfs so you can adjust them. Once that done, lock 'em down and leave them!
If you're taking them off after each practice sesson you'll be for ever trimming.

My setup is 3421's that were fitted with long leads to avoid extensions. Don't have a perfect mechanical setup but was able to get things pretty straight using two channels on my Stylus.
My problem is weight. With an RX I have 4 ounce in the nose and this is after replacing the stock rudder! Considering going to a pushrod system this winter to loose some ballast.
Scott I like those horns. Wish there was a way to adjust them like the MKs. I used the Chip Hyde ones and cut the edge to get them to reach the hinge line. The clevises that come with them are pretty wimpy doubt I would use them again.

Yes, I glued in some small 3/32 aircraft ply doublers (don’t use lite ply as it doesn’t hold the screws as well.)

The nice thing about these homemade horns is you have lots of opportunities to custom fit them to match sides where as once you drill the hole for the MK, you’re committed (in terms of being parallel and the same distance from the hinge line.) BTW, credit for these goes to Checksix!