Goldberg Matrix Elevator Abortion...
 

Anyone doing this model?

I have been very pleased with the kit quality; right up until now.

The elevators are actuated by a push-pull system using 2-56 pushrods and a bellcrank on a shaft (first photo). On each end of the shaft is a servo horn that connects to the elevator horn.

The concept is good, but the execution is FUBAR. Never mind the cheap wire provided for the shaft-to-elevator connection, or the hokey method for hooking up the pushrods to the servo horn at the servo; its typical Pacific Rim junk and easily rectified out of the goodies box (you DO have one of those? No sane ARF'er should be without one...).

What has me severely constipated is that the shaft/bellcrank assembly is incredibly stiff and difficult to move. The shaft rides on two spherical pivots that fit into plates, which attach to the side of the fuselage. Naturally, you don't want any axial play in this arrangement, so you must ensure the spherical pivots are snug into the plates while attaching the output horns (second photo).

These plastic parts are made out of what appears to be glass-reinforced nylon; the same stuff most plastic helicopter frames are made of. The surface texture of this stuff is rather rough. It takes a considerable amount of force to move the bellcrank back and forth. I can put a big-nut servo in there, but any precision in the elevator response is gonna be a maiden's dream.

I have a special oil intended especially for plastics that I use on my plastic helicopter collective pitch mechanisms. It is totally synthetic and won't harm plastic or rubber. I have used some on these pivots and stood there for an hour moving the assembly back and forth, trying to free it up. I THINK it is getting a bit smoother, but its hard to tell. I have no other option, since the horns are attached to the ends of the shaft with screws, and trying to relieve the fit just a smidgen would either result in TOO much play, or buggered holes.

I am NOT happy.

My advice to anyone considering this kit is, throw these parts in the trash and fit a normal elevator pushrod. The holes in the fuselage for this arrangement are covered and must be opened up by the builder, so that's not an issue.

There is a recent review here about the Lanier Razor, which is this same model with a different cowl and color scheme. The reviewer glossed over this elevator arrangement. I was curious about that, as it is a rather unusual set-up for a 40-sized ARF. I think I now know WHY it was glossed over...:eek:

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RE: Goldberg Matrix Elevator Abortion...
 

Hey steve, I think I can help you. Central hobbies sells a very similiar fixture that is ball bearing supported. I have one in a Kaos I just finished and it works as slick as can be. I just bought another one to use on my Matrix instead of the one that comes with the kit. They come in two sizes and the only drawback is the price, its a little steep.

RE: Goldberg Matrix Elevator Abortion...
 

Interesting; do the mounting dimensions jive with the kit parts? Since mine is already installed, there isn't a whole lot of room for adjusting size; specifically, the end plates.

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RE: Goldberg Matrix Elevator Abortion...
 

Steve, what if you smoothed it out with some 600 grit paper and then made a shim out of something like a piece of canopy (light and firm) to go between the fuse and the bracket on the inside?

Ed M.

RE: Goldberg Matrix Elevator Abortion...
 

Steve
Just finished my Matrix. Elevator controls that came with the airplane were
deposited in file 13. --Junk !! Tailwheel assy was replaced also.
I thought the rest of the airplane was very good. I used the MK bellcrank from
Central Hobbies and carbon fiber pushrods, did not set up as pull-pull. If you use
the MK bellcrank you need the wide one. Very good set up with no slop and
friction free. Only problem is the cost, $35.00 plus connectors and pushrods.

tommy s

RE: Goldberg Matrix Elevator Abortion...
 

Steve, I do not think the end plates have the same exact dimensions, but it should be very easy to adapt the bearing component without hacking up the airplane. I will be working most of today and tonight but I will try to compare the parts a little closer and let you know.

RE: Goldberg Matrix Elevator Abortion...
 

Ed,

The "bearings" are on the outside. After looking at it a while, I'm going to remove one of the outside horns and sand the inner surface (which rides against the spherical "bearing") down a tad. That should relieve some of the axial pressure and hopefully free the assembly up. Just got to be careful not to remove too much material.

CCRC1,

Thanks; I appreciate the effort.

Tommy,

What replacement tailwheel assembly did you use? I was looking at that one in the kit last night, thinking it probably needed to go in the circular file too.

I would just throw a DuBro or Sullivan on there, but they would be somewhat "taller", and I'm concerned about prop clearance; I'll be using a 14" prop.

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RE: Goldberg Matrix Elevator Abortion...
 

I used a Klett because I already had one. Just had to extend the plywood mount
about an inch forward. I prefer the Northern Model Products Tailwheel though
because it is simple to hook up and very durable. I changed the Klett unit to hook up
the same as the NMP with a short spring to the bottom of the rudder. This follows the
movement of the rudder for turning but lets the wheel be turned without moving the
rudder so it won't damage the rudder if it gets hit or turned sharply. They're both
around $20.00 - not cheap.

tommy s

RE: Goldberg Matrix Elevator Abortion...
 

Steve, I have both bellcranks in front of me and I have good news. To use the ball bearing unit all you need to do is open the holes on the fuselage sides approx. 1/8" and the unit will drop right in. The end plate screws are even the same pattern as the original bellcrank and will match up to the existing screw holes in the fuselage.
I am still curious why no discussion about this aircraft here at RCU, even after more than 8 weeks have passed since it was released. I am guessing that the hefty prices Goldberg is putting on their ARF's may be pushing customers to other brands.
Does anybody have a Matrix in the air yet? Feedback???
I plan on using a .70 Surpass Ultimate on mine so I can take advantage of the built in fuel pump.

RE: Goldberg Matrix Elevator Abortion...
 

<<...curious as to why no discussion...>>

Me too. You might be right about the price thing. One can get a UCD 46 for $50 less. That's what I was looking for when I walked into the hobby shop. But the last UCD 46 had just walked out the door, this Matrix was just off the UPS truck, it was Xmas, and I was in a buying mood...

Thanks for the leg work on the bellcranks, but I got this one smoothed up; by the simple method of pulling it all apart and fitting the parts properly (NOT per the instructions). Took all yesterday afternoon. I believe there is a distinct possibility that as the parts wear, some slop will develop, which may or may not be taken out with shims. All in all, this is a real cheesy arrangement and not up to the rest of the model's quality.

Have you looked closely at the wing? It is TINY! I'll wager this model will not have near the slow-speed float of the UCD. I hope I'm wrong.

As to a flying report, I'll get this model done eventually. But to be honest, I could have built and finished a Sig SE in the time I've spent dicking around with this ARF; between surgery to get the tank as low as possible (for the inverted engine), getting the MPI on-board glow hooked up and installed (okay, THAT hassle was not the models's fault;)), and now this elevator hook-up, this model has been one crisis after another. Yeah, I know; that's why they call it modeling.

But things should go quickly now, unless something else is lurking in the shadows waiting to bite me. The already-joined wing and integral vertical fin cut assembly time, and so far everything but that bellcrank assembly has fit like a glove. The wing dropped right into place, and the pre-drilled bolt holes line up perfectly. It is a bit cock-eyed and will require shimming one side of the wing saddle, but that's no big deal. BTW, the book says the wing bolts are 5x40mm. The blind nuts which are already installed are 4mm, and 4x35mm bolts are provided; and they're not long enough. Fortunately, I had some 4x45mm bolts handy- that's what you need. And use the biggest washers you can under the heads; the "hardwood" block they tighten against is about the consistency of soft basswood.

So, stay tuned. I guess this will be a good model, but I'm rather neutral about it right now...[&o]

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