I have two Comp-Arf Extra 330's(2.3M & 2.6M) with identical problems.

The elevator holes that the servos sit in is too long!!
This means that the servo hold down screws will screw into AIR on one side of the servo.
In addition to that the servo hold down screw holes are too big and I can't get a good byte
into the wood to secure the servo on the side that I can hit wood.

I have been struggling with this problem for two years. I have not flown either aircraft yet
due to this problem. The flying season is just about upon us now and I am determined to fly
both aircrafts this year.


My Solution:

I am going to cut a hole in the elevators and surface mount the servos, I will reinforce the skin
of the elevators to add the strength needed for the servos.

I have been warned not to do this(I can't remember who), but I can see no other alternative.


I will NEVER buy another Comp-Arf because of this. The Comp-Arfs are somewhat expensive and I should
not have this problem! I am sure that they fly extremely well. I am definately counting on it.


I would like some opinions/guidance on my solution from some of the experts out there.


Thanks in advance

MR G

The 2.6M has servo holes cut for standard size servos. You say that your standard size servos do not fit properly in those holes? That's kind of odd. Anyway, what about adding some plywood plates in the stabs to screw your servos to - that would be better than mounting them to the skin.

Cut a hatch in the skin as others have done and glue a ply mount to the far side of the original, install the servo as per the instructions to clamp the ply in place, that way the ply mount will not change the position of the output arm and get over the probelm as detailed in the manual for bigger screws for mounting the servo's, did you kit not have the bigger screws supplied? if you are having trouble mounting Futaba servos due to the small hole diamiter in the brass ferrral through the servo mount, use JR ferrals they are bigger and will take the bigger screws supplied.

Mike

OK Guys,

I have decided to break down and purchase new stabilizors (OUCH!!!)

BaldEagle, I was unaware of the screws supplied by the kit, thanks I will try and locate these.

Does anyone know the size of the stab tube?? I epoxied my original tube in one of the stabs, and would like to use a CF replacement.

Thanks,

MR G

What servos are you trying to use that don't fit?

Before going to all that trouble and/or expense, why not just use the recommended servos and screws?

I have the Comp-Arf Extra 330, and had no such problems as you are describing.

Jim

Hambone,

I am using Hitec 5945's.

The Comp-Arf website did not specify that Hitec servos would not fit. In fact there are numerous people that have used Hitec servos.
The problem is the servo opening is TOO LONG. I can screw only one side down, while the other side will not reach the wood to screw into.

My elevators may have been an anomoly in the production that have excessively long servo openings.
Despite this obvious problem, I am not asking for free replacements, in fact I am willing to pay $90 a peice for replacements.

I have epoxied my stab tube into one of the stabs and need to replace it also. I would like to use Carbon Fiber.

Do you or anyone else know of a Carbon Fiber source for the size needed for the extra 330 2.3 meter?? Thanks

MR G

I'm not sure about a carbon tube source. I'd have to look around just like you will. I'd try Troybuilt or TNT Landing Gear first.
You're not going to save much weight with a carbon stab tube, but if it costs about the same as a replacement aluminum tube........ why not.

I still would not pay $200 for new stabs. I'd glue in some additional ply to make those stabs work. All it would take is a piece of ply the right thickness and width, that has 1/16th ply on both sides of it that overlaps and glues to the original mount.
It will be a little tedious to get it in place, but not impossible. I'd definitely do that before shelling out $200.

Jim

I agree with Hammbone here, I would not shell out the 200 bucks until such times as I tried to glue in some plywood to make it work...or better yet call comp arf and see what they will do for you. The last time I looked the hitec servos were pretty close to the same size as a standard servo, perhaps your elevators have servos opening cut for 1/4 scale large case servos, but your best bet would be to contact comp arf and see what they say first!.

Can you post a picture so we can see the problem you are having? I have built a couple of composite planes and I haven't seen this problem...

DA is the leading source for Comp Arf wing tubes. They are supplied by PBG Composites out of New Zealand. Before I did anything at the elevators I would contact a Comp Arf rep and discuss the problem with him. I believe Darcy Wingo may be home now.

It's not at all normal for standard sized servos not to fit the servo openings. Are these new kits or were they flown by someone else previously that may have modified them for a 1/4 scale servo? 5945's are close enough in size to 5955's and 8611's to be a good fit in the usual stab servo openings.

I would stay with the stock stab tube unless you are using a very light engine.