I just flew my UCD for about the 15th time and the firewall pulled
loose from the fuse.You cannot believe how poorly this was constructed I cannot understand how this could ever have made it
to the production stage.I have already had the landing gear block come loose but had no idea the firewall was so weak.I am going to take pictures and send them to GP and see what they want to do about it.It was hot glued on both areas which should never happen in a plane that is going to have a four stroke with tons of torque mounted on it. I would like to warn everyone to make some kind of mod to reinforce it or something dangerous could happen. I would like to hear feedback from all the UCD owners to see if this is a common problem which I am sure it will be.

This was a BARF, and you didn't pin the firewall? Thats the 1st thing I do on a BARF.

Not a single complaint about my airframe, Saito 91.

I have a YS 91 AC in mine.I really thought the firewall would be more secure than it is.Anyone that has had theirs come off can attest to the shoddy engineering that was done.I will try to get a digital camera and post pictures.You will not believe what you see!!!!!!!

Did you reinforce the joints or inspect them before you built it?

I bought mine back in Feb before all of the problems were showing up.I have never had a Great Planes airplane that was so cheaply built.And I have owned 4 so far.I do not normally tear an airplane apart especially an ARF from Great Planes to check for structural integrity.

I had the same problem with my UCANDO3D. After a couple of months of flying the firewall pulled out. Luckily I noticed it on the ground.
I have had this problem with all ARF's, however. Every ARF I have seen has the fire wall hot glued in. When you buy an ARF you have to plan on replacing the firewall and landing gear block.

we cut out a pieace of 2x4 and saped it in to a landing gear block and it goes up to just under the wing pin holes. it with stands a lot of good bounce.




3dintheair

I called GP and all they said was the standard response of ,"here
is our mailing address " I will just repair what I have rather than
remove all the servos, pack it up, etc.I will probably run hardwood
rails and tie into the bulkhead and epoxy the firewall and install screws to the rails.If I send it back I will have to do the same thing to the new one.I just wanted people to know that this is as much a safety issue as it is a crash problem .Luckily the landing gear is so weak when it pancaked in the gear absorbed a lot of the impact.I really like the plane but not the construction.Anyway
on to the garage to start the repairs.



U cant 3d without a firewall,lol
Doc

I have a saito 100 and I have not had any prolems yet. I havent really flown it beyond half throttle. As fas as the ladning gear, the block did crack. I used some regular CA and it is holding fine. I also had my wheel pants crack and I refiberglased them. This was done by the person who owned it before me. It probably depends more on the pilot, but I am glad I have read about this problem just so it doesn't happen to me.

I had a Saito 120 on mine and didn't have any problems with the landing gear or the firewall.....

No problems....other than flying through a tree.....but can't blame that on Gp......or can I?

Pugs

Doc sorry to hear of your problem.Well it was built either on a friday afternoon or Monday morning Good luck with your repair's.stefanP

Hi Doc,

I'm just putting a UCD together right now, and I noticed when I bolted the engine mount onto the firewall, the covering on one of the sides of the fuse started to wrinkle up! Is it normal to do this (from the stresses of the mount against the firewall), or does it sound like I have a potential problem on my hands as well? Oh, I also have 2 washers behind both screws on the left side of the mount, as this seems to be what many people are doing for side thrust.

I was planning on dripping some epoxy along the firewall/fuse joint (on the inside). But there isn't really anything else you can do, the way the UCD is built. There isn't enough firewall to pin it, and even with the hole I cut in my cockpit floor, there isn't enough room to get inside to add gussets of any kind.

What should I do, if anything?

Mark

Typical ARF construction. So far have put together five (5) of
these U-Can-Dos (two for myself - love this model). Anyways,
you do need to stand this fuse on it's nose and pour 30-min
epoxy down there and make a fillet all around the firewall and
fuse sides (do plug up those blind nuts with vasoline first).
Then after all has cured, simply retap the blind nuts to make
sure a nice little hole is cleared out thru any hardned epoxy
that may have creeped over the blind nut(s) area. Simple, but
strong. Have way over two hundred flights on my first plane(with
OS91FS); second plane has a Saito100FS with just six flights
so far. No problems showing up with firewall. And yes, I also
had problems with landing gear block. The cure there was to
saw out the original block, and get in there with some hardwood
filler all around and epoxy things back like they should have been
done in the first place. Those people constructing these ARFs
with hot glue need some lessons in model building (but then I
do realize that time is their main concern, not in our best interest
though).

What is the point of buying an ARTf when you have to take it apart to fix it again?

In the case of a UCD3D the answer is evident, there is no kit available.

I own 2 ARF just for this reason.....(sig senior and sig rascal)

Thanks for the reply tombot!

It sounds like quite are few people are doing this with good results. I guess I better go and mix me some epoxy!

I wasn't planning on getting as extreme as you did on the landing gear, though. I cut an access hatch in the floor of my cockpit, to gain access to the landing gear block from the inside. Then I plan on adding gussets, blocks, epoxy, and whatever else I can get in there to try and strengthen it up...hope this works?

Thanks again,

Mark

I am also concerned here, because my third arf will be a ucd3d
it's already in the workshop and I will start on it as soon I have finished with my other project.
I saw plenty of thread talking about mods on the ucd3d, but I plan to build mine fully original with a os 91 surpass II and good BB servos.
what do you think?
Are some mods crucials? (I don't talk about reinforcing firewall and gear)

SALMONBUG

The only major mod that I heard of, was someone that cut the top off his rudder to give it less area, and I don't know if this was actually decided as a 'good' thing. He said it helped improve knife edge coupling in flight...but I don't know how it affected other maneuvers.

From what I've been reading, the plane was obviously designed for the smaller engines in the recommended range. Because for a .90 size engine (I plan on putting an OS 91 4-Stroke in mine), everyone is saying to add 2-3 washers to give it more right thrust.

As far as everything else people are doing, most of it is just preference, and strengthening up what they feel needs it...like the firewall, main landing gear block, tail wheel assembly, and any glue joint that looks suspect.

Hope this helps a little?

Mark

4-40 rods on everything.

Is the YS 1.4 too big for the UCD?

Way too big.A ys 91 is plenty!!.I cant believe people are putting these giant motors on this plane with the firewall problems that we are having with this thing.

I thruly believe by looking the plane that a good .91 4 stroke will be more than enough.
I like on my 3D birds to be able to use all the potential of the engine. Plane hovering at 25% throttle is not a good idea in my opinion. Big engines mean more wingload, more vibrations, more stress on the structure.....
Plane hovering at 60% throttle is good to me and because it will be light, it will exit the hover very good......
I already instaled a SMALLER engine on some of my planes....

I will have to agree. With a saito 100 the plane will easily fly with 25% throttle and 50% power to hover. You certainly won't need more power then a 91, but it came with the 100.

After I posted that I glued back the landing gear and said it was fine, I find that it broke again. I know after I fixed it I only had smooth landings and it still broke.

It seems like a lot of ARF's have the same problem with the firewall, the landing gear and other planes have wings or other parts ripped off while flying. I guess they cut back on glue and wood to make it cheaper.