Excellent choice on the Saito 100 I am going to load mine up in a few minuets It has been bad weather for a week here time to ring it out. I switched to high rates 3-D last week with expo and it's like flying a new plane. Next I will start playing with the CG to bring it back. If I do not stick it in the ground.[:-]

LOL i have faith in you. Wish it was nice here . Was nice for a week but way to much snow on the ground. During that week it melted it all. NOW IT IS SNOWING HARD AGAIN AND FREEZING AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH where is spring

Hi Guys,

I never liked the idea of having the tail wheel rod glued into the rudder. For starters, the rudder always have to absorb the impact upon landing (hard on the rudder servo as well) and two, you cant adjust the tailwheel once the rod is glued in. Since I have my new metal lathe, I try to justify the cost and keep the stupid things to a bare minimum (hard to do) LOL
So for my UCD3D 60, I made my own tail wheel assembly. The aluminum is all hollowed out and the hex head screws have been cut with only about 4 mm threads to keep the weight down.

It seems as though I can't upload the pics. I am getting a message saying it did, but???????

On the aluminum tail wheel be careful using metal to metal have you ever herd of RF problems with rubbing meterals. It can key up right frequency it can screw up your radio in flight . Try to use a carbon fiber or plastic bushing to hold it for the axle. Sometimes good ideas need testing out . I am sure there is someone who can tell you better what can happen. I used a sullivan 60 size on mine works great Good luck show a pic when it is done SL

Hi SL,

I am familiar wirh RF noise. The control arms are spring loaded so there will be no vibration on metal to metal. I build and fly Giant Scale airplanes and have seen my fair share of RF interference and gliching. I have not had any RF glitches so far, knock wood, and try to do my best to prevent them.
Here are the pics finally.

Ok I see what you were talking about. I got your 1 St post mixed up without a pic. I was thinking you made the wheel hub and brackets out of aluminum as well. Nice job. I have a set of control like what you built from kankade on a GS 300. I wish I could say I made them I paid $$ for them. SL

SL,

Trust me, you went the cheaper route by a 1000 times. You would not like to know how much the machine cost to make it I an an electronic technican by profession and have a satellite communication business, but love making all sorts of stuff which is pratical.
Some of the things I make are here www.torkndork.com for fun.

The new and improved Crest 3D will sport a new vertical stab / rudder design. I am trying to accomplish three things:

1. Increase Rudder area
2. Redistribute the rudder area for less coupling in KE
3. Improve the "look" of the rudder.

I am happy with it so far...flight tests will be the proof.

A question for those of you running the YS 1.10
What type of tank are you using? I want to put the tank on the CG.

Very cool, several months ago when this post was new there was a pic of a UCD that sombody chopped off the top of the rudder. He left a little of the counter balance on top. I never read any reports of how it performed, but since that time I have been on the fence about it. Right now, I'm about 90% with this build and I guess it would be the time to do it. To chop or not to chop, that is the question. I'm using a Cline regulator on this one with the tank on the CG and planned on taping it for expansion, but would also be interested in a seamless tank. Joe

Dou you think the stock tank is up to the YS pressure?

I wanted a Sullivan seamless RST styled, but they only go to a 12oz.
Would a Dubro 16oz be up to the task?

Dubro says in writing that they won't burst, but don't they all? Joe

contempo,

Now if you just change the shape of the horizontal-stab/elevator and wingtips you can call this the "U-Can-Flip 3D"...

Seriously though, I have been using the stock tank (mounted on the CG... look back in this thread for pictures) with a YS 91 and have not had a problem (yet... knocking on wood). I haven't done this, but a little silicon-sealer around the neck is said to help avoid leaks...

There is a U-Can-Do flying at one of our local fields that the pilot changed the
vertical fin and rudder to a more "pattern like" design and he says it helped the
flight performance a lot. Less coupling and easier to hold knife edge.

tommy s

PS: I've never seen a Tettra tank burst. I, and a lot of other people, think they
are the best.

contempo and cumn thru...

I have heard about cutting the rudder and I do think something needs to be done b/c by default.. this thing goes to the wheels really bad in KE. But.. why is contempo adding more to the top (actually top trailing edge looks like) and some people are saying to chop. Which is right? Anybody know the scientific/technical answer here?

contempo.. I do not have mine on the cg... dumb beginner.. wish I had, but, I used the stock tank and a ys 1.10 and have had 0 leaks. Even worse than putting the tank in the front.. i dripped some 5 sec ca down the front of the fuse to hold the little wood piece that they give you in the instructions... well.. I glued the tank to the formers and I can't get the stinkin thing out!!! I figure for now it will give the front some stability. If it does leak I will have to get out my surgical tools.

btw... I have been LOVING the ys. Little bit of learning curve for a beginner, but, runs awesome!!!

Contempo Have you got a chance to fly your U-can do with the rudder mods Yet? if so how did it fly. And KE- could you do a decent rudder turn with it?

Long before the UCD was even thought of there were planes that pulled to the top or bottom or rolled during knife edge flight. Butchering the rudder will prove to be fruitless. The following is a quote from a post I wrote awhile back:

"I have two UCD 60's and a UCD 46. The UCD 60's do have a more severe coupling that varies with the amount of rudder deflection and speed. You either have to fly it out with your ailerons and elevator or mix it out with your computer radio.

This "coupling" is characteristic of low wing models that have no dihedral (flat wings) or too little dihedral. It seems that no one is addressing this and are concentrating on the rudder. In the past I've redesigned fins and rudders on other flat wing models but there was no significant change in flight characteristics. Contest pattern fliers used to get rid of this problem by sawing their foam wings in half on a band saw then re-gluing the wings together at a different dihedral angle. The correct dihedral will also help correct the tendency of the model to roll in the opposite direction of rudder deflection."

OK, thats what I said some time ago but I certainly didn't go chopping up my wings, I just live with it as is.

Rman, I too am curious to the effects of the rudder. I've also read that the coupling is in relation to the hor. stab being at a different level as opposed to the wing. The hor. stab. is on the thrust line. Also there is something that you may be able to verify as to the location of the hor. stab. on the .46 model and how does it differ in performance to the .60. Thanks, Joe

cumn thru,
I don't remember all the ramifications of moving the stab to different levels but the height of the stab has some bearing on rudder effectiveness at high angles of attack. I can't say much more about it without fear of dispensing bum information in the forum.
You may notice that some model designs use swept back wing leading edges for better knife edge flight. I believe there is a rule that says 5 degree of sweep in the leading edge is equal to 1 degree of dihedral. There are people in RCU who are modelers and have training in aerodynamics and I hope they can explain the technicalities in detail.

In the case of the UCD 60 and the 46, for me the UCD 46 was a better 3d'er right out of the box. The UCD 60 needs to have the engine thrust vectoring adjusted and you have to play with CG location. As you start to increase elevator deflection in slow flight the UCD starts to get squirrelly before the UCD 46 does.

As far as making modifications to the model's design, I don't even try that anymore. When I see a new model that I like I look it over, check out its specs and hopefully determine whether the characteristics I want are not outweighed by the bad.
When I first saw the UCD 60 I said "wow! Its a giant Topflight Contender" and I knew immediately it would be two handfuls during knife edge flight. I bought it anyway because I knew I'd like the other flight characteristics. The wings look almost exactly like the old Contender designed by Dave Platt many years ago. I built several Contender kits years ago and they were all difficult to keep straight in knife edge flight.

So, you'll just have to learn from experience how to look at a model's configuration and make an educated guess as to how it will fly.

Thanks Rman, I appreciate the info. Joe

The general rule is if it tucks to the gear in KE then move the horizontal stab DOWN, reverse for pitching to the canopy. My 60 tucks to the gear and is real handful when attempting to straighten it out with the elevator.

Shogun, what if it were lowered to in line with the wing. I've noticed on more advanced models the flying surfaces are in line. Joe

Actually there is a relationship between the engine thrustline, wing position and hor stab position. Simply lining them up will not necessarily guarantee posative results. Head over to the aerodynamics forum and run a search, there is a lot of info on the subject.

Something to consider though is moving the engine trust line up higher and see what happens.

Rocketman_

How does the .46 UCD harrier compared to the 60 size? Will the .46 size lock into a harrier or rock around like the .60 size? Always feels like the 60 size could snap out of the harrier any second.

I have a 60 size and love it, does it all except a decent harrier. Tried lots of spoiler but the only thing that works is really high alpha.

geoharry-RCU
I love my UCD 60 also and you're right it does threaten to snap out of a harrier. Its more of a rollover than a violent snap. That really gave me a jolt when it happened at a lower altitude. I can hold it as long as I'm in a slow decent but once I try to maintain a constant altitude I lose it. That could be due to fact that I'm and old flier learning new tricks.
As you said "the only thing that works is really high alpha", but then thats like drifting it around the sky in a near hover.
The UCD 46 actually does harrier, does great blenders and waterfalls and strangely enough is easier to hover. I have more flying time on the UCD 46. But then, maybe thats why I have more flying time on it.
My UCD 60 has been reconfigured for the upcoming flying season. I replaced the OS 91FX with a new Saito 100 with right and down thrust and put a heavier battery in the tail. My battery is inside a hatch in the bottom of the fuselage 29.5 inches back from the wing leading edge. The CG is 5.75 inches back from the leading edge. I also installed a new Futaba 8-channel receiver so I can use the ailevator feature for the two elevator servos and get rid of the "Y" reverser. Increased the elevator high rate too. We'll see what surprises these changes bring.

I just wanted to be the guy with the 2000th post to this thread.