I think what Scott is saying is that when the high end is near the max rpm, just back off maybe half a turn to ensure that the engine doen not lean out. Scott, correct me if I'm wrong.

Scott, Coo and Raj, Thanks for the heads up. It will be a little while untill this stage but knowing this in advance helps. Stay tuned, I'm sure I'll have more questions. Thanks again, Joe

Correct Raj, I got curious and just to see what would happen backed the high neede out on my 100 4 turns rich. Guess what? No change in the running characteristics of the engine. If you do back off the needle it basically is running as rich as the regulator will allow it too, esentially the needle can only be used to lean the high end beyond that "max rich" setting.

It's sorta weird when you first get one of these, it's something you have to kind or "wrap your brain around". I thought something was wrong at first but once I stopped trying to overthink the situation it made sense.

Shogun, thanks for the confirmation. Makes sense to me. I've heard reports on the IB regulator that it allows "200-300 rpm richening". I wonder what are the differences between the Cline and IB ?

The way I understand it is that the IB regulators seat is on the delivery side, fuel pressure attempts to close it while the engines suction pulls the seat open allwing fuel to flow. The Cline is the other way around, fuel pressure is inlet side of the seat and spring tention holds it closed until the demand is great enough to open it.

This just doesn't really make sense to me. I've been using the cline for a while and like I said the needle response is deadened somewhat. But I can gaurentee you that if I turn the needle 4 turns out my engine will run sloppy rich and at a lower RPM. The reason being is because the cline will give the engine what the engine requests. If the needle valve is turned out 4 turns and the throttle is open the engine is requesting a lot of fuel. Too much fuel to run properly. The cline responds by allowing the amount of fuel through that the engine requests. The result is an engine that is burning too much fuel and because of that the engine will be running at a lower RPM. If the needle is turned in and and set up lean the engine is not requesting as much fuel. The cline responds by letting a smaller amount of fuel to the engine. This will effect overall RPM. So you can see that by adjusting the needle you are effectively making the engine request more fuel and when the engine requests fuel the cline will deliver.

The bottom line is that the cline stops more fuel from coming into the engine that what the engine is calling for. A perfect example of this is the syphoning effect. The engine might be calling for an average amount of fuel while at the same time en elevated tank is wanting to push more fuel into the carb than what the engine really wants. Therefore the cline says "The carb is telling me to give it X amount of fuel and thats all I'm giving it." If you turn the needle out the carb will be requesting more fuel and the cline will allow more fuel through. This will lead to changes in rpm.

Thats my take on it. I'm not an elequant writer so I'm sorry if my response is hard to understand.

Well - after 14 months of faithful service, my "Crest" UCD3D is no more. On the 3rd flight of the day, my batteries mysteriously faded out on me costing me the plane. Batteries, voltage regulator, charger, and load tester are all on their way back to the manufacturer for post-mortem.

I think I have decided to build another one. I was running an O.S. .91 Surpass w/ pump. I was pleased with the performance, but I want more power! Pulling out of a hover in summertime was impossible. I am thinking about going with a YS 1.10. Anybody have any experience with this combo?

Thanks

My buddy has the UCD .60 with a YS 1.10. Its power, low idle and reliability are awesome. I believe he's using an APC 17 x 4 prop. I fly mine with a Saito 100 & APC 16 x 4 and love it. The YS powered UCD quickly out accelerates mine when we formation hover and pull out vertical.

Coo I'm just relating what my experiences are with my set up(s).

Think about this for a minute though.....

On my OS 1.60 the needle valve is not on the carb, it's a remote needle. Bill Cline recommends that you place the regulator at the carb inlet between the needle and the carb. If what you say is correct then how could this possibly work since the needle is restricting the amount of fuel that the Cline sees, not the carb?! As strange as this all seems both engines, my 100 four stroke and my 1.60 2 stroke, respond the same to high speed adjustments with the Cline installed both in front of and behind the regulator.

When adjusting both all I seem to be able to get when richening the high speed is about 200 rpm then the rpm's stabilize and that's all I can get. IF I keep backing the needle out nothing changes, it just settles at the rpm it wants, so it seems. The engine runs fine either way, set real rich or only backed off a bit. Both settings make for a good smoke trail behine the airplane, inicating a rich setting.

Scott, Where does that leave the Saito 100 with the needle on the carb? Joe

I'm not sure what you mean Joe. The Saito has the needle on the carb and so that mean the fuel can be restricted(leaned) after it has been passed by the cline to the carb. In the case of the 2 stroke it's the other way around, restriction is before the cline. Both set ups seem to work as advertised and adjust the same, at least on my airplanes anyway...

Sorry to here about your Crest plane Contempo I run the saito 100 in mine with the (Cline reg) and have no problem pulling out of a hover. Two club member run the Ys 91 Fz on there planes and there is a 800 + RPM with a prop size larger. So I think the new ys 110 will work great for the combo.

Steve,

Do you know what size props those two people are using on the YS91FZ? I can't decide between 16x4w or 15x4w for my YS and UCD........?

I may have to dig it up The person his name is Robert and he has a post on RCU is not a 16X4 W although I would like to see the tack specks with a W. And how well it will spool up. In forums type in YZ 91 fz and there is a few post on props for that engine. looks like APC 15"- 8 or 14"-10 on 20 % nitro is working the best. Good luck.

Well,
I have my U CAN DO #2 ready to fly, lost #1 about 3 weeks ago! Im pretty excited about this one. It's a better build than the 1st. I have more control surface throw but tighter gaps in all of my hinged surfaces. I was a little worried about my engine since it was lying separated from the airframe after the crash but it started right up and ran like a top on the bench.

Someone had said that my other plane could be rebuilt and they were correct. I donated it to an old friend at the club and he had the tailsection back on it before I had left his house. The wing repairs were purely academic. He plans to totally re-cover the entire plane. Cant wait to see one with a new color scheme.

Bigned, sorry about your loss. How many flights did you have on #1 ? Pilot error or...?

Hercmate (I think that I am the Robert that Steve is referring to... ), I am using an APC 15x6 on my YS 91FZ. With Powermaster 20/20 the engine is a real wildcat-- I am getting almost 10K (still rich after almost two gallons... I could probably do better). The plane has very decent vertical even at that setting (and we are at sea-level here in the Seattle area).

I do have a 16x4W but have yet to try it. The 15x6 has been fine so far.

Rajul..
It was pilot error. I was learning to torque roll. I am having some success with it, so I started working it closer to the ground. I was about 10-15' above the runway and it drifted directly over my head. I turned around to see it and that was it,,,,, I was able to roll it upright and pull it level as it impacted the ground. Broke the tail off, and the engine mount broke in half separating the engine and cowl from the fuselage. As I mentioned I gave it to a friend in the club and he already has it nearly airworthy again. So #1 will fly again, I just didnt have the patience to rebuild it. Hopefully #2 will last me a while.

I have a UCD .60 and have had it up once. Someone told me I need stronger control linkages so I put 4-40's with metal clevis', swivel ball links, stronger servo arms, and soldered on threaded couplers to connect to the swivel ball links. Look really tough, but, I noticed when I turned on my radio with my high torque servos.. that.. if i kind of flipped the rudder it was shake.. BAD!! it would not stop for like 20 seconds. I then reached up and flipped it with my hand.. I could tell there was quite a bit of play. Looked like it was mostly in the screw on clevis, but, I don't know what to do. I have the thread all the way through plus some. I did put it on the far outside of the servo arm and 2nd from the outside of the horn. I need to do something like this b/c I want to be able to do the throws as far as they will go when on high rates. Are there any tricks to installing metal clevis' that I am unaware of? Anybody have any ideas on how to keep this from happening. I am no expert, but, can imagine that shaking like that in the air would tear the plane apart.

Are you using digital servos?. Sometimes they will flutter for a few seconds after you turn them on. But they definitely should not shake while in flight.
Heres how I cured the "play" problem with metal cleviss.
1. Thread on a 4-40 not before putting the clevis on all the way to the end of the threads or at least till it is out of the clevis's way while you are making adjustments..
2. Thread on the clevis and adjust the clevis's till you get the alignemnt of the surface like you want it.
3. Once the clevis final adjistments are made, tighten the nut up against the clevis and all the play will be gone.

Sounds like your pushrods are in the right places on the servo arm and horn. Should be out as far as possible on the servo arm and in as far as possible on the control horn to get maximum throw.

Here are the servos I am using:
http://horizon.hobbyshopnow.com/prod...p?prod=JRPS811

After further testing.. I noticed that the tighter things got.. the more it would shake. If I unscrew the screw that holds the servo arm.. it does not do it (I guess b/c it has some play). It basically starts happening the more throw I put into it and the less play that is in the linkages. As far as throw.. whether it is out on the arm and part way in on the horn.. or.. in on the horn and part way out on the arm. The more throw.. the worse it gets.

I also noticed that it is the actual servo causing the problem. It is like it is trying to correct back and forth real fast. It does not happen near as bad if I put the trims way to the right or the left and have it start out of center and then flick the stick. The vibration does not stop.. I tested that too. I flicked it and it just keeps going.. Is this a sucky servo.. or.. bad servo? I was told that these were supposed to be pretty good little servos.

Sounds like the servo is in a bind. Take the servo arm off and move it with the transmitter and see if it still flutters.
Also I see that you are using digital servos. I dont use them but my buddies at the club that do have the same thing on almost every plane I see. The servos flutter for about 20 seconds after the TX and RX are turned on.

You may already know all of this, but this I what I would look into.

Heres what I would try if the servo looks good without the servo arm on it.

1. Put the trim on the transmitter at the neutral point.
2. With the sticks on the transmitter in the neutral position and the TX and RX on, put the servo arm on where it is perpindicular to the servo, this should give you max travel in both directions.

Are you using a computer radio?
If so, switch to high rate and back the endpoint on the rudder down to about 25% on left and right throw.
3. Get on the Endpoint screen and go to the rudder EP setting.
4. Give full left rudder and while holding left rudder start cranking the endpoint up giving you more throw. If at any point the rudder starts to shudder, OR stops moving while you are cranking in EP, back off of the EP till you see the throw moving towards neutral again.
5. Once you see the rudder moving again stop and add 1% EP at a time, but stop just before the servo is mechanically limited, either by the rudders ability to move or the servos throw limit.
6. Give full right rudder and repeat the process.
If you arent getting as much throw as you want you on ANY surface need to make sure that the control horn holes where the clevis clips on are directly above the center of the hinge line. If they are back behind the hinge line you arent going to get max potential throw. Also if the hinge gap is too tight or has glue in it its gonna limit your throw. On your U CAN Do if the rudder and elevators are hinged up and the control horns are mounted correctly you should be able to get 45 degrees of throw no problem.

If you arent using a computer radio, check your hinge joint clearances and control horn positions and just take what the transmitter will give you.

I really appreaciate all the help. It appears I am not the only one with the problem. It is not when I turn it on.. it is any time. I can flip the rudder and it starts to shudder. It will never stop if I do not make it stop. I can then flick it with my finger and the thing starts shaking again.

It appears it has to do with digital servos trying to find the center position. Anyways.. here is a post where people were having the same issue:
http://www.rcuniverse.com/forum/Digi...1429229/tm.htm

I was actually able to fix the problem using my jr 8103 and setting the subtrim to the right some. It seems that as long as it is not too busy trying to find that perfect center position.. it is happier. After setting the right trim I just attached the clevis to where that was the center position.

One question on this though. Can I hurt the servo. I was running my high rates at 120% and then set the right subtrim 20 steps. Will this mean that it is actually moving beyond that point? Is that bad on the servo? I am still new to all of this.

You really shoudnt have to use that much subtrim. Its not going to hurt anything but it just screws up the centering of the servo. In a perfect world, after trimming a plane to perfect flight characteristics you would go back and mechanically adjust and take all the servo trims out, other than maybe a little elevator trim that is required during flight as the cg moves due to your fuel tank getting lighter/emptier.
If it were me I would make a note of where the rudder needs to be,, set the subtrim back to zero "if possible" and then adjust the clevis to get back to where you were with subtrim.
I think digital servo flutter is pretty common, due to exactly what you said, looking for their HAPPY place. Sounds like you have found a thread where you guys can work it out. there are certainly guys that have dealt with it that will tell you how to correct it.

I havent used digital servos, yet,,,, so im not sure what the process it to correct the electronic flutter.

c016Y, Welcome to digital servo's. I had this problem and it was not the linkage. You want them as tight and slop free as you can get. The solution is to back off on the servo mounting screws, so the servo is utilizeing the rubber mount grommets. When driveing the screws in untill it bottoms out on the brass sleeves you are bypassing the isolation factor of the rubber. They are there for just this purpose. Also make sure the hole that the servo sits in is not too tight. I tried all kinds of changes on the linkage without relief. Went to "ask Danny" on the JR sub forum and problem solved. Good luck, Joe