At the bottom of each post there is a Balloon comment icon. If there are no comments it will say no comments on this post. Click on it and you can leave a comment for a post. For now its OK to ask a YS question in a YS post or a JR question in a JR post.

I get the comments and and can either respond in that post essentially making it a thread or I will write a new post for the day in the Blog.

I’m learning with you guys on this, however I am interested in comments. I want to know what questions to answer. If you have a question by all means leave a comment on a given thread and I’ll get it answered and we’ll continue the growth of Patternflyer.com

Thanks,

 Troy

There seems to be some questions regarding the YS 170DZ CDI engine. Lots of misinformation is out there regarding this engine.

Here is the scoop on the engine. First off I have been testing it now for about 9-10months.

To begin with there is NO power difference between the two engines. Top end RPM is the same for the same prop and fuel regardless of Glow plug or CDI on Spark. The one thing that the engine does do is provide a better transition and more grunt down lower in the throttle curve over the glow version. This means that you are not having to get as high into the throttle for a given pull on the model. The result is it acts like more power…in that the power band is lowered on the engine. At 50% power the engine is making more on Ignition than it is on glow.

The Fuel is still Alcohol, while the engine will run and transition better on lower nitro fuels, you are giving up power from the 30% to lower your nitro content.  Many have run 20% nitro content and it works very well. I have played with 20% nitro also.  However lots of people do this already on the glow engines. The higher nitro helps the engine run a little cooler and also makes them slightly easier to tune properly. I hope this answers the nitro question. The engine is easier to tune on lower nitro with CDI over glow but you are not going to get the power. I have run mine on 10% nitro and it tunes fine and transitions excellent, but it is not the power we are used to. More testing is going on now. Also oil content of the fuel is a critical issue with tuning. I don’t think 10% nitro and low oil is going to work in the current configuration. I’ll explain why below.

Oil Content, This is where lots of folk that don’t know about the engine are telling folks about it on the internet. Too Much speculation is around. This is the scoop from somebody that has run it and knows what it likes and doesn’t like.  The original YS 170 CDI I flew last winter (January) was not capable of the low oil content. This engine used the exact same fuel as the glow guys. I ran Cool Power 30% heli Performance and also Cool Power 30% Heli LS blends in that engine. Yamada then made several changes to the engine. I’ll explain it a bit how the thing is working and the changes so people can understand. Suffice it to say some new parts are in an engine to allow the low oil content.

Let me explain it this way. CDI doesn’t in and of itself allow low oil content. But CDI with some new engine parts does. I’ll talk about oil more in a bit…but the parts are not the same…CDI is one thing and CDI with low oil is another. Right now the low oil is a CDI thing but many of the test engines are not low oil even though they may have CDI on them. This is testing stuff….So bear with me on this I’ll explain.

The CDI system is more efficient and uses the fuel better. The mixture doesn’t need to be sloppy rich in the mid range to keep the engine from detonating. In fact the engine doesn’t detonate. On glow you have a chemical, pressure and heat reaction. As you load the engine down too much it builds heat. The higher heat means the combustion goes off to early. Remember Compression didn’t change, the catalyst in the glow plug and the heat from the plug didn’t change, and the mixture didn’t change so the higher heat caused by the high load and low RPM means a ignition that happens too soon when uncontrolled like with a glow plug. On your car they call this “Ping” or Knocking. I call it pre-ignition or detonation. Anybody that has gotten a YS lean and thrown a spinner knows the hollow loud sound of this. It’s dangerous for the engine and can break pistons like some have posted on the Internet. Usually the cause of this piston failure is detonation not a flooded condition. However the Flooded or kick back can aggravate this problem. Usually if the detonation that causes those things, can also cause Valve seats being pushed out of the head and other issues from detonation. Detonation is bad and hard on parts. One thing about Nitro content here: Lower nitro required smaller props to keep the rpms right to not overload the engine and heat it up. This is on glow plug as the lower nitro doesn’t make the power and the bigger prop makes the engine work too hard. This makes more heat! People run higher nitro to keep the RPM where it makes the engine happy on the larger prop. On the CDI we can load it down further and get the lower RPM the engine doesn’t complain as much as it did before. Also tuning is easier in one aspect with the CDI. This is why some of the prop choices that are being used. We are turning 19-11’s at 7200-7300 20-10’s and wide blade 18-11 and 12’s at really RPMS too low for a normal 170DZ. Below 7500rpm.

Back to the CDI: The Spark is timed off the rear disc valve of the engine. A small magnet is placed there and a pickup sensor reads as this magnet passes a certain point in the rotation. The timing of the engine is set by the actual rotational position of the crankshaft. It doesn’t pre-ignite as the spark controls the fire and timing is always right.

What does this do for us? First off it means you lean the engine way down. The engine is making more efficient use of the fuel. We were running 20oz tanks. I can get about 12-13mins on Glow plug with that tank full of 30%. CDI allows me to use the same tank and get about 16-17mins out of it. This is NOT the double flight time that some are speculating or claiming but it is significant. I can fly a complete P-09 and F-09 and about 2-3 maneuvers before landing. What I have done is gone down to 12-14oz tanks and can still get through the F3A P-09 or F-09 and work on some other figures…about 10 min flight times on 12oz of fuel. This all depends on how much throttle you are using.

How do we get this longer flight time…First of all the ignition system is more efficient which means its not over rich in the midrange just to keep the top end happy. You can lean the midrange out and keep the detonation problem away because of the spark. This also makes more power in the midrange…more raw grunt here in the middle.

The low oil content will also affect the engines mixture. If you are running say 23% oil and switch to a fuel that has 10% or even 5% oil the mixture will change. Can the parts of the engines take that low oil content? Well yes and no. Standard parts like we have had on the 140-160 and first 170DZ’s CANNOT. However when you put a special crank, and some new lifters on the cam, and maybe a few other parts here and there it can run on lower oil content.

Big Benefit is NO smoke trail.

On Oil content there is lots of testing to be done. Some guys are using anywhere from 5% oil to 12.5% oil content if the engine is capable of the low oil mix. We need to give a big thanks to Cool Power fuels for making up some different fuels for the guys to test out. This testing needs to be more extensive. YS doesn’t want to hand an engine to a customer and say go run 5% or 7% oil in it. Then at 150 flights the engine shoots craps. The idea behind the CDI is to make it more reliable, easier to use and give some other benefits too.

For the record I have run 5% oil in my two engines since June and no issues at all. Some folks have had issues with this lower oil content and are playing with 10%. Usually the problem is not engine longevity but tuning issues. The Needle valve while becoming very easy to set with CDI, becomes hard to set when you start to run really low oil contents like the 5%. Who knows where this is going to end up, perhaps new needle valves or pump assemblies. This is the reason for the testing. Everybody is thinking its out in 2 months….That is not what is happening right now. Perhaps a small run of engines to get more and more guys testing them, but I think full production is still a logically down the road thing. This is something new and we the guys flying it are learning how to handle it. It’s different at this point. Is it better? Yes….when it has a problem is it worse? Well perhaps. The people that are running the engines now are learning them and in some cases what you thought you knew is now changed.

So to conclude The CDI gives some big advantages:

·         Super Low idle 1400rpm Great with big props for slow downlines. 19-11 APC Ignition prop.

·         Lower sound profile (deeper sound) but meets the sound rules because it turns the 19-11 at 7200-7300rpm

·         On low oil content no smoke or 10% oil very little smoke

·         Fuel economy

·         Better Grunt in the mid-range

Disadvantages right now:

Weight, the CDI adds about 4.5 oz to the model. The CDI also tends to make model Nose heavy. If you run separate battery for the CDI it can add up to 7-8oz to the weight of the model and this weight is all ahead of the CG.

We are testing the CDI system running off the RX pack. I flew my model this way at the NATS. Euphoria Bipe with CDI on a 1320mah 2 Cell lipo and you can get 4-5 patterns out of it before charging. Yes we are pulling about 250-300ma per flight. This is because not only are the servos working but the Spark is also coming from this battery too. Various ways to run this system off the same battery pack. Right now it seems 2.4ghz technology allows you to do this no problems. I have heard of issues with 72mhz and the CDI system running off the RX power. For me DSM2 fro JR and Spektrum has been bullet proof and I am running the Ignition directly out of a port on the RX. I caution against this….It’s not tested yet. But so far I know several of us are doing it.

I hope this dispels some the myths and misinformation regarding this engine. I have run all the various versions and have learned the little things about it. So to me its easy to a new person grabbing it the 170DZ CDI might be a big learning curve. It works great and I am very pleased with its performance. I’m with Bill Cunningham I think it’s the only way to go. Have there been some speed bumps? YES, will there be some more? Probably

Troy Newman, Team YS

Pattern guys,

This forum is setup to ask questions so if at any point you have a comment or a question please let me know.

I know this was promised to a couple guys. Sorry for the delay. As the Commercial says Life comes at you Fast.

My buddy Robert and I installed a DEPS system in a  Focus 2 model. I have received tons of email on the subject with guys questioning can it be done and they want some photos. As with everything the DEPS system I use today on all my models has evolved. I install it a little different than when I originally wrote the articles about it several years ago. Today I no longer build a latter system outside the model and try to install it. I keep the two balsa sticks separate and get everything fit into the model. Once you have everything in straight you can install small cross members to support the pushrod stick. This is done use a little of the ship in the bottle technique. This is the same method I use to install the DEPS system in any model even the expensive OXAI planes like my Euphoria are running this elevator pushrod system. Below are some photos of the install.

One note before we get going. I have been using the Teflon sleeve material from CST on all my DEPS installs lately. I have explained in other write ups about the differences between the Teflon sleeves and the nylong hard sleeve material supplied with the DEPS kit from Central Hobbies. For me I know how to not wrap the thread too tight on the sticks…so I use the Teflon version. It does require you to purchase extra sleeve material but it allows for a smaller exit in the fuse side. I also think it provides a little better friction free movement. However the stock sleeves with the DEPS system do work and I have used them many times before. I prefer the Teflon sleeve material now.

Important Note this is Roberts’ model and he did most of the work.

You have to mount your elevator servo. We chose a location to allow for the elevator servo on its side and easy access to the center servo arm screw. The servo was oriented so that a Phillips screw driver could remove the servo arm screw from the Aileron servo lead hole in the fuse.

Next the location of the servo connection for the elevator pushrodsystem is marked on the fuse side.  With elevator control horns and stab installed you can then pull a string to get the side view or elevation view of the pushrod location. Since everything must be straight line from the servo to the elevator horns a string can be pulled between the two points and align the side view or elevation line. I use some tape and a Sharpie to make the approximate exit location. At least this gives us the elevation line. You have to sight down the control horns and think in 2D at this step. We will get to the 3D part and find the exact point where the pushrods will exit the fuse side in the next step.

Just make the string froma  side view pass through the end of the elevator control horn and use masking tape to secure in place at the rear of the model.

We know the exit point from experience is going to be close to the Front of the LE of the stab. Probably about 4-5″ in front of it from a experienced guess. We just don’t know the exact location yet. So I mark a extra long area with masking tape. To keep my thread line I mark this area with a sharpie marker. Now I have the thread line or elevation line marked on the fuse side.

The Next step is to get the “V” distance or the spread of the pushrods at the rear of the fuse. This is done with the Fuse upside down and we are going to pull another string line. This time from the fuse center up at the servo to the Elevator control horn. The actual location up front in the center of the fuse is about 5inches or so behind the actual servo. This is where the pushrod balsa sticks are going to come together to form the apex of the “V”

I place a small tube over the top of the elevator control horn…and tie the string off to it. This case its a Fiberglass Dave Brown Pushrod. I have a few of them now that I don’t use this system for Elevator control. Now pull the string to the servo center location and use Masking tape to hold it in place.

Using a piece of Card Stock…in this case a JR servo card, I align the edge of the card stock with the very point the string “exits” the fuse side. I tape the card stock in place and transfer this line to the side of the fuse and make it intersect with our elevation line. Sharpie markers work great as Denatured Alcohol will remove them from most painted surfaces and Ultracote.

This is now the center of our exit slot. And we have the elevation line will show the angle the pushrod will exit from the fuse. Its important at this stage to realize the pushrod will exit the fuse at a very very shallow angle. This means the slot in the fuse side will be fairly long. Oversizing this slot is not a problem but you don’t want to get carried away. Normally this slot depending on the thickness of the fuse sides can be about 3 inches.

Now the tedious part. Cut the slot and trial fit the pushrod sticks in place. You have a line to mark the cut and a center of the exit is the vertical mark. I use a dremel tool to start, then fine tune the slot with a 1/8″ round file.

Test fit each pushrod on its balsa stick to make sure the pushrods path is through the 2 points in space. Servo arm connection and elevator horn connection. This is the important part and will take some trial and error. If the pushrod binds or bends as it exits open the slot further in the right direction to get a straight shot. Use the small 1/8″ diameter round file to open the fuse sides.

A trick to this fitting and installation is to slide the solid CF rods in the slots from the rear of the model. Then inside the model slide the balsa sticks and sleeves over the top of the CF rods. Carefully you can inch the balsa sticks and sleeves over the top of the CF rods and push them back though the exit slot in the fuse side. This can get a little tedious install it try, pull it out file a little more material away, then try it again.

Another Note: my balsa sticks have a sanded tapered end where they will meet inside the fuse. This keeps the the pushrods from binding as they enter the teflon sleeves. The photo below shows the sticks before installation.

Once you have the pushrodina straight line from the center meeting point to the elevator control horns. You can now do the same measurements and transfer the slot location and length to the other side of the Fuselage. You will notice the further aft you push the balsa sticks the more binding that can occur as the pushrod tries to bow out at the rear. So lengthen you slot, until the pushrod guide tubing passes through the fuse side as if the fuse side was not even there. This means the slot will look excessively long. However once the pushrod is installed in it it will look normal as the pushrod and sleeve will fill the gap for the most part.

At the same time as the pushrodsare fitted for both sides I locate a balsa cross member. In this case I just used 1/4″ x 1/4″ balsa Up front to hold the pushrods at the right elevation to hit the servo arm correctly.

The 1/4″ square balsa cross member is attached with medium CA for now. If you misalign it you can always pop it out  and reinstall. In the photos below the Pushrod sticks are not glue in place. They are just sitting on the cross member.

 Once everything is installed properly and you have a straight line for each pushrod, it is time to glue the balsa sticks/pushrod assemblies into the model. Don’t worry about any other supports at this time. You have the front support above and the slot at the rear of the fuse. For now this is enough support. Once the balsa sticks are glued in place we can add a center support to hold the “V” from bowing in the middle.

Use a slow set epoxy and some microballoons to make it thick like toothpaste. Place some epoxy on the end of each aft end of the push balsa sticks. And slide the sticks one at a time in place. A slow setting epoxy is great as it gives plenty of working time. I use BVM Aero Poxy for this task. Tony Frakowiack turned me onto this stuff about 5 years ago and its awesome stuff. Working time is about 40mins or so.

Also use some epoxy to attach the sticks to the front 1/4″ sq cross member support. Let the whole thing cure over night. I get a little brave and can do all the next steps at one time….I glue it all up and get it aligned, make my supports and everything so that I only wait one night for the epoxy to cure and the pushrods are all glued in. Experience is the key with this…I don’t recommend it to somebody trying it the first few time. Let the balsa stick get glued in place. Once cured they will be easier to work with for addition cross member supports and hooking up the CF pushrods to the servo and the elevator control horns. If you try to do it all at one time you might get a little over loaded and screw it up. So take your time and let the epoxy cure. Its not like the contest is tomorrow morning.

Coming back to the install the next day and install at least one mid-span cross member.  I glue this cross member to a small balsa stick or another section of pushrod material…You can use anything.  Tack glue the cross member to it with some medium CA. I use the Purple Bob Smith CA. I like the Bob Smith stuff the best. Its always available from the LHS, and I like the tips better than other brands.  They are pointed and allow for a fine accurate distribution right where you want it. Some of the other brands have a wide tip or a shorter tip and these make it more difficult to get in a tight spot. Again you can use your choice of CA. My local Hobby Shop always has the fresh Bob Smith CA. I hate the old CA. It doesn’t kick off right and is tough to work with. So I buy smaller bottles and keep it fresh. Costs a little more in the end but lack of frustration also is worth a  price to me.

The idea is a handle to to guide the cross member back to the right location. Glue the cross member in place with some epoxy and once cured, the “handle” gets a little twist and it breaks away leaving the cross member glued in place properly. Use an epoxy brush on a stick to reach back into the fuse and get some glue where its needed.

 Now your DEPS is installed. You just need to attach it to the servo and to the elevator control horns. At the servo connection I just use some thread and thin CA to attach the solid rods to a center pushrod tube. This will geta  titanium fitting and attach to the servo. Its inportant to do the servo connevtion first. Once its all attached and working properly tackle the elevator control horn ends.

 I now use Central Hobbies 1/8″ pushrod tubes with 2mm titanium ends for the elevator side connection. The Small solid pushrods will slide perfectly inside the 1/8″ pushrod tubes. Also these tubes are more rigid and can span larger distances without a problem. JB Weld works great and I attach the 2mm pushrod ends to the 1/8″ CF tubes at the same time I glue the 1/8″ tubes over the top of the solid CF rods.

Below are some more photos of the install. 2mm Titanium ends are used with 1/2 the threads cut off. This also makes the system more rigid as there is less threaded area to possible work harden and fail. Shorter exposed threads makes it stronger. I use the 2mm becasue this is the smallest or Finest adjustment. This is important in setting up your mechanical system. A 4-40 thread you will find very course and 1/2 turn is too much…when making small fine tuning adjustments mechanically.

 NOTE: Be sure to have at least 2″ of solid pushrod that fits inside the 1/8″ tubes.

 Here is an older photo I have of the 1/8″ pushrods from Central Hobbies installed over the top of the solid CF DEPS pushrods. This was from a model a few years ago. I now install these longer and leave only about 2″ of the DEPS solid rods exposed from the exit of the Teflon sleeve and I will trim the excess Teflon sleeve back to about 1-2″ from the exit of the fuse. This means the maximum exposed distance of the Solid 0.070″ CF solid rods is about 4-5″

Some people complained that the too long of exposed distance was a problem. I suspect they were over engineering things a bit. I have run the models with 12-15″ of exposed 0.070″ pushrod and you can’t feel any issues with it. However as an Engineer I feel using the 1/8″ tubes on the exposed section makes a stronger and more rigid connection. That is why I do it now.

SO there it is…..Feel free to ask questions.

Troy Newman

I just wanted to give you guys some info and photos from some other happy Focus Sport owners. The Focus Sport thread and build is solely to get folks interested in flying a Pattern style model. This goal is to get people excited about aerobatics and the hobby that I have such a passion.

 These photos were taken of Randy Hicks new Focus Sport. He really likes the way it flies. Futaba radio and JR servos guide the model. Its all glassed and painted. I really like the canopy look. Its different and looks great.

Randy did a great job with the model.  The photos were taken by Vaughn Tabor

I posted this on Flying Giants last night. I think this is a subject that many folks don’t really get a grip on. It applies to our pattern models too. The problem is much worse on the larger models. In most cases us pattern guys also have large models too. So this is a attempt to share some more information

Ok this is long but I think its worth reading for you guys having this trouble.

A Guy complains that they have a 8711 servo with on a giant scale model. The ailerons are jittering or oscillating at center. When he puts his hand on the surface the bouncing stops. What is going on…..? Another guy posted that he keeps stripping servo gears on an 8611A that is in his wing with dual servos.

What the guys are describing is a worn pot. What causes this? Vibration. So on your Gas burning giant scale models these have fairly high vibration levels. This tends to cause the pots to get a worn spot right in the middle where neutral is. The worn spot doesn’t mean the servo is bad its just worn at center.

The way the thing works is the pot tells the servos “brain” that it is either at the commanded position or its not. When you get a little worn spot on the pot, the “brain” sees that its off just a hair, so it drives it across the worn spot. Then it says wait we went too far and drives it back the other way. As mentioned under air loads this over driving stops in most cases because there is a constant load on the surface.

Why does it wear? The answer is the pot on all servos has a mechanical wiper that is attached to servos gears. As the servo rotates this wiper slides across a carbon disc. As it rotates the resistance changes, and if the servo is not rotated to the commanded position the motor drives it to that position. The JR 8411 8611 and 8711 servos all are very accurate and precise. It knows if the servo is not in the exact position that was commanded and it drives it to it. When this pot gets worn and the servo is precise as the 8711’s it knows its off that micro hair and it drives it back to the position. This is what makes these servos so awesome.

All servos have this problem with vibration. Usually ailerons are the culprit in the wear of the pots before other surfaces. The reason is they take the most beating when the engine is running. the ailerons are being held up against gravity and are often large and sometimes heavy surfaces. If a given servo doesn’t notice the pot wear as fast as another servo its because the sensitivity and precision of the servo is not the same. Say it needs to be a full hair off instead of 1/2 a hair off.

This accuracy and precision is what makes the JR 8711’s so good. You can’t have the accuracy and precision they have without having the issue when the pots get worn.

Now we want the precision of the servo.

How do you stop it or minimize it?

1) reduce vibration. This could be make sure your prop is balanced, a soft motor mount can help. I know they are heavy. Merle Hyde (Chip’s dad) makes Hyde mounts for just about any engine. They help a ton. The problems is they get expensive for the large models and they get heavy too. I don’t always choose to use them myself…but they do reduce the vibration and servo wear by a ton. I know because I see it all the time with my pattern models. Vibration is a killer think about it 60 flights is 10hrs of being shook with high vibration non stop. Then add in the loads we are putting on the models doing the 3D stuff… It might even shake a few fillings loose in your head if you were sitting in it.

2) Servo arm lengths. I know most of these are being used in 3D applications. In that application its tough because you want that high control surface deflection. If you are not using 3D rates then go to a smaller servo arm and a longer control surface horn. This gives the servo the best mechanical advantage over the surface. If you are not using 3D rates and you D/R values are below about 70-80% with ATV’s up at 100% or more then you need to change to smaller servo arms. Rudders seem to be a big spot where this happens. The reason is guys insist on using a equal servo arm length to the control horn length. This 1 to 1 ratio is not needed to for good geometry on rudder cables. You can keep them tight going smaller on the servo arm or wheel and longer on the rudder horn.
This mechanical advantage thing works against you when the servos start to wear. Think about it 50-100flights in a model that is built light and has a DA50 in the front of it….They shake all the large engines shake a ton.
I fly mostly pattern models and have written some stuff on mechanical advantage and how to maximize your linkages. This stuff still applies to the big models, even more because the vibration levels. Our pattern models have Vibration dampening motor mounts. The vibrations levels are 20-30% that of a big gasser.

The link to the article I wrote a couple years ago is good reading material.

http://www.centralhobbies.com/instructional/instrct.htm

Its a 2 part article…the second one talks about pull-pull setups specifically. Poor cable setups will cause the servo on a pull-pull setup to fight its self. Depending on your choice of rudder cables it can stretch…andthen it acts like a rubber band. This causes the servo to really work hard fighting the rubber band action too.

Mechanical advantage issues can also cause problems. Do the best you can for the throw you need. This is why a guy setting up an only precision model might use 2 servos per aileron yet a guy putting together a 3D monster might need 3 servos per aileron. The less mechanical advantage the servo has the more abuse the servo will take. If you don’t’ use the large 3D throws then setup the plane to take advantage of the power and precision the servo offers The less mechanical advantage you have the more a little wear will cause the servo to jump over that worn spot. Also the bigger the deflection gear wear will have with the surface. The simple fact of of the engine tossing that mass back and forth is working the servo. So minimizing the the servo arm size will help reduce the amount of travel in the “slop”

3) Reduce weight in the control surfaces or balance them with mechanical balances. The more mass on the end of the pushrod the harder it is for the servo to keep things at neutral when the engine is making everything shake like crazy. There are easy ways to do this. Lighter control surfaces have less inertia and put less load from vibration on the servos.

4) Vibration also plays a role in gear wear. These metal geared servos get bounced around their gears will get sloppy over time….This exaggerates the worn pot spot. The loads on the surfaces will strip out nylon gear sets…so you are stuck with metal gears.

5) Better mounting techniques on the servos can also help. Make sure the servo is only touching the plane via the little rubber bumpers. Sometimes we will cram a servo into a spot and it is resting the case on the servo rail or perhaps the side of the servo case is touching the wing. This sounds funny but mounting servos on their sides helps the pot wear. Think about it the wings roll back and forth very quickly with the vibration of the engine. This makes the little wiper in the servo pot bounce up and down making it wear faster. Putting the servos on their side the wiper doesn’t bounce tapping the carbon disc. Instead it rotates which is the motion it is designed for. They wear about 50-75% or longer when side mounted.

6) Proper radio setup. If you are getting stripped gears you have one of two problems. First the servos are fighting each other at some point in the travel. A matchbox can help this. Also the Balance feature of the JR 12X is designed to synch up the servos through the entire travel of the servos. If they are binding at any point at all this is causing the pot wear, and gear train wear/damage.

If the servos are not fighting each other then you don’t have enough servo on the surface.

I’m not a 3D expert, however, I do know that at the TOC’s during the free style part of the event the guys were pushing the envelope and often would landwith a couple stripped servos. I have seen this happen at the Tuscon shootout too. I know we try to bang them around like the pros. Yet the pros strip servo gears too when they get a little too hard on the equipment. This was not limited to just JR or Futaba pilots they both did it at the TOC. Granted we have better servos than we had back then in 2002 also. This is much less of a problem today. But the theory is still the same,a nd these guys are the pros…What about a guy that is not as good of a pilot or not as good at setup on his model.

A quick fix for worn servo pots. Take the servo arm off and rotate it one tooth off. Then sub-trim it back to center the surface. This will put the servo pot in a new “fresh spot” that doesn’t have the worn spot. The worn spot is still there but its not the neutral position, instead the servo just passes through it as you deflect the ailerons. In fact you can’t even tell its there because its so small a worn spot. But when the engine is just beating it to death at the same spot it sure shows up.

When the servos get so worn that they don’t stop the wiggle even with pressure then the pot is worn too badly. You need to send them in to be serviced. A new pot can be fitting the servo and it will be good as new. These servos will last for years and years with a new pot every once in a while. JR digitalshave a 3 year warranty so send them in and if they are not abuse, crashed or what ever the Service folks at Horizon will take care of you. I don’t know how Futaba or Hitec handles their service but even if you pay to have the pots replaced is cheap like $15 a servo considering a $115 servo…it will make it good as new.

We pattern guys get a little anal when it comes to servo pots and model linkages. This is because our models can feel it quickly. The F3A pattern planes are extremely precision andsmooth. When we have a worn pot you know it. If my aileron is not centering by 1/64″ my plane is really bad out of trim. On a 50cc or larger model its not as critical flying wise….So guys tend to get into habits that are not the best practices for servo setup and linkages. Plus combine that with the hard mounted DA50 compared to my Soft mounted YS 170…The vibration levels are huge on the gasser compared to the pattern model.

I hope this answers some questions about the servos and pots. I know I know everybody thinks they have a good setup…However if you can improve it with some of the tips above it will make your equipment last longer. This goes for any brand of servo.

Troy Newman
Team JR