Zippi

My Feedback: (10)

I agree about Troy finishing his build. I think his experience has some needed input here. I think the balsa sticks that were falling out were stringers that went across the fuse in the rear to give the white foam more support. I have epoxied the wood blocks back into the firewall and I'm ready for some warm weather and another crack at dialing this plane in. The front of the cowl took a beating as the back plate was rubbing on it the whole flight. It didn't seem like the added weight had much affect on the flight characteristics of the planes or the landing that I could tell. I only had the Saito 125 running at 8300 rpm since it's new so like I said, this looks to be a good combo IMO once it's leaned out. I hope next weekend brings some better flight conditions as I can give a better report on how the plane performs. Of coarse I do not fly in competition nor do I practice pattern flying. I was just looking to get a plane that can fly smooth and perform aerobatics very well.

Troy Newman

Ok we are at the point in my build that its time to look up front ot the engine install. I've been tied up and time to write the install notes has been limited.

I looked everything over regarding the cowl mounts and they look strong enough. Who knows...But I would not add glue to them right now. If the Spinner hits the cowl it can break them loose. But from the construction they look to be notched into the firewall at least part way. This is good as it gives surface area. We will keep in mind a good gap of about 1/8” or so to eliminate the possibility of the spinner and cowl coming in contact. The engine mounting stuff will be in a couple steps.

First is to mount the cowling.

I used card stock as markers. I put an X on the card stock as shown in the photos and aligned it to the middle of the cowling ply mounts. Secure the card stock with some masking tape and then fit the cowl. Mine required a little minor sanding to get it to fit perfectly. The stripes on the painted cowl and the fuse were close. Not dead on perfect but real close.

Once you have the card stock on the fuse in the proper locations to center the screws in the blocks...I used masking tape again to hold the cowling on the nose of the model. I used plenty of tape to keep it from moving. Once secured in the proper location...and after some sanding to help the fit, drill the holes on the "X''. You drill straight throught he cowl and through the ply block. I used a small drill bit at first to make sure the holes aligned well. Then I just drilled them out a little bigger.

I hate to use Blind nuts on stuff like this the screws are metal to metal and they can vibrate out. So a little trick a friend taught me...Use the yellow center from a nyrod. A 4-40 tap can be used to cut threads in them or better yet I use #4 socket head sheet metal screws like those from Dubro. They cut their own threads. If the threads ever strip you juts drill out the old nyrod and replace it. The proper drill size is a #25 drill.

The down side is that over time on and off the nyrod will pull a little out of the hole. So you just take a #11 blade and trim of the sliver of extra material. Use some CA to secure the nyrod pieces in the plywood. See the photos below to see how this done. Its super light weight and the threads will never strip out....The screws will tighten up excellently and you can fix it later on in its life if there is an issue.


I used 1/2" long socket head sheet metal screws for the install. This is shown installed below also.

This also shows the minor misalignment of the cowling to the stripes on the fuse. I told you it was minor.


The cowl is now mounted and its time to setup the engine.

Troy Newman

Engine mounting is next. The way this model is designed….the firewall is square to the model, However there is a thrust plate that bolts to the firewall. Then the engine mount bolts to this plate or block and gets the thrust correct on the model. The manual call this the thrust plate.

Right away we see in Zippi’s work that the bolts that come in the kit are a socket head type. And especially since Zippi changed his motor mount to a different make he had to hack the the mount up to go around the bolts. I opted for a more elegant solution. First you can use a countersunk screw. Or you can counter-bore the bolt heads below the surface of the block. This is where I changed the method a little. First I went to 6-32 bolts and blind nuts. Since my motor mount bolts will be 6-32 I wanted to keep the block bolts the same. I prefer socket head bolts in this application and socket head countersunk bolts are rare, you can get them at micro fasteners, but the hex is small and you can’t torque them well. So I thought well I’ll just a use a Phillips head. Scrambling through my box of junk I could only come up with slotted screws not Phillips 6-32. Now on to plan B….I’ll be slick and just counter-bore the bolt heads below the surface. You want a flat bottom to the counter bore hole, so you can’t use a normal drill bit. I choose a 3/8” Forsner bit. This cuts a super clean hole and the base is flat. I wanted to able to add a washer and give the washer and bolt some surface area…for the 3/8” Forsner bit was used. You only need to go below the surface deep enough to clear the bolt heads. It doesn't need to be deep. In fact you want it as shallow as possible To give maximum beef to the bolt to hold the wood.

I bolted the thrust plate to the firewall using the 6-32 socket head bolts and washers.

The look is very clean. When we are done with this you can use thin CA to seal the thrust plate in the areas where we exposed fresh wood in the counter-bore holes.

To install the thrust plate you need to look at closely. The manual says 3degs right thrust and 1.5deg down. When looking at the plate you can see the 3degs for sure the 1.5deg is a little more subtle....But align it so the thrust plate points to the right with the fuse upright on your table. If you get the fattest part of the block on the left side then everything will be correct. Mark it will a pen or pencil to show which way goes up. See the arrow in the photo. My thrust plate actually worked out to have the number stamped on on upright....But don't trust this. Just look at the block and you can tell which is which the big offset is for the right thrust and you'll have the thing correct.

This will get the thrust plate intsalled and you are ready to do the engine mount to the thrust plate. Justa heads up...I didn't sink the blind nuts in the back of the fire wall too permanent. I'll discuss this later....in the next section...Pull the blind nuts in to the wood gently but not too deep...On my setup I will be removing them as tell you why...As I said before I'm ahead of the writing so....I d=found out something that we had to change...But to get there we have to do these steps and have the thrust plate bolted to the firewall.

Troy Newman

The motor mount portion is the next step on the engine mounting. Zippi showed the hard mount. I was going to use the Dave Brown mount and the Hyde Mount, however a little change came into place while doing this….The thrust plate was too thick for the Hyde mount. Meaning the spinner gap was way too big. Since I decided that the Hyde Mount was going to be in my model I made some changes. This made it tougher to swap out engine mounts without making a new thrust plate. I had planned on doing that…but lazy got too me. Besides I want to get this thing in the air. Zippi seems to have the photos of the hard mount covered. The hard mount or Dave brown mount install goes exactly the same as this I’m going to describe but you don’t need to modify the block like I had to for the Hyde. Its all good and took a few minutes of my time…The result is probably lighter and better than the removable thrust plate.


So lets get to it. I used some good masking tape…super sticky stuff…The 3M blue tape comes in a couple of stickiness level, Low tack, regular and Holy Crap. The HC version works great for this application. You will also need your spinner of choice. The spinner size is 3” I always choose the Tru-turn spinners. I like them better on the 4 stroke engines…heck I like them better on all my engines. You will also need some thick ZAP.

We are going to tack glue the mount to the thrust plate…then put an engine on it and check the spinner fit.

Cover the rear of the mount with masking tape. Next on the thrust plate mine had center lines marked on it. I used a circle template to mark a larger circle that was just a tad smaller than the center hole in the motor mount. Cut the center masking tape away from the mount just to expose the center hole. Now align the mount you it is centered on the thrust plate. Once you trial fit everything. I will rotate my engine slightly to get the exhaust lower in the plane. Since I’m going to use a standard muffler setup…I want it to get the goop as low as possible to keep it away from the landing gear as much as possible. I don’t mind polluting the air a little, and would rather not have to clean as much off the side of the model.

Trial fit is done ready to tack glue it….. There is a cool trick….Spray some kicker on the thrust plate…then apply some glue to the masking tape on the rear of the mount. I used 5-6 drops of thick CA about 1/8” diameter. Now align the mount in the proper spot and press it onto the thrust plate. Hold it for about 20-30secs. This will make sure it cures.

Now this is a fragile setup can’t take much weight or abuse. You are basically held by that Holy Crap sticky level of Masking tape. Carefully mount the engine on the Hyde Mount….In the case of the Dave Brown supplied mount…Just set it on the rails.

The fuse inverted is best at this step of engine mounting. Now slide the cowl on a screw it in place. Use your spinner back plate to check the alignment to the nose of the cowl. This is where I went Oooops…The engine is way to far forward on the Hydemount. On the Dave Brown mount the engine can be pushed back a little. And the gap setup correctly but for the Hyde the Thrust plate is just too thick.

So here is what I did. Pulled the thrust washer or drive washer off the YS 110S…Now my TT spinner back plate will slide up against the front bearing or close to it. The spinner back plate will now touch the cowling. If everything is aligned properly you are set. If not…pull the motor mount off the thrust plate, and move to the new location and repeat the process above. Once you have everything aligned properly for the spinner in the middle of the cowl…carefully remove the engine from the mount.

The mount is still tack glued to the thrust plate…I used a long 1/8” drill bit to drill the motor mount holes into the thrust plate….I drilled them all the way through the firewall. Now I have a keyed position to get motor mount back in the proper location…and I can thin out that thrust plate. The thrust plate was well over ¼” too thick when using the Hyde Mount…..This is the biggest problem I have run into with the model. It took some time to thin the plate down.

First I marked off 3/16” on the plate using a combination square…this line went all the way around the edge of the thrust plate. Then off the belt/disc sander with the block I went. I marked the edge of the late to designate the top side and the front of the plate. I used a Sharpie marker and did it such a way that my sanding will not remove the mark. I’m going to sand the face of the block but I don’t want to remove my index marks on the edge.

After some trial and error I got the 3/16” off the block, and came back to the model with a smile and some saw dust covering me from head to toe. Bolted it all back up in place and this time I found that the bolts holding the thrust plate to the firewall were not needed. I had hole straight through from the motor mount to the back of the firewall. SO I moved my 6-32 blind nuts to these motor mount bolts. The thrust plate is not sandwich style between the firewall and the motor mount.

Spinner gap was still a bit much but everything was still aligned….If its not you didn’t sand evenly to your mark lines to keep the 1.5 deg down and 3 deg right thrust…So go back and slowly shape the block to get it back with the spinner in the middle properly.

The disc sander will cut fairly fast if you are not careful. Allow the sand paper to cut and don’t push hard as you can change the angle. This gets a little tricky but is not too hard.

Finally I got the spinner gap correct and the spinner back aligned properly with the cowl…guess what the gap was the same all around behind the spinner so this means The thrust line was correct and I just thinned out the block.

Whew!...That was a little extra work but I got it done. By the way….all that work to counter-bore the bolt heads was no use other than in initial setup…because npow the block is so thin on the right side that the bolt heads can’t be hidden. The good news is I don’t need them…I’m using the motor mount bolts to hold to the firewall. Once it was all setup correctly….Apply a little 30min epoxy to the rear of the thrust plate and glue it on the firewall. Just bolt the motor mount back in place and let the epoxy cure. The thrust plate will be clamped to the firewall in the proper location. Now it will always be there and aligned properly. Future changes to the spinner gap can be accomplished using some plywood shims…Right now I have no extra material and have slightly less than 1/8” gap between the spinner back plate and the nose of the cowl.

If you stayed with me here are some photos. This is one aspect that could have been done much better. I don’t like the thrust plate idea but I understand why it was built this way. I wish I could come up with a better solution….Maybe have a new block made at the factory for the Hyde mount…Or just built the thrust into the firewall. More engineering work here….Its not bad and you can get there from here but its not the easy task it should be for installing the engine mount. Tough call and Piedmont picked one method. They didn’t choose poorly but I think with a little extra brain power there is a better solution…As of now what I have is perfect and will work great. Maybe a center bolt on the firewall to the hold the thrust block in place and then drill the motor mount holes like I did to get it just right. Once the plate is glued to the nose of the model you are setup and the mount will be in the correct spot all the time.

When you are done sink those blind nuts into the rear of the firewall good and put a little thick CA on the edges of the “T” nuts to keep them from popping out of the plywood.

The Dave Brown mount doesn’t need the sanding of the thrust plate…So set the engine on the rails of the mount in the correct spot. Carefully remove the cowling and mark the beams for the mounting lug hole locations. Drill these holes and mount your engine. It’s a done deal. The spinner gap needs to be bigger

Notice my rotational offset. The thickness of the thrust plate is shown and other details as well.


This is a really long post so I hope I explained it well enough…I’ll wait tonight to add anything more are there may be questions….

Next are hinges, servos, and the fun part. The hard work before radio setup and servo linkages is all done…Wings aligned properly, engine in properly. I’ve looked at the weigh since there was a question…I don’t think its going to be anywhere near 9lbs…I think it might be under 8.5lbs. Of course there is a little question on some of the hardware supplied with the kit if it is really the best for weight….There are also some upgrades we can do later like CF tube and so on…but for now its all going stock, HydeMount, and all supplied horns and landing gear. We’ll see what happens. I’ll do comparisons as we come to those bits and pieces.

Zippi

My Feedback: (10)

I got back out today with winds less than 5 mph and put 4 flights on the Focus and found out it's way to nose heavy. I flipped it inverted and it wanted to dive really bad so a lot of the weight can come off the nose. It had some copling towards the canopy but was not hard to hold on line. On this fourth flight I did a stall turn and as I was coming straight down I gave it full throttle and started to pull up on the elevator slightly and was going to make a long low pass over the runway. Just as the nose started to pull up the plane started snapping hard right until it went straight down on the concrete runway. This all happened in a matter of 3 seconds and needless to say it was totally destroyed, Saito 125 and all. The crash was so severe that it was hard to tell what really might have failed. Don't really know if it was a machical or electrical failure. It really bothers me that I won't be a able to tell what happened. This is the second plane I have lost in the past few months since I switched to the JR 7202 PCM radio. Both planes acted the same way when they went in, snapping to the ground. Same TX but different RX. On the first crash I sent the TX and RX in to be checked and was told it was ok. Airtronics is coming out with the new RD 8000 2.4 GH in 2008 so I'll be switching back to Airtronics.

JoeSpitfire

My Feedback: (18)

Hi Troy. It's Joe from Menomonee Falls. Thanks for the time and effort to document all these build notes. I've picked up several great tips along the way.

I've got a question for you about your cowl mounting. I'm wondering why you chose to drill the cowl mounting holes prior to mounting the engine. It seems to me that you wouldn't want to commit to the cowl location before you new exactly where the center of the engine thrust was. Wouldn't it be easier to get the spinner gap exactly right by fitting the cowl at the same time you were locating the engine mounting holes and such. Can you elaborate on that?

Thanks,
Joe

onewasp

.Zippi see your PM's

majortom-RCU

My Feedback: (40)

Zippi, I'm sorry to see what's left of your plane, I know it's got to be distressing and frustrating. I've snapped my share of beautiful models into the ground, so I know the feeling.

At the very least, we hope to gain some learning from a disaster like this. I won't say I know what caused your snap, but I can think of a couple likely suspects, and suggest a few new habits to cultivate.

First off, it would be great if you could find yourself a pattern flyer to give you some coaching. One of the first things he would advise is that when the nose is pointed down, the throttle stick comes back, all the way to idle if it's pointed straight down, or almost idle if it's 45 degrees down. The only time a pattern flyer uses full throttle is when his nose is pointed straight up. Straight & level flying is at about the same speed as the plane exhibits coming straight down with engine at idle. That would normally be around half throttle or slightly more.

Second, I see from your wreckage photo the elevator servo arm has the pushrod all the way out on the end of the servo arm. My pattern and IMAC planes have the pushrod all the way in on servo arms, and half of them are set up with servo wheels instead of arms, about 10-12 mm from center of servo hub to center of connection point. With the other end of the pushrod linked to a control horn at 1-1/2 to 2" from the hingeline, you'll have very moderate (but adequate) throws, full or nearly full resolution from your servo, leverage favoring the servo by about 4:1 or 5:1, which means slower actuation between servo movement and control surface movement. In the case of snappiness, slower is good.

Third, I see your left aileron completely separated from the wing. I'm guessing the aileron was installed with CA hinges. If you did your aileron servo linkage similar to your elevators (long servo arm, short control horn), you had low flutter resistance in that surface. High speed flutter can definitely make short work of CA hinges, even good ones. Ailerons on pattern planes should get the same linkage treatment as elevators, which means short distance from servo hub to pushrod connection point, long distance from hingeline to pushrod connection point on the control horn.

Fourth, if I were test-flying a pattern plane, the first parameter (after trimming for straight & level) I would want to correct would be CG. If I could see my CG was clearly off, to nose or tail, on its first flight, I would land the plane and take it home and make my best guess adjustment. On occasion, I might be able to make a change right there at the field, and would try that so as not to waste a trip. But I would definitely not try to wring out a new model when I knew my CG was off. That's just goofing off with a serious model. I try to limit my gppfing off to fun-fly models, and disposable ones at that. I've yet to have a bad surprise while flying precision aerobatics by the book, but often had it happen when I fly with no particular purpose other than watch the plane go whizzing around.

What makes a model snappy? Overweight, control surfaces too large, throws too much, too much throw on a surface applied too fast, CG way off (usually too far back, but too far forward would also work). What makes a surface flutter? Too much speed (as in full throttle nosedive or anything approaching that); too much linkage slop; hingeline not sealed; servo torque inadequate to the installation; low quality servo with too much gear lash.

Unfortunately, when you look at the hardware included with many kits and ARFs, and the photos in the manuals, and the photos of the latest hot model in the magazines, what you usually see is linkage that looks like your wreckage photo. To my eye, that is all 3D setup, meant to be flown at low speeds, meant for pilots who like to turn their planes inside out. All that is the complete opposite of what pattern flying does and is.

jlkonn

My Feedback: (1)

Zippi,
I so sorry about the plane.
JLK

Zippi

My Feedback: (10)

majortom-RCU,

I appreciate your comments. Even though the linkage was longer that what should have been there was very little movement on the surface. The control surfaces were sealed which is a standard in my book and I was using CF control rods and there was no slop. I had the CG set at what the manual had stated and once in the air I found out that the CG made for a nose heavy plane and there was no way to adjust this at the field. There is very little wood behind the Ailerons on the trailing edge of the wing and I'm not sure if this was the reason for the Aileron coming out or not. With the plane tore up as bad as it was it's hard to tell what really happened. I've come to my conclusion as to what had happened and I've listened to others as well. It's best to learn from this and move on. Thanks.

IShootSharpStix

My Feedback: (4)

Troy, I will probably be flamed for this post but I really think it needs to be said. What started out as one of the most detailed, well thought out, documented and presented build threads has been completely cluttered with unnecessary and irrelevant posts. Is there any way the moderators can clean up the thread to include only your posts or perhaps split the others off into a general Focus Sport thread? Your methods of setting up a model can obviously be adapted to any build and as such can provide real value to a wide range of modelers. Having to wade through all of the other posts is tiresome....

MHester

My Feedback: (1)

Such is the nature of a build thread.

Usually whenever the thread is completed, somebody goes through and compiles it into a PDF file. You just have to know who has it

I'd love to see user moderated build threads for just that reason. The trouble is, a lot of people have questions and they need to be answered (even if they don't listen LOL).

Tiresome as it may be, it's the nature of the beast as it is.

-M

Troy Newman

I have all the documentation with photos going in a Word file at the same time I write it.

I just returned fromt he D7 champs and plan to get things finished up this weekend. Goal is to have it flying next weekend.

I enjoyed the break from life last weekend...I actually got to fly some models. I havn't done much since the NATS...I'm pretty excited to get back in flying. The weather has been great.

Plus I have to get the Focus finished up becasue I have to repair a model that went through a mid-air over the weekend.


Troy

Troy Newman

*****

Troy Newman

Next on our list of duties is the hinge work. I made some changes. First off I added an extra hinge to each elevator half. Was it needed? Maybe maybe not. Here is my logic. I want to place the hinges as close to the edges of the surface as possible. What this does is secures the ends of the control surface. If the hinge at the root of the elevator is not right next to the control horn then the surface will bend or raise and lower as the control horn pushes on the surface. The hinge being as close as possible to this lever arm (control horn) will keep elevator from flexing at the root while the surface moves up and down. Next if the hinge at the tip should be as close to the tip as possible again so that the tip doesn’t flex vertically under loads.

I want to make this clear….I’m not talking about motion as rotational around the hinge centerline. I’m talking about the surface moving up and down and not pivoting. The more hinges you use the better the surface will be at reducing this bending of the elevator and flexing vertically. If you put too many hinges the action will stiffen up and the servo will work hard, also it will be difficult to get precision control. In looking at the elevators on the Focus Sport I felt the 3 equal spaced hinges didn’t cover the root and tip well enough and then the unsupported space in the middle was not as good as I liked. So I added one hinge to each elevator and now it has 4 on each side. Is this overkill…YES it is. However I want to make sure the elevators stay as true as possible and good solid hindging is a key to this. I do really like the CA style hinges, however if I were using a Pinned hinge I think the 3 hinges would have likely been good enough. Since they are CA hinges call me a crazy fool, but I put in a 4th.

Trial fit the hinges….look at the way the surface lines up on the trailing edge of the stab. One of my elevators the hinge slot in the stab was low….so when you put it together all was good until it got to the tip. Then the surface was about 1/32” low from being perfect on the centerline. This was an easy fix. I re-cut the slot that 1/32” higher on the stab Trailing edge and all lined up very very well. It wasn’t absolutely perfect but it was really really close. I think it will be fine with a little trim work, and it will not show in the flying.

But don’t trust that the factory put the slots in the right spot put it together and look at it closely feel the root and tip and make sure it lines up.

Next step was to mess with the rudder hinges. Again only 3 hinges on the rudder was not good enough for my quirks. So I added an extra hinge down low. First off there will be a tail wheel assembly putting some load on the rudder, then the rudder control horn and the pull-pull setup…The factory config was to have only one hinge about 1.5” below the rudder horn and about 2” above the tail wheel. I changed this and put another hinge in between the two load points. This meant they were right next to each other basically in the white stripe of the fuse. I cut the hinge slots in the fuse portion as they were not factory cut but the fin part was aligned and cut correctly at the factory. I think the 2 hinges above the rudder horn are fine…but if you wanted another extra hinge here would be fine. Remember too many hinges can make the control surface stiff…so be careful adding 2 more hinges if you decide it needs it. I felt the rudder would be fine with the factory two above the horn but added a second below the horn.

Once you have it aligned and dry fit you are ready to glue the hinges but NOT yet……..DO NOT GLUE THE RUDDER YET….This will be an almost last thing. We need to synch up the elevators and with the rudder not permanently attached this is a help in the alignment. To know that the hinges all line up is great just set it aside on the rudder and don’t glue it.

Upon hinging the rudder I also notice the rudder is a little tall on both ends. I aligned the stripes with the fuse. The top of the rudder as shown in the photo is about 1/16” too tall with the strip aligned. Also the bottom of the rudder is about 1/16” too low with the stripe aligned. The bottom one is pretty minor its small the top one is a little more. Again this an ARF and its not going to be perfect. If you really want to you can remove the covering its Flame Red Ultracote and sand the rudder to fit. The little off the top will make the fit and finish look a little better. Its not going to make it fly any better…So its up to you. Its an easy fix to remove the red stripe on top the rudder and at the bottom of the rudder. Then sand the balsa blocks that are there to get absolute perfect fit. Once it fits perfect then a a 5min covering job and it will look as good as new. The choice is yours. I felt it was not off enough to affect the flying of the model and you had to look close to see the difference so I selected the leave it alone fix. The stripes are aligned and the extra length is a little on top and a little on bottom.



See the photos below of the extra rudder hinge in the fuse area and the rudder.

Also note the control horns installed in the elevators that’s the next step after we hinge the ailerons. And glue the hinges on all but the rudder.

Troy Newman

Hinging of the ailerons comes next. The number of hinges on the ailerons was good; you could if you wanted to add another hinge. I put one on each side of the aileron control horn and then used the normal layout from the factory. This means the hinging at the control horn is good and the surface will not move vertically at this load point. Again dry fit everything and look at the ailerons alignment vertically with the root and the tip. I find that this is a difficult thing to get correct no matter how hard we try. A surface hinged lower than the center of the tip or higher at the tip on the wing will affect flying. We need to get it correct. My Focus Sport had the left aileron low at the tip and the right Aileron high at the tip. A #11 blade and re-cut the slot in the correct location and the ailerons matched up correctly. I think on one of these the knife blade slipped when the guy at the factory was making his slot. It was an easy fix today that means I less problems when trimming the model out. Overall I think the work done so far was good. The hinging was pretty good; I would give it a score or B+ with only a couple little things. They were easy fixes so no complaints. I’m glad the surfaces did not come pre-glued as I would not be able to fix the problem without re-hinging it. So kudos to Piedmont on letting me finalize the hinges and glue them in.

Now it is time to glue the hinges in place on the ailerons and elevators. Remember one more reminder DO NOT GLUE THE RUDDER HINGES YET!!!!!

With CA hinges I’m very picky. Get a fresh bottle of glue. This can make a huge difference. I usually use the Blue Bob Smith stuff as its what is readily available from my local Hobby Shop. The ZAP stuff is always good and I have heard good things about Mercury but have not tried them yet. I like the Bob Smith with the small capillary tips for hinges. I’m sure the Mercury and ZAP glues have similar tips too. I plan on trying the Mercury stuff next time around. These fine capillary tips make a huge difference in CA hinges. Its very important to have fresh thin glue. As it ages it will start to thicken and will take longer to soak into the hinges. So a fresh bottle of glue is important. I actually will buy a fresh small bottle to hinge with.

A couple more tricks. Using a 1/16” drill bit drill a small hole in the hinge slot right in the middle of the hinge location. This hole is parallel to the hinge and only needs to go in as far as the hinge will go. This will allow the glue to flow easier deep into the wood and the hinge surface. I do this for all the hinge slots on the wing, stab and fin, as well as the control surfaces themselves.

Next trick is to use a small straight pin or “T” pin in the middle of the hinge. This insures the hinge material is not getting pushed too deep into the surface and not getting good bite on the other side. These pins are only used while lining everything up and inserting the hinges. Remove these pins before gluing as they will not allow you to get the gaps tight. Below is a photo of the pins I used. Once the surface is up tight against the pins then remove them and push the surface tight together.

The glue trick….Take one hinge at a time. Put a drop using the fine tip capillary tip on the glue bottle. Place one drop at a time on one side of the hinge and watch for it to soak into the fiber hinge. Too Much glue will run down the hinge line and make a mess only a small drop right on the fiber of the CA hinge. This drop will soak in, and then add another drop. Continue this process until the drops don’t soak in as fast. Then flip it over and drop by drop the same thing on the other side of the same hinge. Never use Kicker or accelerator this will make the hinges brittle. When the hinge stops soaking up the small drops of CA it is done saturated and doesn’t need anymore Glue. Move to the next hinge. Again drop by drop until it will not soak up anymore…Be sure to apply some to both sides in the drop by drop manner. The reason to do one hinge at a time is if the CA kicks off before it get saturated it will not let anymore glue in and will not have enough for the bond. The idea is to keep it wet and absorbing until it can’t absorb anymore. Then it has enough….So watch the drop soak in then apply another immediately until it is saturated. Once you have all the hinges on a surface glued set it aside. Don’t go messing around with the moving the hinge just let it cure.

After about 10-15mins the hinges will be glued in place. The surface will be stiff…Move it back and forth and the glue will break free right in the middle and the surface will move freely. It may crunch or making a cracking noise. This is not the hinge breaking it’s the glue on the surface popping loose. You surfaces are now hinged.

Do the Elevators and Ailerons only at this time.

Troy Newman

Once these hinges are glued in place I seal the ailerons and elevators. I use a small strip of clear Ultracote. Fold it backward with the backing or glue side out. Make a hard crease in it. Now you can use a straight edge to trim off the excess material before you put it into the hinge gap. I will cut the trip folded over about ¼’ wide. This means when you unfold it its about ½” wide. Remove the backing material from the strip and the glue side out. Using a metal ruler you can help hold the clear strip in the hinge line and carefully iron it down on both sides. Remember to clean the bevel and hinge line area with some rubbing alcohol and let it dry before putting the clear Ultracote in the gap. This will seal the hinge lines so air can pass. It doesn’t matter how tight the gaps are…they need to be sealed. This is easy and works well. If you clean it well the clear covering will never come loose.

Now is the time to seal it up.

Next is control horns. I ran a 6-32 tap down the hole in the hard point on the elevators and ailerons. I then installed the 6-32 control horn bolts. These were run almost all the way down with just about 1/8” sticking up as shown in the photo. I think wicked some thin CA on the bolt and let it soak down into the hard dowel…Before the glue kicked off I ran the bolt all the way down. Not it is basically glued in place…yet the CA will not stick too well to the metal bolt. If you need to take it out you can but it will not back out on its own.

Troy Newman

Elevator Servos are next. The fuse is not quite wide enough back here for full size servos. The solution is to use smaller servos. The major manufacturers make all kinds of sizes of servos. As we discussed in the section on picking good servos, I’m going to use JR 3421SA servos. The plane was built around the Futaba 9650 but I like the fact the JR 3421SA have a nice tight precise nylon gear train. This is the main reason for choosing the JR servos back here. These servos are also light. They are about 1oz each so this saves a full 2 oz of tail weight over a full sized servo. This accounts for another 45-oz of lead on the nose to balance this. By choosing wisely the servos for the tail I just saved a possible 6-7oz of total model weight. The fuse has some plywood plates for the servo mounting screws. Using the JR 3421SA the plates were spaced a little too far apart about ¼”. So I used some thick CA and put some 1/8” ply strips inside the fuse. Then I added some balsa as a spacer to get the servo mounting flat with the side of the fuse. This added very light weight and is plenty strong. See the photos for some details.

You don't want the servo case to be jammed into the hole it should have some wiggle room but not too much. If it fit it too tight just sand the new rail a little to make it a slip fit...Binding here can warp the servo case and cause problems with the servo...making it hunt at center or draw excessive current.

bla bla

Hummm... very sad...but I'd guess there's a far bigger chance that it isn't radio failure at all.

burtona

My Feedback: (50)

btt

JPal101

My Feedback: (32)

Where is Troy????????

burtona

My Feedback: (50)

Yeah, Troy,
How's it set up and how's it fly?

Troy Newman

OK guys I am back. The model is just about done. We need ot catch up on a bunch of little details. So here goes.

Elevator servo mounts finished time to work on the linkages and such.

First off the elevator servos need extension leads to get the wires to the RX up front in the canopy area. Since these leads are long and its very important to have good power and connection to the servos in the tail I always use the JR heavy duty gold leads. JRPA102 is the part number for the 24” Heavy duty gold connector leads.

I use un-waxed dental floss to tie the connections together. Then I use a small dot of the Purple Bob Smith CA. This is the medium glue. I put the dab of glue on the knot to keep it from coming apart. I also hit this with a little kicker. Not too much...just a little to kick the medium CA. Now when its time to remove the dental floss you cut it with an x-acto and then the CA blob will pop right off the body of the connector. BE VERY CAREFUL you don’t want to get any CA on the joint, or down in the pins. Just a small dab on the knot of the dental floss for it gets held to the body of the connector.

The photos below show the story.

Troy Newman

Pushrods. I chose to use the Central Hobbies 1/8” CF pushrods. These are small diameter CF tubes that are very rigid. You glue Titanium threaded ends into the CF tubes. This gives adjustment and captures the ends of the CF tubing. If glued properly these things will not fail, and the Titanium pushrod ends are way better than any kind of steel all thread. The all thread material can work on the CF tube and cut it over time, also the steel will work harden over time and with the vibration. The titanium is a little pricier in this application but super light, and extremely strong. On the Pattern models since we are using the Titanium ends we can get away with smaller diameters that if we used steel. I like the 2mm stuff because it has the finest thread. This means I can make small small adjustments that say a 4-40 might be too big of change. If you use a steel pushrod you have to use 4-40 stuff… These are lighter on the wallet but heavier on the model. For me I have reused pushrod ends on many models. The ends can be removed with some acetone and a little sanding then they are ready to go into fresh clean CF pushrod material on the next model. The linkages can be a huge place to save weight. The Central Pushrods are super light and extremely stiff, even better than the heavier 4-40 rods.

The 2mm ends come with about 1” of adjustment. I don’t need that much thread and since the Titanium end is heavier than the CF pushrod material I would rather have more CF tube and less metal fitting. So I cut the threaded portion of the Titanium ends in 1/2 . I do this in most of my applications…but not always sometimes the longer threaded section works well. Reality is the shorter the threaded section the stiffer the pushrod will be. So I cut about 3/8” to ½” off each pushrod end.

Use a Dremel cut off wheel and eye protection glasses. I clamp the pushrod end in a small vise, and then attach a vise grip type of pliers to the end that will be cut loose. The photos below will show the details of the cutting and the sizes before and after. You will need (2) pushrod ends for each pushrod. One for the servos side and one for the control horn side. In order to do both elevator pushrods you will need (4) ends total. These ends come (4) to a package.

Once you have the pushrod ends cut off I clean up the ends with a little redneck machine work. Chuck the pushrod end up in your cordless drill and take it to a disk sander. If you hold the drill at a very slight angle off the 90deg point you can clean up he end of the treads very easy. The idea is to just taper the first 1-2 threads and clean it not. Not sand the threads on the end. You don’t want to change the length of the fitting just take the burr off from the cutting with the Dremel and make it easy for the threaded section to turn into a clevis or ball link. The photos below show what I’m talking about.

I then use the drill to thread the clevis links onto the pushrod ends. I purchase the MK 2mm Ball Bearing Clevis for this application. The 2mm threads are already inside the clevis. The fitting will thread in perfect with a little friction. I don't recommend running a tap into the clevis unless you are changing the thread. Then only tap the first part of the clevis and let the threads on the fitting cut their way the last part. This will make for a better connection and the friction of the clevis on the fitting will keep the linkage tight.

In this case we are using the kit supplied 6-32 bolts for control horns. The MK clevis is designed to work on a 3mm thread for the Mk control horns. If using the MK horns you don’t need to do anything just thread the adjuster part of the clevis on the MK horn. In our case using the 6-32 bolts as control horns…I had to run a 6-32 tap into the adjuster portion. NOTE it is very important to not tap the adjuster all the way through. Just about ½ way to allow the threads to start. Then the bolt will cut its own thread in the nylon material. Again like the clevis this keeps the connection tight so that it will not twist under load. I use a slow speed in my cordless drill for the tap. I know this is a redneck machinist technique but it works for me and I’m a little lazy. Please you guys that are machinists I know its not a good idea and you have to be careful to not damage the material when cutting the threads.

Troy Newman

Attach the adjuster potion of the clevis to the control horn. I then attach the clevis with its 2mm bolt and its 2mm titanium pushrod end. Measure the distance from the hinge pivot to the center of the 2mm bolt clevis pin. This is your moment arm for the control horn on the elevator. I set them close to start and will tune it later. The basic number on my setup is 31mm for this distance. I use a thin metal ruler than has mm markings. This allows me to get down into the hinge pivot point and also measure with a small increment. For me its easier to say 31mm than 1 and 7/32”. For now just get it close. We’ll build the pushrods then final adjustments and tuning can be done. The key is to have both sides the same.

I also do the same procedure to the servo connection end. In this case I’m using NMP DARE 2mm fittings. These are a dual axis rod end. They allow for movement in 2 directions or axis at the same time. These things are very lightweight and super smooth.

There is one caution. The ball is a ceramic material. If you tighten the center bolt too much it will induce friction as the ceramic ball gets crushed. This will cause it to spread and bind up. You have to adjust the tightening of the 2mm bolt to make sure it’s not sloppy around the bolt yet the ball is not being crushed and causing friction. This step takes just a couple minutes to setup both sides. Then you tighten the nylon jam nut to fix the tension in place. Properly done these ball links will outlast the model. I have never worn one out. If you don’t take the time to adjust them properly then they can get sloppy or have friction. I prefer to have a connection that I can setup perfectly with the tension and the light weight then lock it in place with a nylon lock nut and have it never change.
As mentioned before you can use normal clevis links but these can wear over time. With these connections a 2mm bolt is your clevis pin and pivot point. It also allows for easy removal and friction free connection. If using just a clevis into the control horn or the servo wheel I recommend a metal pin clevis and this metal will wear the servo wheel hole over time. The bolt on connection doesn’t wear out with vibration over time.

This is a model we want to trim out and keep working the same as long as possible. Since wear happens slowly sometimes you won’t feel it happening. We want to eliminate these things up front so the hope is we never have to touch it again. Sometimes you have too in extreme cases or if damage occurs but in normal flying these things just don’t wear out.

Servo wheel connections. First we need to program the radio a little