Posts: 2380
Joined: 12/30/2001 From: Goodyear,
AZ, USA Status: offline
John,
If you use the method described where you just put enough CA on the hinge to saturate it you will not have any issues with the foam. The CA hinge and the wood will soak up the thin CA glue and it will not melt the foam...There may be a little bit of melting right on the edge right at the hinge. But the CA is not going to be running down into the wing.
Use the drop by drop method and it will be fine.
What you don't want to do is squirt a bunch of CA in the slots....just drip it onto the hinge until its saturated.
Posts: 2380
Joined: 12/30/2001 From: Goodyear,
AZ, USA Status: offline
Other question I have received.
The question was what is the distance from the canopy frame down tot he trailing edge of the wing. This reference could be used for the wing incidence alignment. Yes it can. that number is 2.25" to the middle of the trailing edge at the root of the wing will give you the 1/2 deg positive in the wings.
The Big reason I choose to not use this reference although easier, was the manufacture ring process and the all wood model. Lets say for example the wing tube is just a little higher in the fuse on one plane versus another. This means my reference value is not going to work for that other model. Next thing you say that the reference should be the same as the parts were laser cut....We yes but sanding errors, and also there are some tolerances. The idea is to get the wing flying at 1/2 deg pos incidence when the tail is blocked according tot he instructions. SO the reference I give is good for my plane and will get you close on your plane. However will it be 0.4degs or 0.5degs. or is it 0.6degs .
Can we really accurately measure the difference between these three angles. No its very tough to measure to that accuracy. However settign up the fuse like I explained would really be the best to insure the accurate 1/2 deg incidence.
The next cat call comes well if its off just a little that just means we will have to trim it. Yes I will agree with you there. The incidence that is called out is the 1/2 deg pos and in the test flying I have had no need to adjust more or less positive into the wing. SO in my opinion so far 1/2 deg is the number. This model is designed around a new pattern flyer and a sport flyer looking for a good model that flies like a pattern plane. Most of the pilots in this category don't have a super tight grasp on trimming a model and what needs to happen and when. My goal has been to provide enough detail that anyone could build this model the same way I did and have the plane flying the same.
As I said before there are many ways to get to the end result. I wanted to get as accurate as we could with a basic understanding of what, why and where to do the dirty deed.
Posts: 318
Joined: 8/30/2004 From: Staten Island,
NY, USA Status: offline
Hi Troy,
I have been following your wonderful thread since the beginning and am about to start building mine. Would you be compiling a list of all the parts you used? I would like to purchase everything at one time to have on hand as I assemble my Focus.
Posts: 2380
Joined: 12/30/2001 From: Goodyear,
AZ, USA Status: offline
Here is the list of what I used on my model. The results have been very good. Of course we all have our own opinions on what and where to use it. I choose to use the supplied 6-32 bolts for Control Horns. However the MK bolt through style control horns are good as well. They cost a coupl extra bucks but look better and a couple grams lighter in the end.
List of parts:
(1) Truturn 3" Spinner (1) Truturn YS adpater jam nut assembly (1) APC 15-10 prop for Cool Power 30% heli fuel. (if running less nitro choose a smaller prop like a 14-10, 14-11)
(1) YS 110S (1) Hyde Type A motor Mount (1) Central Hobbies Fuel Dots (Package of 2) (1) Tettra fuel "T" fittings (package of 2) Medium Fuel tubing about 2ft (1) Tettra 16-20oz fuel tank. I actually have a 20oz in mine (Now at 15-17min flights) (1) Throttle Linkage (I used 0.047" Music wire), EZ connector on the servo end and ball link on the carb side.)
(1) Central Hobbies 1/8” Pushrod kit with 2mm ends (1) extra package of 2mm ends for 1/8” CF Pushrods (4) MKD 0810 MK BB Clevis devices (Ail – Elev) (2) Dubro 2-56 clevis (rudder) (3) Ball links 2-56 thread (various brands Dubro, H9 and others I had extra around) (1) Pull-Pull Rudder setup. (1) Bottle of the Bob Smith Insta-Flex CA for hinges. This is the Thin flexible CA works great on the hinges.
Servos, leads: (2) JR 3421SA Elev (2) JR 9411SA Ail (1) JR 8411SA Rudder (1) JR 537 Throttle (821 would work well also) (2) 18” JR HD Gold extensions (Elev) (4) 6” JR HD Gold extensions (Ail) (1) JR Charge Switch (1) JR 1650mah 4 cell Nimh battery
I’m using the JR X9303 2.4ghz Spektrum system with the JR 921 RX, only using one remote RX.
Misc Velcro, Foam Rubber, CA, and Epoxy and a Heat Sealing iron for the covering. I also have stock wheels and landing gear. Its fine the model is light and tons of power at the 8.5lbs build weight.
As it stands now I don't know of a Carbon gear that is a direct replacement. The models weight is low even with the heavy Aluminum gear. I didn't do anything special to save weight and the plane is 8.5lbs ready to fly.
I would recommend against the upgrade to the CF gear unless you wanted to rework the gear plates. As it is built now the Gear struts slide into a pocket that is the right thickness for the stock gear. This is 0.155" The Bolly CF gear are about 0.121" thick on the mounting tabs. So you would have to re-build the mounting blocks. Also the Bolly gear is wider on the mounting tab than the Stock gear is.
The aluminum gear is very stout...I don't think you could break them and would take a bunch to bend them. Yes they weigh a couple ounces more but they work well and the model is light enough as it sits.
CF wing tube would be a good upgrade if you desired as it would be a drop in replacement and would save about 2.5oz
Smaller battery pack say a lipo or li-ion with a Jaccio regulator or Perfect Switch regulator combo would save another oz maybe 1.5oz.
Smaller tank I would say a 14oz tank would probably be good for two patterns if flying Sportsman-Advanced. Flying Masters and FAI the 14oz tank will likely only do 1 sequence. This could save another maybe 1.5-2oz
Bolly Wheel pants, NMP Axles and tettra wheels would save another 2oz easy.
This is where I would spent my weight saving money...These are all drop in replacements and don't need the model to be rebuilt in order to make the changes.
Posts: 318
Joined: 8/30/2004 From: Staten Island,
NY, USA Status: offline
Thanks Troy
You have always been a great help, I spoke to you in the past when I had problems with my YS and you were very helpful. This thread takes all the guess work out of building a competetive airplane, thank you very much
Posts: 3
Joined: 2/9/2007 From: Clearwater,
FL, USA Status: offline
Troy, I've been following your build for the last month while I've been building a Focus Sport, and flew it for the first time this weekend. What a great plane! It's my first true patten plane, I bought it after wrecking my Showtime 90, which is a pattern hybrid. I bought mine ARC, mainly because I didn't really care for the color scheme, and I fell in love with the one that I found. I have a YS 110, 16oz tank, all digital servos (JR & Futaba), 2700 mah 6v pack, Futaba 9C PCM, DEPS elevator pushrods, rudder pull-pull, and Central Hobbies CF, clevis', and ball links all the way around. It came out at 8.13#, and the balance was exactly where it stated, with the rcvr & batt right behind the fuel tank. It practically jumps off the ground in about 25 feet, and needed a couple of clicks of up ele to be almost perfectly trimmed, as far as my limited experience can tell. Thanks for all the great tips, instructions, and hints. I've really learned a lot just building it, mainly how to check, align, and set up the airframe in more detail than just using a triangle and an incidence meter, and I've been building for over 20 years! I can't wait to get more time in the air and advance my flying skills as well. Fortunately, here in sunny Florida, we get to fly all year round! Thanks again for all your effort! Steve
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Joined: 12/30/2001 From: Goodyear,
AZ, USA Status: offline
Thanks for the kind words Steve.
I have been lucky enough to have some great modelers show me how to do these things. It’s only right that I pass along what I have learned. It’s very difficult to get the proper setups and idea via photos and the internet. Many things that we pattern flyers take for granted are just not normal modeling skills like they once were. People get chased off by things like the soft mounts for the engines, nose rings, and even when you say trim the model....most modelers think of moving the little tabs on the TX to make it fly straight and level upright. When in reality there can be much more to it.
Below are photos of my linkage on the Focus Sport. Notice the Blue lines on the top view. This shows that even though the pushrod is not parallel to the Servo case...The servo wheel connection is 90degs to the Pushrod. This makes the control throw of the aileron symmetrical mechanically. This is very important to have the model roll correctly and not has adverse yawing while rolling. On this model the control horn bolt locations were already done for me so I was stuck with either changing the location or modifying my servo arm orientation to get the linkage correct. In an idea situation I would prefer the control horn over closer to the servo. However it works fine this way. You just need to be aware of it. The servos axis is not always the same as the linkage axis.
Also notice I used the stock JR small round servo wheels. These wheels at the current connection point and the Control horns at the current spot give me about 15degs of throw each direction. My Travel Volume is about 130% on each servo. The ATV or Travel volume numbers are then set to get the proper throw angle on the surface. You want to get within about 5-10% values here. The closer your Travel adjust values the more symmetrical your linkage. What is important here is not that radio says 130% for both sides of each servo. WHAT is absolutely important is that both Ailerons are moving the exact same up and down. To get this you need an accurate method to read the throws. There are many meters out there. Some are more accurate than others. For me an accurate meter is:
#1 light--a heavy meter clipped to the control surface can give error in your reading as the servo will fight to hold the aileron up against the weight of the meter.
#2 Easy to read scale--The scale should be easy to read. I would say its best to get within about 1/10 to 1/4 degree. I know this is pretty accurate and many of the scales used on throw meters available out there are just not that accurate. The thickness of the wire pendulum might only be good to about 1/2 degree as a approximation. If you have a meter that has a course scale or very fine print...this invites errors in the reading. You would not use a yard stick to measure 1/16" so don't use a meter that is 1deg increments when we are only using 10-15degs. It would be best to be down around 1/4degs graduations or maybe even smaller.
#3 The meter you use should be easy to setup to give a repeatable number. You should be able to read the same value now, 10mins from now, take the model down and re-set it up and get the same numbers. Repeatability is as important as accuracy. If you have a meter with a complex setup then it invites error in the reading. If the meter has friction in a bearing assembly then it too can vary the readings. This makes it not good for repeatability.
By the way my flying rates for the Focus Sport:
12.5degs up and down on Ailerons 10degs up elevator 11.5degs down elevator Rudder is about 28 degs each way.
these are the numbers I originally. The only difference was the rudder increased to about 35degs of travel.
This gives the model a very balanced feel.
Back to the aileron linkages: If you ATV (Travel Adjust) values end up too far off like one is 120% and the other is 135% to get the same travel of the aileron then you have differential built into the linkage somewhere. Perhaps your servo horn is not 90degs to the pushrod. Perhaps the Pivot of the clevis is not directly over the hinge line. Since we have 6-32 bolts the horns are easily bent to get the proper alignment. Subtrim your servo arm to the proper location and then re-adjust the length of the linkage to get these paired up. If one servo is moving more than the other say one servo is around 130% both sides yet the other servo is around 115% to get the same travel. Then your control horns at the surface are not the same length or you servo arms are not the same length. Adjust these to get the values for both servo as close to the same as possible.
NOTE: It is extremely rare for two servos and two seperate linkages to come out exactly the same on the ATV values. No two servos are the same. As hard as you try its difficult to get the linkages as absolutely the same and perfectly straight. No matter how hard we try the difference of 2-3% ATV is a very very small difference. We just can't get that accurate mechanically. Remember the control horn is a 6-32 bolt. so one turn on this clevis down on the control horn moves it 1/32 of an inch. The length of the pushrod is only adjustable to within 1/2 turn of a 2mm clevis. So we can't get it dead perfect two times in a row. The servo mounting may be a little off from one side to another. Lots of things can happen to the linkage. So we use the ATV, EPA, Travel adjust what ever your radio calls it to match up the values. This means that when you adjust your rates later on say D/R is 80% you don't have to worry about one side being 84% and the other 79%...the servos are matched up in the ATV to get the baseline or benchmark number.
Its funny when a guy shows me his radio and magically all the ATV's are the same for both aileron servos. This tells us that he is either one of the absolute best builders in the world, and you want him to build you next model. This is because he has machinist talent that will rival the guy building the next NASA Space Craft. OR......... he didn't measure his aileron deflections very accurately.
The question from the skeptical guy will say you can't feel that difference? I submit that its there and can be felt. Ever have a model that rolls fine to the left but needs differential to the right? Ever have a model that rolls great with a given differential on high rate say 100% but on low rate 70-80% it needs a different differential setting? How about a model that rolls faster the left than it does to the right? Yes there are aerodynamic issues than can cause these things. But our pattern models are designed and pure enough that they don't have these issues, especially not to the degree that some models at the local contest have them. This is not a lecture that this guy or that is not doing it right. Instead its intended to be a call to do it better than you may be doing it now. It could show up in your score sheet. I can almost guaranty it will make your workload as a pilot lower. This means you have more time to concentrate on the geometry of the figure you are flying rather than overcoming some silly little problem with the model. Today’s Radios can get this feel correct in various ways...but if you do it in ATV then your other changes like any mixing, ot differential you need to add in, or other things like changing rates will not affect the models characteristics in flight. Merely you flip a switch and now your ailerons are moving the same as before but proportionally less or more than they were before the switch. I flew for many years fighting these conditions trying to get it as accurate as I thought it needed to be, when a friend Tony Frackowiak showed me the difference in flight. Since I felt the right way to do I can now feel it when it’s not as good in another model. This extra work means better FLYING in the end for you. We spend high $$ on the best quality servos and we want them to help us fly better. Well given a good setup they will. But you can't measure with micrometer, mark it with a crayon and cut it with an Axe and expect it to be accurate as Micrometer said it was.
Ok enough lecture. I can't stress how important this is. Must be my engineering education, or maybe I'm just anal as my wife accuses me. I dig out the laser level to hang pictures on the wall. I use GPS positioning to get the sofa in the right spot, and I use a sound meter to setup the surround sound system.
Photos below are the Focus Sport wing I have setup.
Posts: 2380
Joined: 12/30/2001 From: Goodyear,
AZ, USA Status: offline
Ok had a question regarding the aileron linkages. The modeler’s question was the high angle his pushrod was at compared to the connection on the control horn. He wanted to get a good mechanical advantage but the problem is the ball links would be at an extreme angle. Above I posted my Focus Sport linkage and then post the post the photo he sent me some suggestions. This is my Linkage using the supplied 6-32 bolt for a control horn. The Clevis is the MK BB style. The photo from my friend shows his problem. I give some advice in the pink text on his photo to get it a better linkage.
The next thing is looking at the servo wheel chosen it looks like the servo arm length is quite large. You can get away with smaller servo wheels. I use the small JR round wheels. Futaba small round wheels are a little smaller diameter but they make the 5 pointed star one that works. Or Futaba has the big round ones that you drill yourself. The round wheels are great because they do not flex like the small "X" style arms. On pattern models you don't need the aluminum servo horns. They’re pretty and they work well, but The limit your choices on where you can align your servo arm. With the wheel you can reduce the amount of subtrim needed to get the linkage all squared up. The reason is on a wheel or an "X" if one side of the horn is off a bunch then rotate the servo wheel to the other side (rotate 180degs) and the hole with be within 1/2 servo gear tooth of where it was before. This is due to the fact that Futaba and JR servos have odd number of teeth on this output gear. Futaba has a cool little system of tiny numbers moldered into the surface of the wheel. The JR doesn't have the numbers but it does have an injection mold mark...I use this mark as the reference and it works as good as the numbers. The mark or the number is just a reference to align the horns in same angle relationship to the servo output gear.
Hi Troy, thanks for sharing that important setup secrets.
One question. With the mechanical setup such as yours, you maximized the mechanical advantage. Do you think the limited max throws that result are enough to perform the most demanding figures (i.e. snaps and spins) ? For example, I think about aileron and elevator throws (about 15 degrees if I figured out right).
Posts: 2380
Joined: 12/30/2001 From: Goodyear,
AZ, USA Status: offline
Yes on most pattern model designs the 15 degs is enough aileron....Now dis-regard this is you are applying to a Scale Aerobatics plane that is larger like a 33+% model or a biplane these are different animals. I'm talking F3A pattern planes that are mono-planes.
Spins usually the aileron plays a very limited role. I don't think rudder and elevator only spins are what we do that looks correct. Inverted yes a little aileron to the start the spin, but most of it is taken out. on the upright spins most planes need a little aileron to help keep the one wing stalled. This is not a large amount of aileron and only part of the 15degs travel in most cases.
Where you need the throw is on elevator and rudder for the spins. On elevator I usually will have a little more travel about 18degs as the max value. Rudder is another story and why we put big powerful servos on the rudder. In most cases you need 30degs of rudder travel for the stall turns, and spins. So we are giving up mechanical advantage to get needed control throw gain. This lack of mechanical advantage means the we need more servo to do the ta
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RE: Focus Sport 110 YS Powered - 
