flyguyeddy

ok i am building a fw190 and i need some advice.

i have seen how people use rubber bands to hold there wings on. is this a good idea? how are they installed?

where does one get BiDi tape locally?

i plan on using the spruce spars that came with my wing. bad idea?

wooden aileron: how and why?

and i have a brand new O.S. .20 FP that i plan to run on this thing. is that enough?

thanks for the advice in advance!

ps i did a search for several of the things i have asked and came up empty handed, so i did search first.

Alex Treneff

That's pretty much the only way it's done for combat. Put about a dozen rubber bands on, and then criss-cross one over each dowel to make sure they don't come off. Shouldn't be a problem.

You can sometimes find regular rolls at some office stores (office max, depot, etc) or we have economy rolls (3x) online for a few bucks more. [link=http://www.treneffrc.com/proddetail.asp?prod=TSA%2D401%2DBIDI%2D2x60]3x-long Bi-Di[/link]

If you're just doing that one airplane, unless you're going to cover the whole wing, 1 regular size roll should do it.

The wood spars that come in the kit should be fine. Wood spars aren't as brittle as some other types so they don't shatter the way some do, fiberglass for example. And when they break, they are easy to glue back together.

Wooden (balsa) ailerons are normal. You can attach the aileron with the Bi-Di tape. Lay the aileron inverted on the top of the wing and put a strip of Bi-Di along the entire hinge line. Then reflex the ailerons down and put a strip across the entire top of the hinge line. Lou Melancon used to have an article about hinging the ailerons but I can't locate it.

The kit is designed for 1/12 scale combat which (at competitve contests) are flown with .25's with tuned exhausts. The .20FP might fly it, but probably not like it's designed.


I have no idea how they fly or how well they hold up. I've never seen one in the air. Let us know how it goes.

flyguyeddy

my kit says to glue the wing on permanently and has no provisions for any kind of wooden dowel to be installed. im lookig for an install guide someone may have done for there JKA plane.

i think i will get the OS .25LA. is that a good enough engine to be running on this plane?

Alex Treneff

I don't know about the dowels, I've never built a JKA combat plane, but if you are flying the plane in contests you'll probably want a 25FX. For sport flying the 25LA might be ok.

On the Battle Axe for example, we always recommend the FX over the LA becuase it has way better horsepower/weight ratio. Depends how you'll be flying the plane.

yankee samurai

My Feedback: (175)

The coro doublers usually have a spot punched so the dowels can go through them if you use them. Watch the CG it has a short nose moment on it. An OS FX .25 would be a better choice than the LA, spend the extra money. Darin Bellis had an excellent article on building and modifing JKA kits, do a search for JKA it has been some years ago. The planes fly great.

flyguyeddy

i searched through demon's posts but didnt find anything that stood out to me on the matter. i dont believe my doublers have any spots punched in them for dowels either. i shall look again tomorrow to try and find this article.

does anyone have it linked or bookmarked? care to shorten my search?

muchos gracias fellow pilots

i think i will get the FX. whats a few more dollars anyway.

Clean

Are you going to use this for combat? If not, you really don't need to use the BiDi or rubberbanded wings, glue it on and play with it. But if you are flying for combat you will want to use the Bi-Di. Use the FX extra nose weight and power. If you're coro isn't setup for wing hold down dowels use an appropriate sized brass rod, heat it up and lightly press on the coro and cut your own holes into the coro. Let it cool and, sharpen the inside of the brass rod using a xacto knife and drill through the fuse and out the other side of the coro. You could also make 4 mil coro doublers out of the tailstock scrap. Then run your own dowels through the fuse to secure the wing. In combat, if the wing can shift instead of break you have an advantage and that is why they are rubberbanded on. Plus it makes them easier to maintain and transport.

Combat planes tend to look a little rougher than fun flying planes but Darrins usually just look like works of art anyways. But, if you aren't going to fly combat, you can take a little extra time and make the plane look really nice. Although taped on ailerons are the norm, you can use cya hinges and foam safe glue to index them and keep them from floating up and down with the tape hinge. Learned that from some slope soaring guys and it reminds me that my Sw-126's ailerons are still floating above the wing, sigh.

So tell us, you gonna play combat with that thing or not.

Back when we first started using the foam construction birds everyone else was flying balsa ships. Then you could mount the wings on permanent because the only thing giving you problems with wing shift was the ground. You'd plow right through a balsa ship and keep going. It was a wonderful experience this quick build foam ship making a 20 hour build disappear.

flyguyeddy

this will be my first combat plane. i had a friend and his dad get planes so we can practice on our own in a nice big field before we go to matches.

so yes, this will be combated eventually.

so balsa trailing edge and hinge pin style hinges for the wings is the general consensus here? if so i can whip that up no problem. i just dont like cutting the hinge slots. i guess i could laminate the things together if i wanted to......


will the coro handle the bressure of the rubber bands? should i glass some of the foam around where they will go to make sure it does? i dont want any tearouts on this bad boy.

Clean

They'll work. You don't have to have them and I didn't on mine, but I've never been able to get a good, solid hinge that doesn't slop around a bit. Plane still flew good but I wonder if it couldn't have flown better.

As far as the coro handling the stress. As I posted earlier you can add another piece of coro at the front and back of the wing, both sides of the fuse to help retain the dowels, but you have a huge chunk of foam that is the fuse that holds them in too.

Make sure and have a 6 ounce tank on that 25fx. You'll probably need it for a round of RCCA combat. I flew mine with Norvels and could get away with 4 ounce tanks because they were so sippy on the fuel. But those are long gone AND kinda a pain in ways that the FX won't be.

After you launch the FW, remember to throttle back after you've gained a bit of altitude. These are fast little planes and tend to get small fast. I remember flying mine in October after a 6 month layoff not being able to believe how fast it was flying, then remembering I was flying it full throttle, scraping the brush in combat the last time I flew it. It's truly amazing how much better a pilot you can turn into if there is a piece of streamer hanging 10 feet in front of your nose.

Well, some folks just go bats and smack it into the ground too. I mean, not everybody is as good as I am.

Vomit bags are stored under your seats.

yankee samurai

My Feedback: (175)

flyguyeddy,
In the search box type in JKAerotech, go to page six, the 21st item down is Questions for Demon there you will find a gold mine of tips.

Clean

Oh hooey, I taught Demon everything he knows, everything he DID know and everything he'll EVER know. You know?

But I think [link=http://www.rcuniverse.com/forum/m_448451/anchors_448451/mpage_1/key_jkAerotech/anchor/tm.htm#448451]THIS[/link] is the thread your talking about

sgilkey

My Feedback: (180)

for a short wing like this, coro will work well for ailerons. coro has an advantage in that it takes prop strikes better, and if it's sliced by a prop, it's easy to fix with tape and bamboo skewers. A balsa aileron will often splinter when struck by a prop, and is harder to field-repair. You definitely want a fuse reinforcement for the wing dowels, there is a lot of tension on the rubber bands and they will rip the dowels out of plain foam. One solution is the coro doublers as mentioned, or about a 1 inch square of 1/16 birch ply or lite ply, glued to the inside of the fuse, with the dowel hole drilled through (use f/g rods for the "dowels" instead of wood, the wood will split in an impact, f/g "dowels" are virtually indestructible). an even better solution is to use .100" to 1/8" dia. f/g rod fuselage longerons, buried in the foam, that go from the firewall back to the tail- this will really toughen the fuse (not sure if the JKA has those by design... some planes do). run the lower longeron just above the high point of the wing saddle and the upper longeron near the top of the fuse side, where it starts to wrap over to the top. you can make the grooves for the f/g rods with a soldering iron dragged along a straightedge. bury them in the fuse with PU glue and a few wraps of strapping tape to hold them in till the glue dries. then when you install the wing dowels, drill the holes just above the lower longerons. this will just about ensure the dowels never rip out of the fuse. You still need doulers (ply or coro) to keep the dowels from tearing forward or backward, but the biggest load is downward, and this is absorbed by the longerons. don't notch the firewall for the longerons- have them butt up against the back of the firewall. otherwise, in a dirt nap, the longerons will poke forward with enough force to pierce engine parts such as the muffler. if they're butted up against the f/w, this is usually avoided, but what WILL happen is rods will tend to bow OUT and explode the fuse, that's why you wrap strapping tape around the fuse to hold it together.

Now that you have a rubber banded wing that can absorb impacts, you run into another big area where scale planes get ripped up- when the wing shifts a lot in a big hit, aileron torque rods will either get hung up and bind on the fuse sides, or they'll just rip the fuse to shreds. you can avoid this by laying down the servo in a well in the wing, and driving the ailerons with cables buried in the wing (make the cable grooves with a soldering iron), OR use dual mini servos for aileron (much easier but more costly). I'd recommend MG servos for aileron, if you use minis (ie HS81 or 85 MG). A standard size, resin-gear servo will usually work OK for scale plane aileron servo, but even those will strip in a major hit.

Tape aileron hinges are very durable. Conventional CA or pin hinges buried in the TE will rip out. The way to keep a tape hinge from allowing the aileron to pop up or down over the hinge line is to use a criss-cross arrangement. Using strapping tape, cut two strips about 1 1/2 inch long each. Stick them together sticky-to-sticky with about a 1/4 inch overlap, so you have a strip with adhesive on opposite sides, with the small center overlap. Using such strips in pairs, tape the aileron to the wing TE such that one strip is stuck to the top of the aileron, with the overlap area THROUGH the hinge line, and the other side of the strip stuck to the bottom of the wing. Right next to it, attach another strip opposite( ie stock to the top of the wing, overlap thru the hinge line, stuck to bottom of aileron). Use three or four such pairs of mating strips per aileron, and you have a nearly indestrucible hinge that won't creep. Then cover the hingeline with packing tape when you cover the plane. If your aileron is damaged, it's pretty easy to repair if it's coro, but if it's shredded, you can easily slit the tape hinges and tape on a new aileron in minutes.

Try to keep as much foam as possible in the front end of the fuse, ie make your tank cutout as small as possible. In an impact, the front end absorbs the brunt and you want as much structure there as possible. This is where f/g rod longerons really help.

Lay out your radio equip so the rx battery is in front of anything damageable, esp. your Rx. and use the small, light 300-400 nimh cells instead of heavier nicads, or 700-size nimhs. in an impact the battery becomes a battering ram and will crush the Rx or anything in front of it. It's much easier to control the smaller nimh packs, they are much less destructive!!

wrapping your fuse or other parts with fiberglass will not add anything but weight. fiberglass actually tears very easily and in an impact or prop strike it will fail. Try it yourself- glass a piece of scrap foam, bend it, and then notch it with an xacto knife- the notch will propagate and BOOM the part will break in a spectacular fashion. Using water-based polyurethane to adhere the f/g cloth, rather than epoxy, is an improvement but the f/g is still relatively brittle. Strapping tape is much tougher and will yield when bent, and is not so notch-sensitive.

A few more hours spent making these modifications when building will help keep your plane in the air, and help it endure the inevitable impacts to come!

flyguyeddy

after you do the aileron hinge criss cross hinge things, do you go ahead and do the regular hinge method or is that all you need?

i have some fiberglass tent pole material that i am going to use for a wing hold down.

i also have 4 hs81 servos in my LMH110 that i can steal. should i just go ahead and get some GWS servos or something and use them?

i am not quite sure how torque rods would work on my wing but i really dont see how it would. i think i may be stuck with cables or something

Alex Treneff

A word of advice: Only use them if they are HS-81MG (metal gear) servos. Nylon micro servos probably won't last a full flight on a combat plane.

flyguyeddy

they are not. so i should just leave them in the helicopter then [sm=thumbs_up.gif]

i am reading the words of advice from demon in the above quoted link and i am seeing two very different and conflicting ways to go about doing the wing at the least.

the link says balsa TE and wood aileron with CA hinges (demon) and sgilkey says no balsa, coro aileron and no torque rods.

i am at a loss on what way to go.

heres what i have right now as far as the wing goes. its glued together and the spruce spars that come wtih the kit are installed.

should i fiberglass the center after this or start taping?

im not anywhere near the fuselage right now (i know, im building out of sequence) but i also cant see how i am going to fit a 6 oz tank AND my battery up front. anyone have any details?

i thought about cutting the tank so that it sandwiches between the fuse halves and there is no access panel, along with the battery. anyone care to comment?

sgilkey

My Feedback: (180)

I agree that HS81 will strip easily, even if you use two of them for ailerons. you need MG if you use the HS81, 85, or 225. even those will strip- Hitec leaves one plastic gear in the MG servos, and it will strip in a hard hit, just not as easy as the plastic (the hitec plastic gear mini servos strip pretty easy and are usable only for throttle). so if you have, say, an HS81MG and you strip the one little plastic gear, you can replace it with the one from the plastic replacement gear set (which is cheap- you don't need to get the expensive MG replacement set).

To me, all the hitec resin gear servos strip easier than the futabas. I use the Futaba s3003 by the dozens, they do strip, but are pretty tough. Stay away from the HB (Karbonite) hitecs, the do NOT take impact well and break way too easily for combat use.

diffrent strokes for diffrent folks on the wing construction, follow the method that appeals to you most. when i want to evaluate a construction method, I build a test part- using some scrap or your wing shucks, try building a foam "core" with balsa TE and aileron, CA hinge, and then pull/bend/beat/smack with a prop on it as if it were taking a midair or crash. Do the same with a strapping tape/coro setup, and judge for yourself which one will absorb battle damage. The balsa setup is lighter.....if you do the criss-cross strapping tape hinges, you need no other hinge material, but just cover over the hinge line with packing tape when you cover the wing, to seal the gap.

If you have full-span spruce spars with no joint in the center, I don't think f/glassing the center will do anything of value. What I would do, if you have wood spars, is wrap a strip of strapping tape SPANWISE around your wing. Start at one tip, and wrap over the spars to the other tip, around the tip, over the spars on the other side, around the tip, and overlap the starting point. One continuous strip. This will help support the wood spars.

On the tank, it's tricky, the front end does get crowded. What I do on some planes (usually the narrow, in-line engine ones) is cut the fuel tank pocket to just fit the tank, in both halves of the fuse, before I join them. I cut a notch in the firewall so the tank can slide in/out from the FRONT, which is much easier to service, especially in the field. The engine mount partially covers the hole in the firewall, and retains the tank in the fuse. Makes it very easy to fix plumbing problems or replace a leaky tank. If you need to fish the tank out from the radio compartment, usually there's a throttle servo and a bunch of other junk in the way.

Don't worry about leaving room for foam padding around the tank, like you would on a conventional glow plane. Most combat planes have the fuel tank mounted right in the foam fuse, with no padding. The 25FX is such a smooth engine, foaming is not usually a problem. Some engines such as the cheaper brands do vibrate more....leaving room for foam padding only means less foam structure for the fuse, in an area where you really need structure! Now if you have a plane where there is ROOM for padding, or an open-type plane where you can mount the tank with padding, that's a different story, but still, with a 25FX, padding is not needed and I usually use two-sided tape and zip ties to mount the tank.

Notching the firewall for tank access can weaken it, use at least 1/4 birch ply though two layers would be even better. I use 1/4 lexan, which is very tough. Glue it on with PU (the only thing I've found that remotely sticks to lexan and foam) and then wrap some strips of strapping tape across the front of the f/wall onto the fuse sides, to help hold it on. With either wood or lexan, I use #4 sheet metal screws to hold the engine mount to the f/wall.

Depending on balance, I usually try to work it out so I can put the battery flat, in a small pocket under the rear of the fuel tank, up front where it won't hurt anything (this is where the small flat 300-400 nimh packs come in handy). Then I locate my throttle servo where it makes the most sense (due to packaging constraints, p/rod routing, etc), and then cut a hole in the side of the fuse and stick the elev servo in (on the outside) wherevever it needs to be to achieve the correct balance point, somewhere between the wing TE and the hstab.

for a roomier radial-engine type, it may be much easier to package everything in the front end and still have plenty of "beef" to absorb impacts.

flyguyeddy

do you have a way you can illustrate these firewall notches you speak of? i think im going to sandwich my tank in between the two halves of my fuselage so it doesnt move.

i have been thinking about a cable driven setup for my ailerons. i cant seem to find any examples or pictures of how others have done it. i would really like to just use the standard servos i have at least for the aileron since it takes so much of a beating. the elevator and throttle will probably be gws naro pros.

Clean

Cables get kinked when someone folds your wing with their fuse. The wing may bounce back but the cable stays bent.

Montague

I generally agree with what Scott (sgilkey) has been saying.

In my all my combat planes, I use a balsa TE on the foam core, then I use the tape hinging that Scott talked about, the over-under using strips. I've been doing that for years, and it's strong enough that I've had the whole core torn apart, but the aileron stayed on and sometimes keeps working.

Personally I use balsa ailerons, they flex and flutter less than coro. But I do run a strip of bi-di tape down them. When they get hit, the wood can break a bit, but the tape holds things mostly together so I can still fly it and make a landing. Repairs are easy, I poke a bunch of holes through the tape with a T-pin, and wick in some super-thin CA. Even a shattered aileron turns in to balsa-CA concrete and is plenty strong in seconds.

I strongly encourage you to go with dual aileron servos. It's more expensive, but it generally works out to be more durable and you're more likely to fly out of a mid-air with at least one aileron still working. (you can fly on one aileron pretty easily).

For wing spars, I personally think wood is a mistake. When I was flying the JKA P-47, I used 1/8" fiberglass rods for spars, and never regretted it, while I've seen plenty of scale planes using wood spards get their wings cut in half. Fiberglass spars just hold up better in all cases. And they are really easy to sister, though it's rare that it becomes necessary.

For the fuel tank, I mostly do kind of like what Scott said. Hatches through the side of the fuse are something I really avoid. I've even just sealed the tanks inside the fuse and had no problems for years. (some of my Firebrands will be seeing combat for the 5th year with the tank still sealed up in the fuse with no problems.

If you make the tank hard to get to, be careful with the glue when you join the fuse halfs. I personally use PU glue for all that kind of stuff. You want to avoid having the glue actually get into the tank compartment. I find I do better if the tank is losely held in by a touching-but-not-tight compartment, but can foam if the tank is too tight in there, and the PU glue really likes to make things too tight.

Personally, I don't fiberglass the wing centers of my scale ships. I do run a strip of bi-di on top of the spars from tip to tip, kind of like Scott said, but I do top and bottom seperatly rather than trying to do one complete wrap around (I have short arms, unlike Scott). I also run a strip of Bi-ti around the TE and another around the LE, which helps keep things contained in a mid-air.

sgilkey

My Feedback: (180)

All these methods will work, and all recommendations are coming from experienced pilots. Diffr'nt strokes. Pick what sounds best for you and go for it. Balsa is indeed stiffer, coro ails will twist and may flutter if you have a fast 2610 ship and center (ie torque rod) driven ailerons. If you have cable driven ailerons or dual servos, you can drive the ails from nearer their center, and even coro ailerons are stiff enough, at least in my experience, on any scale plane. on open planes, they're just too long and they will twist.

I'd never use wood for a spar, f/g rods are superior in every way IMHO.

I'd never use torque rods in a rubber-banded wing combat plane, when the wing shifts, the torque rods are likely to get hung up or rip the heck out of the fuse sides. Had that happen way too many times. On the other hand I have used cable driven ailerons in our 2610 fleet since 2003 and have never had a failure of any sort. Dual servos also work great, there is the rare possibility of a servo lead getting severed but even then you still have the other side and can usually continue flying, unless you're unlucky enough to have the severed aileron stopped at full deflection!!!

For my cable driven ailerons, I use 1/16 braided galvanized iron cable from McMaster Carr. The "sheath" is DuBro Antenna Tube (looks like small NyRod sheath but is clear, and fits the cable perfectly). I recess the servo in the center of the wing so it is flat and flush with the wing top, so when the wing shifts, the servo does not hang up on the fuse side. I've flown planes with the wing shifted 45 degrees (at least it looked that way!) and they were still flyable, this would never happen with torque rods. From the servo output arm, i lay out the cables to run outboard, and then make a gentle sweep to the TE at about mid-span of the aileron. Burn a channel for the sheath using a soldering iron. the sheath will be in two pieces, with a gap in the center. in the center, tin the iron cable and make a z bend. Thread on the servo arm, then the sheaths, and bury the sheaths in the wing with PU glue. Cut the cable ends to length and solder on threaded ends. I first used the Dubro (I think...) brass solder-on ones but they are soft and I found on the first one that it could snap off. So I changed to the Sullivan galvanized 1" 2-56 stud. DON'T USE stainless threaded rod, it won't solder! I wrap soft copper wire around the stud/cable and solder it in place, then thread on a metal clevis.

I use a plain old S148 or S3003 servo. yes, if your servo arm breaks, you're hosed due to the way it's threaded on the cable, but i've never broken one (knock on wood).

All this is a bit of a pain, esp. the first time, if you batch-build, subsequent wings get easier. Overall, dual aileron servos are much easier, but more costly. Because we had to build our first (and to date, only) two 2548 planes in a week, we took the quick way and used dual S3003s which have worked great and was very simple (but a bit heavy, but not so much a concern in 2548 due to the min weight requirement.)

Wood ails work and as kirk said can be repaired using the CA concrete method. If a hole is cut in the ail, you can bridge it by gluing strips of ply top and bottom across the gap. I just think repairing coro ails is easier with a tape-covered wing (my old RSN covered planes have balsa ails, never figured out how to adhere RSN to coro) but again, preference....balsa will work of course, and is lighter and stiffer

Montague

As Scott said, much of building combat planes is personal preference. I've come to like how I do things, which isn't always the same as other guys, but you can't argue with how well Scott's planes fly (Scott's flying is another story of course).

The key is to look at how things might fail, what might break or move or jam and what you can do about it. In my scale ships I use two aileron servos, so I can loose one servo or one pushrod or whatnot and still fly. Scott puts into the wing so that the aileron servo can't jam, and it's really hard to damage in the wing. (I loose pushrods and control horns on a fairly routine basis, actually, but I bring spares to contests, and it's ok with me).

On another note, make sure your ailerons don't end right next to the fuse, or close to the rubber band dowls. I've seen more than one plane go in when the wing got knocked on an angle and the aileron jammed against the fuse or rubber band dowl. As Scott said, you can stay in the fight if the wing is just rotated a few degrees or knocked off-center and everything keeps working. And not having the aileron hinges get ripped up by the fuse or rubber bands in a crash makes the plane easier to get back into the air for the next round.

sgilkey

My Feedback: (180)

Kirk, you've got it backwards, my flying is awesome, I am hampered by substandard planes!!! yes, I did not mention the part about making sure the ailerons do not go all the way up to the wing root, very important, so they will continue to flop around even if the wing shifts.

Montague

Scott, your flying does, indeed, strike awe into those who behold it. Just not quite in the way you imagine that it does. (and given the way that Brian and Eric throw your planes around, I'm pretty sure the issue isn't the airplane...)

Alex Treneff

I always thought that was why we wore hard hats?? [X(]

flyguyeddy

haha i didnt think my thread would turn into smack talking so soon!

question again.

where are people orienting their tanks in relation to engine centerline? i want to mount mine low and close to the wing saddle. will this give me fueling issues? or should i do tank centerline to engine centerline?