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May 16, 2010, 08:47 PM
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Mini-HowTo

DW Foamies 40" Juka build (WARNING High Res photos!)


I got myself a 40" Juka the other day to fly at Spring Fling, because I didn't really have anything flying, besides my little wing.

I decided to do a built thread on it since I haven't seen one yet.

The DW Foamies 40" Juka Build Thread!

First things first, unpacking everything from the DW Foamies box.

You'll find all the foam parts placed neatly inside a plastic sleeve to keep them all in once place, with manual ontop and vinyls beneath, and the carbon.

(excuse the mess on the workbench, I'm currently in the middle of rebuilding the engine)


Inside you should find all the foam parts to assemble the airframe, 4 carbon rods (2 small, 2 big), a carbon flat spar, manual, vinyls, and a hardware package.

Materials

Here is the necessary items required to assemble the airplane:


Foam Safe CA, Foam Safe Kicker (courtesy of BSI), Xacto knife with #11 blade, a ruler, 3M Blenderm tape, sandpaper (120-150 grit is fine) and velcro to mount the battery, ESC and receiver

For a power system, DW Foamies has 2 power systems listed: A Scorpion power system and a Dynamo power system, both of which will provide plenty of power for hard 3D flight. If you're going to buy something else, I am going to suggest something with at least 200 watts of power, and can swing an APC 10x4.7SF prop on 3 cell ~1000mah 20C lipos. Generally, any 28mm ~1000kv outrunner should be up to the task of delivering the power required.

For this build though, I will be using the following:

(x1) DW Foamies Juka 40" Kit
(x1) DW Foamies Glue Kit
(x1) Himax HC2812-1080 Outrunner
(x1) Castle Creations Thunderbird 18 ESC
(x1) APC 10x4.7SF Propeller
(x1) NEUEnergy 3s 800 MAH EP 30C Lipo Pack
(x4) Corona DS929MG Digital Metal Geared Servos


The power system I am using yields nearly 240 watts, and draws around 16.5 amps in flight. I have used this in my 38" kits for years no problems.

DW Foamies 40" Juka Kit
DW Foamies Glue Kit
Himax HC2812-1080 Outrunner
Castle Creations Thunderbird 18 ESC
APC 10x4.7SF Propeller
NEUEnergy 3S 800 MAH EP 30C Lipo Pack
Corona DS929MG Digital Metal Geared Servos (for lighter weight, use the Corona DS928BB Digital Servos which will be plenty for this airframe)

There are plenty of other setups out there that will work just as well, but for this build I will be using this setup.

The plane will be guided by the Hitec AFHSS 2.4 Spectra Module and Optima 7 receiver being controlled by my Hitec Optic 6.
Last edited by Xpress..; May 30, 2010 at 02:46 PM.
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May 16, 2010, 08:47 PM
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Beveling the Control Surfaces

The next steps are to bevel the control surfaces. The manual suggests 45* on the surfaces, and 10* on the horizontal/vertical surface for extreme 3D. I did it the way I've always done and went about 60* on the control surfaces.

You will need to pay close attention here, otherwise you can get the bevels backwards.

Set your ailerons on your workbench, so you have one right, and one left. When you bevel, make sure you have a right and a left aileron, not two rights or two lefts!

The manual suggests a great method for beveling the control surfaces. This photo will explain it:



The way I've always beveled was to put the ruler ontop of the control surface, nice and flush with the edge of the control surface, and then run the xacto down the surface at an angle, and with the handle angled forward, so you're not chopping through the foam.


Ailerons nicely beveled.


Elevator mid bevel.


All surfaces beveled.

Gluing the Wing together

The next step is to glue the two wing half's together. Some of you long time DW fans might remember when wings came as one piece on the 38" kits. They now come in 2 pieces, and the 40" are the same.


Wing half's right out of the box. Of course you should always use the best CA/Kicker out there. Note the 9mm foam.

I always put a good sized bead in this joint to make sure it stays together in the air, even during WOT blenders.


Make sure to get a good bead!

Installing the Wing Spar


Lay the wing panels on your flat workbench to keep everything flat.
Last edited by Xpress..; May 17, 2010 at 10:56 PM.
May 16, 2010, 08:48 PM
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Installing the Wing Spar (cont.)

Now, we will place the wing spar in the wing. It's the big long flat thing.

I have always taped my spars in place with 3M Blenderm. This provides a strong and secure way of mounting the spar, without wasting glue.


Before you start, make sure you have a full roll of blenderm. It takes just about an entire roll to complete the airframe.


I always leave about 1/4-1/2" of overlap for safety.

Hinging the Control Surfaces

Now you can go ahead and hinge all of the control surfaces. What I do is I lay everything flat on my workbench, and then butt the control surfaces right up to the flying surface. You can leave about a 1/16" gap if you wish, or if your bevel isn't perfect, but since my bevels have a sharp edge I go ahead and do this.

I always tend to put my bevels on the underside of the airframe, to keep the top clean.


Wing completed and ready for installation.


Everything hinged

Installing the Elevator Stiffener

IMPORTANT STEP!

Before you do anything else, locate the elevator stiffener piece. It's a white expanded PVC plastic piece with holes in it.

Glue this in on the underside of your elevator. This will stiffen up the center joint, and make it last a very long time.


[i]As you can see, I got a bit anxious to finish the airframe and neglected to glue it in until after I had glued the fuselage together. It's much easier to do without the elevator glued in.[i]

Assembling the Fuselage

The next thing that needs to be done is assembling the top vertical fuse and then gluing the horizontal surface to the horizontal fuse.

What I do is i apply a bead to the forward horizontal fuse first, then stick the canopy piece to that, and let it dry, then I apply glue to the forward fuse/canopy and glue the rear fuse on. Do this on a flat surface so everything comes out flat. The last thing you want is a bent up or crooked fuselage.

With the horizontal fuse, you should notice a tab sticking out inside the mating surface. Don't cut this, this is part of the fuselage, and helps align the horizontal stab up. Glue them together.

When gluing the horizontal stabilizer in place, pay attention to which side the control horn slot is on the elevator. It needs to be on the same side as the servo mount slot on the horizontal fuselage!


Done, and ready to be glued together.

Now you can begin assembling the fuselage!

What you want to do here is slide the horizontal fuselage into the nose of the vertical fuselage, then slide the tail of the horizontal fuse into the cutout. Now, put everything on the corner of your workbench, so the horizontal fuse is flat, and glue together by running a bead of foam safe CA along the joint.


Gluing the fuselage joints together (don't pay attention to the trashed foamies in the background...).

Yipee! The plane is finally coming together!

Now, you can mount the wing up. Included in the hardware pack is a few wooden dowels that are used to add strength to the motor mount, but also serve as alignment pins for the wing, so everything comes out straight.

Stick the wing in it's spot, and then push the alignment pins into place to center everything.


Aligned up and ready to be glued

Now, the next step is pretty important if you want the plane to last a long time.

The wing should not be glued around the horizontal fuselage edges.

If you glue the wing around the edges, the wing or fuselage can crack in a crash, or worse, mid flight!

Instead, what you do is you lift the horizontal fuselage up, and put glue inbetween the horizontal fuselage and the wing. I usually put 3-4 drops in there, good sized ones,then do a very light mist of kicker, and sandwich the two pieces together until dry (takes about 20 seconds max with BSI CA). Be careful to not get glue onto the pins! You will need them for the motor mount.


Wing glued in place.
Last edited by Xpress..; May 17, 2010 at 05:15 PM.
May 16, 2010, 08:51 PM
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Keel Installation

The last step in assembling the fuselage is to glue the fuselage keel in. Here I had done the wing, then went to check on something else, and completely forgot to take a picture of the process.

However, have no fear, it's rather easy to do. Place the keel in place, and then glue the rear of it to the lower half of the vertical fuselage. Do not glue it to the horizontal fuse just yet.

Now glue it to the forward section. Once this is done, you can go ahead and run a bead down the corners to glue it in.

Looks like a plane now, doesn't it?

Motor Mount Installation

Now, we can go ahead and move onto gluing the motor mount in.

The newer DW kits will come with these expanded PVC motor mounts, which are just as light as the original plywood/foam ones, but IMO are more durable, and look better on the white airframes (they can be painted if need be). You should also find 4 triangle pieces, which need to be beveled.


New motor mount, and triangle pcs.

I did the method I described for beveling the control surfaces. As it turns out, I did them perfectly this time, so I'm so happy about this!

The only thing I can suggest is taking your time when doing this. It will yield a good solid result and will fit perfectly. And remember, it doesn't have to be exactly 45*. It's just foam, you can make it fit.


Motor mount fitted to airframe, and foam pieces all nicely beveled.

When I glue the motor mount in, I start from the top. Get it all perfectly level so the mount will sit with 0* of right and downthrust. The last thing you want on one of these models is thrust alignment which will mess with your axial rolls.

Apply a bead of glue to the edges of the motor mount on one side, then wiggle it a bit to get the glue worked inbetween the foam and motor mount, then push it flush. Spray a very light mist of kicker and hold in place until the glue dries. Then go ahead and glue the other 4 sides.

The thing I've seen most often is people gluing only the back of the motor mount. The whole setup was designed so that you glue around all the edges of the motor mount. I marked the areas in red where you will also need to glue.

Once the motor mount is in, you can position your triangles and glue them in. I suggest using Thin Foam Safe CA if you have any. Otherwise medium should work fine. Just be sure to get it between the foam, then do a light mist of kicker over it all.


Red lines indicate where CA must go. Triangles installed here as well.

By now, you should have a plane that looks like it's ready for electronics. Looks pretty good, doesn't it?

Power System installation

Mounting your power system isn't very difficult.

The first thing I do is install my motor. Align it up so it's centered evenly, then using your hobby knife, push it into the motor mount inbetween the motor mount holes, and then spin the knife around to create your mounting marks. Do this in 2 places for now.

Take your motor mount screws and then screw them into their places. Now repeat for the last 2 mounting holes.


Motor installed

Using a piece of velcro, mount your ESC. You can mount it either to the underside of the wing at the fuselage, or on the vertical fuselage. I have always mounted my ESC's on the horizontal fuselage for lateral balancing. After initial test flights, you may wish to change its location to the vertical fuselage.



Do not install your battery just yet! The last thing you will do is find where your battery will be located (it should be around the cutouts for the battery strap).

Servo Installation

Included with your kit should be 4 expanded PVC servo mounts. There will be 2 for the 6mm tailfeather foam, and 2 for the 9mm foam ailerons. Pay attention to which ones are which!

Set the 6mm ones aside for now. We will be working with the wing right now.

Get your servos, and install any mounting hardware that came with them. Normally they will include a set of rubber grommets and a brass cylinder that goes inside.

Install your servo onto the plastic mounts using the provided screws with the output shaft facing forward.


Here, the servo has already been mounted in the wing- don't mount them in the foam just yet.

Once you've got the servo screwed in, plug it into your receiver, and power the system up. Make sure the radio is the first thing on!

Center the servo, and install the servo arm, so that it is approximately 90* parallel to the servo arm.

Now you can go ahead and glue it into the foam using Foam Safe CA. I always test fit the mounts into the cutouts so that I can ensure they will slide right in.

Apply a bead of CA to both sides of the servo mount, and then slip it into its slot. Spray a mist of kicker over the glue that will have beaded out to set it in place.

Tada! You've just installed your first servo! Now repeat the same process to install the other aileron servo and then finally the tailfeather servos.

Control Horn Installation

Locate the expanded PVC plastic control horns. There will also be a set of 6mm and a set of 9mm pieces. Set the 6mm pieces aside.

Test fit the control horns into the aileron slot to ensure they fit perfectly, and so that the hole in the control horn will be directly over the hinge line.


Hole in control horn is directly over hinge line.

When you are ready, go ahead and glue the control horns into place using Foam Safe CA. Apply a bead to both sides, and stick it into its spot. Spray a light mist of kicker over it when it is in to dry up the glue.

Repeat this process for the other aileron, and then finally the tailfeathers.

Control Rods

Inside the kit you should find 2 carbon rods that will be used for the control rods. There will be 4 carbon rods in the kit. Locate the control rods that will fit inside the easy linkages.

Center all of the control surfaces by taping the counterbalances. This will keep the surfaces nice and centered for installation.

Install the easy linkages so that the easy link is in alignment with the control horn.

Put a washer onto the easy link shaft, then slide it into the outermost hole on the servos control horn, place another washer on, then install the retaining nut. Tighten it so that the entire assembly can spin freely, making sure to not keep it too loose, otherwise you will get slop. When it is set, apply a drop of Medium Foam Safe CA to lock the nut in place, and keep it from falling off.


Correct assembly of easy linkage. Orientation will vary depending on your setup.

Install another linkage onto the control horn, orientating it so it lines up with the easy link you just installed.

Install the grub screw ontop, slide the carbon rod through both easy linkages, then tighten the grub screw enough to lock the carbon rod in place. I tend to leave about 1/4-1/2" of carbon rod left over to allow for fine tuning. You are going to want to measure the carbon rod after getting it in place so you can cut off the excess carbon rod. There will be a good length of it left over.

Remove the carbon rod, and get your Xacto to cut the rod. Lay the rod on a flat surface, and using a rolling action, cut the excess carbon rod off you do not need. Press onto the rod firmly while rolling it to get an even cut.

Cutting using this method will not fray the end of the carbon rod, which is what using regular cutting methods can do.

Reinstall the rod and lock it in place, then remove the tape from the control surface.

Repeat this process for the other 3 control surfaces.

You're just about done here!

The final steps are to install the carbon braces on the tail, and then mount up your lipo pack.

Installing the Fuselage Stiffeners

Locate the two lengths of unused carbon rod.

The horizontal stab and fuselage keel will have cutouts for these rods. Measure up a length of carbon rod to run from the horizontal stab to the cutout in the fuselage, leaving about 1/8" more than you will need. Cut the rod, measure up another piece, and cut. Install them into the airframe without gluing them in yet so you can get everything aligned up.

Making sure the horizontal stab is centered, glue one carbon rod end into the horizontal stab, followed by the other, making sure everything is still centered. I find it best to roll the carbon rod while applying the glue to get glue all around inside the slot.

When you're ready, glue the carbon rod into the fuselage.


Both carbon rods have been glued in here.

Next, measure up 2 lengths of carbon about 7" long, and sand the ends of each rod into a point. Push one end of the rod into the slot where the previous carbon rods have been glued in, then, on the horizontal fuselage, push the carbon into the foam to make a slot for it. Once it's all centered up, glue the carbon rod in place, again using the rolling action to spread the glue around.

Alternatively, instead of using Medium Foam Safe CA, you can use Thin Foam Safe CA here if you have it. This will eliminate the need to roll the carbon, as the thin stuff should wick in everywhere. Keep in mind that the Thin stuff will get everywhere pretty quickly.

Use a light mist of kicker to dry the CA. Too much kicker with the Thin CA will heat the CA up too much and begin to melt the foam.

Repeat the process to install the second carbon rod.


Carbon rods have been installed

On this particular airframe, you only need carbon rod down one side of the fuselage to make it nice and stiff. Putting carbon onto the other side of the fuselage is unnecessary and will add weight.

Receiver Installation

Installing your receiver should be fairly straightforward. Plug your ESC and ailerons into it. One aileron lead will need to go through the slot in the fuselage.

Pull the leads back so there is just a little bit of slack on them, then install a piece of velcro onto the fuselage where the receiver will mount. Stick it in place, hook up your tailfeather servos, and you're just about ready to go.


Hitec Optima 7 receiver installed with antenna pulled back.

Installing the Battery

The very last thing you have to do now is install the battery!

The CG with the DW Foamies 40" Juka is about 1" behind the carbon spar.

Make a set of marks there, and balance the plane. It will be tailheavy.

Place your battery onto the fuselage where you think it needs to go. Right around the slots for the battery strap is where it should go.

Move the battery back and forth until the plane balances, then install your velcro there. If you want to, you can put a long strip of velcro on to allow you to adjust the CG depending on the conditions, or to your liking. Also, it will allow for larger and smaller battery packs to be used, incase you're like me, and have a handful of different packs.

Slide the strap through the slots, place your battery onto the velcro, tighten the strap, and you're ready for flight!


Battery installed, ready for flight.
Last edited by Xpress..; May 17, 2010 at 05:16 PM.
May 16, 2010, 11:17 PM
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From this point, you can apply the included vinyl graphics, then if you wish to, you can color the airframe using sharpies, paint pens, spray paint, airbrushing,
even colored packing tape.

Here is a simple, yet great and highly visible color scheme I did using the colored tape that DW Foamies sells.





When thinking of a color scheme, keep in mind that most materials will add weight onto the airframe. Sharpies or paint pens are great ways to get a good looking color scheme and keep the weight down.

Control Surface Setup

For the control surfaces, you may wish to setup your dual rates and exponential.

DUAL RATES

Low Rates


Ailerons: 15 up and down
Elevator: 15 up and down
Rudder: 20 up and down


High Rates

Ailerons: Maxed out
Elevator: Maxed out
Rudder: Maxed out


EXPO

Low Rates


30% all around*


High Rates


50% all around*


*This is a suggestion. Your preferred expo settings may vary.

Flight Report

Early on Saturday morning before Spring Fling (an electric event down here in San Diego) I took her up for a test flight to get her trimmed out before showing it off at the event.

My control throws were already maxed out, and my expo setting was at -30% (Hitec/Futaba systems will use negative expo, whereas JR/Spektrum/Airtronics will use positive expo to soften the control surfaces around center stick) for initial flights. Later in the day I removed all expo.

It took a couple clicks of down trim to get her to fly level, of which I corrected because my elevator was trimmed up very slightly, and away she went.

Initial trimming was done with the packs to yield a perfect CG where the airframe flew upright and inverted hands off, both in level flight and on a 45* upline.

After a few minutes of trimming it out, I landed, swapped packs, and went back up to do some 3D.

Point rolls, upright and inverted harriers, spins, rolling circles, rolling loops, knife edge- it will do EVERYTHING you ask of it. What's really impressive about DW Foamies airframes is the ammount of rudder that's needed to hold knife edge. This Juka in particular needs just a touch of rudder around half throttle to hold knife edge.

Snap rolls are quick and crisp, both upright and inverted.

The 9mm wing is really something on this airframe. It just gives it an amazing feel in the air, and it's only something that can be experienced. I can't find the right words to describe it.

The only thing I can tell you is BUY ONE!!

-Positives-
Quick, easy to assemble airframe
Builds very straight and true
Rock solid in the air
Floats really well
A huge variety of power systems and servos can be used
Full color photos in the manual

-Negatives-
Need more lipo packs
Sun goes down too quickly

That about sums it all up. Overall, I'm highly satisfied with the kit. Personally I think it's the best flying foamie I've ever owned.

If you have any questions, comments, or suggestions, go ahead and post and i'll see what I can do

Last edited by Xpress..; May 19, 2010 at 11:36 PM.
May 17, 2010, 05:29 PM
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watchingcarpet's Avatar
Nice build-log Xpress, I gotta get me one of those 40 inchers! I have a Yak, Juka, Skua, and Gen-x, and I haven't been dissapointed with one yet!

I'd bet everything that I own that a DW Foamie can out-fly any other foamy, specifically one from a company who claims their foam is fancy, but just isn't up to par. I have 30$ right now....a little more and I'll be adding the 40" Juka to my hangar!

Anthony
May 18, 2010, 08:52 PM
Playin' for a Livin'! Fly On!!
Very nice build log, Xpress!! Excelent job! Good looking plane too. I'll be ordering some of that tape with my next kit.

There is a 40" and a 28" DW in my near future, just gotta decide which one first. Decisions, decisions.......
May 18, 2010, 09:57 PM
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For sure go with the 40" Juka first!

Better yet, buy both and don't worry about having to buy another (at least night right away)
Latest blog entry: My relationship with Hitec
May 19, 2010, 02:01 AM
Playin' for a Livin'! Fly On!!
LOL! Good point! I have most of the electronics for both. I could probably have both flying for a little more than putting one together needing everything. Now that my summer job is kicking in, I can afford to do all this stuff again. Ha. I should have my LOGO 400 back in the air soon too. Can't wait!
May 29, 2010, 11:26 PM
You brought two too many.
FlopGun's Avatar
Nice Xpress! Great build trhead -- and entertaining too. This 40" Juka is my favorite DW yet. Not sure why but that 9mm wing does make it feel different -- and better. l waterfalls, tailslides, rollers but the thing that I really had fun with was the hovers and torque rolls. The TRs are so easy to control. Fast ones or slow ones the TRs are just so fun.

Xpress, mine came out to about 17 oz with gear and 1300 lipo. what power system do you like at this weight? I am using some Turnigy 1000kv 65 gram motor on 11x4.7, it's ok for 3D but not enough power for snaps and walls and stuff. And it smells a little funny like it's going to burn up soon.
May 29, 2010, 11:39 PM
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I am still using the very power system I posted. It's got enough power for pretty much everything I want to do
Latest blog entry: My relationship with Hitec
May 29, 2010, 11:53 PM
You brought two too many.
FlopGun's Avatar
I think this motor I got which I won at a raffle is from a poor batch, it barely had any power at all on 10x4.7 and is just ok on the 11". I should probably put it on the wattmeter.

I am going to buy another one. So if you were to buy a motor for this plane you'd get that Himax?
May 30, 2010, 02:45 PM
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Yeah. Actually, I think I'd go with a Himax HC2816-0890 on a 10x4.7SF, for the extra power on a 25 amp ESC at the weight i'm flying at.
Latest blog entry: My relationship with Hitec
Aug 10, 2010, 08:38 PM
Buzz Buzz
A10 man's Avatar
Good build that actually helped my with my construction!
Oct 01, 2010, 06:12 AM
Blackhawk
I am thinking of building one. Will it fly ok with the E-Flite Park 400 Outrunner 920kv on a 3s Lipo 1000 mah?


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