Splash 3D Build - Newbie Edition - RC Groups
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Feb 13, 2007, 07:03 PM
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Build Log

Splash 3D Build - Newbie Edition

The Splash 3D was the first foamy that I ever built, and admittedly I was intimidated and hesitant to attempt the build at first. However, after a few minutes of reading and researching others' build logs, I took the plunge and purchased a Splash 3D kit from Ben-Rod. Speaking of where to buy the kits, here is the original Splash 3D thread:

Original Splash 3D Thread

Here is a useful build log by tdearth:

Outline of my Splash 3D Build Log

Step 1 - Deck assembly
Step 2 - Sponson assembly
Step 3 - Tail and Cockpit
Step 3a - Decorating (optional)
Step 4 - Control horns/rods
Step 5 - Electronics
Step 6 - Repair

This is my SECOND Splash 3D build; after building the first one, I figured I'd build the 2nd as efficiently and as lightly as possible. The materials I am using for the build are as follows:

* Sumo Glue (that's right, I'm using Sumo Glue exclusively for this build)

Additional Building Supplies Recommended:
* 3M Masking Tape
* Toothpicks
* Extra c/f flatbar
* Extra music wire (can be purchased at almost any hobby shop)
* Wax Paper
* A flat piece of scrap OSB or Plywood to act as a table top

Step 1 - Deck Assembly

Glue the deck pieces, including the inner sponsons. Run a fine bead of glue along the inner side of the tabbed areas of the deck pieces, then fit the pieces in so that the glue is forced upward toward the BOTTOM of the deck (the side with the carbon spar slots). Wipe any excess glue with a DAMP paper towel or cloth, this will speed glue cure time. Once the deck pieces are assembled, glue in the carbon spars. Again, run a bead of Sumo Glue down the spar slot, making absolutely sure to keep the bead AWAY from the pre-cut rectangular areas in the deck where the motor mount and tail pieces will fit into the deck, then spread it thin with a toothpick. Cut the rod to the correct size, making sure the REAR carbon spar does NOT extend into the outer sponson slot on the deck. You should be able to see the alignment of the spars in the photos below.

I recommend gluing the inner sponsons immediately after the deck pieces are glued together. Problems can arise if excess glue gets into the inner sponson slots (especially where the carbon spars intersect the slots), it will cure as hard as concrete, making it difficult to fit the inner sponson pieces flush to the deck slots. Sumo Glue dries on white, so it's not noticeable on depron. Add masking tape to ensure the pieces stay flush to the deck during curing.

This is a good time to break before Step 2, which will cover the assembly of the S3D sponsons. Allow the glue to cure 2-3 hours before proceeding to the next step.
Last edited by ChrisWNY; Feb 26, 2007 at 02:55 PM.
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Feb 13, 2007, 10:25 PM
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Step 2 - Sponson Assembly

** Build tip: Keep the tail slots in the rear of the S3D absolutely CLEAR of any Sumo glue. If you get any glue in the tail slots, wipe it off with a dry paper towel before it has the chance to cure, use rubbing (isopropyl) Alcohol to ensure that glue does not intrude here. You'll have a very rough time installing the tail rudders if you allow Sumo Glue to get inside these slots.

The same applies for the open slots where your carbon spar runs across the S3D airframe. Keep the exposed areas of the carbon spars free of any glue as you will need to fit the depron motor mount and tail pieces over the spars to secure them to the airframe. When you run your beads of Sumo glue, stop the bead about a 1/2" shy of the these open slots to ensure that glue does not protrude into these areas.

The sponson assembly is undoubtedly the most time-consuming step in the airframe build. However, it's relatively easy if you're careful and follow the instructions.

As you should notice in the photos, I used Sumo Glue to seal the inner portion of the sponsons where they contact the deck. This will prevent water from getting into the sponsons and is necessary unless you plan on sealing the sponsons using covering film, such as So-Lite.

Glue in the step formers, these are the trapezoidal shaped foam pieces that are attached in the kit. You'll need to use a razor or an exacto knife to separate the pieces. Additionally, since these pieces need to lean forward toward the front of the Splash 3D, you'll need to "bevel" the part of the former that will make contact with the S3D deck. Simply use a sanding block, tilt the former at a 45 degree angle, and use long, straight strokes, and repeatedly slide the former over the sanding block. Soon enough, you will have a perfect 45 degree bevel that will allow the step former to fit flush against the S3D deck.

The rear sponson pieces fit in nicely like a jigsaw puzzle. Run a thin bead of glue along the slot in the deck and glue into place. Use masking tape to keep the pieces in place while the glue dries to ensure a tight, secure bond.

Allow the glue to cure again for a couple of hours. In the next portion of Step 2, the bottom and outer portions of the front sponsons will be bonded to the Splash 3D.
Last edited by ChrisWNY; Feb 16, 2007 at 09:38 AM.
Feb 16, 2007, 09:09 AM
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Step 2, part B

After the glue has cured and those rear sponsons are locked in place, go ahead and glue in the BOTTOM front sponson pieces. You should've received an addendum to the S3D instructions in your kit noting that the bottom sponson pieces are to be glued BEFORE the front outer pieces. The bottoms are a real pain-in-the-arse to glue on if you follow the original build instructions.

First, run a thin, fine bead of glue along the part of the inner sponson and step former where the bottom piece will make contact. It's always a good idea to "test fit" the pieces before adding any glue to observe how things fit together. Use a very small amount of glue here, you don't need much. In order to glue the bottoms on successfully, start at the rear of the sponson and work your way forward, using masking tape to secure the bottom piece once you have lined it up appropriately with the inner sponson and former. Slowly continue to work your way forward, adding more masking tape every inch or two. The bottom will bend nicely and fit perfectly as the tabs will align and guide you forward, fitting flush against the inner sponson piece that you glued during the deck assembly covered in Step 1. Once both bottoms are aligned and taped, allow the Sumo glue to cure for at least an hour before moving on to the outer sponson pieces.

The outer sponsons are glued in similarly to the bottom pieces, except that you will have to mask both the top and bottom portions of the outer sponson pieces to the deck and also to the sponson bottoms. Run a thin, fine bead of Sumo along the bottom sponson and deck area that will make contact with the front outer sponson piece. Again, work your way forward, from the step former to the front of the sponson, bending the piece carefully and adding masking tape along the way to ensure a proper fit. You will need to add extra masking tape to the very tip of the front outer sponson piece to ensure that the assembled sponson comes to a nice, neat point at the front of the S3D.

You *may* have a small gap between the deck and outer sponson piece, even with the masking tape holding the outer sponson piece to the deck. This is perfectly fine, and it's essentially unavoidable. Once the outer sponson has dried and the masking tape has been removed, add some CA to the small gap, and use Hobbylite Filler (can be purchased at most local hobby shops) to fill the gap and give the S3D a smooth, finished appearance. The sponsons can be lightly sanded with 220 grit to give a smooth finish. Make sure that you keep the bottom and outer edges sharp as this will be important when running your S3D on water. The sponson assembly is now finished, you wipe the sweat off your forehead knowing that you completed the most challenging portion of the Splash 3D build. From here on out, the rest of the S3D assembly is simple and virtually impossible to mess up.

Step 3 will cover the installation of the tail and laminating of the S3D motor mount pieces, quick and painless. It is a good idea to have some extra c/f flat bar handy for the tail section. There is 1 piece of c/f flatbar included with the kit that is meant for the front of the top tail section, but I also recommend adding extra c/f flatbar along all front edges of the tail rudders.
Last edited by ChrisWNY; Feb 19, 2007 at 11:46 PM. Reason: Adding photos...
Feb 19, 2007, 11:34 PM
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Step 3 - Tail, Motor Mount, and cockpit

The tail installation is a snap. It is important to first add the c/f flat bar piece to the front of the upper horizontal, as this adds necessary strength to the tail section. ** Optional: add c/f flat bar to front and top ridge of rudder for a very rigid tail, should be able to endure a moderate crash. Add Sumo glue to the bottom portion of the rudders that will make contact with the slots in the deck, then carefully work them into the slots. The rudders fit very tightly into the slot, so just be careful and work them in slowly. Once the rudders are in place, go ahead and add glue to the slots near the top of the rudder where the upper horizontal will mount in place. Use .070" c/f rod to brace the rear of the tail. Sharpen the c/f rods (just use sand paper) and coat the sharpened ends with Sumo glue, then pierce the crease where the rudders meet the deck, and allow the c/f rod to extend into the rear sponson. I used a toothpick to poke a small hole through the very middle of the upper horizontal, then expanded the hole with the c/f rods so that they would easily slide into place. If you pierce the deck area directly below the slot for the rudder control horn, you should be fine with rudder clearance on both sides. Add some Sumo glue to the top where the rods pierce the upper horizontal.

The motor mount needs to be laminated carefully - ensure that the pieces are lined up as perfectly as possible, especially the area that will fit over the carbon spar in the front portion of the Splash 3D deck. Place adequate weight on top of the motor mount so that the pieces bond together tightly. Once the Sumo glue has dried within the motor mount, go ahead and add the 10mm stick. Coat the rear of the stick with Sumo Glue and slide it into slot, which has the 3-degree right thrust built in. Make sure the stick is flush against the right-most side of the slot so that the 3-degree thrust is fully achieved.

It's starting to look like a Splash now! The aroma of the finish line is in the air. Now is a good time to add filler (Hobbylite) and sand/decorate as necessary. The control horns can also be glued in place (this will be covered in Step 4).
Last edited by ChrisWNY; Feb 27, 2007 at 01:42 PM.
Feb 23, 2007, 06:57 PM
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Step 3a (Optional) - Decorate

Now that the tail and motor mount are all set and the glue has cured, you can go ahead and paint/decorate/cover with So-Lite film, your choice. For this Splash 3D build, I began by using Krylon Short-Cuts spray paint (purchased from MisterArt.com) to color the mid and rear areas of the S3D airframe. I will be covering the front portion (including the sponsons) with black So-Lite covering film to completely seal off and to strengthen the sponsons.


For an even, smooth paint job at a reasonable cost, spray paint is the way to go for coloring foamies. First and foremost, *most* spray paints are NOT safe to use on depron. Krylon Short-Cuts is the best aerosol paint for foam, and I've never seen it eat foam, even if it's over-applied. Others claim that Krylon Fusion is the way to go, but if you use even slightly too much of it, it will eat the depron in seconds. Krylon Short-Cuts is hard to find at stores, but if you have a Michael's craft shop nearby, you should be able to find some there.

It's best to spray paint in your garage or outside, use flat cardboard or a plastic garbage bag underneath to catch excess paint spray. Use spray paint sparingly on depron, it does add weight. Carefully apply quick, light sprays in a straight line, and repeat until you achieve the desired results. The paint will be dry to the touch in about 30 minutes.


To add sheen/gloss, Minwax Polycrylic works very well and is safe for depron. It is water-based and has a low odor. Apply the polycrylic using a paintbrush, making sure that the coat is thin, but even. Allow 2 hours to dry, dry-time may be longer in humid climates. If you aren't satisfied with the first coat, you can lightly sand the first coat with 220 grit, wipe down with a damp cloth, then apply a 2nd coat. Applying more than 2 coats will add too much weight, better to stay on the light side. 1 coat should do the trick, foam does not absorb Polycrylic, as it's not porous like wood.

**Note: some prefer to add Polycrylic BEFORE painting. I always paint before coating, this way the Polycrylic will add a nice gloss over the paint, and it will seal/protect the paint from chipping and scratching. Think of how your car is painted -- first primer, then paint, then clear coat.


So-Lite (aka Nelson's Lite Film) covering film can be purchased for $12 per 2 yard roll at http://www.radicalrc.com. 2 rolls are more than enough to cover the entire S3D. I only recommend 2 rolls to account for mistakes/mishaps (and repair). You will also need a Coverite iron, such as this one available here at Tower Hobbies. For my first Splash 3D build, I covered the entire airframe using So-Lite film. It is very light, weighing about 0.6oz per yard, and provides better protection than Polycrylic, it'll even resist/repel fuel. The best part about covering film is that there is NO wait time for drying/curing, it's set and ready once you heat it onto depron.

So-Lite is very easy to apply, try to cover as large of an area as possible to keep seams and overlaps to a minimum. Overlapping is perfectly fine, overlapping should be kept to a minimum, especially if you are using a lighter color (black, for example, doesn't show any overlapping). Heat your Coverite iron to 250-290F (make sure you use the included Coverite sock!!), cut the film using a new, sharp razor or exacto knife and a straight edge, then peel the backing from the film (this can be tricky thanks to static electricity). Lay the adhesive side of the film on the depron airframe, begin heating the film with the Coverite iron, while pulling on the film to keep it taught (this will prevent wrinkling). Work the iron forward slowly, from inside to out, to push any air out from under the film for a smooth application. It will take some time to perfect your technique, patience is key here. Overlap the So-Lite film near seams and edges, this will help seal things off and add strength, while making it difficult to notice any seams that are formed from overlapping.

I have used all 3 methods above to decorate my 2nd Splash 3D build. I chose to use So-Lite covering film on the sponsons to seal out water (and for easier/more effective repair, which I will cover in the last step), but used paint and Polycrylic on the mid and rear sections of the S3D as it is faster and easier than applying covering film. I spray-painted the cockpit pieces separately, it's easier to paint before assembling the cockpit.

So-Lite has a huge advantage when it comes to repairs. Generally, the most likely areas to break on the Splash 3D (or any hydro) are the sponsons. The sponsons bear most of the weight, and unless you have an abnormal crash, the sponsons will be the first portion of the hydro to make contact with the ground (or a tree/pole) in a crash. If you cover your sponsons in So-Lite, they will not only be somewhat stronger, but also MUCH easier to repair in the event of a crash. More details (regarding repair) to come in Step 6...
Last edited by ChrisWNY; Feb 27, 2007 at 05:57 PM.
Feb 27, 2007, 03:20 PM
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Step 3 (cont'd) - Cockpit

Cockpit assembly can be somewhat tricky, it's also made of 3mm depron, so treat it more cautiously as it will break more easily under pressure. Before bonding the cockpit to the S3D deck, cut the black vent material (included in the kit) and glue to the inner portion of the front vent holes in the cockpit pieces. Use masking tape to keep the vent material securely pressed against the 3mm depron. Make sure you leave enough clearance between the upper and lower vents as the center portion of the side cockpit pieces will be bonded directly to the S3D deck/nose area. You'll only need to use a small portion of the vent material provided. Allow the glue around the vent areas to dry before proceeding.

Now it's time to bond the 2 large cockpit pieces to the Splash 3D air frame. First, test fit the pieces on the UPPER deck, as this portion will be bonded first. Add a fine bead of Sumo glue to the tabs on the former and run a fine bead along the inner edge of the cockpit piece where it will make contact with the deck. Slide the piece over the deck and line up the tabs appropriately. Tape the cockpit to secure it in place while the glue dries. Repeat for the other piece. You'll need to secure the front pieces of the cockpit firmly as more force will be required to keep the point of the cockpit pieces flush against the S3D nose piece. Glue in the top rear vent, adding glue to the tab that fits into the deck, and add glue to the sides of the rear vent, then fit the rear of the cockpit pieces to the vent, and tape in place. The rear vent has a slit in the tab so that it can be safely bent forward to line up with the rear of the cockpit sides. Once the Sumo glue begins to cure where the cockpit contacts the deck, you can run a bead of glue along the inner seam (inside the cockpit) to really seal it off. Allow the glue to cure for an hour or so.

Moving onto the underside of the deck, line the bottom portions of the cockpit with the tabs on the formers, and add glue along the tabbed areas. Use masking tape again to keep things in place while the glue dries. Due to the carbon spars, the bottom cockpit will NOT fit flush against the deck. In fact, things are designed to line up this way. This area should stay dry regardless, although you can carefully use Sumo glue to seal the area off underneath. IMO, this will only add unnecessary weight.
Mar 10, 2007, 01:28 PM
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Step 4 - Control Horns and Rods

I must emphasize that the pre-cut slots in the rudders and elevons NEED to be deepened, perhaps cut all the way through, before gluing in those ply and carbon control horns. The ply control horns will attach to the rudders and the inner portion of the lower elevons. The carbon control horns will bond to the upper and lower outer edges of the S3D elevons. Take a minute or two to look at the pre-cut lines on the elevons and rudders to find out where you will be bonding the control horns.

First, grab an exacto knife or a jeweler's screwdriver and dig out those rudder and elevon slots, being careful not to widen the slots so much that the thin control horns no longer fit securely in the slots. On the rudders, it is ok to dig all the way through the slot, because those control horns will go in at bad angles and could snap off during your maiden flight if you do not sufficiently "deepen" the slots. Add Sumo glue to the bottom edge of the control horns (for the rudders), and make sure you glue the horn in the correct direction. The control horn should "point" toward the center of the S3D, with the holes in the horns lining up over the hinges of the rudders.

For the elevon control horns, do the same thing, gouge out those slots with an exacto knife, then use Sumo glue to bond the horns in the deepened slots. again, make sure the PLY horn is glued to the inner portion of the lower elevon (underneath the S3D deck), and that the holes in the control horn are almost over the hinge line. Be careful NOT to reverse the control horns or you will have virtually no throw to your elevons. The carbon horns glue in more easily and will actually bond stronger to the elevons than the ply horns. Your S3D should be upside-down during the bonding process. Try to get the horns as close to 90 degrees to the deck as possible.

[instructions for control rods and photos are on the way]

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