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Old Jul 05, 2014, 05:14 PM
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Fort Worth, TX USA
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New Product
Sky Mule Float Plane conversion

When this model first showed up on my computer I thought they finally came out with a true amphibian RC model. . . . .Not
It didn't take long to find out it was geared toward the FPV guys or modelers new to multi engine planes. I took too long to hit the "buy now" icon so I missed the first batch they made but I'm here now.

With 4 of the conversion kits already sent out it is high time I show how it is done.
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Old Jul 05, 2014, 05:19 PM
RC 4 Life
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Fort Worth, TX USA
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Given the draft of the aft bottom fuselage and the slope of the nose this model is being asked to fly off water. The large propellers do present a small water to tip problem but is easy to resolve with smaller props or raising the prop shaft.
Here the model is sitting in my float plane buoyancy tank testing the angles and clearances. With a few defects noted it was back to the shop.
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Old Jul 05, 2014, 05:26 PM
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Fort Worth, TX USA
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The plastic tooling took about three weeks to complete ( my spare time ) and the parts count went beyond what I intended.
Since the upgrade and conversion kits I offer are based on the amount of plastic used to make them, I try to keep the count low.
This one simply needed to much to make it "cool".
I suppose the scale modeler in me took hold some where along the way.

In the end I turned my Sky Mule into what would best be described as an Albatross.
If you are a rivet counting scale expert just call it the "Sea Mule."
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Old Jul 05, 2014, 05:28 PM
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I don't have a lake in my backyard and there is a limited amount of float flys in my area so making this float plane conversion a true amphibian was a needed option for me.
This and my scale inspiration was the cause for all the parts needed.
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Old Jul 05, 2014, 05:35 PM
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Fort Worth, TX USA
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I have the taxi test video posted.
My normal flying pond was barricaded, blocked and closed because of the fireworks they will be shooting tonight.
Should have thought of that before leaving the house . . .it being the 4th and all.

Had to go to a water ski practice pond , lots of obstacles and a cable stretched over the only accessible shoreline.
I know I called it a flight at the end and Iíll admit it was about like the Spruce Goose test flight.
In two weeks there is a float fly here with a chase boat and everything; Iíll save the flight for then.

Anyway, the test went very well aside from the water that enters the side air exit hole.
A patch of clear tape will block that easily and still leave the hole available for flying from the field.

There is a little wake splash hitting the props but I quickly learned a touch of down elevator will get the plane on step and make it go away.
Think of it as an indicator that the model is moving fast enough to be put on step.

Sky Mule Test (2 min 16 sec)
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Old Jul 05, 2014, 05:42 PM
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Fort Worth, TX USA
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The conversion kit is available on the Parkflyerplastics web site.

Please read the product description.

I have made the kit available as partial sets as well.
This is for kit bashers or for replacement parts.
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Old Jul 05, 2014, 05:46 PM
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About the plastic.

The clear plastic is the PETG type. The same material soda bottles are made with.
It can be bonded with super glue , epoxies, silicone adhesives or polyurethane adhesives (gorilla glue).

I haven't found a paint that will not work with this plastic if properly prepared by light sanding and a cote of primer.

The white plastic is the HEPA type. It is not comparable with CA, super glue will make it crack .
Model airplane glue , epoxies , silicone and polyurethane adhesives work with this material.
If enamels or lacquer paint is used apply thin coats.
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Old Jul 06, 2014, 05:12 PM
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With all that out of the way here is how it was done.
I used gorilla glue almost exclusively because it sticks so well to the foam this model is made with.
We all know how well the decals stick to the plane so adhesive choice was important.
Save all the plastic cut offs , some scrap material is used during assembly.
For instance the back of the canopy is formed at the same angle the tip float wire will be bent to.
Let the gorilla glue set up completely before moving on to the next step, this does not mean you cannot work other sections of the model to save time . . . . .Duh.
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Old Jul 07, 2014, 06:05 PM
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The hull.

From the Sky Mule review thread here on RC groups it has been discussed that a support plate around the nose wheel bearing is needed. I added the plate as a precaution. Poking dents in the foam gives the glue a little something extra to hold on to.

Trim the edges of the hull wheel well leaving the square indention in the aft end. This square indention locates the wheel wells position on the bottom of the fuselage.
Sand the plastic surfaces with rough sandpaper where it will contact the fuselage and hull.
Mark the center line on the front of the wheel well with a pen so it is easy to see. Apply gorilla glue to the plastic and bond the wheel well in place.
Hold it in position with tape.


Note that I use the white gorilla glue because it sets faster. The brown stuff works well too.
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Old Jul 08, 2014, 05:02 PM
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Amphibian models only.

If your Sky Mule will be a water only plane you can skip this step.
With a rotary tool, cut a hole in the wheel well directly over the steering bearing hole. Cut the hole only large enough to fit the wheel and allow for turning.

Before you bond the hull in place you will need to cut a hole in the hull only slightly larger than the hole in the wheel well. This will give your gear doors support and a shelf to sit on when float flying.
The door is sealed and held in place with clear tape later.
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Old Jul 08, 2014, 05:04 PM
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Trim the flange off the forward hull and along the most aft edge of the step found at the rear end.
Place the hull on the fuselage and mark a line along the point the two contact. Remove the hull and sand the inside of the hull around the bond area. You can trim the excess plastic away but leave at least a 3/4 inch bond area.


Use a brass tube to cut a hole in the fuselage right where the aft corners of the hull will come to rest.
Apply gorilla glue to the edges of the wheel well and a bead along the hull edge. About 3/16 in width and 1/4 inch from the edge is plenty.
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Old Jul 08, 2014, 05:05 PM
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Put the hull in place on the fuselage; allow it to contact the wheel well then pull it aft until the front contacts the nose of the model. Apply plastic tape to the aft edge first then around the edges.

Note the clamps used for the amphibian version of the nose gear hole.
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Old Jul 08, 2014, 05:06 PM
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Plastic tape note:
Any plastic tape will work . All you are looking for is an air tight seal between the parts so when the glue foams up it will travel inward.
I'm using blue tape here for illustration.
Masking tape will work to hold the part in place but not make the seal we want.
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Old Jul 10, 2014, 04:44 PM
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Put the tip of the gorilla glue bottle in one of the holes we cut in the belly and squeeze the bottle.
Hold the fuselage at an angle that will allow the glue to run down the corner where the fuselage meets the plastic hull.
When one side is done repeat for the other side.

It takes a while and I grew inpatient waiting for it to run down to the nose of the model so I added more glue to the hole. This may have been a mistake when you see how much glue foamed up at the nose.
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Old Jul 10, 2014, 04:46 PM
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Fort Worth, TX USA
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Use a scraper to remove any glue that has foamed from the gear wheel well and hull seam.
Place the plastic gear doors over the hull and mark the edge then trim to fit the opening.

This piece will be held in place with 2 inch clear packing tape when float flying.
To install;
Cut the tape 1/4 inch larger than the gear door edges and apply the tape overlapping the tape on the center line.
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