Last November, at the Horizon Indoor Electric Festival, I had a chance to test and sort out a few issues I was having with my Mini Vapor float design. The event’s indoor water runway is the perfect place to fly a lightweight floatplane model!
My original float design worked well for the Vapor, so I shrunk it to Mini Vapor size. However, I was having trouble getting the Mini Vapor to take off from the water.
The first thing that I tried was to increase the size of the flat foam piece that I used on the bottom front of the floats to increase the area. This seemed to help. The floats were performing better, and I got it to lift off once or twice. However, it was obvious that the model now needed more power.
I had an extra 6mm motor from a ParkZone Ultra Micro J-3 Cub with me, so I installed it in the airplane. The 6mm J-3 motor is a powerful one, and I knew that it would give the aircraft the punch that it needed. Now the Mini Vapor will take off from, and land on, the water with ease!
Mini Vapor Floats
I wanted to make my floats as light as possible, so I used 1/2mm Depron that I purchased from Kenway Micro Flight several years ago. Kenway does not currently sell 1/2mm foam, but 1mm Depron is available and can be sanded down with a sanding block. I haven’t tested it, but I think that 1mm Pro-Formance foam also would work.
You can leave the foam white and cut it out per my plans, or spray the foam with inkAID (an ink-jet-receptive coating product), and print my graphics onto the foam using an inkjet printer. I use the white matte precoat and sprayed four coats onto the foam.
Mix the inkAID with water using a 70% inkAID to 30% water ratio. You may have to adjust this depending on the airbrush that you are using. You can also apply inkAID thinned with water using a brush, but airbrushing gives the best results.
After cutting out the parts, use a small metal ruler to bend down each side of the floats. Use the gray outline as a guide.
Glue on and trim the bottom float parts using foam-safe glue. I used UHU por. Add the flat-foam plate parts to the front of each float as shown on the plans. The flat foam adds to the floats’ buoyancy, and helps the model lift off from the water on takeoff.
Cut two lengths of 0.8mm carbon rod to 41/8 inches. I purchased my 0.8mm carbon rod from Homefly. Line up each float side by side and glue on each carbon rod at the locations shown on the plans, connecting the floats.
Cut two pieces of 0.8mm carbon rod to 3.5 inches. These will form the rear fuselage support. Insert each 3.5-inch rod into the rear of the floats at the location marked by a black dot. Connect the two carbon rods at the top with thread as shown on the plans and glue with thin CA.
Place the Mini Vapor on the floats to check the alignment. Glue the rods to the floats when you are satisfied with the fit. Mount the Mini Vapor to the floats by gluing each wheel to the side of the floats slightly behind the front carbon rod as shown on the plans. The rear of the fuselage is connected to the rear support by a small rubber band.
You will need to change out the motor to the ParkZone Ultra Micro J-3 before flying off of the water. The motor will slip right into the Mini Vapor gearbox, but its wires will not reach the receiver. To solve this problem, I cut the Mini Vapor’s 6mm motor wire an inch or two from the motor, removed it, and soldered the J-3 6mm motor wires right onto them. The J-3 6mm draws more current and needs a slightly larger battery for decent flight time. I used a 50 mAh cell from Ares. The battery is perfect for this setup.
Flying the Mini Vapor with the motor upgrade is fun. It performs great, and I was even able to loop the model a few times, which was surprising because of the increased weight of the floats!
Using a Glue Stick to Cover Balsa Models
I have been building balsa model airplanes since I was a child, and I have tried many techniques to apply tissue or other coverings. We all have our proven and favorite methods. Mine is using a glue stick to apply the material. I prefer the Avery brand.
I recently finished the easy-to-build, great-flying Retro RC camp e’Racer. Joe Hass did a great review of the kit in the September 2013 issue of MA. The model uses a light, preprinted, paper covering material.
The instructions say to apply it with spray adhesive, which works fine. However, I used the technique on the wings and had a problem repositioning the material, and then I put a nice smudge mark on one wing panel.
After doing this, I decided to try covering it again using my glue stick technique. I contacted Mark Freeland of Retro RC, who helped me find some new graphics for the wing panels.
To apply the covering material, put a thin layer of glue on the part you are covering, position the material in place, and smooth it with your fingers. With the glue stick method, you can easily reposition the material if necessary.
The glue stick method did not add weight, but the spray adhesive did. My model weighed in at 41 grams ready to fly, which is on the lighter side of the model’s suggested weight!
I also used permanent markers to color all of the plywood parts.