“BeeGee” EPP Foam Build

I've been flying a Lightflite RC Bug for about a month (BUG Review HERE) and I have been having so much fun with it I decided I'd try my hand at building a foamie using some of the Bug's construction techniques in the process.


I wanted to try some construction ideas I had, so I bought some EPP foam and carbon fiber materials from SloFly.com, along with a CD ROM motor and ESC from Lightflite.com. I chose a "BeeGee" shape because I like the look and I liberally used the Lightflite Bug as a starting point for size and construction techniques.

 

BG

Material List:

  • 1 40" x 3mm x 1mm flat carbon fiber strip
  • 1 40" x 5mm x 0.5mm flat carbon fiber strip
  • 1 30" x 1/8" (3mm) carbon fiber tube
  • 1 48" x 1/16" carbon fiber rod
  • 2 9mm EPP 35" x 11" EPP sheets
  • 1 CD ROM motor, Mounting Tube and GWS 10 x 6 HD Prop
  • 1 Castle Creations Thunderbird 9 ESC
  • Spektrum AR 6000 receiver, 3 Spektrum S75 servos
  • Thunder Power 2 cell 910 mah lipo, JST male/female plugs
  • Miscellaneous lengths of small surgical, vinyl and heatshrink tubing, and 1/16" wire
  • 2 Wingsavers
  • Lightweight wheels
  • "UHU Creativ" Glue and CA plus kicker, Blenderm tape for hinges

Some of this material I had on hand, but I would estimate the total cost without receiver and servos at about $130. I would add that in working with foam, you need an absolutely sharp cutting tool, either a new razor blade or X-Acto knife with a new blade.

I took one piece of EPP to use as the wing; I marked off the center and used a 40" carbon fiber strap to mark and round off the wing:

 

Wing Cut

I traced and then cut the BeeGee body (18" x 6½" at the tail) from the second piece:

 

Body

I then cut the ailerons (2 x 4" x 11½") from what was left, rounding the edges. Then I cut the rudder from the body, fashioning slots/tabs to hold the body to the wing and a space for the motor mount:

 

Parts

The light line you see in the wing is a carbon fiber strap embedded into the wing. I used a straight edge to cut a slot halfway through the wing, then glued the strap into the wing using the UHU glue. To keep the wing flat, I put plastic wrap over the slit and weighted the wing down with heavy books, letting it set overnight. Also glue a carbon fiber tube to the wing's leading edge on the bottom surface.

I used the Blenderm tape for hinges – smear a small amount of UHU glue along the edges of the ailerons and rudder, letting it get tacky, and then tape. The UHU is also used to glue the carbon fiber strap along the wing's edge. Glue one side using tape to hold it in place, and then glue the other side. Last glue the motor tube into place.

The result:

 

Body Fin

Now begin to add all the stuff that makes it go. One other wing reinforcement I did was to add a carbon fiber strap on each side of the wing – this to limit the wing's flexing. The aileron servos were placed on the bottom:

 

Bottom

To mount the servos, I taped the sides contacting the body with a strip of Blenderm tape, then used the UHU to glue the servo in place. By taping the servo first, it's easier to remove – the glue stays on the tape, not the servo's body. Once the servo is mounted, hook up the receiver, center the servo arm and then use a piece of 1/16" wire for the control rod:

 

Ail Servo

For the ailerons, I used the longest aileron servo arm for the S75 and cut off one side. I used a wing tip protector for the control horn, drilling a 1/16" hole near the top for the control rod:

 

Ail Horn

 

{mospagebreak}

The battery is held in place with velcro; the receiver is zip-tied on one side…

 

Bat

…while the ESC is on the other:

 

ESC

The rudder servo is also on this side. The control rod for the rudder is a copy of the techniques used in the Lightflite Bug – embed/UHU glue a short length of carbon fiber rod in the rudder, use a short length of tubing to CA it to a longer carbon fiber rod, then epoxy or CA a short piece of 1/16" wire from the servo arm to the cf rod. The plastic tubing at the rudder flexes, giving a nice throw:

 

Rud Rod

The CD ROM motor is held on the tube with a small screw:

 

Motor Mount

The landing gear is another copy from the Lightflite Bug – take a length of cf rod and bend it into a "U" shape – this was 20" long. Cut another piece 11" for the axle. Mount a piece of plastic tubing (3" long) on the center of the axle. On the "U" shaped tube – this is for the landing gear's shock absorber.

The shock absorber consists of a 5" length of cf rod, one end attached to the landing gear and the other to the body. I used a short length of surgical tubing to mount the cf rod to the plane's body. You can't drill into EPP – I used a small phillips head screwdriver as a drill, twisting it slowly into the foam. Once the surgical tubing is glued into the body, I then glued a small plastic strip over it to keep the tube from ripping out on landing.

 

LG Shock

The landing gear is held to the body with zip-ties to the cf tube on the wing's leading edge. I used four short lengths of surgical tubing to hold it in place (what's nice about the surgical tubing is that you don't have to glue it).

 

LG Zip

The axle is held in place with a 2" length of vinyl tubing – cut a small slit in the middle and place one side of the "U" in it and the axle in the other – use CA with kicker to glue it:

 

LG Joint

I used a wheel from a SIG Jenny, held in place with a short length of surgical tubing:

 

Wheel

The cf strap along the wing is reinforced using tape on the front and rear:

 

Wing Side

Last, I fashioned a rear tail strut from a small piece of EPP; I glued a plastic strip from a zip tie on its surface to give it some protection from landing:

 

Tail Drag

Flying Notes

I only had a chance for the three flights in-between rain storms – here's the video:

BeeGee Flight Video

I used low rates and exponential and found it still quite responsive. You MUST check the rudder and aileron surfaces to ensure that they are absolutely flat to the wing and body – any deviation and you will see it right away. Overall I'm very pleased with how the "BeeGee" turned out – it's easy to slow-fly it and super responsive.

Key Dimensions

  • Wing 11 3/4" x 24"
  • Aileron 4" x 11 1/2"
  • Body 4" x 15" with tallest 6"
  • Rudder 3 1/2" x 6 1/4"
  • Carbon fiber strap 3" from wing's rear edge
  • Servo rods – rudder 10" total length, aileron 5 5/8"
  • Rudder servo 4 3/4" from wing rear edge
  • Aileron servo 5 1/2" from wing rear edge
  • CG 4 1/2" from LE
  • Weight less battery 6 ounces
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