Extra 230 (oz14322)

About this Plan

Extra 230. Radio control sport scale model.

Quote: "You say you don't have a lot of money, you don't have much time - then why not build this super .40 size Sport Scale! Extra 230, by Scott Hermann.

The popular full-size Extra 230 was designed by Walter Extra of Germany, and has been flown by many competition pilots from around the world. This Sport Scale model of the Extra 230 uses simple construction techniques that build a strong yet lightweight airplane. The midwing configuraiion does create a bit of a problem in the radio compartment, but standard servos install with plenty of room if hooked up with Z-bends on the pushrods. Ailerons are controlled by separate servos mounted in each wing panel to reduce radio installation problems.

The engine area is easily accessible by the removable front top section of the fuselage. A removable hatch is not one of my favorite means of fuel tank installation, but after fuelproofing the engine compartment and complete tank compartment, no oil has gotten into the airplane.

This airplane flies like it's on rails with limited control throws. When you flip the high rate switches to full control throw, you get an unbelievable roll rate and snap maneuvers that are hard and predictable. With the OS 46 used in the prototype, the vertical performance is awesome and vertical slow rolls are a beautiful sight.

If you think this sounds like your kind of airplane, I think you'll be surprised how easy it is built and how quickly you'll be in the air with this sharp looking sport scale model, that gets a lot of looks on the ground and many oohs and ahhs in the air.

Construction: Wings: Start construction of the wings by cutting two panels from 2 in polystyrene foam. This white foam can be purchased from most lumber stores and is very easy to work with. I cut my cores with a bow, and this technique is relatively simple as long as you go slowly and are careful. (The RCM book on foam wings is very helpful if this process is new to you.) I use a standard automotive battery charger with thin music wire on my bow and get excellent results with this set-up.

After the cores have been cut, sanded lightly, and cleaned of all dust, the sheeting for the wing can be matched and the edges can be glued together. Edge glue all four wing sheets together from two full 4 in sheets-of 1/16 balsa and another sheet cut diagonally to save some material. By cutting this way, only 10 sheets are required instead of 12 sheets with a lot of waste.

Sheet the wing cores with the skins using 3M spray 77 adhesive or equivalent, but make sure that any other product doesn't attack the foam, Trim all perimeter edges and sand flush with the edges of the wing core.

Add the 3/8 sq trailing edges using white glue and hold them in place with masking tape until the glue is completely dry. At the same time, cut the 1 in leading edges from 3 x 3/8 sheet and glue them in place. Glue the 1/4 in sheet tip blocks in place in the same manner. When the glue is dry, carve all of the edges to the rough shape and then sand the wing panels to their final shape.

Cut out the servo openings in the foam and sheeting on the bottom of the wing to suit your servos and then, using a heated piece of 1/2 in copper tubing, melt tunnels in the core from the center of the wings to the cut-outs to route your servo wires. Notch the sheeting at the wing center on the bottom surface so you don't lose the location of these tunnels after the wings are joined.

Sand the wing root to the proper angle for joining the wings, bottom side up on a flat surface, When satisfied with the fit, join the panels with epoxy, making sure the leading and trailing edges are perfectly matched. Inset the 1/8 ply reinforcing plates to the top of the wing as shown on plan.

Wrap the wing center joint with 2 in fiberglass cloth and epoxy or resin. I usually add a double layer of cloth where the wing bolts go on the rear edge of the wing for extra reinforcement, Set aside the wings for later fitting of the ailerons..."

Direct submission to Outerzone.

Scan by MarkD, cleanup by Circlip.

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