Ohio R/C extra 300L

Model Airplane News, Nov 1999 by Kuper, Michael J

At this point, you can install the wings loosely on the wing tube. Position them so that the centers of both the LE and the TE are at the same distance from the thrust line. To ensure accurate incidence, I installed wing incidence adjusters. At the root, scribe a line parallel to the fuselage side on the sheeting, then trim the sheeting to fit. I thought the sheeting that overhangs the root ribs would be prone to damage, so I glued a 3/16-inchsquare balsa doubler to the inside of the sheet about an 13 inch back to strengthen this area and make it fit tightly against the fuselage. Cut grooves in the doubler to allow it to bend, then match the doubler to the curvature of the sheeting. Next, spread a thick microballoon and epoxy mixture along the inside of the sheeting between the edge and doubler. Then line the fuselage side with wax paper and install the wing. I used Anchor Bond* 30-minute epoxy and found the measured pumps to be very nice to use.

After aligning and installing the horizontal stab, you install the vertical fin. Getting an airfoiled fin perfectly perpendicular to an airfoiled stab can be tricky because there are no straight, flat surfaces to measure against, so I used a trick I learned from Dan Wolanski: install 1/32inch-ply dummy hinges into the stab. Place a piece of scrap wood on the dummy hinge (aligned with the centerline of the TE), then attach it with glue. Now, you have a flat surface onto which you can place a triangle to set the vertical alignment of the fin.

RADIO INSTALLATION

I installed Futaba* 9402 servos on all of the control surfaces (111 oz.-in. torque). One servo in each wing controls the ailerons, and both halves of the elevator are controlled separately by two servos mounted in the fuselage, under the stab. For the rudder, there are two servos mounted in the tail. I used a 5-cell Cermark* 1700mAh battery and Cermark 22gauge extensions. To balance my plane properly, I needed to put the battery in the tail (in front of F11). A Futaba 9ZAW transmitter controls the airplane through a Futaba R149DP PCM receiver.

ENGINE

A Brison 6.4 twin-cylinder gas engine powers my plane with a Mejzlik Modellbau 26x12 carbon-fiber prop. The Brison engine is powerful, reliable, durable and easy-handling. With this powerplant, vertical performance is truly unlimited. Vertical maneuvers, including snaps or multiple rolls on uplines, are possible without needing to excessively slow the plane. I installed a CH Electronics* ignition with 1/4-32 spark plugs. By using these plugs, the engine fit entirely within the cowl without cutouts for the spark plugs. A muffler from Bisson Custom Mufflers* quiets the craft and fits nicely in the cowl. A Cermark 1500mAh, 4-cell pack for the ignition and a Revolution Enterprises Inc.* 4.5inch, bar-stock aluminum spinner completed the package.

COVERING AND PAINT

I used Ultracote* to cover the plane and PPG Deltron Acrylic Urethane (DAU) automotive paint to paint the cowl and wheel pants. If you use DAU, be aware that it is a catalyzed paint that requires careful handling and use of a good respirator. DAU will give you an excellent finish; the gloss you see when the final coat is sprayed is the exact gloss you'll see when the paint dries. It has also been proven very durable on airplanes.