SR BATTERIES INC. Eindecker E1

Model Airplane News, Jun 2005 by Carter, Tom

Antique look-modern flight performance!

I'M A WW I BUFF, and when I first I saw SR Batteries' ¼-scale Eindecker E1 fly, I knew I had to add it to my hangar. The full-size E1 was unique among its contemporaries in that it could be transported by truck. It was also one of the first airplanes with synchronized machine guns that could shoot through the prop arc without damaging the prop. The SR Batteries kit version is also unique because it uses many new building techniques and concepts and is designed for gas, glow and electric power. I could hardly wait to get started!

KIT FEATURES

The plywood and balsa ribs are all laser cut, and the landing gear and hard support wires come ready for installation. A Lexan windscreen, spun-aluminum cowl and high-quality hardware are also included. Four 72x24-inch full-size plan sheets detail all the parts needed for construction. My first step was to read the 108-page manual and familiarize myself with the construction process.

* Wing assembly Before constructing the wing, I built the wing-squaring jig to square the wing ribs when I assembled them. I put talcum powder on the two composite spars to make it easier to slide the ribs into their proper locations. The box contained two, 1-inch-square, approximately 13-inch-long blocks of balsa; I set the spars on these to hold them off the table during assembly. At this point, I used the two supplied "combs" and placed one near the leading edge and one near the rear spar. They allowed me to set the ribs at the proper spacing and alignment. The plans show how to make a little "keeper" by using a rubber band to hold the leading edge and the rear spar together and properly aligned.

I slid my squaring jig over the main spar and squared up the root rib. When I was satisfied that everything was correctly positioned, I glued the root rib in and tacked down the ribs that were closest to the root. After tacking down four ribs, I moved the two combs to the next five ribs toward the wingtip so that the remaining ribs would be aligned with the ribs that I had already glued; then I tacked down the next four ribs. I continued this process until I had tacked down all the ribs. This alignment system worked really well.

When I glued on the trailing edge, I left room for the box that the servo tray fits into. I made the aileron-servo tray, installed the servo on it, and then glued the unit into the aileron-servo box at the rear of the wing. I installed the blocks to which the anchor flying wires will be connected. Next, I assembled the wingtips, which were easy to construct, and then I built the ailerons, which are made up of small ribs. The handy little comb jigs helped me to make short work of the assembly.

* Horizontal stabilizer A certain amount of lamination is required for the tail-feather construction. The stabilizer's leading edge is a composite tube, and the trailing-edge requires lamination. The stabilizer and elevator tips are made of laminated balsa over a plywood framework. This construction method creates a strong, light piece.

At this point, I decided to go with the pull-pull system instead of a pushrod connection. The control horns are supplied, and SR offers a complete pull-pull system for $19.95. I built the two elevators; their leading edge is laminated balsa, and the trailing edge is a composite tube.

* Rudder All the pieces of the rudder are laser cut and fit together quite well. Here, again, the use of laminated balsa over plywood made it very easy to shape the rudder. The rudder uses a short, composite tube that slides into the center of the spar; this reinforcement facilitates control and makes a strong rudder.

* Fuselage I laid out the plans and covered them with wax paper. The fuselage is easy to build because everything is clearly marked with very concise directions. My only deviation from the instructions was that I used weights to hold down the plywood fuselage sides to keep them flat while I was building. With the fuselage sides over the plans, glue in the uprights, the gussets and the stringers. At this point, make sure that you are making a right and a left fuselage side. Add the stabilizer mounts and doubters to each side, and then install the bulkheads and servo trays on one of the sides. Make sure that everything is at 90 degrees to the fuselage side.

Put one side on top of the other side. Use weights to hold it in position, and double-check to make sure that the top and bottom are aligned and at 90 degrees. Be sure to check the tail alignment. I glued all the 3/8-inch reinforcements into the bulkheads and installed all the bellcranks in the locations shown on the plans. The firewall can be mounted with either side facing out; I used the one with the Zenoah 26 mounting pattern. The other side shows the mounting for an electrical motor. I made the removable hatch that incorporates the wire A-frame for the flying wires and then the cockpit where the pilot is installed. The A-frame must be set and epoxied into place according to the position shown on the plans. I installed my aluminum cowl on the firewall, making sure that I had 5 ¼-inch clearance from the firewall to the back of the prop. I built the two cowl cheeks, covered them with aluminum and glued them into the fuselage side. Be sure to leave the correct amount of clearance for the wing roots. To finish the fuselage, I reached inside and glued in the floor for the fuel tank.