Curtiss Condor. Free flight scale twin biplane bomber. The article also mentions adapting this design for control line use.
Quote: "Curtiss Condor Bomber, by Frank Ehling.
MANY old-timers will remember at a glance this model of the Curtiss Condor; however, they may not admit it (even though they are much older than I). It is certainly a pleasure to see the Condor in flight, as here we have a biplane full of interesting details, along with twin engines. This type of airplane cannot be made in an evening, but it is not the least bit difficult to build because there is no trick construction, just straightforward, everyday modeling.
The ship was not highly doped since we wanted to hold the weight to approximately 8 oz, which makes for slower flying, and in turn spells longer life. The plans are full size and no enlarging will be required.
First make the fuselage. It is best to cut the sides from sheet, then the bulkheads, and cement the latter in place. The top sheet can now be cemented to the assembly along with the bottom; make top and bottom a little oversize and trim them flush with the fuselage sides after the assembly has dried. The underside of the nose is covered with celluloid and represents the bombardiers location, which is clearly seen on the cover painting of this issue. Add the nose block after drilling it out for the gunner. The windshield is cut out and cemented in place at this time. The tail wheel is then fastened to .040 wire and cemented to the fuselage.
Since the entire tail assembly is made from sheet, it can be built up as a unit on the bench, then cemented directly on the fuselage top. The horizontal areas are made and shaped in the same manner as a hand-launched glider wing. Cut out all the parts, sand to a streamlined section, then cement to-gether, finally mounting everything on the fuselage.
Begin the wing by cutting all the ribs that will be needed. Lay out the leading and trailing edges and cement the ribs in place, adding the tips so as to have the complete wing frame all drying at once. Be sure to let the cement dry well before removing the wing from the plan; this will assure you of a wing with minimum warps. Build the lower wing first and you can cement it to the fuselage while the top wing is drying. The nacelles are next; these are cut from soft balsa, and on the original model they are left solid. Trim the firewall to size and cement in place; then drill the holes for the gunner positions.
Cut the landing gear wires and form them to shape. Drill 1/4 holes into wing and motor nacelles at the points where the wires enter. Then cut 1/4 dowelling into short sections (1/2 long is about right), and drill a 1/16 hole lengthwise through each section. Push the landing gear wires through the dowels, bend the wire over at the upper end, and cement well. When dry, the entire assembly of wire, dowels, and wheels may be cemented onto the air-plane. This form of construction is sturdy but not too heavy.
The strutting can now be put in the lower wing. Birch dowel serves well for this purpose. Drill holes in the upper wing to take the dowels and cement the wing in place. The wings should be covered and doped first, as this will save you a lot of work getting in and around the struts. A coat of light dope, followed by a good grade of fuel proofer will finish off the wings. The wing wires can be added next; these may be made from a discarded set of con-troline flying wires. Cut each wire a bit longer than needed; then force the ends into the wings and apply a drop of cement to secure them.
Now mount the engines in place; we found the little K & B Infants ideal, as they gave the model very nice flight characteristics. We used the metering system to assure that both engines run the same length of time. However, even if one engine runs a little longer than the other, it does no damage because the model is big enough to fly on only one engine without going into a sharp turn or rpm.
This model was originally built with two English K Hawk diesels, operating from a single tank in the fuselage. This arrangement worked nicely, as both motors always cut out together. However, it was felt advisable to install American motors, which are obtainable everywhere in the country, and Baby Spitfires were tried next. The results were spectacular, but the ship was just too hot to handle, at least for free flight. With these engines, it flies beautifully as a controliner though, and modifications are shown on the plans for such use.
Next, the Infants were installed, and proved just right. When the model was first flown with these, the aluminum props that are furnished with the engines were used. The propellers were bent until there was very little pitch so that the thrust was low. As the ship was tested and adjusted, more and more pitch was put in the Ellades, until they were at the optimum angle for highest thrust. Later, a pair of Cub Special props were tried out, (they are shown in the illustrations) and operate very nicely. In all three engine installations, both props turned the same direction.
When decorating the model, remember that lightness is imperative. Dye the covering or use colored tissue rather than build up weight with heavy colored dope. The wing insignia can be cut from colored tissue and tacked to the wing with thinner. The thinner will soften the dope, which re-hardens to make the trim a permanent part of the covering. The lettering also can be cut from colored tissue, or you can use Trim-Film for a really brilliant decorating job.
Do not try power flight until the glide is flat; our model was a little tail heavy, so add weight if needed. Then start the engines and launch as you would a sport model (not as you would a contest job - that straight-up stuff is okay if you are after every last second in climb, but here we want the model to fly as much like the real ship as possible). As noted before, with larger engines, the Condor will fly as well as a controline model; in this case, the plane could be colored-doped, the motors cowled in, and you would have a real threat in any beauty contest."
Update 10/01/2019: Added article, thanks to RFJ.
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