About this Plan
Bostonair. Rubber sport model.
Direct submission to Outerzone.
Update 11/06/2020: Added article, thanks to RFJ.
Quote: "Designed for the 14-gram Bostonian category, this competitive little sweetheart will win adoration everywhere. When built and trimmed properly (the full-size plans are on pages 82-83) it will win its share of the trophies as well. Bostonair, by Perry Peterson.
PATTERNED AFTER the Sig Cabinaire but 20% smaller, the Bostonaire was designed to offer the looks and performance of Paul Mcllrath's great-flying sport model while still fulfilling the 14-gram rule. This model is a hardy and robust little flier, scaled down and ready to send up sparks in Bostonian competition.
I will always have a soft spot in my heart for the Cabinaire model. It was the first plane to give me over 100 flights, and it went on to log over 300 flights before meeting its demise in a 'hangar' accident. I've since built over 60 rubber-powered models, including two more Cabinaires. The Cabinaires all flew very well. Since this airplane is also easy to build, the Cabinaire kit is one I recommend to inexperienced modelers.
As for the Bostonian version, its charms are irresistible. One look at the plans or photos, and the debate is off - this plane just has to be built! It looks great, is a terrific outdoor flier, and will also give a good account of itself in a gymnasium.
Construction. Begin the fuselage by building the side frames over the plan, pinning down as you go. Use a sheet of thin plastic wrap taped over the plans. Select medium-weight, straight-grained 1/16-sq balsa strips for the longerons. Use strips of lighter weight for the uprights aft of the landing gear. Make the motor peg retainers of medium-weight balsa, and harden them with cyanoacrylate (CyA) glue after the holes have been drilled.
After the side frames are completed, glue them together at the tail post. Working over the top plan view, add the top and bottom crosspieces as you move forward. Make sure both sides remain at 45 ° to the work-bench. Add bulkheads F-2 through F-4; test fit the bulkhead between F-2 and F-3 as you build. Add the top and bottom stringers, cut-ting notches for each stringer as you go.
Use the cutout on F-1 and F-2 as a pattern to make the plug-in portion of the nose block. Make a removable nose by laminat-ing two 3/32 sheet balsa pieces together and gluing to the rear of the nose block. Drill a /8-in. hole in the nose block for a small plas-tic nose button. This hole should be drilled to allow 2 ° downthrust and 2 ° right thrust.
To make the landing gear, bend .025-in. music wire over the pattern on the plan, and sandwich it between %6 sheet balsa retain-ers. Wheel pants are made from very light-weight balsa cut out and laminated as shown on the plans. The center sections are cut from two pieces of %2 sheet, and the outside pieces are %6 sheet. Sand them carefully to matching, streamlined shapes.
The wheels can be made from two cross-grained laminations of 1/32 sheet balsa. You can also make the wheels of Sleek Streak-type plastic half-wheels. These should be sanded on a block from the rear until they fit into the wheel pants with plenty of clear-ance.
After the wheel pants and wheels are sanded to shape, slide in the landing gear wire from the rear of the wheel pants to trap the wheels firmly inside. Cut a slight notch in the rear of the wheel pants so that about half of the vertical section of the wire is re-cessed. Apply five-minute epoxy to the partly recessed wire. Use epoxy sparingly - if you don't, this is where you can build up weight in a hurry.
Flying surfaces: Outlines are laminated from four strips of basswood cut .012 x 1/16 (available from Peck-Polymers). Make a template by tracing the inside of the outline on poster board. Coat the template outline with wax to prevent glue sticking during the laminating process.
Mix up a solution of about 60% white glue and 40% water in the lid of a plastic butter-tub. Drag each piece of basswood in-dividually through this solution, letting the edge of the lid remove the excess glue. Stack them on a clean area of your work-bench as you go. Tape this stack to one end of the template with masking tape and pull around the form, keeping some tension as you go. Tape the other end, and let dry. Sand these strips before removing from the template.
Build the wing over the plan using 1/16 sheet ribs cut to the pattern on the plan side view. Leading and trailing edges are 1/16-sq balsa. Use 5/8 in of dihedral at each wing tip.
Prop: Make the spinner from a balsa block. Cut the blade slots at 45° angles with a razor saw. The blades are cut from a plastic 8-oz yogurt container as shown on the plan. Slip them in the spinner slots to form a fast, easy, lightweight, and efficient prop. If the slots are narrow enough for a tight press-fit, the blades will not need glue, leav-ing you free to experiment with different blade sizes if you wish.
Covering and finishing: Select a good grade of Japanese tissue for covering. Try to avoid the heavy, coarse domestic tissues. Use a small, soft brush (water color brushes are excellent for this) to paint on a solution of 50% white glue and 50% water to the out-side framework of each area to be covered. Lay the tissue on the framework, gently pull out wrinkles, and pat down. When dry, carefully trim away excess tissue with a sharp razor blade. Drying can be hastened with the aid of a blow dryer set to low speed just be careful not to blow all the unused tissue from your workbench.
When everything is covered, shrink the tissue by spraying a fine mist of water on all surfaces. Do not saturate - you want the covering to just sag a little. Spray the underside of the wing, and let dry before spraying the top. Brush on a thinned coat of dope; make sure you use the nonshrink type. Tis-sue trim may be applied using dope thinner. The thinner will activate the dope under-neath, providing a bonding surface to which the trim is then attached.
Make a paper windshield pattern for test fitting. When you are satisfied with the exact size, transfer the pattern to a sheet of clear, thin acetate. Glue the windshield to the rear and lower side portions of the fuselage only. R/C 56 glue used sparingly works well for the windows; it holds securely and dries clear. Make the landing gear fairings out of bond paper. Paint the wheel pants, nose block, spinner, and propeller blades. Make sure the paint you use for the prop blades is one that won't attack the plastic. I use a spray-can enamel paint made for plastic models.
Flying. Now comes the moment of truth: Will your Bostonaire fly? Make up a test motor about 15 in. long. The amount of power you eventually use will depend on many things. If you use Sig rubber, you will need a wider strip because it is thinner than most other brands. If, like me, you live sev-eral thousand feet above sea level (5,000 ft altitude, in my case) you'll need more power than if you're flying at sea level. Finally, outdoor flying requires more power than flying indoors.
Your Bostonaire should fly equally well to the right or the left. If you fly to the left, use left rudder and leave in the right thrust - it will help keep your plane from spiraling in to the left. I also like to give washout (ie, the trailing edge is higher than the leading edge) to the right wing; this keeps the plane circling in flat left turns without using warps in the left wing. A temporary right wing tab in the up position will also accomplish this.
ROG (rise-off-ground) takeoffs look beter with a right power pattern. With left power patterns, the left wing tip will scrape before takeoff. However, since right power patterns generally gain more altitude, they're less suited for flying indoors under a low ceiling. Enjoy experimenting with your Bostonaire - that's half the fun of flying!"
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