California Coaster (oz14475)

About this Plan

California Coaster. Radio control sailplane model.

Quote: "Have you been looking for a fast way to get into R/C soaring? Other than out and out theft, you couldn't acquire a top performance glider any faster than to build this all balsa floater. California Coaster, by Matt Tennison.

The first time we spotted the California Coaster was during the North-South (California) Soaring Tournament in Bakersfield (reported by Bob Hahn in the Marchl April issue of MB). At first sight, when the plane happened to be some 3 or 400 feet in the air, we thought it was Rick Walters' popular White Trash (oz14107). The general configuration is quite similar, pencil-thin fuselage, polyhedral wing, fairly high aspect ratio, etc. And not only did it look the same, there was obvious similarity in its performance - a thermal hanger that could hold a tight, flat circular pattern, able to take advantage of the smallest 'up bubble'.

Once on the ground (and in the 100 point rectangle, incidentally) we knew for sure that this was a trash, er, plane of quite different breeding. The peculiar 2-1/2 inch wide color stripes from leading to trailing edge, which we had noticed on the total underside of the winch now made sense. A 9 foot, Jedelsky-style, single surface, sheet balsa wing, with the exposed ribs acting as color dividers!

Immediately we switched hats from contestant/spectator to editor looking for construction article material. The perfect answer for the modeler who is short on building time and long on wanting a high performance R/C sailplane. With all sheet flying surfaces, a simple box fuselage and clean, functional lines, the California Coaster is right on! With materials on hand, a week's work should do it. depending on your building speed and finishing methods.

Don't read this construction article - unless you're willing to risk getting hooked. 'Course, if you do, we just happen to have full size plans.

If you've never built a Jedelsky type wing, you'll find it an interesting new experience in model construction, so save it for later and let's get on with the more mundane business of creating the fuselage.

Experience points out that the nose of a sailplane takes the most punishment. That, and providing protection for the valuable bunch of electronics that will be housed in the nose, are good reasons for lining the interior of the fuselage sides with 1/32 plywood as far back as the rear wing dowel. Contact cement is the best adhesive for this job. Make sure of two things during this operation: One, that you make a left and a right hand side. (If you forget, and build two left sides and somebody sees them, you'll have to build two Coasters in order to hide your stupidity!). Two, that you align the doublers very carefully when making contact. The way they meet is the way they stay!

Next, for added strength and to give you enough meat to round off the corners, glue 1/8 square longerons from the ply doubler on back to the tail post. These also provide extra gluing surface for the 3/32 top and bottom sheeting. Incidentally, the fuselage sides are designed to be cut from one piece of 3/32 x 4 x 48 inch sheet stock.

The 3/32 plywood piece which is contact cemented to the floor of the cabin under the forward wing dowel, is for the tow hook, and is most important. The tow hook is doubled 1/16 music wire, bent and passed through a hole drilled in the cabin floor, one inch behind the wing leading edge. Epoxy in place to prevent wobble.

The nose block is built up from 1/2 in hard balsa pieces and its size and shape is designed to hold a square shaped battery pack wrapped in 1/4 in plastic foam. Of course, the idea is to get the equipment weight as far forward as possible to avoid carrying dead ballast. The original California Coaster required no additional balancing weight. Bundle the receiver in plastic foam and stuff it in right behind the battery pack. Two KPS-10 servos were taped to the fuselage sides, as far forward as possible. This puts everything in the front compartment, leaving only the 1/4 inch square balsa push rods to go back to the tail. Carl Goldberg's bicycle spoke and nylon devises make the hook up from the servos to the short nylon control horns on the tail.

A few improvements have been made in the plans that are not on the plane in the photos. For example, the original had the elevator push rod exiting on the left side to a bottom mounted elevator horn, The plans show the elevator horn on top. It's better this way unless you like to untangle bits of weed and grass from it after every landing.

The 1/16 plywood elevator platform is glued on the fuselage with 1/8 inch positive incidence. This causes the fuselage to fly 'tail high' and more nearly in line with the true flight path. The horizontal stabilizer bolts onto this platform with six 2/56 brass machine screws. The nuts are epoxied to the under side of the platform. This allows the horizontal stabilizer to be removed for packing in small cars and/or on long trips.

The elevator and horizontal stabilizer are both covered with Super Monokote so I could use my favorite hinge system. Monokote hinges are most easily made by cutting two strips about as long as the surface to be hinged and about one inch wide. Turn them sticky sides together, and carefully overlap about 1/8 inch. Now seal them to each other with the tip of your iron, From this strip, cut off hinges about one inch wide and iron them on in the best U-control, cloth hinge tradition. Use at least SIX sets of three hinges each for the elevator and three sets for the rudder.

The fin runs through the top sheeting down to the bottom of the fuselage. The triangular dorsal piece adds strength to the rather skinny fuselage forward of the rudder. Note how the hinge line of the rudder is slightly swept forward. It helps to maximize the movable area and reduce the fixed area. Don't forget the doubler at the bottom of the rudder..."

Direct submission to Outerzone.

Scan by MarkD, cleanup by Circlip.

Supplementary file notes

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