About this Plan
Spirit 2M. Radio control glider model.
Discontinued kit from Great Planes.
Quote: "An entry-level sailplane that's internationally known. Named 1991 R/C Glider of the Year, the Spirit is the perfect entry-level sailplane. Easy to build and easy to fly, it's docile enough for beginners, yet can still achieve the high speeds needed for competition.
Great Planes' classic interlocking construction, top-quality, machine-cut balsa parts, full-size plans and photo-illustrated instructions make building easy
The 2-meter wing features a modified Selig 3010 airfoil, triple taper planform and polyhedral shape for maximum stability and minimum drag.
Can be built for 2-channel operation or as a 3-channel model with optional spoilers. Smooth and graceful at low speeds, the Spirit can also achieve the high speeds needed for competitive flying. 1st place winner at the 1990 AMA Nats.
Stock Number: GPMA0530
Wingspan: 78.5 in (2000 mm)
Wing Area: 676 sq in (44 sq dm)
Weight: 30 oz (850 g)
Wing Loading: 6.5 oz/sq ft (20 g/sq dm)
Fuselage Length: 39.25 in (1000 mm)
Requires: 2-3 channel radio & 2+ rolls MonoKote"
Update 24/07/2021: Added kit review from Flying Models, May 1992, thanks to RFJ.
Quote: "An FM Product Review: Great Planes' Spirit. By Dave Garwood. Jack of all soaring tasks, this kit features well-cut wood parts and all-around, good flight performance.
Are you tired of wimpy sailplanes A, that handle only gentle launches without folding a wing? Sick of liders that can fly only in light wind so they can still make it home? Disgusted by models that shatter a wing on every tip strike landing? Are you ready for a tough bird, one that won't embarrass you at contests? The Great Planes Model Manufacturing Company (PO Box 788; Urbana, Illinois 61801; 217 367-2069) gives us the Spirit, a kit that is well within the building capabilities of less experienced hobbyists, but also delivers performance that experienced glider pilots and contest flyers want.
Inside the box: The kit includes all the balsa, plywood, hardwood, and hardware needed to build the basic version. Going beyond the basics, some unexpected parts are provided, including a rib alignment gauge, stickers, a tow hook, a clear canopy, and molded pilot. Careful wood selection, quality machine cutting, and superb die cutting make really top notch parts. The pre-cut shear webs really fit. Those who feel "lite ply" is not strong enough for glider fuselage sides will be pleased to find the kit contains all balsa fuselage sides, doublers and triplers.
The full size, rolled plans are exceptionally clear, comprehensive, and informative. Builders who aren't familiar with terms such as "stringer" or "shear web" need only study the plans to find and identify these parts.
The comprehensive instruction manual takes the builder through the construction process with 40 pages of detailed text supported by 98 photographs and 14 diagrams. It has three view drawings to help plan a color scheme, "Contest Practice Record" forms, plus sections on trimming and test flying, on the theory and practice of thermal hunting, and on slope soaring.
Get it together: The Spirit kit, with its high grade parts, clear plans and outstanding instruction manual is a delight to build. The model is constructed entirely of balsa and plywood using traditional techniques and thick, medium, and thin CyA adhesive for the structure, and epoxy for the rudder and elevator hinges.
The kit provides the builder with options, including spoilers, one-or two-piece wing, and bolt-on versus rubber band wing mount_ Instructions are provided for each option, though not all optional materials are included in the kit. My Spirit was built with spoilers set into a one-piece, bolt-on wing.
The fuselage is a long box built up from interlocking balsa sides and doublers with lite ply formers, and the clear instructions make it an easy job to build it straight and strong. Here's a tip: three T-nuts are provided for alternative towhook mounting positions. If you hammer them into the plywood plate at the bottom of the fuselage before the sides are glued in place, you won't risk hitting the fuselage sides with the hammer.
The wings are built up from balsa ribs with basswood spars incorporating a strong shear web system. Balsa sheeting covers the top leading edge of the inner panels (to add strength), but not on the outer panels (to lighten the tips for quicker turning).
The instruction book made building and sheeting the wing so simple, that for once - I didn't resort to slow setting carpenter glue and pins to give more time to get it right.
The fin, rudder, and stabilizer are built up from sticks and die-cut parts. Tapered balsa is provided for the elevator. Local artist Sarah Garwood was kind enough to paint the pilot and cockpit.
Wing covering is Top Flite's MonoKote (now distributed by Great Planes Model Manufacturing Company) and the fuselage was painted with spray primer, sanded and finished with spray enamel. Striping was done with Trim Tape (Pactra Hobby, 1000 Lake Road, Medina, OH 44256; 216-349-4241).
Building is thoroughly explained in the instruction manual, and shouldn't present a problem, even to less experienced builders. Construction and covering took 33 hours, plus about nine hours for optional structures and decorations.
Radio, balance and final prep: Modern, standard size radio receivers and servos fit easily in the Spirit. I used a Futaba Attack 4NBL system with three S-148 servos. (Futaba Corporation of America, 4 Studebaker, Irvine CA 92187; 714-455-9888). The elevator and rudder servos are
When framed up (above of balsa in the tail is the attached to servo rails with screws, and the spoiler servo is mounted to a plywood shelf with double stick servo mount tape. Final assembly includes balancing the plane and the essential step of de-warping the wing. My Spirit took two ounces of nose weight to balance at the back of the C.G. range recommended on the plans. For testing I added another 3 ounce of washers in the battery compartment to move the C.G. to the front of the recommended range. The flying weight for my three channel spoiler version is 34 ounces, yielding a wing loading of 7.2 ounces per square foot of wing area.
Flying: Hand tosses in the local school yard indicated the balance and trim were fine as built. First high-start flights were conducted in a hay field. The Spirit climbs quickly with the pull of the high start, which exaggerates any tendency of the pilot to deviate from a straight-up launch. On half of my first dozen launches I got seriously sideways and had to make fast, radical course corrections. On three of those launches, the sailplane popped off the line prematurely.
I discovered that bending the towhook closer to the fuselage cured the pop-off, and found I was over-controlling the plane on launch. Releasing the model with wings level and no control input resulted in smooth launches. Yes folks, the Spirit will launch itself on a high start, if the pilot will only leave it alone. Clearly, a model that will self launch is a stable flyer. Keep in mind that for this to work, the airplane has to be trimmed for hands-off, straight and level flight, and it must be released directly into the wind with wingtips level.
Level flight is stable and the Spirit exhibits a fairly wide speed range. Forward stalls are gentle and predictable. Loops are easy. If slowed too much in a turn, however, my model drops a wingtip and begins a spiral dive. Keeping the speed up prevents this problem.
For the next thermal flying day, I gave the model 1/8 inch washout at the trailing edge to see if it would reduce the tendency to tip stall. There was no change as far as I could notice. My friend, Jim Harrigan, a second season Gentle Lady pilot, flew the Spirit and observed that it flew fast and found the tip stall and spin a bit disconcerting.
Later we flew at a small slope in 15 mph wind. Twenty year R/C veteran Bob Powers piloted the Spirit for the flying photos. Bob was pleased with the performance and handling of the ship, observing, "You never run out of stick with this airplane." We launched three times and logged more than an hour of air time. The Spirit really feels comfortable in slope lift.
I entered the Spirit in the Hudson River Soar-In at Saugerties, New York. The model easily handled vigorous zoom launches from the contest winches. The wind was 15 mph, gusting to 20 mph and the model was loaded with six ounces of ballast. The Spirit handled the wind intrepidly, maxing one round, nailing landing points in two rounds, and taking third place in the two meter class. Don't think the Spirit limits you to finishing with a third place, however; remember that in the capable hands of Paul Carlson, the Spirit finished first in the two meter class at the 1990 AMA Nationals.
With the 7.2 ounce (and higher when ballasted) wing loading the Spirit's flight performance is, well, spirited. This is not your father's Oldsmobile (nor your beginner's gas-bag floater). It flies fast, responds accurately to control input, and penetrates well. It can be uncomfortably hot on the landing approach, so be careful about downwind landings.
Overall, the Spirit is impressive and exhilarating to fly. It absorbs an amazing amount of punishment from hard landings, and while the spoilers look small, they are quite effective.
Summing it up: Great Planes has given us an up-to-date sailplane design at an attractive cost in money and time. If you've built a balsa and plywood airplane before, you'll likely have no difficulty building this one. If you've soloed in a two meter R/C sailplane before, this model should give you little trouble in the air. It is worthwhile to take the time to learn to handle tip stalls, either by experimenting carefully on your own, or with the help of a seasoned glider pilot acting as an instructor.
After flying the model for a year the only change I'd make would be to substitute commercial tube-in-tube pushrods for the balsa stick control linkages provided in the kit. The balsa pushrods are fragile and make it difficult to place ballast at the C.G. in the two channel version.
The Spirit costs less than $70 to build, counting $47.95 for the kit, $14 for two rolls of covering, and $5 for adhesives. Ten dollars buys the optional parts and supplies for competition modifications. Given the high quality parts, clear drawings and superb instruction manual, construction is pleasurable and nearly foolproof, making the kit a real value. Flight performance ranges from good to excellent, depending on pilot skill and experience, making the design worth building. I'd say the Spirit should be in your sailplane arsenal."
Update 25/07/2021: Added kit instructions, thanks to theshadow.
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