THUNDER TIGER: 3D Spirit

Model Airplane News, Oct 2004 by Harris, Al

Catch the 3D spirit!

These are exciting times for 3D aerobatics. Never have there been so many 30-capable airplanes to choose from. Thunder Tiger's 3D Spirit is the latest almost-ready-to-fly (ARF) model to join the 3D ranks. It has many features that enhance its flight performance, including oversize, counterbalanced control surfaces for quick maneuvering and lightweight construction for an optimum power-to-weight ratio. The elevators use a unique push-pull setup for positive control authority, which eliminates the need for a servo on each elevator half.

KIT CONTENTS

The fuselage, wing, tail feathers and control surfaces are built and covered with transparent Ultracote. The one-piece wing features a thick, symmetrical airfoil for great all-around flight performance. The fiberglass cowl is painted, and the kit also includes wire landing gear, a spinner, wheels, a fuel tank, a smoked canopy and flame-style decals. The high-quality hardware includes just about everything you'll need to assemble the 3D Spirit.

ASSEMBLY

Very little effort is required to get the Spirit in the air, and I was able to complete the assembly at a leisurely pace in three evenings. Major steps include mounting the engine and fuel tank, aligning and mounting the wing, gluing on the tail feathers and installing the radion system. You'll need a work surface large enough to accommodate the one-piece wing. The instructions are straightforward and easy to understand.

* Wing. I started assembly by mounting the wing on the fuselage and removing the covering from the servo bays and from the wing's center section for the servo extensions. A pair of dowels in the wing's center-section cutout that mates with a fuselage former and a single bolt into the rear securely hold the wing in place. For convenience, the wing-bolt blind nut should be installed in the plywood mounting plate before you insert the plate into the rear of the fuselage. After installing the blind nut and mounting plate, I aligned the wing by measuring equal distances from each wingtip to the rear of the fuselage. I then secured the wing so it couldn't move, drilled a hole in the rear of the wing and lined it up with the blind nut. After the wing had been bolted into place, I hinged the ailerons to it. I used a Great Planes Slot Machine to make the hinge slots and thin CA to attach the hinges. I also hinged the elevators and cut hinge slots in the rudder.

FUSELAGE

I prepared the fuselage for the tail surfaces by removing the covering from the slots in which they would be installed. While I was at it, I also removed the covering where the servos are mounted. I aligned the stab assembly and glued it into place with epoxy.

Next, I trimmed the canopy and installed it with transparent tape. There's a recess in the bottom of the fuselage for the landing gear, and it's held in place with a couple of wood blocks and 5-minute epoxy. The recommended engine for the 3D Spirit is Thunder Tiger's Pro-46, which is what I used. I can't say enough good things about a nitro powerplant that starts with a flick of the wrist and performs like a perfectly tuned and well broken-in favorite. I plumbed the fuel tank and installed it as shown in the instructions. I fit the cowl and made the necessary openings in it for the muffler, needle valve and cooling holes.

The hardest part of the assembly is putting the long, thin flame decals on the wing. I sprayed the wing with window cleaner, positioned the decals and carefully rubbed them into place.

FINAL ASSEMBLY

Radio installation is simple, as the model has plenty of room for the radio gear, and the component locations were well thought out. I started by installing the servos in the wing and fuselage and then added the control horns and pushrods. You'll need to add a 12-inch servo extension to the rudder, tor and aileron servos. I installed the receiver and battery side by side in the wing-saddle area of the fuselage using Velcro®.

The elevator servo is mounted at a 45-degree angle in the fuselage and uses a push-pull arrangement to a torque tube that passes through the fuselage. The left elevator pushrod is then connected to the torque tube's bellcrank, and the right pushrod is connected to the torque tube via a bellcrank on the other side of the fuselage. This arrangement makes for a very tight, slop-free control system with straight pushrod runs. Another advantage is that you need only one servo for the elevator.

Final details include balancing the model, setting up the control throws and double-checking all systems.

BUILDER'S FINAL THOUGHTS

The 3D Spirit is one of the best-performing planes I have ever flown. Short takeoffs, enough power to hover and climb vertically and control surfaces large enough for radical maneuvers all help to make the 3D Spirit a real blast to fly! If I could have only one sport plane, the 3D Spirit would be my choice.

Great Planes (217) 398-6300; (800) 682-8948; greatplanes.com.

Hitec RCD (858) 748-6948; hitecrcd.com.

Thunder Tiger; distributed by Ace Hobby Distributors (949) 833-0088; acehobby.com.