Tower Hobbies Ultimate Bipe GP/EP ARF

Written by Terry Dunn Everyday aerobatics with two wings Abridged product review Photos by the author Read the full product review in the January 2016 issue of Model Aviation.

Bonus video

Specifications

Model type: Semiscale ARF Wingspan: 45.5 inches Wing area: 840 square inches Length: 50 inches Radio: Futaba 14SG 2.4 GHz transmitter; Futaba R617FS receiver; six Tactic TSX25 digital mini servos Needed to complete: Minimum four-channel radio; four to seven mini servos; .46 to .55 two-stroke or .72 to .81 four-stroke engine (if glow powered); RimFire .55 brushless motor; 75-amp ESC, six-cell 3,800 mAh LiPo battery (if electric powered); adhesives; and basic assembly tools Minimum flying area: Club field Price: $219.99 ARF airframe Power system: RimFire .55 brushless motor; 16 x 8 electric propeller; Great Planes Silver Series 60-amp ESC; Castle Creations CC BEC; FlightPower 3S 3,800 mAh 30C LiPo battery (two in series) Power output: 58.9 amps, 1,331 watts Flying weight: 7.2 pounds Flight time: Six-plus minutes Wing loading: 19.7 ounces per square foot

Pluses

• Superb build quality. • Electric and glow power options. • Nice flight performance.

Minuses

• Wheel pants required sanding to fit. • Wing removal is time consuming.

Abridged product review

Sometimes numbers can be deceiving. When I first glanced at the specification chart for the Tower Hobbies Ultimate, I only noticed the 45.5-inch wingspan. This made me picture a smallish model in my head. That image was shattered as soon as I opened the box. The airplane is longer than it is wide, giving it a broad footprint. When outfitted with one of the recommended propulsion systems, it is powerful, too. This model of the Ultimate is a substantial airplane in every respect.

The completed Ultimate is deceptively large. The wings can be removed to accommodate transporting it in smaller vehicles.

Assembling the Ultimate

The Ultimate is a balsa-and-plywood ARF. I found all of the components to be well built and finished. You can use either glow or electric power. I chose to use an electric power system, which included the suggested ElectriFly RimFire .55 brushless motor. Assembly of the Ultimate went smoothly. Modelers who have built a balsa and plywood ARF should have no trouble with this one. All of the parts fit together well and the included hardware is high quality. The only issue I had involved the fiberglass wheel pants. I had to grind away a small amount of material on both pants so that they would fit over the bases of the wheel axles.

The Tower Hobbies Ultimate Bipe GP/EP ARF includes well-built components and a superb covering job. Parts for using nitro or electric power systems are included.

The Great Planes Silver Series 60-amp ESC can be mounted to the side of the plywood motor box. Note the beefy aluminum mount for the RimFire .55 brushless motor.

Two screws hold the canopy hatch in place. I’m sure this is a more secure method than magnets or spring-loaded latches, but it requires you to bring a screwdriver to the flightline. My biggest concern with this arrangement was that I would drop a screw in the grass and lose it. I mitigated this possibility by fabricating short tethers for the screws using thread and plastic sheeting. Although the Ultimate goes together with little fuss, there is a significant amount of work to do. Plan to spend several evenings getting the model completed and set up. The finished airplane is stunning.

The canopy hatch is held in place with a pair of machine screws. I fabricated simple tethers to prevent losing the screws on the flightline.

The flight battery mounts to a separate tray making insertion and removal easy. I used two 3S Flight Power 3,800 mAh LiPo batteries in series to power the Ultimate.

There is plenty of room in the radio bay for the necessary components. Plastic tubes were installed to position the receiver antennas.

Flying the Ultimate

I configured the throws on every control surface according to the manual. Three sets of rates are listed—low, high, and 3-D. For takeoff, I gradually add power. The tail lifts quickly and little rudder correction is required to track straight down the runway. With a little elevator input to rotate, the Ultimate will lift off and climb away at any angle you choose. This airplane is smooth and predictable. Although the wing loading is not high, it tracks like a heavier model. More than once, I’ve had onlookers ask me what kind of electronic stabilization system I’m using in the Ultimate. They seem surprised when I tell them that there is no artificial stabilization onboard. Aerodynamics are doing all of the work. Control response is brisk. Even the suggested low rates are more than adequate for aerobatics, including snap maneuvers. Rolls are quick and axial. Inverted flight is no problem. I especially like how well the Ultimate can perform knife-edge flight. It will fly equally well on either side for the full length of the field. There is just a hint of roll coupling to counter. Even with a flight full of aerobatics, I rarely sustain full throttle for more than a few seconds at a time. It simply isn’t necessary. Although the Ultimate certainly has the power and control authority to pull off 3-D maneuvers, I think the wing loading and cube loading are too high for it to be a thoroughbred 3-D machine. This airplane is at its best performing pattern-style aerobatics that display its smooth style. Because I’m not heavy on the throttle, I can easily get 6-minute flights with the Ultimate. I always try to save some juice in the tank for landing. I’m sure I could stretch the flight time even more by cutting back on aerobatics, but where is the fun in that?

The Ultimate excels at large, smooth aerobatic maneuvers. Knife-edge flight is impressive.

Final Thoughts

The size of the Tower Hobbies Ultimate Bipe GP/EP ARF is what initially caught me off guard, but there were other surprises, too. With most ARFs, you typically expect to replace some shabby hardware or deal with a few assembly problems. Only the wheel pants caused any hiccups with the Ultimate, and that issue was easily solved. Likewise, you might expect a few quirks in the flight behavior of a mass-produced model. The Ultimate again defies this notion with solid sport flying chops and impressive aerobatics. It is a well-rounded model that assembles easily, looks good, and flies well. —Terry Dunn [email protected]

Manufacturer/distributor

Tower Hobbies (800) 637-7660 www.towerhobbies.com

Sources

ElectriFly (800) 637-7660 www.electrifly.com FlightPower (888) 598-8037 www.flightpowerbatteries.com