Author: Rick Campbell
Edition: Model Aviation - 2009/02
Page Numbers: 70,71,72,74,76
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Plane Talk: Top Flite Score Control Line ARF

RICK CAMPBELL

WHEN TOP FLITE released the Nobler ARF, it gave the CL world quite a shock. I remember a ragged JPEG copy of a fax posted on the Stuka Stunt CL forum, announcing the new model. I wasn't the only one who thought it was an April Fools' prank. Wasn't Top Flite the company that dropped all its CL kits from production years ago?

When I called the local hobby shop, RC Buyers Warehouse in Nashua, New Hampshire, I learned that it was no joke. In fact, the people at the store said that they had never seen such great interest in an ARF release.

Top Flite has broken ground again with the Score: its first ARF competition-level CL Precision Aerobatics (Stunt) model. It has a thick wing, moderate-size flaps, a large (24%) tail on a long moment arm, and a clean look that straddles the line between classic and current.

At roughly 680 square inches, the Score is a midsize aircraft that matches a vast selection of engines, from .51 to .75. Pick a two-stroke, four-stroke, modern, old-school, or whatever floats your boat—er, flies your Stunt model.

The only rig that might not work is a modern tuned-pipe setup—but only from an aesthetic point of view. The Score has little to no belly beneath the wing; there's nowhere to hide the pipe. However, if you think it looks fine exposed, hanging under the fuselage with a strange, vintage-Corvette side-pipe sort of vibe, go for it.

The Score comes in a huge box with everything bagged, taped securely in place, and well protected. The model is beautifully covered in plastic film. But after a couple of weeks out in the open, down in the humid cellar, that covering job starts to wrinkle and sag like grandma's stockings. It's no big deal; shrink it back up. Stay away from the heat gun when reshrinking the film on an ARF that has an elaborate trim scheme such as the Score's. The trim film will often shrink away from the base film and look terrible; use an iron instead. It’s slower going but will yield better results.

The big box includes many items that aren’t supplied with other ARFs, such as the spinner, tip weight, fuel line, and fuel tank. This kit is complete! The only things the builder has to supply are an engine, propeller, and glue. There’s also a full hardware package—much of which, as far as the control system goes, a competition pilot should consider replacing.

The supplied hinges are of the cyanoacrylate-installed, semiflexible, “easy” variety. The Score is intended to be a competition machine, and this type of hinge has no place. I replaced the hinges with the pinned mechanical variety. I cut the film covering away and notched the flaps for hinge pockets, then installed the pinned hinges with slow-setting epoxy. Come to think of it, that is exactly how Top Flite had us do it on the ARF Nobler; the company had it right the first time.

The aluminum-tube flap-to-elevator pushrod is stiff enough, but the threaded ends are soft, thin, RC-clevis stuff that is not up to the task. The bellcrank is a 3-inch metal unit with unbushed, braided-cable leadouts; this was never considered a good combination, because the cable pivot points would fatigue easily.

The horns are nice, strong, stiff, and nearly 1/8 inch thick; they are plated, too. But the hole placement makes a 1-to-1 flap-to-elevator ratio impossible to achieve as supplied. I weighed all the bits in the kit, added my engine, and determined that my Score would come out at approximately 67 ounces. For this size model, I don't think that anything less than a 1-to-1 flap-to-elevator ratio would be good.

Also, the controls would be extremely fast if assembled as directed. This is the opposite of current thinking. I consulted with two experienced Stunt-design gurus, and both agreed that a slower 1-to-1 control setup would be the way to go. With that in mind, I replaced the stock bellcrank with a 4-inch model, threading new leadouts through the wing and adjustable leadout guide. I cleared out the mount and installed the new bellcrank, foam-wing style, on a 1/8-inch-diameter steel rod suspended between plywood plates and glued to the outside of the wing. I opened up the adjacent wing rib to allow a wider range of motion. I replaced the flap horn with a taller unit, which did align with the stock elevator horn for a 1-to-1 flap-to-elevator ratio. I replaced the stock pushrods with carbon-fiber/ball-link units. The flap-to-elevator pushrod I made is adjustable in length; the adjustability proved invaluable.

Construction: The assembly manual is clear and full of useful tips and photographs. I'll touch on the few places that are worthy of attention or where I did my own thing.

Top Flite instructs the builder to hinge the flaps to the wing and the elevators to the stabilizer before installing these components in the fuselage. I didn't. Had I done it that way, I could not have used my incidence meter to make sure that the wing and stabilizer were installed in the fuselage level with the thrustline.

Is that essential? The TLAR (That Looks About Right) method doesn't cut it. Just because the wing or stabilizer fits the fuselage cutout perfectly does not guarantee that it is aligned correctly. Always check this. Straight Stunt models fly better.

The wing went into the fuselage needing no adjustment to be level with the thrustline. The stabilizer settled into its cutout showing a slight amount of negative incidence. I carefully trimmed the saddle until the stabilizer was level with the wing.

One can build the Score with removable wing and stabilizer; I didn't. Seeking maximum rigidity and resistance to oil penetration, I glued and screwed those parts to the fuselage.

The fuselage has two removable hatches below the stabilizer—one on each side. I glued one hatch in place and left the other removable, held per the directions by four small screws, to gain access to the adjustable pushrod.

Top Flite recommends a .40–.51 engine. I know of several Scores that are flying with SuperTigre .51s. The truth is, pilots have been flying airplanes this size since the 1980s with muffled .60s and, later, piped .40s–.65s. Maybe you'd put a muffled .46 in an aircraft this size back in '76, but not today; Stunt fliers want more. The Score is no lightweight, so a .60 or .65 is probably best.

I chose the Discovery Retro .60, which Yuri Yatsenko makes in Ukraine. Its rear-exhaust/muffler setup is a bit more difficult to install than a side-exhaust engine, but it looks cleaner.

The firewall has a generous amount of right thrust built in. For the tip of the spinner to end up in the correct place, centered in the fuselage, the engine mounts must be installed offset to one side of the firewall. It seems weird at first glance, but Top Flite did the math and its instructions are correct; follow them carefully.

The supplied fuel tank weighs slightly less than 5 ounces. This is fine for my engine, which is a fuel miser, but it will not be enough for most .60s. The tank is held in with long tie-wraps. I like that idea; it's simple, lightweight, and secure but easy to remove.

The Score features a moderate amount of wing asymmetry. On my model, the small fixed portion of the flap on the inboard wingtip had a narrower chord than the adjacent part of the flap. Not having another kit to inspect, I shaved the inboard flap's trailing edge a bit to match the wingtip. Most of the modern models I build have a slightly wider outboard flap, so this little fix suited me fine.

The Discovery Retro .60 spins a monstrous 13.4-inch wood propeller. The Score's supplied landing gear wasn't tall enough to provide safe ground clearance for this propeller, so I had to bend a new set. That was too bad, because the supplied gear was beautiful—rigid, accurately bent to fit the supplied fiberglass wheel pants, and nicely plated.

My model finished up at 67 ounces, with the CG at the aft end of Top Flite's recommended range. I adjusted the leadouts so that the center point between the two lines was an inch aft of the CG. Top Flite instructs the builder to start with an ounce of tip weight.

I sealed the hinge lines with transparent UltraCote Lite before I flew the Score. This covering may be the best thing for sealing hinge lines on plastic-film-covered models. It's thin and flexible. Since its adhesive is activated by heat, it has zero tendency to stick in the hinge line after application. So far, the UltraCote Lite has held up incredibly well to fuel/oil goo and repeated cleanings.

I hung the Score out on 66 feet (center to center) of braided .018-inch-diameter lines, with my own version of a Fancher cableless handle.

Flying

From the first flight, I knew I had work to do. The tank was nowhere near the correct height, and the engine ran inconsistently. Taking the engine off of uniflow fixed the erratic run, but then it sped up way too much from launch to landing.

I tried removing the cowl for more cooling, but it was apparent that the engine didn't care for the type of plumbing I used or the tank's height. In addition, the model seemed to need a good flap tweak to level the wings. This was unexpected, because I had installed both flaps with the incidence meter. It was time to go home, measure, and do some research on the Discovery Retro .60's preferences.

Poking around on the Internet, I got an idea of what tank and venting would be best for my engine. I also learned that its designer advocates a bit more oil in the fuel than I was using. Ya gotta love living in the information age! While in the cellar, I also tweaked the flaps.

Two fuel tanks later, I experienced success. The engine ran better, allowing me to focus on flight trim. I made another gentle adjustment to the flap tweak, moved the leadouts a bit, added a little more tip weight, and I was doing patterns.

To improve the groove in level flight, I drooped the elevator roughly 1/8 inch at neutral flap. The adjustable-length pushrod made that easy; I'll never build another Stunter without this feature. Then the Score grooved well and still turned equally inside and outside.

Back at home, that flap tweak was still bugging me. I knew I assembled the flaps straight, so why did it fly banked out upright and banked inward when inverted?

It turns out that leaving the wheel pants off to save weight was a big mistake. The 1½ ounces of wheel pants (and a lighter substitute landing gear) I omitted from the lowest point on the model upset the vertical CG. I found some heavier wheels that were the equivalent weight of the stock wheels plus the pants.

Subsequent flights with these wheels proved the flap tweak to be unnecessary. I removed it, and the Score sat squarely on the lines, upright and inverted.

If you think this sounds like voodoo, please read Chris Lella’s “Balancing for Roll in CL Stunt Ships” article in the May 1976 MA. You can check it out in the “Members Only” section of the AMA Web site. Moral of the story: You really can have more fun with your pants on.

The Score reminds me of a friend’s model I flew years ago; it is stable but still aerobatic. You steer this airplane through maneuvers—not “hit it and pray.” It is easy to fly, fun, and forgiving, but it might be less taxing to fly if it were a bit lighter.

My model is still balanced at the aft end of Top Flite’s recommended range, but I’ll try moving it a bit farther aft. With the slower controls I installed, I think I can get away with that; the design certainly has the tail volume to handle it. As my friend, Steve Yampolsky, is fond of saying, “Try it. All you have to risk is 4 ounces of fuel.”

Where does the Score fit in? You can fly it in any contest but Open at the Nats. You only lose appearance points for not being compliant with the Builder of the Model rule; that’s fine with me. I usually build my own stuff and have no problem taking the penalty when I don’t.

What attracted me to the Score was the chance to try a new engine. I didn’t have a model I could easily retrofit (pun intended) for the Discovery Retro .60. I have precious little building time, so I’m hesitant to scratch- or kit-build a model around an unfamiliar power plant. The Score proved to be a perfect test bed for that engine, and it flies a competitive pattern.

With minimal time invested in assembly, I was able to take a chance on a new power plant. If replacement engine mounts become available from Top Flite/Great Planes, the Score will be a perfect test bed for all larger Stunt engines. Meanwhile, I have a nice-flying new aircraft in my stable.

Looking around at opinions and experiences posted on the Internet, I found that almost everyone else who is flying the Score replaced the controls as I did. Flying weights vary from as light as 60 ounces up to 68 ounces. Several different engines were used, but there’s not enough difference in their weight to make an 8-ounce difference in finished weight.

I have been told that one Score is powered by a SuperTigre .60. I guess that’s the acid test for those RC-type plastic engine mounts. If a SuperTigre .60 can run consistently and doesn’t shake the nose apart, almost anything can run well in this model.

Grab your favorite engine and give the Top Flite Score a go!

MA

Rick Campbell [email protected]

Specifications

  • Model type: ARF
  • Wingspan: 56.5 inches
  • Wing area: 677 square inches
  • Length: 46 inches
  • Weight: 60–70 ounces (test model's weight: 67 ounces)
  • Airfoil: Fully symmetrical midwing
  • CG: 4-1/8 inches (105 mm)
  • Engine: .40–.51 cu. in. (test model's engine: Discovery Retro .60)
  • Construction: Balsa and plywood
  • Finish: Plastic film covering
  • Price: $109.99

Pluses and Minuses

  • Fast, easy, strong assembly.
  • Complete kit.
  • Flies competitively.
  • Excellent as engine test bed, practice airplane, or quick route to full-size competition model.
  • Inadequate, out-of-date control-system hardware is inconsistent with a competition model.
  • Small fuel tank.
  • Heavy!

Manufacturer / Distributor

  • Top Flite / Great Planes Model Distributors
  • Box 9021
  • Champaign, IL 61826
  • (217) 398-8970
  • www.top-flite.com

Sources

Transcribed from original scans by AI. Minor OCR errors may remain.