Author: Frank Granelli
Edition: Model Aviation - 2010/04
Page Numbers: 65,66,67,68
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Plane Talk: Great Planes Cherokee ARF

FRANK GRANELLI

The Piper Cherokee (PA-28-32) has long been both a popular private aircraft and a favorite modeling project. However, except for limited-distribution kits, there have been few models of this subject available.

Great Planes has changed that with the introduction of its ARF Cherokee. While labeled an ARF, this design is actually an RTF into which you install only the engine and radio system.

Exactly which Cherokee version this model represents is uncertain. It has the famous constant-chord "Hershey Bar" wing that made the airplane a delight to handle; Piper used this wing from 1961 until 1975. This model version also has the third side window, which was added to the PA-28 series in 1968. The registration "N9584R" on the model is no help, because it belongs to a 1959 Bonanza.

Whatever 1968–1975 Cherokee Great Planes copied, it did a heck of a job—especially on the flying abilities.

It seems inadequate to call the Cherokee an ARF. The wing halves fit together nicely over an aluminum spar and are fixed in place with a nylon landing-gear strap, as on most RTFs. The wing bolts and dual leading-edge dowels also serve to keep the wing securely joined.

Both tail surfaces bolt onto the fuselage using three 6-32 bolts. All control surfaces are hinged and glued in place at the factory.

There is total access to the model’s interior; the large canopy is easy to remove by loosening only two bolts. The entire top is open, while the bottom is accessed through the wing saddle.

"Building" is not the right word to describe preparing this airplane for flight. Neither is "assembling," because there is little of that. Getting the Cherokee airborne is more like "shaking the box" than anything else.

Construction

Begin by shaking the wing box. The two aileron servos are mounted on the preformed aileron servo hatch plate using the supplied hardwood blocks. Epoxy the blocks in place. I double-secure these important pieces with an extra servo screw.

Use the supplied control rods to position the control horns. Make sure that the holes are over the hinge line. This is an extremely capable airplane, and you don’t want to induce control differences that will hurt its performance.

This Cherokee is equipped with working flaps. If you don’t want them, plastic strips are supplied to lock them in the up position. Employing the flaps helps manage the landing approach path as well as the touchdown point. Landings are more fun with flaps.

The flap servos mount the same way the aileron servos did. My model’s flaps worked best at 30° full deployment and required zero compensating elevator input.

Mount the wing to the fuselage, and then secure the wing halves together using the supplied nylon strap. Having the wing already mounted ensures that its halves are tightly bound and aligned when the strap is installed.

The attractive wheel pants and landing gear install with no problems. Remember to use thread-locking compound on the wheel collar retaining bolts and on the wheel pant bolts.

Use thread-locking compound on the three 6-32 cap bolts to mount the stabilizer and vertical fin. Unlike the flimsier RTF systems used on many basic trainers, this one uses heavy bolts through sleeves into blind nuts to hold everything together. The fin’s dorsal section also nests into a fuselage slot, ensuring that everything is straight.

After mounting the tail parts, I installed the wing and checked the alignment. The wingtips were less than 1/64 inch (the smallest amount I can measure) out of alignment. The stabilizer was parallel to the wing, and the fin was vertical when measured.

When you are mounting the fuselage servos in the factory-installed mounting plate, you might notice that Great Planes reinforced the servo screw plate with additional hardwood on the underside. This attention to detail and durability has long been needed in the ARF world. Good job! Servo installation and control hookup is standard and made easy because of the excellent access through the fuselage top.

Even the fuel tank area is exposed for easy installation. Mounting the engine is no hassle, because, big surprise, the Cherokee uses the popular Great Planes adjustable fiberglass mount—a perfect fit for the O.S. .46 AX.

Position the thrust washer 4 15/16 inches from the firewall and drill the mounting holes. Tap for 6-32, and then mount the engine. Using the Great Planes Dead Center Engine Mount Hole Locator (item GPMR8130) makes this job extremely easy.

Parts are included for powering the Cherokee with an electric system, including the wood parts needed to mount the RimFire 42-50-800 motor (item GPMG4700) on an ElectriFly Medium Brushless Motor Mount (item GPMG1255). The recommended ESC is the ElectriFly Silver Series 60 amp (item GPMM1850). It's as plug-and-play as the glow-power system is.

Great Planes recommends power from one three-cell, 11.1-volt, 3200 mAh 20C battery or from a two-cell, 7.4-volt, 3200 mAh 20C Li-Poly battery. According to Great Planes, the Li-Polys will fly the Cherokee well and for a longer period when using an APC 10 x 5E propeller (item APCQ4120). The APC 11 x 5.5E (item APCQ1055) offers more performance but costs flying time.

The full-scale Cherokee has engine noise, and so does my smaller version. Some engine noise is nice in a scale airplane, but not too much.

To that end, I installed a Bisson Custom Mufflers Pitts-style muffler (item 4046) on the .46 AX. The exhaust tubes are nearly invisible, because they exit the cowling bottom. If you choose the Pitts option, cut the twin exhaust tubes 1.5 inches shorter and almost perpendicular to the ground. The hot exhaust then streams rearward, away from the painted nose wheel pant.

Total time it took to "shake the box" was four hours, with engine mounting requiring one hour. The Cherokee was an easy airplane to work on, and everything fit well.

This model's total weight came out at 6.36 pounds (measured using a T-5000 electronic scale). The factory weight was listed as 6.75–7.25 pounds. I cannot explain why this Cherokee turned out so light.

True, the Futaba T7C FASST system is light because there are seven Futaba S3003 servos. But still, there are seven servos. The 1850 mAh, five-cell NiMH battery weighed 5.1 ounces.

No doubt the 7.25-pound figure refers to the electric version, but my Cherokee was still 6 ounces less than the light glow version. I think Great Planes just designed a lighter airplane than it knew. That is fine by me.

Weight is all-important, especially in a 40-size aircraft. The Cherokee's flying characteristics reflected this lighter weight. Before getting to the flying part, I'll give you the details.

The O.S. .46 AX turns the Master Airscrew 10 x 6 propeller at just less than 12,000 rpm and will idle at 2,300 rpm. After trimming, elevator movement is 32° up and 30° down. More down-elevator travel can cause rolling during inverted pushups.

The right aileron moves up 18° and down 16°. The left aileron travels upward 19° and 16° down. The differences eliminate unwanted adverse yaw that the Cherokee's barn-door ailerons can cause at slow airspeeds and during vertical climbs.

The flaps deploy 30° and require no elevator compensation at approach speeds. Left rudder travel is 40°, while right rudder is limited to 33°. The difference is caused by control-rod geometry. The CG is exactly by the book, at 3 1/16 inches back from the wing's leading edge.

Flying

As editor of Model Aviation's Sport Aviator online magazine, I have written more than 80 airplane reviews. How the aircraft handles in the air is the most important part of the story to me. Most of today's models fly great, which means that the flying parts of the reviews are usually positive. But each aircraft has problems to report, so my flying reviews don't read like a manufacturer's catalog pages.

Here's where I have a problem: I am concerned that this flying report is going to read like a catalog page. I have made 16 flights on this Cherokee and am still shocked by how well it flies. Nonaerobatic, 40-size sport-scale airplanes are not supposed to, and really can't, fly this well.

What do I mean by "well"? Let's go through a typical Cherokee aerobatic flight.

Takeoff from medium-length grass, despite the wheel pants, is achieved in approximately 80 feet. Initial climbout is surprising: the model holds a 60° angle without losing airspeed. Right rudder input is minimal.

Leveling off at close to 250 feet, the airplane accelerates to its relatively slow top speed of approximately 90 mph. Throttle reduction to nearly 80% results in only a moderate speed loss. This is beginning to look like one of those low-drag, "slippery" models. The rolls are crisp, at an estimate of one per second.

Another surprise is the almost total lack of roll coupling. Full rudder input does not cause the aircraft to bank appreciably. This will make stall turns and point rolls much easier to perform.

Knife-edge flight using right rudder has no pulling tendency to either the canopy or the bottom. The more critical left knife-edge uses only a 6% correction to stop a small pull to the bottom.

There is enough fuselage side area and rudder effectiveness to fly 100-foot-long knife edges before losing altitude in the maneuver. Once trimmed, slow rolls are beautiful.

The Cherokee seems far more capable of aerobatics than the average nonaerobatic sport-scale aircraft. I tried flying the current RC Aerobatics (Pattern) Masters pattern, despite knowing ahead of time that it was an unfair and impossible mission.

The schedule starts with a Half Clover maneuver, which demands the utmost vertical performance from an airplane. The Cherokee pulled vertical in the center, climbed 100 feet, performed two points of a 4-Point Roll, climbed another 100 feet, and then pushed over the top into an Outside Half Loop.

That was a 300-foot rolling vertical, and the airplane barely slowed at all. The Outside Half Loop was round. The airplane still had enough flying speed to hold a circular path in the loop. Inverted flight across the bottom was steady and level. The second Outside Half Loop back to the top was also round.

The vertical down-line with its Half Roll was anticlimactic after the Cherokee’s amazing vertical performance. Once in the right corner, it pulled into another vertical, did another two of a 4-Point Roll (again 300 feet up), and pulled over the top.

Pulling out of the down-line, the airplane did an excellent 8-Point Roll into a Half Cuban Eight with two Half Rolls, exited inverted, and flew to center into a Half Outside Loop (still round), a 1 1/2 Snap Roll, and a Half Inside Loop, also still round.

This is crazy! The 46-size scale models that are not Extras, Edges, or CAPs do not fly like this, ever.

Quitting the pattern, I flew the Cherokee into a Figure M that has a 3/4 Roll in the first up vertical, a Stall Turn, another 3/4 Roll down into a Half Outside Loop in the center, up to another 3/4 rolling vertical, followed by another 300-foot-high Stall Turn, then rolling 3/4 down and pulling out. This airplane’s vertical performance is amazing.

Rolling verticals wouldn’t stop climbing. More than a few times, I pulled the airplane into the vertical from cruise flight, only adding full throttle during the pull-up. I had to wait for the climb to stop. Every time I thought the model had slowed enough to fall out of the vertical, it continued to pull even more into it.

From cruise, verticals would not top out until after approximately 500 feet. The ailerons remained effective in the climb, and there was no pitch to either top or bottom.

Vertical down-lines showed no tendency to pull out, as they do when performed by most sport models. However, the Cherokee did prove its slipperiness as it quickly gained airspeed in the down-line.

Although this is not an expensive Pattern airplane, it flies a great deal like one. So I tried it: the Cherokee will fly the entire 23-maneuver Masters pattern, keeping things round where they should be, vertical when they need to be, and snappy when snappy is required.

After flying the sequence, I moved back to more mundane tasks. Stalls occurred at a reasonably slow airspeed—roughly 15 mph. While the ailerons remained effective throughout the stall, too much aileron input would eventually cause a snap during the deep stalls.

Rudder remained effective almost until the model came to an airborne halt. Stall recovery required only removing the full up-elevator; then the airplane was flying again.

Left spins were good using both rudder and aileron. Spins to the right were more like tight spirals. Inverted spins needed only rudder for the entry and were tight. Still, neutralizing the controls immediately stopped any spin.

Landings were on the quick side, at probably 25 mph. Managing both the approach path and the touchdown is much easier using the flaps. Landings can be prolonged without them, because the Cherokee doesn’t like flying much less than 25 mph when clean and doesn’t slow well. Because this is such a slippery aircraft when clean, approach speeds can climb quickly unless the pilot is exceedingly careful. I strongly recommend using the flaps.

Any pilot just off a basic trainer can safely fly this model without problems. In the hands of a more experienced pilot, it can make the sky sing with joy.

This is a unique airplane. It is a sport-scale aircraft that flies much better than it ever should, yet almost anyone can fly it. It looks great, and those wheel pants set it off as something special. There is no "building" and little assembly.

The Cherokee is strong, light, and straight. It’s one of those models you might want to keep ready for those times when you want to fly for fun and excitement.

Frank Granelli [email protected]

Specifications

  • Model type: RC sport scale ARF
  • Skill level: Beginner builder, novice pilot
  • Wingspan: 60 inches
  • Wing area: 606 square inches
  • Length: 46 inches
  • Weight: 6.75–7.25 pounds (factory)
  • Wing loading: 26.7 ounces/square foot
  • Engine: .40–.46 two-stroke, .52–.56 four-stroke
  • Radio: Four channels minimum, seven standard servos
  • Construction: Balsa, light plywood; fiberglass cowl and wheel pants; plastic canopy
  • Covering/finish: Top Flite MonoKote, fuelproof polyurethane paint
  • Price: $159.99

Test-Model Details

  • Engine used: O.S. 46AX
  • Propeller: Master Airscrew 10 x 6
  • Fuel tank: 14 ounces
  • Radio system: Futaba T7C 2.4 GHz FASST transmitter; R617 FASST receiver; seven Futaba S3003 servos; four 9-inch extensions; two Y harnesses; 1850 mAh, 6.0-volt battery
  • Ready-to-fly weight: 6.36 pounds
  • Flight duration: Approximately 20 minutes

Pluses and Minuses

+ Easy to fly. + Extraordinarily light weight. + Extremely attractive. + Quality construction and materials. + Two-stroke, four-stroke, or electric-power versatility.

  • Wish I knew what model Cherokee it's supposed to be.

Manufacturer/Distributor

Great Planes Model Distributors Box 9021 Champaign, IL 61826 (217) 398-8970 www.greatplanes.com

Sources

Other Published Reviews

  • RC Universe: September 2008
  • RCGroups: August 2008

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