Great Planes Cherokee ARF? Review

Great Planes Cherokee ARF? Review

by Eric Henderson

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 model kits available for it. Great Planes has changed all that with its introduction of their ARF Cherokee. While labeled as an Almost Ready-to-Fly airplane, the Great Planes Cherokee is not just an ARF. Actually, it is almost a Ready-To-Fly airplane into which you install the engine and radio system.

Exactly what 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. It also has the third side window that was added to the PA-28 series in 1968. The N9584R number provided with the kit is no help as that is from a 1959 Bonanza.

Charlie Ammar, a model Aviation reader and a knowledgeable Cherokee owner-pilot sent in this helpful information: “By looking at the pictures in the article, it seems it is a later model Cherokee 180; that is 1971 or later because of the 3rd window. Cherokee 140, 150 and 160’s did not have that window.” Thanks Mr. Ammar, for the information

Whatever 1968 (’71)-75 Cherokee Great Planes copied, they did a heck of job on it; especially on its flying abilities.

It seems almost unfair to call this Cherokee an ARF aircraft. The wing halves fit together nicely over an aluminum spare and are fixed in place with a nylon landing gear strap as is done on most RTF airplanes. 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 factory hinged and glued in place.

There is total access to the airplane’s inside as the large canopy is easily removed by removing only two bolts. The entire top is open (see photo) while the bottom is accessed through the wing saddle as well. “Building” is not the right word to describe getting this airplane ready for flight. Neither is “assembly” because there is little of that. Getting the Cherokee airborne is more just “shaking the box” than anything else. But remember to put the radio equipment and engine system in the box before shaking it! The 2.4 GHz Futaba T7C FASST transmitter performs well when trimming the Cherokee for aerobatic flight.

There is a lot of hardware included; all useable. The fiberglass wheel pants are exceptional for an ARF airplane. The foam wheels are strong, but very light (0.4 oz. each).

The engine mount is the self-centering Great Planes type. It fits the O.S. Max “40-size series up to the powerful .55 cu. in. engine. While it will fly with any four-stroke engine in the equivalent size range, this airplane was really designed for a two-stroke.

This airplane uses the O.S. Max .46 AX two-stroke engine. The engine is very powerful, more so than most, but is also easy to manage and has a good, reliable idle around 2,200 rpm once broken in.

Shake the wing box first. About the only work that needs doing on the wing is to mount the two aileron servos and the two flap servos, install the control linkages and then bolt the landing gear in place. (With the wheels and pants attached of course.) Flap use will be discussed later, but please, use the flaps if at all possible. The airplane needs them to make those pretty, easy to control landings.

The twin aileron and flap servos are mounted on the pre-formed and covered aileron servo hatch plates using the supplied hardwood blocks. Epoxy the blocks in place to fit your servo. I double-secure these important blocks using an extra servo screw as shown in photo 7. Drill and install the screws after the epoxy has cured.

Temporarily use a piece of card stock as a spacer to keep the servo from resting against the wood. This protects it from vibration. Use the supplied, precut control rods to position the control horns. Make sure the horn’s holes are over the hinge line. This is an extremely capable airplane and you don’t want to induce control surface variations that will hurt its performance.

This Cherokee is equipped with working flaps. If you don’t want them, there are some plastic strips to lock the flaps in the up position. Using the flaps helps manage the landing approach path as well the touchdown point. Landings are more fun with the flaps. The flap servos mount the same way as did the aileron servos. My flaps worked best at 30 degrees full deployment and required zero compensating elevator input.

Slide the wing halves over the aluminum tube. Mount the wing to the fuselage. Then, secure the wing halves together using the supplied nylon strap; identical to the straps that will hold the gear in place. Having the wing already mounted insures that the wing halves are tightly bound together and aligned when the strap is installed.

The beautifully painted wheel pants already have the mounting groove, blind nuts and axle cap piece in place. Grind a flat spot into each outer axle so the wheel collar bolt gets a good grip.

Remember to use thread locking compound on the wheel collar retaining bolts and on the wheel pant bolts. Then mount the landing gear using the four supplied nylon straps and eight screws. Make sure that the gear leg fits flush with the bottom of the wing. Radius the mount’s corner if necessary to allow room for the axle bends.

OK, wing done in 45 minutes. On to the fuselage! Use thread locking compound on the three 6-32 cap bolts to mount the stabilizer and vertical fin. Unlike the more flimsy RTF systems used on many basic trainers, this system uses heavy bolts through aluminum sleeves into blind nuts to hold everything together. The fin’s dorsal section also nestles into a fuselage slot insuring that everything is straight.

Note the aluminum, insert inside the bolt holes in the vertical fin fillet. These inserts insure that the wood does not enlarge over time due to flight stresses.

After mounting the tail parts, I mounted the wing and checked the alignment. The wing tips were less than 1/64 in. (the smallest I can measure) out of alignment. The stabilizer was exactly parallel to the wing and the fin was a true vertical fin when measured. Great Planes includes extra red covering to cover the bolt holes after installation.

When you are mounting the fuselage servos in the factory-installed mounting plate, you might notice that Great Planes has 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 on this one. Servo installation and control hookup is standard and made easier to accomplish because of the excellent access through the fuselage top.

Even the fuel tank area is exposed for easy installation. Mounting the motor is no hassle because, big surprise here, the Cherokee uses to popular Great Planes adjustable fiberglass mount. It was a perfect fit for the O.S. Max 46 AX engine. Position the thrust washer 4 15/16 in. from the firewall and drill the mounting holes. Tap for 6-32 then mount the engine. Using the Great Planes “Dead Center Engine Mount Hole Locator” (GPMR8130) makes this job extremely easy.

Parts are included for making this into an electric-powered airplane including the wood parts needed to mount the RimFire 42-50-800 motor (GPMG4700) on a Great Planes Medium Brushless Motor Mount (GPMG1255). The recommended ESC is the Great Planes Silver Series 60 Amp (GPMM1850). Power is from one 3-cell, 11.1 Volt, 3200 mAh 20C battery hooked in series with a second 2-cell, 7.4 Volt 3200 mAh 20C Li-Poly battery.

The Lithium Polymer batteries will fly the airplane well and for a longer period, so Great Planes says, when using an APC 10 x 5E Propeller (APCQ4120). The APC 11 x 5.5E propeller (APCQ1055) offers more performance but costs flying time.

But the full-size Cherokee has engine noise and so does my smaller version. Some engine noise is nice in a scale airplane, but not too much, please. To that end, a Bisson Custom Mufflers’ Pitts style muffler (04046) was installed on the .46AX. The exhaust tubes are nearly invisible as they exit out the cowling bottom. If using the Pitts option, cut the twin exhaust tubes 1.5 in. shorter and almost perpendicular to the ground (see photo). The hot exhaust then streams rearward, away from the painted nose wheel pant.

Total “shaking the box” time was four hours (including photos) with engine mounting requiring one hour. The Cherokee was a very easy airplane to work on and everything actually did fit well. This Cherokee’s total weight proved to be 6.36 lb (using a T-5000 electronic scale). The factory weight was listed as 6.75 to 7.25 pounds.

I can not explain why this Cherokee turned out so light. True, the T7C FASST System is light as are the seven Futaba S3003 servos. But still, there are seven servos! The 1850 mAh 5-cell Ni-MH battery weighed 5.1 oz. No doubt the 7.25 lb. weight refers to the electric version but my Cherokee was still 6 ounces lighter than the light glow version. I think Great Planes just designed a lighter airplane than they know. 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, here are the details.

The O.S 46 AX turns the G/F 3 series 10 x 6 in. Master Airscrew at just under 12,000 rpm and will idle at 2,200 rpm. After trimming, elevator movement is 32º up and 30º down. More “down” elevator travel can cause rolling during inverted push ups.

The right aileron moves up 18ºand down 16º. The left aileron travels upwards 19º and 16º down. The differences eliminate unwanted adverse yaw that the Cherokee’s barn-door ailerons can cause at very slow airspeeds and during rolling vertical climbs.

The flaps deploy 30º and do not require any elevator compensation at approach speeds. Left rudder travel is 40º while right rudder is limited to only 33º. The difference is caused by control rod geometry. The CG is exactly by the book at 3 1/16 in. back from the wing’s leading edge.

Please excuse this short break, but I need to explain something. As editor of this magazine – Model Aviation’s Sport Aviator, I have written more 80 airplane reviews. How the aircraft handles in the air is always the most important part of the story to me. Most of today’s airplanes do fly very well. That means that the flying part of the review is usually very positive.

But there are always problems to report so my flying reviews usually don’t read like they are a manufacturer’s catalog page. But here I have a problem and am concerned this flying report is going to read like a catalog page. I have flown 41 flights on this Cherokee and I am still in shock at how well it flies. Non-aerobatic, 40-size sport scale airplanes are not supposed to, and really can’t, fly this well. What do I mean by “well”?

Let’s fly through a typical Cherokee aerobatic flight and maybe that will explain what I mean. Takeoff from medium-length grass, despite the wheel pants, happens in about 80 ft.

Initial climbout is surprising as the aircraft holds a 50-60º angle without losing airspeed for the first two hundred feet. Right rudder input is minimal. Leveling off at around 250 ft., the airplane accelerates to its relatively slow top speed in the 90 mph range. Throttle reduction to about 80% results in only a moderate speed loss.

This is beginning to look like one of those low-drag, “slippery” airplanes at speeds under 80 mph. However, speeds much over that are retarded due to extra airframe drag as happens with most sport airplanes.

The rolls are crisp; about one roll per second. Another surprise is the almost total lack of roll coupling. Full rudder input does not cause the airplane to bank appreciatively. This will make stall turns and point rolls much easier to fly. Knife edge flight using right rudder has no, repeat, no pulling tendency to either the canopy or 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 ft. long knife edges before beginning to lose altitude in the maneuver. Once trimmed, slow rolls are beautiful with this airplane. The Cherokee seems to be far more aerobatic-capable than the average non-aerobatic sport scale aircraft. Let’s see just what it can do for real.

I tried flying the current Master’s Pattern despite knowing ahead of time that it was an unfair and impossible mission. The Pattern starts with a maneuver called a Half Clover that demands the upmost vertical performance from an airplane. The Cherokee pulled vertical in the center, climbed 100 ft., performed 2 points of a 4 point roll, climbed another 100 ft. and then pushed over the top into an outside half loop. Huh?

That was a 300 ft. 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 up to the top was also round. This can’t be happening!

I am not claiming that the Cherokee could fly this maneuver as well as could a modern Pattern (Precision Aerobatic) airplane. The maneuver, despite being 300 feet high, remains well under the Pattern Airplane’s 5- 600 foot height for the Half Clover. The Cherokee used far more rudder inputs to keep the pushover and inverted flight portions on track as well. The pilot’s workload was higher by a good amount. Still, the airplane flew this maneuver respectfully. Most 40-sized sport airplanes cannot.

The vertical down line with its half roll was anti-climatic after the Cherokee’s amazing vertical performance. Once in the right corner, the Cherokee pulled into another vertical, did another 2 of 4 roll, again 300 ft. up and pulled over the top. Pulling out of the down line, the airplane did an excellent 8-point roll into a half Cuban 8 with two half rolls, exited inverted and flew to center into a half outside loop (still round), a 1 1/2 snap roll into a half inside loop; also still round.

Ok. Stop right there. This is crazy. .46 scale airplanes that are not Extras, Edges or Caps, etc. do not fly like this, ever. The Cherokee’s light weight was making itself very apparent in these maneuvers. Its high-lift Hersey Bar wing was also providing the extra lift and control needed in these unusual attitudes.

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 a another 300 ft. high stall turn then rolling 3/4 down and pulling out.

This airplane’s vertical performance is amazing for its class. Rolling verticals wouldn’t stop climbing. More than a few times, I pulled the Cherokee into the vertical from cruise flight, only adding full throttle during the pull up. I had to just wait and wait for the climb to stop. Every time I thought the airplane 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 about 500 ft. 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 do most sport airplanes.

However, the Cherokee did prove its slipperiness as it quickly gained airspeed back to about 80 mph in the down line. While not an expensive Pattern airplane, the Cherokee flies an awful lot like one. So, I tried it. Yes, the Cherokee will fly the entire 23 maneuver Master’s Pattern keeping things round where they should be, vertical when they need to be and snappy when snappy is required. But, the pattern was smaller, and lower, than a competition Pattern Airplane’s pattern flight. The pilot’s workload was also higher due to the extra rudder inputs and energy management tasks required.

After flying the Pattern, we moved back to more mundane tasks. Stalls occurred at a reasonably slow airspeed; around 15 mph with the flaps down and a little faster with no flaps. While the ailerons remained effective throughout both stalls, too much aileron input would finally cause a snap during the “deep” stalls. Rudder remained effective almost until the airplane came to an airborne halt.

Stall recovery just required removing the full “up” elevator and 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 around 25 mph. Managing both the approach path and touchdown is made much easier using the flaps. Without them, landings can be prolonged as the Cherokee doesn’t like flying much less than 25 mph when clean and it doesn’t slow down well at slower airspeeds.

Because the Cherokee is such a slippery airplane when slow and clean, approach speeds can climb quickly unless the pilot is very careful. I strongly recommend using the flaps.

While any pilot graduating from a basic trainer can safely fly this airplane without problems, the landing technique is different from a trainer’s. This airplane should be landed as are most scale aircraft using throttle to control altitude and elevator for airspeed. See the Sport Aviator article – Basic Landing Techniques in the Pri-Fly Section.

Do not use the trainer landing technique of cutting the throttle and just lowering the nose to glide into the flair. Do that and the Cherokee will gain too much airspeed and will float to the runway’s end; especially without flaps deployed. Hold the nose level or slightly up, manage the throttle and elevator and fly the Cherokee into the flair. Once about a foot off the runway, slowly remove the last of the throttle and flair.

In the hands of a more experienced pilot, this airplane can make the sky sing with joy. The airplane is honest, will not snap out of a tight turn and can fly most anything within reason. The only exception is its prolonged knife-edge flight’s limitation to about 100 feet. But that is more than enough for slow and point rolls.

This is a unique airplane. It is a sport scale aircraft that flies much better than it ever should yet it can be flown by almost any pilot out of a trainer It looks great and those wheel pants set it off as something special. There is no “building” and very little assembly. The Cherokee is strong, light and straight. This is one of those airplanes that you want to always keep ready for those times when you just want to fly for fun and excitement.

For more information on this special ARF, go to: Tower Hobbies

Notable Positives

• Easy to fly
• Extremely fast assembly
• Very good looks
• Light flying weight
• 2 or 4-stroke or electric versatility
• Very aerobatic

Notable Negatives

• Full-size parent not identifiable
• Weak Knife-Edge performance

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Aircraft Specifications

• Manufacturer: Great Planes Model Manufacturing Company
  • Champaign, IL
  • (217) 398-8970
  • greatplanes.com
• Cost: $155.00
• Airfoil: Semi-Symmetrical; Low Wing
• Special Airframe Features: Semi-Symmetrical Wing, Lighter than specification, Quick Assembly.
• Length: 46 in.
• Wingspan: 60 in.
• Wing Area: 606 sq. in.
• Wing Loading: 24.2 oz./sq. ft.
• Weight (as tested): 6.363 lb.
• Options:
  • Radio Options: 4+ channel radio system (5-channel required for operational flaps) w/4-7 standard servos
  • Electric Power Options: ElectriFly™ RimFire™ 42-50-800 Outrunner Brushless Motor (GPMG4700); ElectriFly Silver Series SS-60 Brushless Electronic Speed Control (GPMM1850); 18.5V 3200mAh LiPo battery (GPMP0622 or GPMP0623); propeller (10x5E or 11x5E)
  • Glow Power Options: 2-stroke .40-.46 cu or 4-stroke .52-.56 cu in engine

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Additional Equipment used in Test:

• Engine: O.S. Max 46 AX
  • Manufacturer: O.S. Max
  • Osaka, Japan
  • os-engines.co.jp
• Muffler: Bisson .46 SF/FX/AX Pitt (04046)
  • Manufacturer: Bisson Custom Mufflers
  • 9 Moffat Road
  • Perry Sound
  • Canada P2A 2W7
  • bissonmufflers.com
• Radio: Futaba FASST T7C 2.4 GHz
• Servos: 7 x Futaba S3003
  • Manufacturer: Futaba Corporation
  • Champaign, IL
  • futaba-rc.com

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