Phoenix Models J-3 Cub

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Everyone loves (or hates) the ubiquitous J-3 Cub and everyone has their own individual reason(s) to justify their stance on that issue. Personally, I feel everyone should, at one time or another, own and fly a Cub. Maybe a Cub it is not the best Primary Trainer, but it is a GREAT left thumb trainer as you need to use rudder to take-off straight, perform a coordinated turn and of course land. You may wonder why Phoenix has released this ‘almost ¼ scale’ Cub, as there are so many various sized Cubs on the marketplace. I’m not exactly sure why, but I knew I HAD to have this one!

After I downloaded the manual, there were a couple of surprises for me…  

First, they show flaps on a J-3! It never happened on a full-scale aircraft that I know of.  They’re pretty much standard issue on a Super Cub, but not a J-3. Nonetheless, I love to fly planes with flaps, especially slow planes that can fly even slower with the flaps dropped! Now throw in a good crosswind, and I can spend all afternoon happily attempting touch and goes. To each their own, I guess.

Second,  was the landing gear – it looked impressive in the manual and I’m sure I’ll be vigorously testing its durability! I see they also offer floats – surprisingly enough, Arizona does have lakes, so that’s another feature worth exploring!

I’m going to write this review directed toward relative newcomers to this great hobby who are considering a couple of options:

1) A first gas powered airplane

2) Installing, as well as using, flaps for the first time.

Experienced modelers, please, bear with me on this one!

Specifications

Wingspan:   90.5” (2300mm)

Length:   60.6” (1541mm)

Wing Area:   1219 Sq. In (78.6 Sq. dm)

Weight:   13.2-14.3 lbs (6000-6500 g)

Wing Loading:   25-27 oz./sq. ft (76-82 g/sq.dm)

Wing Type:   Flat Bottomed

Radio:   4-6 Channel minimum (manual states 8)

Servos:   (7) Standard Servos w/torque 50 oz. minimum

Glow Engine:   1.20 two-stroke

Gas Engine:   20cc

Electric Motor:   RimFire 1.20 (63-62-250) recommended or Brushless 2000-2400 W, 450 KV

Speed Control:   80 AMP ESC

Batteries:   (1) 6 cell LiPo

Price:   $299.99 at time of submission.

Online Manual:   www.towerhobbies.com/manuals/pmm/pmma0320_manual.pdf

First Look

There was a bit of rattling inside the box as I brought it into the ‘workroom’ and found a few of the push rods had gotten loose in transport. The main components were secured with soft, light foam and taped to the inside of the box, except the wing panel on the bottom of the box – it wasn’t secured at all. Surprisingly, no damage was found. The covering (Oracover) was without a wrinkle, fingerprint or blemish.  All the components were removed from the box and pictures were taken. The painted landing gear weighs over one pound!

Materials Used

(1) Tactic TTX850 Transmitter

(7) Tactic TSX45 servos

(2) 24” servo extensions

(2) “Y” connectors

(1) Tactic TR825 Receiver

(1) DLE 20 Engine

(2) 1800 mAh Life Batteries

(1) Top Flite Power Point 15×8 Propeller

(1) Du-Bro gas stopper for Du-Bro 8 oz. tank and 3 feet Du-Bro Tygon tubing

Various glues and Metric screwdrivers and wrenches 

Manual

The manual focuses on illustration more than written instruction. As a whole, it does a good job of guiding the modeler through assembly of the J-3 Cub.

Assembling

Assembling Order: Wings, Main Gear, Wing Struts, Engine and Cowl, Tail Feathers, Radio Installation and Final Setup.

Reviewer’s Note: While the wing was being worked on, the interior of the front of the fuselage was curing from a coating of 30-Minute Z-Poxy mixed with milled fiberglass. This could be thought of as overkill because the interior firewall area looked fine, but to encourage the longevity of the airframe (especially when using a gas engine), more fuel proofing is better.

Assembly: Wings

The first step in the manual suggested a heating iron be used to remove all the wrinkle before starting assembly – the trouble was, not a wrinkle could be found! Some small wrinkles started to appear about two days later as our humidity was in the single digits – much lower than the humidity where the Cub was manufactured.

A habit I developed many years ago was to mark (with a permanent marker) the locations of the servo arms on the wing before removing the servo hatches. This has worked well for me, as it has helped line up the servo arm and pushrod with the control horn mounting location.

As you can see in the last photo,  one of the servo hatches was randomly positioned without regard to their appropriate orientation! The diagram in the manual was spot on,and that should be the reference point for the servo installation. For those new to the hobby (see comments in italics), you should find the location of the control horn FIRST, and then orientate the servo so its arm lines up with the horn. The push rod from the servo to the flight control(s)  should be at a right angle.

Newbie note: How do you find that ‘hard point’ where the control horn goes? There are a couple of ways to do this. One is to just feel for a harder section of wood along the top or bottom of the (say in this case) aileron. Sometimes the covering will give it away by exposing the outline of the harder wood. Other times just holding the part up to a bright light source will clearly show where there is wood and where there isn’t!

With the servo hatch orientation corrected, the next step was to attach the flaps and ailerons to the wing. The flying surfaces were removed from the wing and the hinges were realigned and inserted b into the wing. The use of a ‘T’ pin prevented the hinge from disappearing into the surface as it was reinstalled. A very small gap between the aileron and wing is best and when this was achieved, some thin CA was applied to the hinge(s) area. This was done to both the top and bottom of the wing. Once the CA had cured, the aileron was flexed a couple of time making certain it was free to move up and down. The flap hinges were similarly glued into the wing.

Newbie note: If some CA happens to ‘drop’ on the plane’s covering, use some CA ‘De-bonder’. This product is sold right next the CA at your local hobby shop. Take a small paper towel and pour some de-bonder on it. Now rub the spot where the drop (or run) of CA wasn’t supposed to be and it will be slowly dissolved. You may end up with what appears to be a cloudy stain, but go over the area with some rubbing alcohol and I think you will be happy with the results.

Now we can work on installing the servos. The Tactic TSX45 servos are very powerful and more than what is needed on this airplane – but they were sent to me by Tower Hobbies for this review. The servos almost fit the servo hatches, but some excess glue prevented the servo from fitting perfectly. A little work with a small piece of sandpaper resolved that situation. A 1/16th inch drill bit was used to drill holes needed for the servo mounting. The servo screws were first turned into their respective holes, then removed,  and a couple drops of thin CA was applied around and IN the holes. This makes the screw mounting more secure, preventing the screws from working loose due to engine vibration. Shown in the last photo are the flap servos – the ailerons would have their servo arms perpendicular to the servo hatch.

A 24″ servo wire extension is required for each aileron, as well as a Y-Harness to connect the aileron servos to the receiver. The Flaps will also require a Y-Harness for connection to the receiver. With the servos and ailerons centered, and the flaps in the ‘Up’ position, the pushrods and control horns were assembled and installed. I really like these control horns!

Newbie note: The servo arms should be positioned the same, but look closely at the servo arm itself – near the center – and notice some very small numbers (1-4). These number represent something unique…. Each of those numbers indicate that servo arm is slightly angled (#1 for 1 degree; #2 for 2 degrees, etc).

The reason is simple – not all servos will ‘center’ exactly, and depending on the number of splines on the servo, you probably cannot position the arm to be at exactly 90 degrees. By repositioning the arm, and using those numbers as a guide, you can now achieve a 90 degree orientation. 

Assembly: Main Landing Gear

The pre-assembled landing gear was attached to the bottom of the fuselage with four Socket-head machine screws and washers, and a pair of wheel collars held each wheel on its respective axle. Don’t forget to add a drop of thread locking compound to the wheel collar set screw, so you don’t lose a wheel in flight!

Assembly: Wing Struts

With the wing panels completed, it was time to test fit them on the fuselage. The two aluminum wing joiner tubes are different lengths (the longer one goes into the hole closer to the leading edge of the wing) and both were very ‘snug’ when inserted into the fuselage, but the wing panels slid onto the joiners easily.

The fuselage was then placed on its back as the struts were installed.

Installing the wing struts began with attaching the strut bracket to the bottom of the fuselage. The struts were then connected with pins and clips, followed by attaching the struts to the wing’s hard point for a non-stress connection. A scale item missing from this Cub would be the “Jury Struts”, which connect the struts to the wing vertically around the mid point of the strut. However, as a spot-scale model there is no need for them, as they are not functional on this Cub, and would only add assembly time at the field.

Two minor ‘adjustments’ to the instructions were needed: 1) The joining brackets attached to the fuselage had to be bent so the struts could be attached,  and 2) The aluminum ‘ball’ had to be inserted into the socket on the end of the strut. Neither of these were clearly shown in the instructions.

Assembly: Engine Installation

I am installing the DLE 20 in my Phoenix J-3 Cub. I really like this engine – they are reliable, have plenty of power, and are relatively inexpensive. I like this engine so much, that this is the fourth one added to my hangar!

The supplied Nylon reinforced engine mount comes with all the necessary hardware to mount a nitro engine or a gas engine like the DLE20. Also supplied is an electric conversion kit, should you decide to power your J-3 Cub with an electric motor setup. The two piece mount fit perfectly into the pre-installed M4 blind nuts on the back side of the firewall. No modifications were necessary to secure the engine’s thrust washer exactly 145mm from the firewall. I used the Great Planes Dead Center Hole Locator tool to accurately mark the DLE 20’s mounting pattern.

Newbie note: For those of you that are new to gas engines, DLE requires you to mount the throttle arm on the engine. Flip the engine over you will notice there is another throttle arm (notice it lacks holes for a push rod. When installing the throttle arm, you may notice the throttle always returns to the ‘idle’ position.  This automatic ‘throttle return’ is caused by a small spring and it is best that this be disconnected (NOT REMOVED) simply by pushing the short wire off the throttle arm. Your throttle servo will return the engine to idle and by disconnecting the spring, your servo will not have to fight against the spring while flying. After disconnecting the spring, you may notice a huge screw that has a pointed end touching that throttle arm – this should be removed as your trim on the transmitter will fine tune your idle.

Then the muffler was installed on the DLE20 and the muffler measurements were made. The firewall already had many openings so no holes had to be drilled for the throttle and fuel line. The fuel tank assembled easily, and installed per the manual without any concerns. Remember to use the correct fuel line for your type of engine – in this case, Tygon Fuel line was used.

 

These dimensions where then transferred to the cowl. It just so happened that additional portions of the cowl had to be removed in order to slide the cowl over the engine and muffler. The stock muffler is actually outside a good proportion of the cowl.

Some of the cowl was removed to clear the cylinder head and to make room for the spark plug boot. The cowl was modified with a rotary tool without the muffler installed. Then the cowl was mounted to the fuselage in its final location and to my surprise the engine’s thrust washer was about 1/16” inside the cowl opening! Re-measuring the distance from the firewall to the propeller hub was exactly the recommended 145mm, so I added 3mm wood spacers to the back of the motor mount to provide clearance for the engine’s propeller hub.

Once all the edges of the cut-outs where cleaned up, the dummy engine was glued to each side of the cowl with a new (to me) glue by Pacer Industries. The instructions called for CA to be used to secure the ABS plastic parts to the fuselage. In the past, this has not worked well for me. Frequently the CA would run, causing all sort of grief, or the gluing surface was not smooth making for a weak gluing surface. Zap-RT is marketed as a ‘Rubber Toughened CA’, so I tried some on a few scrap pieces and liked that it did not run like thin CA, and it filled in many of the gaps! Needless to say, I tried it on the Phoenix J-3 Cub and liked it. Now will it withstand the shakes, rattles and rolls of a gas engine – we’re going to test that!

Assembly: Tail Feathers

The Phoenix J-3 Cub had an excellent covering job, but a small portion of both the horizontal and vertical stabilizers required the removal of ORACOVER (UltraCote) in order to permit the wood-to-wood gluing surfaces.

To remove the covering, a Hobbico Hot Knife (PN LXSD16) was used to melt the covering and not cut into the balsa.

Newbie note: In order to make your horizontal stabilizer is ‘square’ with the fuselage and wing; a long piece of non-stretchable chord was secured via a T-pin located in the center of the firewall. This chord was then pulled to one corner of the stabilizer, then to the other corner. When both lengths are equal, the stabilizer is perpendicular to the center line of the fuselage. (Assuming the stabilizer is centered) Simple huh?

Newbie note: When mixing epoxy, it is important to use both parts of the two-part chemical. More than one modeler has mixed the resin with some more resin (rather than hardener) because both bottles ‘sort-of’ look alike and in the heat of the moment – oops – that will never cure. A sure-fire method of not making that error is to have both bottles lying flat on the workbench. After you pour the appropriate amount, the natural thing to do is to set the bottle upright after you replace the cap. Now the used portion is vertical – and the unused bottle of epoxy is still lying down. You get distracted: phone call, crying child enters workroom and/or a host of other events prevents you from continuing. When you do return to finish mixing the epoxy the part that is needed to be mixed is laying on its side and THAT is the correct one to mix with the previous portion. I can’t count the number of times I started mixing epoxy only to hear “Dinner’s ready”.

While I’m on the soapbox, notice what is included in the picture of the two epoxy bottles. Yep, bottle of Testor’s Enamel Paint – in this case a yellow bottle. When mixing the epoxy, a toothpick was dipped into the paint and added to the epoxy and mixed until the epoxy was yellow. It doesn’t take much paint. When the epoxy cures the glue color will match the plane, and just might go unnoticed! This makes for a neater glue joint that may show where the epoxy that has seeped out.

Once the horizontal and vertical stabilizers had been epoxied in place, and the epoxy had cured, the elevator halves and rudder were mounted without any problems. Some “T” pins were used to keep the thin CA hinge centered. Thin CA was then applied to both sides of the hinges, and after the CA had cured the control surfaces were moved a few times to break in the CA hinge.

The tail bracing and steerable tail wheel were installed next, finishing up the tail end of the Cub.

Assembly: Radio Installation

Three servos were mounted in the fuselage with the throttle servo furthest toward the left side, elevator servo slightly off center and the rudder servo closest to the door. This arrangement produced straight shots from the servos to their destinations. The receiver was positioned behind the servos and two switches were mounted on the side of the fuselage because opening the side door every time the radio was to be turned on/off, would be more hassle than I prefer – the top part of the door is not connected to the fuselage, and will fall out when the bottom half is opened!

With all of the servos installed and connected, I set the control surface travel according to the manual.

Ailerons: 15mm; 25mm; 35mm

Elevator: 13mm; 25mm; 40mm

Rudder:  50mm

Flaps 25mm; 35mm

At this point the J-3 balanced slightly to the aft by about 3 mm, so the batteries were located just slightly ahead of the CG.

Before final CG check, I added the pilot figure and seat. Unfortunately, a full-scale J-3 Cub is flown solo from the rear seat, so the seat itself had to be removed to position the pilot far enough rearward to look correct. The pilot was attached to the former at the rear of the cabin area to keep ‘him’ secured.

Assembly: Decal Application

For a newbie this could be frustrating as the instruction manual just shows you where to place the decals, not how to apply them! The process is relatively simple but the first time may result in a nightmare, so I’ll pass on some hints.

Newbie note: Don’t try and stick down the long sheets of decals (like the NC 54271 number). You should first trim the decal as close to the colored portion possible. Mix up a solution of soap and water in a spray bottle and spray the area where the decal is going to be located. Peel the decal off the sticky-backed paper and place where you want the decal to be and because of the soapy water, you can maneuver the decal to get it in the correct orientation. Immediately use a credit card or something similar to squeegee the solution out from under the decal. Look for bubbles or raised edges and lift, spray and reposition as necessary. It is best to start with a small decal and progress from there.

Personally I like to cut out each individual number for the NC54271 number as the clear sections of the long decal always seem to have a different appearance than the surrounding covering. By marking a line (I use black permanent markers) along the wing I have a reference line so the letters/numbers are in a straight line. Then use the long one piece decal to mark where the letters/numbers should go (see pic). Now each individual decal can be placed, moved, and secured one at a time. I think it looks better, but that is only my opinion.

Photo Shoot

Flight Report

Before the first flight the brand new DLE20 was run first on a test stand, then mounted on the plane (without the cowl) so any engine adjustments could be easily made. With about 4 oz. of 32:1 Redline oil and premium gas, the engine was running fine.

The next day the cowl was put on so pictures could be taken and to test if the temperature may affect the engine. At the start of the testing, it was a balmy 97 F and the last flight was done in 107 F temperatures. The temperature may have contributed to the overheating problem as all 5 flights ended in a dead stick landing (uneventful, buy the way). The cowl was removed and a couple more short flights proved the cowl was restricting the airflow around the engine.

The first flights were ‘interesting’ to say the least as we noticed the left wing was at a higher incidence angle than the right wing. Not a warp but just the whole wing was angled a bit. With this knowledge a ‘slight’ right turn should occur when taking off and that was confirmed! It took a lot of aileron and rudder trim to fly straight and level. Once trimmed out, the Cub flew, well, like a Cub should.

The first flights proved the rudder is very POWERFUL, the recommended control throws are on the conservative side, and the hard plastic wheels have to go! Every landing (both on hard dirt and soft grass) resulted in a bounce.

Turns at low (suggested) rates resulted in some smooth changes in direction. At my ‘middle’ settings, the Cub flew a bit more aggressive with rolls, and the elevator had a bit more authority. At the ‘high’ rates the fun really started – even with significant expo dialed in, the Cub seemed to be ‘jerky’, which was O.K. for our attempts at snap rolls, knife edge and spins.

The cowl was opened up a bit more providing more airflow and no overheating problems occurred after that modification. Most of the time we flew at the ‘middle’ rates and the video was shot on the second day of flight testing when the temperature was only 105 F, 30% humidity and with almost no wind! With the 8 oz. tank we would get 15+ minutes of flying time and that flying maneuvers, not just putt-putting around the sky!

Landings can be a challenge as this plane doesn’t like to show down and lose altitude. Especially when there isn’t a headwind! Some of the fly-bys on the video were actually my first attempts at doing some touch and goes! I fear spot landings are going to take a lot of trial and error to get down pat. Of course our windless days with a high density altitude didn’t do us any favors. Perhaps a larger prop would help slow down the Cub for these conditions.

The flaps work VERY well…. One notch and up she goes. We tried to dial in some down elevator to mix with the flaps but so far it is down (push) elevator to lose altitude!

Sadly after  six or seven flights, the dummy engine on the left side fell off and was considered lost in action.

 

Check out my Videos to see the Phoenix Models J-3 Cub in Action!

 

Pluses/Minuses

Pluses:

Paint for cowl matched the Oracover perfectly.

Light strong structure with many lightening holes.

Very complete hardware package.

Part fit was excellent.

Front and side windows were neatly installed.

Engine selection was excellent.

Tail wheel assembly is also excellent.

Minuses:

The wing panels were at different angles of incidence.

You really need a metric set of wrenches and screwdrivers to assemble this plane.

Exterior muffler doesn’t look good. Maybe angle the engine?

Top window should be hinged.

Strut attachment to fuselage method is difficult for old eyes.

Supplied fuel tank OK for glow; too large for gas.

Conclusion

I like it! The Phoenix J-3 Cub looks like and flies like a Cub. Individual wing panels are the right size for transport. The use of the rudder is required on the ground, while flying and of course on landings. The DLE20 was an excellent choice and uses so little gas (the supplied tank was replaced by an 8-oz tank) that after 10 minutes of flying, almost 1/3 of fuel is left! It may not be a true SCALE Cub, but no one has called it anything other than a Cub! If you love Cubs, have a small gasser lying around, consider adding this one to your collection!

Contact Information

Phoenix Models:   www.phoenixmodel.com

Tower Hobbies:   www.towerhobbies.com

Tactic:   www.tacticrc.com

DLE Engines:   www.dle-engines.com

Top Flite:   www.top-flite.com

DuBro:   www.dubro.com

Pacer Adhesives:   www.franktiano.com

 

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