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Great Planes Piper J3 Electricub ARF Review

Jon Walker, guru of all things microheli, selects this great looking park flyer for his return to fixed wing flight after -- !30+ years! -- and finds the aircraft to be a perfect lady even in the hands of a nervous almost-novice.

Splash

Introduction


Model Specifications
Wingspan:41
Length:29.5
Wing Area:269 sq in
Weight:14 oz
Wing Loading:7.5 oz/sq. ft.
Motor:T-280 with 3.5:1 gearbox (Supplied)
ESC:Great Planes C-5 (Supplied)
Battery:Great Planes 8-Cell 600mah NimH (Supplied)
Prop:10x7 (Supplied)
Manufacturer:Great Planes Model Manufacturing Co.
Available From:Great Planes Dealer Locator or Tower Hobbies online
Requires
Servos:2 x Micro
Receiver:3-Ch minimum
Transmitter:3-Ch minimum
Charger(s)
Hand tools
Adhesives
As Reviewed
Servos:2 x GWS Pico BB
Transmitter:Futaba 8UHPS
Receiver:Berg 5
All Up Weight:17.25 oz
Wing Loading:9.2 oz/sq. ft.

You've got your first trainer well under control. You can take off, circuit, and land without any mishaps, and you're starting to think about your next aircraft. You know that the super-scales and hot aerobatics planes are still a little way off. So what to get? Well, how about the Great Planes J-3 Electricub? It's an ARTF (ARF to you Americans) for easy assembly, it includes the power system (but not the radio gear), it has the three channel control system that you've trained on, and it has a nice semi-scale look to boot. Need further convincing? Well it's an unwritten rule that every R/C Pilot must own and fly a Piper Cub at some stage :). Great Planes market this nice looking park flyer specifically at the 'second aircraft' segment of the market. So let's take a look at it and see how well it fills its niche.

Kit Contents

The motor, gearbox, ESC, battery and prop are all included in with the kit. This is a great idea! It removes the guesswork normally involved in working out what powerplant to use, and is a feature that beginners to electric flight will really appreciate. But it doesn't include the radio system, which you already own from your trainer, so why pay to buy another! Just add your own servos, receiver, transmitter, and charger(s) and you're in business!

The Great Planes J3 Eletriclub is an ARTF, which is pre-constructed using traditional Balsa/Ply methods. All the major components are built and covered. Just final assembly and fitting of your electronics is required to complete the aircraft ready for flying.

As you can see from the photographs, the kit is extremely comprehensive, and even includes such 'extras' as velcro strapping for securing the electronics and rubber bands for the wings. A few hand tools, adhesives, and radio equipment are all that is required to finish it. The quality of assembly was excellent, with no warping, and no badly fitted parts evident through the translucent Cub Yellow covering. Only a few odd wrinkles marred a near perfect covering finish.

Assembly

As mentioned, this aircraft is an ARTF, so even a blow-by-blow is going to be a short write-up!

The comprehensive instruction manual runs to some 20 pages. The manual caters well to the beginners' needs with a lot of supplementary information covering balance, safety, pre-flighting and some basic flying hints. Each stage of the aircraft's construction is described in detail with copious supporting B&W photographs.

Wing

After gluing the panels together, I decided to tidy up the wing joint by wrapping a single layer of black tape around it.

Fuselage

The fuselage was a little more involved. I installed the landing gear and wing dowels, cleared the cooling holes in the removable battery cover (most important!) and installed the cover latch. That pretty much finished the fuselage!

Tail

One of the most important items in terms of affecting the handling of the aircraft, and consequently an area that it pays to take your time over, is mounting the tail. The method for aligning the stab was well documented in the manual, but I thought it worth while to photo it here as well.

OOPS!

This is one of the few areas of the aircraft that I wasn't 100% happy with. The fit of the fin/rudder actually fouled the movement of the elevator. I ended up trimming a little out of the elevator to give some clearance, but in retrospect it would have been better to shorten the rudder tab where it inserts into the tail plane.

Radio & Power Plant Installation

The radio installation took nearly as long as building the rest of the aircraft! I guess you tend to get that with ARTFs. I must admit I had a bit of a struggle getting the esc servos and receiver suitably located and fixed. This wasn't an issue with the aircraft though, just me and my big ham fists :). After a little manipulation, everything was in place and ready for final setting up.

Setting up Control throws and Centre of Gravity

Great Planes went to great lengths to ensure that you set your Electricub up correctly. Dimensions are given for all of the critical items, which I have listed in the table below.

Elevator Throw 5/8" Up and 5/8" Down at High Rate1/2" Up and 1/2" Down at Low Rate
Rudder Throw 5/8" Right and 5/8" Left at high rate3/8" Right and 3/8" Left at Low Rate
If no dual rates USE LOW RATES ONLY FOR FIRST FLIGHTS
Centre of Gravity Initial - 2-1/16" back from wing leading edgeAlter by +/- 1/4" to suit once familiar with handling
Dihedral 3-3'4"

If you have radio equipment capable of dual-rates, Great Planes supplied throws for both high and low rates. They suggest that you use the low rates for your initial flights, and then move over to high rate as you become competent flying the aircraft. If you don't own a dual rate radio they recommend that you set your throws at the low rate setting initially.

Great Planes also strongly recommend that you use the suggested initial CofG balance point. One you are familiar with the aircraft, you can move it up to 1/4" forward or backward of the start point but never go outside of that range.

One other key point highlighted in the manual, sadly lacking in many other kits, is the importance of checking lateral balance as well as the fore/aft CofG. This is done by lifting the model by the prop shaft and the tail end of the fuselage and checking if either wing consistently drops. If one wing always drops when you do this, you need to balance the aircraft by adding weight to the 'high' wing until neither drops consistently.

Completion

After installing all the electronics, there was very little left to be done. The addition of the canopy and cowling went without issue. The instructions indicated that the two holes in the cowling would need to be cut out, but on the review example this had already been done.

I affixed the decals, using the box photo as a guide. I also decided to extend the black trim theme from the wing centre, and ran a matching strip down the top of the fuselage. An added bonus from this was that I now had a very quick visual check that my wing was correctly fitted and centred!

The final touch was to make up and fit the the simulated wing struts. These struts were simply yellow cord strung between ply mounting plates on the wings and fuselage. Although they provided no structural gain to the aircraft at all, along with the realistic decals they certainly helped to create 'the look' of a Piper Cub.

Final Centre of Gravity Check and Flying Weight

A final check of the Centre of Gravity showed it to bit a little too far aft compared to the recommended position. I ended up adding 0.8 oz of weight at the firewall to bring the CofG into the correct starting position.

The all up weight was a little over the advertised 14 oz. Mine came in at 17.25 oz completed and ready to fly. This brought the final wing loading up to 9.5 oz / square foot.

Flying

All that was left now was to wait for suitable flying weather. And so I waited... And waited.... And waited.....for two and a half MONTHS!

Of all the times to have the worst summer weather in 140+ years, it had to be this year!

Having received the Cub in late October 2004, and having it ready to fly from the first week in November 2004, I ended up having to wait until mid January 2005 before we got conditions to maiden the aircraft. The sudden, unexpected break in the weather on the day I flew took place in the evening. So it was a full on rush to get out to the field and get some flights in before sun-set.

As a consequence, I'm afraid that this flying report will be a little short, and there are no in-flight photos and videos at this stage. With the indulgence of the editors, I plan to return to this review in a month or so. Hopefully this turn in the weather will continue long term. If so, I'll be able to get out and put more hours on the clock, and get some in-flight video and photos to fill this review out more completely.

Basics

First up I rigged the aircraft ready for flight and double checked the CofG, my control orientations, and ensured that I had my dual rate switches set to low rate. A quick run up of the motor to check that all was well, and it was off to the flight line.

Taking Off, Circuits and Landing

One look at the state of our strip (remember the weather I mentioned?) made the decision to hand launch easy. I ran the motor up to full power, gave Deane the nod, and with a gentle straight and level push we were off!

The little Cub left Deane's hands and flew away straight and true. The 280 motor in full song provided a healthy climb rate. There was no tendency to dip after leaving the hand launch, nor was the climb-out so steep as to get a newcomer into trouble.

Once I'd reached about 50ft altitude I made a gentle turn to the right. The Cub banked around nicely, with only a small amount of up elevator required to maintain altitude through the turn. Once I reached cruising altitude I found that I could throttle back to about 80% power and still maintain altitude and airspeed comfortably.

After cruising around for what seemed like forever (about 10 minutes according to the guys I was flying with) it was time to try a landing. Throttling back, I found that the Cub would keep flying right down to not much more than walking speed! I must admit that my landing skills were very rusty, but even my ham-handed approaches didn't phase the little Cub. I couldn't say that the plane is un-stallable, but I sure didn't find the limits despite being badly out of practice!

Speaking of airspeed, with the throttle at max, and a bit of down elevator to prevent a climb, the Cub is capable of a surprising fast turn of speed! It's quite a contrast to the extremely slow flying speed at the opposite end of the rage.

The only fault I really found with the Cub's flying characteristics was that the elevator response was pretty twitchy even when set at the lower throw rates. I will be reducing the throws on this and will report the outcome in the updated flying review.

I ended up getting three flights in before the light started to drop, and the wind started to come up again. As I settled back into 'fixed wing mode' I found each minute of each flight more and more relaxing. This little plane is a real pleasure to fly. It has sufficient power for a reasonable climb out, can fly so slowly that I could just about jog alongside it, and has very gentle handling. Once trimmed out, it will fly 'hands-off' just about forever!

The guys I were flying with were VERY impressed. They all commented on how nice the Cub looked in the air, and how well it handled. Another real bonus was the noise - or the lack thereof! This aircraft is really quiet. Even in the dead calm air, you could hardly hear it once airborne. It's definitely a very neighborhood-friendly park flyer!

Although time and conditions were against me testing it out, I suspect that a ROG take-off would be quite attainable from a smooth take-off surface. I also think that with some altitude and a dive to build up some airspeed, the Cub would be capable of pulling a loop. I hope to be able to test these ideas in the upcoming weeks, and hopefully report back here.

Is This For a Beginner?

OK, confession time... Although I have been flying MicroHelis for the past five years, up until today I hadn't flown a fixed wing aircraft for nearly 30 years! So although I have flying skills, I think I can just about qualify as a beginner again when it comes to fixed wing aircraft.

I started off this review looking at the Great Planes Piper J3 Electricub as a potential 'second aircraft'. Now, having built and flown it, I have to change my opinion! Provided that an experienced pilot was available to oversee/assist with construction, trimming and flight lessons, I would say that this aircraft would make a great first aircraft. It has a very forgiving nature and no nasty habits. The tiny 600mah battery pack seems to provide a good 10 minutes of flight, which is more than ample for the beginner.

As a few of my 'landings' demonstrated, traditional construction methods still stand up well in anything less than a full on crash. The worst I managed to do was bend the undercarriage legs back a little, and they were easily bent back into shape.

Conclusion

The Great Planes Piper J3 Electricub truly deserves to be called a Great Plane!

As a first aircraft for beginners (I recommend some expert assistance), second aircraft, or as a very pleasurable and relaxing park flyer, the Cub meets the requirements fully. The cub is a quick easy build and has everything you need except the radio gear.

My cub came out a little overweight, and the interference of the rudder post with the elevator was an annoying problem that would likely stump a beginner. I do still want to explore the elevator low rates further to see if a softer low rate, which would better suit a beginner, will still fly the model safely. Otherwise, perhaps some exponential is what the little cub needs around neutral.

It looks great, both on the ground and in the air, and flies beautifully. It's the ideal small aircraft to 'find' in the trunk of the car when you arrive at your destination on a family outing ;).

Discussion

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Old Feb 11, 2005, 11:18 AM
Registered User
Lawrence, Kansas
Joined Dec 2001
610 Posts
Apparently this model is completely different from the Great Planes ElectriCub kit that has been on the market for over a decade. My ElectriCub has a wingspan more in the neighborhood of 60 inches and it weighs 3 or 4 times what this model weighs. Is Great Planes marketing a parkflyer in the UK under the same name as it sells a much larger model in the US? All I see on the Tower Hobbies web site is the most recent version of the larger model.

- - Dave
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Old Feb 11, 2005, 04:26 PM
Registered User
Christchurch, New Zealand
Joined Feb 2002
105 Posts
Hi Dave,

Yup, you are pretty much right on that. Great Planes make two Electricubs.

The 60 incher that you have is GPMA0156 - http://www.electrifly.com/largeelectrics/gpma0156.html

The 40 incher that I reveiwed here is GPMA1153 - http://www.electrifly.com/parkflyers/gpma1153.html

And just to confuse us they call both of them J-3 Electricub .

As far as I know though, both of them are available in the US. Here's the link to the 41" Park flyer at Tower Hobbies for you http://www2.towerhobbies.com/cgi-bin...=PR&I=GPMA1153

Hope this helps,

Regards,

Jon
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Old Feb 23, 2008, 05:59 PM
Registered User
Joined Feb 2008
5 Posts
Hi,

I've got kind of a new-guy question regarding this model. I have finished assembly and have looking at the electronics set up. I can't figure out how to have the battery power both the engine and the receiver.
I'm used to gas where the battery only runs the receiver and servos so I'm a little confused. Is there anyway that you could post an electrical system diagram.
I think I need to get a splitter for the battery so it can power both the engine (2 pin connector) and the receiver/servos (3 pin).
Or maybe I am horribly wrong. Before I cut or fry anything, I thought I would ask.

Thanks,

Jorge
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Old Feb 24, 2008, 01:29 PM
Suspended Account
holmes county ohio
Joined Apr 2007
113 Posts
j3

you should have an electronic speed control.....your battery goes in...then hooks to your motor as well.
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Old Feb 24, 2008, 02:56 PM
Registered User
Joined Feb 2008
5 Posts
Right, I get that. But my battery only has one chord, therefore I can only put power to the ESC. The receiver also requires power. It can't be going through the ESC to the receiver because my receiver has a three pin connector for a battery (which I have a battery for it, but I didn't think flying with two batteries would be wise as weight is an issue).

Here's a rough diagram of what's going on:

|----------Switch
|
ESC------------------------->Receiver
| |
| |--><----Battery
|
|------><-----Engine


Now, the issue is that the receiver isn't getting any power.

The one thing this kit is missing is electrical diagrams. Everything else is A+, though. And the electrical thing is probably my own confusion.
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Old Mar 03, 2008, 08:22 AM
Registered User
Bellingham WA
Joined Feb 2008
17 Posts
receiver power

Hello, Hope you got for receiver working for the weekend. I just dusted off my park flyer (Miss Bohemia w/Electrifly C-20 ESC) to check the ESC to Futaba receiver connection. The 3 wire ESC goes to connection 3 for throttle. There is NO connection to the battery input.

What I am assuming is that this single connection serves 2 functions: Allows the receiver to control the ESC but it also allows the ESC to power the receiver.

The C-20 ESC also has BEC which shuts off the motor if the battery voltage dropps below 4.8 volts. With the servos powered you can make a controlled landing. Good Luck ~ Ron
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Old May 31, 2008, 09:20 AM
Registered User
Joined Sep 2002
86 Posts
Only need one battery, the throttle wire from ESC feeds power to the receiver/servos
see the ESC manual here http://manuals.hobbico.com/gpm/gpmm2005-2015-manual.pdf


Quote:
Originally Posted by JorgeC
Right, I get that. But my battery only has one chord, therefore I can only put power to the ESC. The receiver also requires power. It can't be going through the ESC to the receiver because my receiver has a three pin connector for a battery (which I have a battery for it, but I didn't think flying with two batteries would be wise as weight is an issue).

Here's a rough diagram of what's going on:

|----------Switch
|
ESC------------------------->Receiver
| |
| |--><----Battery
|
|------><-----Engine


Now, the issue is that the receiver isn't getting any power.

The one thing this kit is missing is electrical diagrams. Everything else is A+, though. And the electrical thing is probably my own confusion.
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