Super Flying Model J3 Cub Build

[Dazzy]

Finally got the Super Flying Model J3 kit delivered yesterday from https://www.rcmodelaircraft.com.au/super-flying-model-piper-j-3-cub-40-build-kit , so Ive spent the day pulling out all the laser cut parts out and based on what Ive seen so far the laser cutting has been very good. 99% of parts where intact and there was only a couple of broken pieces that I needed to re-glue together. There are many extra parts in this kit that was a real surprise and for the money I think that overall it looks really good.

So in this kit ( not covering small parts ) there are 30 pages of instructions in booklet form, a 2 sheet plan covering fuselage, wing, rudder, elevator and over head views and the details look quite acceptable to me. There are many associated balsa parts and shapes, decals kit, heavy gauge wire for the landing gear, and many other parts. Overall the kit looks to be quite comprehensive.

So Im off to buy some wood glue called pva, since I cant find my original bottle. So my goal here is to learn the art of balsa building with help from forum members as I progress along the build, setup this design with suitable electronics down the track.

 

[TooJung2Die]

You're in Australia and you bought this kit new? I bought an old -SF- Apollo sailplane ARF kit a couple of years ago at a rummage sale. It's a very nice sailplane but I have never been able to find out anything about it or the manufacturer. Knowing now that -SF- stands for Super-Flying is the most information I have been able to learn. Thanks!!! A friend has it now and he's been wondering about it too.
Apollo EP-5 Sailplane

Looking forward to your Super Flying Models J3 Cub build.
Jon

 

[Dazzy]

You're in Australia and you bought this kit new? I bought an old -SF- Apollo sailplane ARF kit a couple of years ago at a rummage sale. It's a very nice sailplane but I have never been able to find out anything about it or the manufacturer. Knowing now that -SF- stands for Super-Flying is the most information I have been able to learn. Thanks!!! A friend has it now and he's been wondering about it too.
Apollo EP-5 Sailplane

Looking forward to your Super Flying Models J3 Cub build.
Jon

@TooJung2Die , Hey Jon, yes I bought it new and its from www.mth.com.tw also email: mthhobby@mth.com.tw

Darryl

 

[TooJung2Die]

@TooJung2Die , Hey Jon, yes I bought it new and its from www.mth.com.tw also email: mthhobby@mth.com.tw

Darryl

Thanks Darryl! Mystery solved. No more Apollo but they have a lot of nice looking airplanes.
Jon

 

[Dazzy]

In the instructions it says that you need instant glue, UHU glue, Epoxy 5-10 minute glue and white glue.

Whats UHU glue?
White glue, I presume wood glue?

Also it mentions attaching the four clutch nails to the former F3 which holds the motor .10cc gas engine. Should I add these clutch nails now since Im gunna change to an electric motor?

Edit, Why so many different glues?
Isnt wood glue enough for all joints?

Darryl

 

[OliverW]

In the instructions it says that you need instant glue, UHU glue, Epoxy 5-10 minute glue and white glue.

Whats UHU glue?
White glue, I presume wood glue?

Also it mentions attaching the four clutch nails to the former F3 which holds the motor .10cc gas engine. Should I add these clutch nails now since Im gunna change to an electric motor?

Edit, Why so many different glues?
Isnt wood glue enough for all joints?
View attachment 175770

Darryl

You need epoxy for attaching the firewall as it is one of the strongest glues that you can use. Each glue has a purpose since each one is either a longer drying kind, or a quick drying kind, or an indestructible kind

 

[vhandon]

Also it mentions attaching the four clutch nails to the former F3 which holds the motor .10cc gas engine. Should I add these clutch nails now since Im gunna change to an electric motor?

You may still want to use the clutch nails or blind nuts as I know them. You will want to match them to the pattern of your electric motor mount. If you don't have the engine yet then I would not install them. If you have access to the back of the former after the fuselage is built then you can put them in once you get the engine. Otherwise you may want to work on the wing until you get the motor.

 

[speedbirdted]

Not real familiar with UHU glue, only used it once, but I'm pretty sure it's a rubberized type of glue similar to cement. White glue is almost certainly referring to PVA glue which is usually just known indeed as wood glue.

Instant glue is probably referring to CA. I would pick up different consistencies of it; particularily, the thin stuff, because it's very good at wicking into joints that are already in place, something PVA or epoxy cannot do.

 

[Dazzy]

Thankyou guys for fast replies.

Ok so the instructions say an engine of either:
10cc 2 stroke gas
.46 2 stroke
.60 4 stroke
or
Elec #600 850kv brushless

and

Propellors for:
EP: 12 X 8"
GP 12 X 6 GAS
GP 11 X 6

I presume EP is short for extreme performance?
GP is short for general performance?

Since Im mostly stuck with Hobbyking and or aussie resellers ( cov19 suppliers and USPS are incredibly slow ) can you suggest suitable parts here?

Finally can you point me to a link on propellors?

Thanks Darryl

 

[TooJung2Die]

Whats UHU glue?
White glue, I presume wood glue?

UHU is a European glue manufacturer. They makes lots of different glues. The one I see used most for model building is UHU POR. It's a contact cement. White glue is as you guessed, wood glue. If you have wood glue, CA glue and epoxy you have everything you'll need. I recommend you use a 30 minute set epoxy instead of 5 minute quick set. The 5 minute quick set becomes brittle, the 30 minute does not and is much stronger. The additional 25 minute set time is worth the wait.

I presume EP is short for extreme performance?
GP is short for general performance?

EP = electric powered
GP = gas powered

 

[Dazzy]

Thanks Jon got it now.

 

[Dazzy]

So Ive got a Turnigy I6 tx, 4S 3300mah battery and a 60 esc ordered from Hobbyking coming. I still need some help with the e motor and prop though.

Anyway before I got some glue I did a dry fit to understand the instructions ( theres nothing like reading chinglish is there 😃 ) and so far its going together quite well with all parts fitting really well together.

I will expand in more detail once I start glueing parts together things to look out for in the detail.

 

[speedbirdted]

looking good! Basically what you want in terms of a motor is one that will produce about 100 watts per pound of airplane and draws less than 60 amps. Typically though in this amp range I usually leave a 10-15 amp gap in between the maximum motor draw and maximum ESC output because often times the manufacturer's stated amp draw for a motor is not accurate given its given application; things like the prop selection can often alter how much amperage a motor draws. The only way to determine for sure is with a watt meter, and you can only do that once you've bought the motor, so you want a bit of buffer zone. If the motor outstrips the capability of the ESC, the ESC will have a bad time and usually protest such mistreatment by exploding.

 

[Dazzy]

Hi guys/gals I think I might have found a suitable Turnigy motor for this build, can someone please check?

https://hobbyking.com/en_us/turnigy...226&indexName=hbk_live_magento_en_us_products

Ive already got a Turnigy 330mah 4 cell battery. Also a 60amp esc.

 

[Dazzy]

Okay so Ive made more progress on the SFM J3 Cub build, see the pics below.

Preparing the motor mount and fixing the clutch nuts into place.

Just glueing the formers F13, F14 & F15 into position.

Those blue texta arrows point to the location tabs/marks for the correct orientation of parts for the fuselage.

Completed the basics of the fuselage here.

Just discovered that the kit is missing the extra clutch nuts required so I just worked around this problem by creating a poor mans clutch nut instead. So what did was just tighten a screw against the nut to draw the nut into the balsa wood instead.

See below for the clutch nut repair that I used. Using a larger washer over the screw head helps stop the screw being drawn into the balsa and just the nut drawn into the balsa only, the black plastic tube helps to keep the screw centered in the hole.

I then glued the F18 piece into place.

Im definitely not the best gluer but I guesss thats in part because Im using a cheap glue gun, I will replace this soon.

 

[Dazzy]

So heres an image of the mostly completed fuselage with all parts attached.

I discovered that the front upper cowling cover frame/former was not quite the correct size so I had to reshape it by cutting into 2 pieces then glueing a joiner in to extend its length just slightly. No big deal but no whats expected on a AU$150+ purchase.

I havent updated my glue gun yet.

 

[Arcfyre]

Hi guys/gals I think I might have found a suitable Turnigy motor for this build, can someone please check?

https://hobbyking.com/en_us/turnigy...226&indexName=hbk_live_magento_en_us_products

Ive already got a Turnigy 330mah 4 cell battery. Also a 60amp esc.

Based on the 2400g weight of the plane and your desire to fly 4S, I would say that that motor looks to be about perfect.

Back of the napkin math here, but assume your plane weighs about 6 lbs when done. For sport performance you want roughly 130 watts per pound. 130 x 6 = 780 watts, and that motor is listed as having a max output of 750, so I'd call that close enough. You may need to play with prop sizes to get the thrust you want, but prop changes are simple and cheap.

 

[Dazzy]

Started work on the tail section and had some good results but Im disappointed that the designers decided to glue balsa sheets together and do a crappy job and skimping on the glue. Parts were just breaking part so I had did repairs 1st.

 

[Dazzy]

Finished the basics of the tail section and sanded all the leading and trailing edges based on advice from FT members.

I discovered that the kit does not have any rudder or elevator hinges, so I created my own from plastic milk bottle cartons. the hinges just to the right of the rudder are just a draft size and I test fitted them 1st. So the hinges are about 25mm square with a 12-14mm slit in the center, this slit is important as without this slit the hinge would be too stiff to rotate by the servo, after further examination I bent the hinge backwards and forwards to lessen the resistance for the servo.

Once I was happy with the ease of bending the hinge ( guessing here on the servos torque ) I then added slits in the balsa for the rudder by using a 1mm drill bit and drilling down into the balsa rudder assembly.

I fixed the plastic hinges into place by drilling a 2mm then a 6mm ( thats the only round balsa I had ) hole into the rudder and going through the balsa and hinge together.

The rudder bent open to demo the strength of the hinge.

Elevator preparation, using the same techniques as listed above.

Semi complete rudder and elevator section sitting on a vice just for reference.

 

[Dazzy]

New parts arrived just the other day for the SFM J3 Cub build.

Turnigy 3300mah S3 battery, Turnigy Aerodrive SK3 - 3548-840kv Brushless Outrunner Motor, YEP 60amp esc,
TGY-50090M Analog Servo 20T MG 1.6kg / 0.08sec / 9g, HobbyKing™ High Torque Servo MG/BB W/Proof 12.8kg / 0.22sec / 58g,
30cm Twisted Servo Y Lead (JR) 24AWG (5pcs/Bag), JXF Poly Composite Propeller 14x8 (1pc) and Durafly® ™ 12x6 Carbon Fiber Propeller (Perfect For Tundra And Zazzy).

more to come soon...