Large Scale Piper J-3 Cub Help

[constantmotion]

I have just acquired a large scale Piper J-3 Cub Gasser for free. It was flown one time about 7 years ago and put up. From my measurements, I believe that it is a 1/5th scale. Wingspan is 85". Width of the wing is 15 1/2". Fuselage is 60 1/2" long (without cowl from front of fuse to the end of the rudder). The fuselage is 6 1/2" wide (at the widest point). I am trying to figure out who made this kit. From my research, I believe that it's a SIG, but I don't know where their length measurement starts and ends. The other things that has me puzzled is, there is no access door on the side and the wing is one solid piece. Most large scale Cubs have a two piece wing. I am sure that might was built to have a solid wing or access door.

Any help would be appreciated. I can provide more pics or measurements if needed.




It weights in at around 10lbs without motor and fuel tank. I am going to convert it to electric. I plan one pulling all the monocoat off and redoing it. While it's off, I am going to try lightening it up a little bit. I have ordered the SIG cowl to see if it'll work out.

[constantmotion]

I pulled the covering off the wing today and good thing I did. It had some dirt dobber nests in it. There was some sort of a rattle in the center section, so I pulled all the balsa sheets off. It doesn't look like the plans called for a splittable wing. It doesn't look jerry rigged to make it solid. Might just resheet what I pulled off and leave it be.



I did find an instrument panel in the rear of the fuselage. It looks exactly like the Hangar 9 one. But I cannot find any kits (current or discontinued) within my wingspan range. The Robart landing gear is what took me to Hanger 9. Their description for the 1/4 scale gear mentioned "For the Hangar 9 & Sig and any other 1/4 Scale Cub's with up to a 6 1/2" wide Fuselage". The 1/5 scale was for 5 1/8" wide fuselage



http://www.hangar-9.com/Products/Def...?ProdID=HAN183

[kyleservicetech]

Originally Posted by constantmotion

I have just acquired a large scale Piper J-3 Cub Gasser for free. It was flown one time about 7 years ago and put up. From my measurements, I believe that it is a 1/5th scale. Wingspan is 85". Width of the wing is 15 1/2". Fuselage is 60 1/2" long (without cowl from front of fuse to the end of the rudder). The fuselage is 6 1/2" wide (at the widest point). I am trying to figure out who made this kit. From my research, I believe that it's a SIG, but I don't know where their length measurement starts and ends. The other things that has me puzzled is, there is no access door on the side and the wing is one solid piece. Most large scale Cubs have a two piece wing. I am sure that might was built to have a solid wing or access door.

Any help would be appreciated. I can provide more pics or measurements if needed.


It weights in at around 10lbs without motor and fuel tank. I am going to convert it to electric. I plan one pulling all the monocoat off and redoing it. While it's off, I am going to try lightening it up a little bit. I have ordered the SIG cowl to see if it'll work out.

I flew one like that in the late 1990's, using an Astroflight Geared 90 brush type motor with 38 nicad cells. Weight was 16 pounds. That motor turned a 20X10 standard wood prop at around 5900 RPM, for just under 1000 watts. This provided for about a 50 foot take off run off of short grass. I put several hundred flights on it, before selling it to a guy that was planning to put a glow engine in it.

The model flew very well with this power setup. Nowdays, one of the brushless motors rated at perhaps 1000 - 1500 watts would work well. Such as a Hacker A60 series motor. You need to turn a big prop at low RPM for this model. It is not designed to fly fast.

Note that this model REQUIRES the use of the rudder during turns to adjust for adverse yaw. It will turn with ailerons, but looks very strange with the wings banked for a South turn, while the nose looks headed North.

[constantmotion]

I think I have the scale figured out. Clipped wing 1/4 scale.

Standard 1:1 J-3 Cub has a 35’-1-1/2 Wingspan. 1/5 scale is 84.3" 1/4 scale is 105.375"
Clipped wing standard 1:1 J-Cub has a 28’-5-1/2 Wingspan. 1/5 scale is 68.3" 1/4 scale is 85.375"

Mine is a smidgen over 85"

I am another step closer. The build instructions for the SIG 1/4 Clipped Wing J-3 cub are identical. Solid wing, bracing is the same, etc. The wing build is the same construction unlike other brands of this scale.

[kyleservicetech]

Originally Posted by constantmotion

I think I have the scale figured out. Clipped wing 1/4 scale.

Standard 1:1 J-3 Cub has a 35’-1-1/2 Wingspan. 1/5 scale is 84.3" 1/4 scale is 105.375"
Clipped wing standard 1:1 J-Cub has a 28’-5-1/2 Wingspan. 1/5 scale is 68.3" 1/4 scale is 85.375"

Mine is a smidgen over 85"

I am another step closer. The build instructions for the SIG 1/4 Clipped Wing J-3 cub are identical. Solid wing, bracing is the same, etc. The wing build is the same construction unlike other brands of this scale.

Mine was a full 1/4 scale, for a 9 foot wingspan.

[Big Johnny]

What in the heck is that thing hanging off the front with the prop. Is that a old Maloney engine

[constantmotion]

Originally Posted by Big Johnny

What in the heck is that thing hanging off the front with the prop. Is that a old Maloney engine

I found out that it's a 2 stroke chainsaw engine.

[Henry Sistrunk]

It sure looks like an old Maloney engine.

[PaperAirplane]

It's amazing how the wood still looks fresh underneath all that nasty covering. Looks like it could turn out a nice plane for sure.

[constantmotion]

This is how it sits as of now.....hadn't made much progress.



Waiting on some materials. Going to make an access door. I have ordered an interior from dbalsa.com

[cpmalish]

thats a good looking cub I have a 1/6 scale that I put together a while back it was a ARF made by green models I did a build thread on here but if your taking yours this far down probably nothbing I did will help but can't wait to see it completed,Chris

[CHELLIE]

Nice Cub here is a Good 1300 Watt motor that will Power up a 13 + Pound plane, its a 90 size Equall with a 100 AMP ESC Combo for $99.99 , use a 7 Cell lipo battery, one 4 cell and one 3 cell hooked in series, because the 100 AMP ESC is limited to a 7 cell lipo only, Hope that helps, Chellie

you will need to use a high voltage UBEC as the 100 AMP ESC does not come with a BEC.

http://www.hobbypartz.com/ubhvoulbe.html

http://www.graysonhobby.com/catalog/...b23488b28347b5


0.90 Gas Conversion - GH4130-08 & 100A ESC
[Combo - 4130]Regular Price: $129.99
Special Price: $99.99
Click to enlarge

Powerful motor replacement for .60-.90 size glow engine airplanes
Motor Stats
Wire Winds / Turns: 16
Ni-Mh Battery : 16 - 24 cells
Li-Po Battery : 5 / 8 cells
RPM per volt : 380
Max efficiency : 88%
Max efficiency current : 18 - 40A (>81%)
No Load Current / 10V : 1.5A
Max Current : 60A / 60 sec
Dimension : 50 x 65mm
Shaft : 6mm
Max Watts: 1300W
Continuous Watts: 1000W
Weight : 400g (14oz)
Recommended Model Weight : 3,000 - 6,000g (6.6 lbs to 13.25 lbs)

Grayson / Welgard 100A ESC

Advanced Edition

• Weight: 84 .9 grams / 2.99 oz..
• Size: 3.11 x 1.77 x 0.89 in. in. (79.1 x 45 x 22)
• Battery Input: 2-7 Li-Poly Cells
• Throttle Calibration: Auto
• Constant Current: 100 A
• Max Current: 125A / 10 Sec
• AUTO CELL DETECT!!!
• BEC: None (see below)
• Timing: Programmable - 1/7/15/30
• High rate Switching: Programmable - 8/16K
• Voltage cutoff: Programmable
• Brake: Programmable On/Off
• Auto shut down when signal is lost

No Onboard BEC. Requires External U-BEC (Battery Eliminating Circuit)

[CHELLIE]

with 7 cells, its a good idea to use a anti spark device.

http://mgm-compro.com/pdf/en-antispark-d230808.pdf


Here are some Ways of mounting the Electric motor to the plane that might be of help.

http://www.wattflyer.com/forums/showthread.php?t=39483

[constantmotion]

Chellie....thanks for that info. I was actually looking at that motor last night. I didn't like that ESC b/c it was only limited to 7cells. I found a Turnigy motor (http://www.hobbyking.com/hobbyking/s...idProduct=4913) that is pretty close to that one. I know most most of the Grayson Hobby motor are just rebadged Turnigy motors anyway.

[CHELLIE]

Originally Posted by constantmotion

Chellie....thanks for that info. I was actually looking at that motor last night. I didn't like that ESC b/c it was only limited to 7cells. I found a Turnigy motor (http://www.hobbyking.com/hobbyking/s...idProduct=4913) that is pretty close to that one. I know most most of the Grayson Hobby motor are just rebadged Turnigy motors anyway.

Hi The larger Turnigy Motors dont seem to hold up very well, I think the BP motors are made by Gemini but i could be wrong, I like the smaller Gold Turnigy Motors, 40mm cans and smaller, but the larger turnigy motors seem to like to throw magnets, unless they are glued in some more with high temp epoxy, You might want to look into using a E-Flite 90 motor or power 90, they seem to be a little better than the turnigy motors, with out costing a lot more, Just my 2 cents worth, Take care and have fun, Chellie

http://www.chiefaircraft.com/rcmsec/...e-Power90.html


http://www.amazon.com/Power-Brushles.../dp/B0013B2BFW

[constantmotion]

Didn't know that. Thanks. I was thinking that I might try to splurge a little on the motor just b/c this plane is a lot more expensive and fragile that my others.

[Big Johnny]

I have had excellent service from the Exceed Monster Power Motors from Hobby Partz. I have their Monster .32, .46, .60 & 1.10. The Price is right too. The Monster 1.10 on 8s1p 5000 would pull that Cub till the cows come home. The only problem is finding an inexpensive HV ESC. I finally bit the bullet and bought a Castle ICE 75 ESC http://www3.towerhobbies.com/cgi-bin...&I=LXVJN1&P=ML I made the right decision.

[JetPlaneFlyer]

Is it me or the camera, or is the fuselage twisted/bent?.. Kooking at the front view in the first post the wing saddle looks well out of line with the rest of the fuselage

Guess you can sort this out during the re-build.

Steve

[constantmotion]

It might be the camera phone doing that. The plane had a rough landing on it's first and only flight several years ago and the damage happened right behing the wing straddle on the port side. I haven't seen anything out of whack. I will double check that to be sure.

Originally Posted by JetPlaneFlyer

Is it me or the camera, or is the fuselage twisted/bent?.. Kooking at the front view in the first post the wing saddle looks well out of line with the rest of the fuselage

Guess you can sort this out during the re-build.

Steve

[kyleservicetech]

Originally Posted by constantmotion

Chellie....thanks for that info. I was actually looking at that motor last night. I didn't like that ESC b/c it was only limited to 7cells. I found a Turnigy motor (http://www.hobbyking.com/hobbyking/s...idProduct=4913) that is pretty close to that one. I know most most of the Grayson Hobby motor are just rebadged Turnigy motors anyway.

I'm an admitted Hacker nut, but with 7 of them that have three years flying on them, they've all performed well. No problems what so ever, except for one crash with a model where one aileron came completely off during flight due to bad design of the aileron hinges. That bent up the motor shaft and ball dented the bearings. A call to Hacker got me new bearings and a shaft for less than $20 for a Hacker A40-12L motor. (Replacing those parts is not for the faint of heart, best to have Hacker do it.)

And, I'm running all of them right at their maximum peak power rating. After landing they usually are about 10-15 degrees F above ambient temperature, as measured by a thermocouple temperature probe on a Fluke 87V digital multimeter.

http://www.aero-model.com/Hacker-Bru...By-Series.aspx

And these motors perform within 5 or 10% of predicted values as indicated by www.motocalc.com. Something that is not always true on some other name brand motors.

[BEAR-AvHistory]

Been running this motor on a 5S5000, 80amp ESC, 7.5amp UBEC & a 15X8 cherry wood prop (all from Hobby King) for about 14 months. Plane weighs 12lbs AUW with a 94" WS.

Flys very well at 50% throttle. Use 100% only at the end of a long run scale takeoff. At 100% power it pulls 1250watts @ 66amps

Also have a 1/4 scale 15lb Piper PA-12 running on a SK 5065/270 & 8S batteries (4X2) which would be overkill for 10lb plane.

Regardless of which brand motor you settle on something in the 1200-1300 watt range should have enough extra power to get you out of any trouble

[constantmotion]

I did end up getting the motor/esc combo from Grayson Hobby. It's a .90 sized brushless motor. It's a 4130-08 380KV. I'll give it a try. Now to try to figure out the motor mount length and prop size. Once that's done, the electrics will be complete and I can finish up a little more wood work and then decided on the covering. I am not sure if I want to waste the money and try it myself and pay someone else to do it. I have never done any covering before.

[Big Johnny]

Originally Posted by kyleservicetech

I'm an admitted Hacker nut, but with 7 of them that have three years flying on them, they've all performed well. No problems what so ever, except for one crash with a model where one aileron came completely off during flight due to bad design of the aileron hinges. That bent up the motor shaft and ball dented the bearings. A call to Hacker got me new bearings and a shaft for less than $20 for a Hacker A40-12L motor. (Replacing those parts is not for the faint of heart, best to have Hacker do it.)

And, I'm running all of them right at their maximum peak power rating. After landing they usually are about 10-15 degrees F above ambient temperature, as measured by a thermocouple temperature probe on a Fluke 87V digital multimeter.

http://www.aero-model.com/Hacker-Bru...By-Series.aspx

And these motors perform within 5 or 10% of predicted values as indicated by www.motocalc.com. Something that is not always true on some other name brand motors.

Yaeh I know Hackers are the Cats Meow, but I had to save up to buy my last Hacker.(A60 20M) Most of the time, I have to go the best bang for the buck route. I work the mess out of the Monsters and yet to have one bite the dust.

[kyleservicetech]

Originally Posted by Big Johnny

Yaeh I know Hackers are the Cats Meow, but I had to save up to buy my last Hacker.(A60 20M) Most of the time, I have to go the best bang for the buck route. I work the mess out of the Monsters and yet to have one bite the dust.

LOL
I started buying parts for my Extra 330 Giant Scale model back in October. Finally got enough parts to complete the model in January. The cost of these larger models sky rockets with the third power of the wingspan of the model