BJ-J3 Cub - NOT a Failure Story - Plans and Build Instructions
- Thread starter BanditJacksRC
- Start date
varg
Build cheap, crash cheap
After putting ten or so batteries through it (and a couple of crashes) I'm back with a more detailed flight report for my modded build of this plane; It is slow and forgiving, but surprisingly aerobatic. Very high roll rates are possible if you don't limit deflection, and seems to fly better with some differential. It will do snap rolls, tight loops, hammerhead, it can almost manage knife edge flight (maybe it can and I can't yet, we'll see). It gets tossed about with the wind because of its size but has enough control authority to be controllable on all axes. With the punchy c power pack setup, even a few degrees of down thrust weren't enough - I had to mix in some down elevator to keep it from going into a steep climb at full throttle. With no mix and no downthrust it would do tight loops on the throttle. I'm not sure if the wooden spar was necessary, with how draggy the plane is it might not be fast enough to fold the wing with just the foam spar. The extra weight didn't hurt though, it still floats in for a landing fine and will climb straight up out of sight if you let it. The design is pretty durable with the nose doublers, even after putting it into the ground nose-first while trying spins and crumpling the power pod, the fuselage was easily repairable. It's now taped and glued and I'm having a lot of fun with it; pushing and finding limits every time I fly.
Last edited:
Strix
Member
That's great, Varg! Glad to hear you are enjoying this one. Kudos to the original designer and anyone who helped him out with it. This is a fantastic flyer, gentle and forgiving yet very aerobatic as you have noted. I'm looking forward to comparing it to the FT Cub.
I have noticed is that this is a extremely high lift wing, and of course, the higher the airspeed, the greater the lift. Mine doesn't pitch up too badly at all when you increase the throttle, but once the airspeed starts increasing it really climbs out.
I have noticed is that this is a extremely high lift wing, and of course, the higher the airspeed, the greater the lift. Mine doesn't pitch up too badly at all when you increase the throttle, but once the airspeed starts increasing it really climbs out.
Jayrod0821@gmail
Jetasen74
i have built 2 and and haven't crashed them. they are awesome little planes.
FPVology
Member
Hey everyone! Im stoked everyone is still enjoying these plans!
ive been so interested in the mad scratch builders page I haven't checked out this one in a while. I'm glad everyone is enjoying the BJ-j3 still! I have a set of plans ive been wanting to tape together forever now, just don't have the time these days... only to stock the forums and envy everyone else's beautiful builds! lol
I think FTs new cub looks alot like mine, no??? Ill build em both too and compare.
ive been so interested in the mad scratch builders page I haven't checked out this one in a while. I'm glad everyone is enjoying the BJ-j3 still! I have a set of plans ive been wanting to tape together forever now, just don't have the time these days... only to stock the forums and envy everyone else's beautiful builds! lol
I think FTs new cub looks alot like mine, no??? Ill build em both too and compare.
BanditJacksRC
New member
BOOM! and i can still log into this account... wans't sure if i remembered the password! haha
Hey everyone! Im stoked everyone is still enjoying these plans!
ive been so interested in the mad scratch builders page I haven't checked out this one in a while. I'm glad everyone is enjoying the BJ-j3 still! I have a set of plans ive been wanting to tape together forever now, just don't have the time these days... only to stock the forums and envy everyone else's beautiful builds! lol
I think FTs new cub looks alot like mine, no??? Ill build em both too and compare.
Hi FPVology,
I would like to see that comparison. It would be great to see a picture of the two planes side by side. I was thinking about building the BJ-j3. I always had a love for the bush style Cub's. I am a rookie at RC. The BJ-j3 would be one of my first scratch built plane.
Would anyone else like to see the comparison of the two planes ?
Al
jpot1
Elite member
I have already built the BJ-J3 and am building the FT cub now. Was teaching my daughter to fly on the BJ-J3 so she got to pick the color.
I will share pics when done.
View attachment 90208
Attachments
Jayrod0821@gmail
Jetasen74
I have already built the BJ-J3 and am building the FT cub now. Was teaching my daughter to fly on the BJ-J3 so she got to pick the color.
I will share pics when done.
View attachment 90208
I like your daughters chose of color.
Al
Here is my build, I used a newer neon yellow 6mm depron like foam that has started showing up at the local Dollaramas.
The colored side of the foam board was covered with a clear sticky vinyl available at Dollarama
The non-painted white side was covered with a thin brown packing tape from DollarTree. This adds tremendous strength and waterproofing without adding any significant weight.
The plan was edited a bit to make it ready for the laser cutter, the complete plane needed three sheets of foam (laser cutter bed is limited to 24"x18" sheets, so had to waste some foam).
This foam took significantly more power to cut compared to the Adams FB. I was concerned about the folds due to the 6mm foam thickness, however, everything fit into place with no major effort.
The plane was built using UHU Por, Gorilla glue, and 3m77. Hot glue was sparingly used to tack the wing folds and for servo mounting.
The port side of the vertical stabilizer and the underside of the fuse were covered in yellow and orange packing tape respectively. A steerable tail wheel was added. All black decals were done with black packing tape, coloured decals were face tattoos from Dollar Store
The dry weight without battery came out to ~400grams. I'm using a HK ST2004 outrunner spinning a 8x6 prop with a 2s-2000mah.
The colored side of the foam board was covered with a clear sticky vinyl available at Dollarama
The non-painted white side was covered with a thin brown packing tape from DollarTree. This adds tremendous strength and waterproofing without adding any significant weight.
The plan was edited a bit to make it ready for the laser cutter, the complete plane needed three sheets of foam (laser cutter bed is limited to 24"x18" sheets, so had to waste some foam).
This foam took significantly more power to cut compared to the Adams FB. I was concerned about the folds due to the 6mm foam thickness, however, everything fit into place with no major effort.
The plane was built using UHU Por, Gorilla glue, and 3m77. Hot glue was sparingly used to tack the wing folds and for servo mounting.
The port side of the vertical stabilizer and the underside of the fuse were covered in yellow and orange packing tape respectively. A steerable tail wheel was added. All black decals were done with black packing tape, coloured decals were face tattoos from Dollar Store
The dry weight without battery came out to ~400grams. I'm using a HK ST2004 outrunner spinning a 8x6 prop with a 2s-2000mah.
Attachments
BanditJacksRC
New member
looks awesome man! love that little tail wheel
I finished mine at Flite Fest and have been flying it at our local field ever since.
It flies fantastic! Thanks Strix for your help.
I'm still a newbie at this but I'm super happy with the way this plane performs.
Now I'm adding some finishing touches and painting it.
It flies fantastic! Thanks Strix for your help.
I'm still a newbie at this but I'm super happy with the way this plane performs.
Now I'm adding some finishing touches and painting it.
Attachments
It is good to know that the planes of the cub "oficial" airplane has serious problems in the stabilizer and dihedral wings
http://forum.flitetest.com/showthread.php?36051-Simple-Cub-Rolls-Left-Suggestions&highlight=CUB
Thank you very much for the contribution
http://forum.flitetest.com/showthread.php?36051-Simple-Cub-Rolls-Left-Suggestions&highlight=CUB
Thank you very much for the contribution
It is good to know that the planes of the cub "oficial" airplane has serious problems in the stabilizer and dihedral wings
http://forum.flitetest.com/showthread.php?36051-Simple-Cub-Rolls-Left-Suggestions&highlight=CUB
Thank you very much for the contribution
http://forum.flitetest.com/showthread.php?36051-Simple-Cub-Rolls-Left-Suggestions&highlight=CUB
Thank you very much for the contribution
Strix
Member
The 'cub "oficial" airplane' design has no 'serious problems'. I don't know where you got that. The referenced thread contains no such suggestion. The OP admits to assembly errors, and his most recent update reports that the actions taken to correct the issues have been largely successful.
The FT Simple Cub and this one are both great airplanes.
The FT Simple Cub and this one are both great airplanes.
BanditJacksRC
New member
yeah, seems the guy just didn't build it square. I haven't built/flown the FT cub but would be very surprised if it was inadequate lol
varg
Build cheap, crash cheap
I found the limits of my Cub and crashed it the other day. After a few flights doing aggressive stuff like power on spins and just playing around with no particular goal, just aggressive maneuvers, one side of the elevator tore free as I tried to make a tight turn to chase a Tundra and I lost control. It's probably beyond repair because it bounced into a few inches of standing water and though the outside was waterproofed the inside isn't. There was surprisingly little damage to the plane, the power pod wasn't taped and the firewall ripping off saved the airframe from more damage. I may try to fix it and turn the throws down for light duty flying.
Crash happens after 5:47 in this video:
The next one/repair will have a better reinforced elevator for sure.
Crash happens after 5:47 in this video:
The next one/repair will have a better reinforced elevator for sure.
Was traveling for work, so didn't get a chance to maiden it until today. Got the CG right on the spar with a 2S 2200mah. It flew amazingly well, has a wide speed envelope, can slow it down to a crawl without stalling. There was a steady breeze and it was able to fight the wind pretty good. Surprisingly, didn't have to touch any of the trims!, love this plane, reminds me of Multiplex Pico Cub, which was my first plane that I bought 17 years ago..but this one is lighter and has ailerons
Thanks for an excellent design :applause:
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