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HZ Super Cub Mod from parts

#1
I got some sad news a couple weeks ago, the LHS is closing:( The owners are from out of state and are opening a new store in their home state. Another franchise will be coming to town, but it will likely be August or September before they open their store. Being a good customer, the manager was willing to work with me on prices on a few things.

I have been vacillating between a HZ Super Cub and the Fun Cub. To be honest, I was leaning towards the fun cub, but with the deal I got on the parts, the Super Cub made more sense from a money standpoint. For not much over $70, I have all the needed foam.

Here's my plan:

1. Flatten the wing a bit. I don't know if I want all the dihedral gone, but at least a fair portion of it. At this point, I need to devise a good way to build a carbon spar with some dihedral. Not having worked much with carbon fiber, I am not sure of the best way to accomplish this so research is in order. I was thinking about making a plywood center piece and bonding the arrow shaft to the plywood. Any thoughts or experience with this are appreciated. I would just leave the dihedral, but I really want to be able to fly this plane inverted.

2. Add flaperons. I had thought about going the route of separate flaps and ailerons, but with some of the other mods I am doing, I am not sure I want the extra weight. This of course is not set in stone, but is just the current thought. I have also heard that to run the two extra servos a BEC is needed, and I am trying to just reuse the electronic gear I already have.

3. Cover the plane with Econokote. Foam is okay, but I want this plane to be a little more sleek, and in the how-to's I have watched on YouTube, the covered foam planes look really good! I have not entirely decided on a color, but right now I am of course leaning towards Cub yellow Yes I know it's not a J-3, but it just feels right to have a yellow cub. Plus, I have always wanted a yellow cub.

4. Tundra tires. I will be flying from grass and gravel quite a bit, so fatter tires are in order. I'll likely use some 2-1/2 inch foam tires I already have.

5. Brushless motor. I already have the electronics in a foam board plane that is getting a bit long in the tooth (i.e. way too many unplanned landings). I plan on using my Turnigy 1100kV 3530-14. The calcs show that it should work well with a 10x6 prop on this plane. I have already acquired a CNC machined brushless adapter. There has already been trial fit and it stacks up just right.

6. Reinforce all the key locations on the fuselage. I will add the wood behind the wing, and reinforce the battery box mounting points.

7. Modify the battery box to fit in 2200 mAh lipos. This looks like a pretty straight forward mod and certainly worth doing.

For the electronics I am running a 35A HK speed control, and Orange 6 channel receiver, and Hitech HS-55 servos. The motor is as listed above. I'll typically run 2200 mAh batteries. It would be better if the ESC was rated a little higher, but I have been running it in a plane that is roughly equivalent in size and weight and it has not been running hot.

Right now, it's just a pile of foam parts. With the hobby shop closing, they weren't doing anymore special orders, so I have to track down some cub yellow Econokote on my own.

The foam bits:



I'll keep this post updated as I make progress.
 
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earthsciteach

Moderator
Moderator
#2
Bah-toss the econocoat. Just flatten and shorten the wing by cutting out the middle, dihedral section. Install a solid, light wingd spar. Paint as you see fit. Replace with a 450 to 480 brushless outrunner and you will have an airplane that will be your favorite for years to come!
 

FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#3
You don't even have to cut the wing. I was able to glue in a solid spar and just press the wing flat while the glue set. You'll want to cut a spot in the front for the battery, unless it was a fuse designed for a brushless motor. Otherwise you'll have a hard time getting the CG correct because the BL motor will be so much lighter.

I've done a project like this, and it was a fun little plane. It lives on with a friend, who uses it to teach kids to fly.
 
#4
Based on the necubflyer videos, with the battery box cut out and a 2200 in vertically, the CG works out nicely. I might put the speed control up front to get CG to work out, if that is needed.

If I go completely flat on the wing, it's easy to glue in a carbon fiber arrow shaft and get a ton of stiffness out of it (the carbon arrows are less expensive than the carbon slats of equivalent stiffness). At the local sporting goods store, carbon long bow arrows are less than $6. But, like I said, I wouldn't mind a little dihedral. I will still look for a way to keep a little dihedral. I am also looking to keep the landing speed slow, so I want to keep as much wing area as possible.

I want the covering for two reasons. One, it makes it look SOOOOO much nicer, and two it adds a lot of strength. I have painted some foam, and it looks okay, but the covering is so sleek.
 

robschonk

Senior Member
#6
Here's a blog from RCG about building a SC from parts.

http://www.rcgroups.com/forums/member.php?u=186665

He builds it just about stock, but most folks replace the brick, brushed motor and gearbox soon after purchase, so you can save money there. There are a lot ov videos on youtube. Just search on super cub mods. I'd leave off paint or film, since they tend to get beat around a bit. Use clear packing tape on the leading edge.

Don't forget a set of floats!
 

Attachments

#8
This motor is 315W, so it should really motivate the cub. Since it is a tad heavier than the 480 I might not need the speed control up front.



Ak Flyer, I did check out your article. I am going to try to combine the best of all the articles. I really like your tape idea, but I have heard that the tape doesn't play well with the covering.

Here's a question, running with flaperons is the 16 x 1.25" a good size? Necubflyer made his a bit bigger, but I don't think he's running flaperons. Since I am running a Dx6i I can only program in total flap travel and I am limited to one position. I might have to monkey with it a bit to find a good setting. Before my homebrew foamie completely bites the dust, I am going to mess with flaperon settings a bit and see how they work.

EDIT:
I have to put the covering film on, it looks so nice! I know it will get nicked and dinged, and probably even ripped up, but that's how it goes. I want that pretty, smooth, yellow finish. I know it doesn't matter much when it's flying, but it sure looks good in the hangar:D
 
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Ak Flyer

Fly the wings off
Mentor
#9
The tape probably wouldn't work well with covering but it's tough as nails. Cubs tend to be basher planes lol. I placed my esc up front to keep it cool without having to cut holes in the fuselage for cooling. It helped the CG too I suppose. I never really messed with the CG on that plane though, I usually just fly it and see what happens since like I said it's kind of a basher.

Through my own experience, I would stay away from flaperons. They are okay if you don't have flaps, you can sort of get by but you can't beat a real set of flaps. Since you are starting fresh with a new wing I highly recommend adding flaps.
 
#10
Some updates!! Today I did the fuselage mods and got the covering on the fuse. 30 years ago, I helped cover one of my planes, but never did it all myself. Yesterday and today, I did some patching on some ARFs that a friend gave me, to practice a bit and refresh my memory on how the covering works. That is the sum total of my covering experience. All in all, I am really pleased with the outcome.

The wing saddle upgrade:



The batter box reinforcement:



The cut out battery box:



The iron I borrowed from a friend. I don't know how old it is, but it still did the job. My friend said he hoarked it from his dad, when his dad graduated to full scale planes.



The "sock" to cover the iron:



The iron with the sock in place:)



The wing saddle completed:



The bottom completed:




The rest completed:







There are a few wrinkles here an there, but overall I don't think it's too shabby for a first effort. I ended up with a couple of very minute wrinkles in the sides and then the top of the windshield has a couple creases. I would have cranked up the heat, but I think I was close to the limit for the econokote and the foam. I know it adds a little weight, but I sure do think it looks better than paint or bare foam. The only bummer, I couldn't get the front wing dowel out. I even tried pliers and couldn't get it to come apart. I felt if I forced it any harder, it was going to break... It wasn't so bad with the covering, but it's going to make the window decal a pain in the arse.

Tomorrow I'll get the flaps and ailerons cut into the wing and maybe get it covered as well.
 
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earthsciteach

Moderator
Moderator
#11
Nice job!

Don't know how you guys feel about this, but I've never modded my battery box. I fly a 2200 mah in the plane mostly. I just set it on top of the battery box. Works out nicely. Currently, my battery box is a bomb bay.
 

FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#12
Something you might want to consider if you do this again, is adding some light ply to reinforce the wing mounting rod area. Especially if you're covering it anyhow.
 
#13
I am certain I will be doing it again. Based on my flying skills, or lack thereof, I will need a new plane before the summer is over.:black_eyed: I will probably have a whole list of lessons learned to incorporate into the next one. Reinforcing the dowels is an excellent idea!
 
#14
I got the dihedral reduced in the wing. I used my dremel to route out a groove of varying depth, being deepest towards the center. I propped the ends of the wing up on equal sized blocks and used a couple of 2.5 lb weights to keep the wings flat. The blocks also supported the ends of the arrow, pushing it up into the wing. I did it this way because I noticed that just pushing out on the ends curved the wing and didn't make it flat. I also discovered that the wing is not completely flat on the bottom. I mixed up a couple tablespoons of 15 min epoxy and partially filled the groove. The arrow isn't as stiff as some other things I could have used, but it's a lot of a bang for the buck and it makes for a pretty stiff wing. The arrow combined with the covering will make it really stiff. I will make some templates and use the dremel for routing out the servo holes as well.

the groove:


the arrow I recovered from foamie wing:


from the front:


top view:
 
#16
I need every inch of wingspan/wing area I can get! I might clip the next one, but this one is keeping all it's wingspan.

I got the control surfaces cut out and covered. I also got the bottom of the wing covered, but in my haste, I forgot to cut out the servo holes :eek: Once I finish covering the wing, I'll mount the control surfaces and get the servos in the wing. Luckily, the econokote is pretty forgiving. I'll have some patches to cover the servo holes, but they won't be that noticeable.

So far, I really like how it's coming together. I need to get the plastic bits and the tail surfaces painted, but it's getting closer. I'll try to get some more pictures tomorrow. So far, the wife has been pretty patient with me taking over the kitchen on the weekend. I got pretty lucky, she actually likes to fly planes as well. She's still learning, but she's coming along.
 

Ak Flyer

Fly the wings off
Mentor
#17
Nice job!

Don't know how you guys feel about this, but I've never modded my battery box. I fly a 2200 mah in the plane mostly. I just set it on top of the battery box. Works out nicely. Currently, my battery box is a bomb bay.
That's cool. I spent the time modding my battery box so I could change the battery from the bottom without removing the wing because of all the extra wiring I have in the wing with all the flaps and ailerons and the way I mounted my receiver to the wing. How did you work your bomb drop battery box?
 
#18
So here's a quandary.... I have my wing covered now and I noticed that one wing tip has a slight amount of washout. Has anyone been able to get a twist out of a wing? I am thinking I can heat it with it braced and get it to do what I want, but I don't know if it will set and stay in position when the bracing is removed. Any suggestions? I suspect I can counter the washout with some aileron trim, but optimally, I would like twist gone. I knew this was a risk when I covered it, but for $20 and some covering, I was willing to take the chance. The washout is in the first tip I covered and I think I may have gotten a little carried away trying to get the film tight. In hindsight, I should have just slit the covering and not tried to stretch it so tight. The answer might be removing the covering and recovering the tip to see if it goes away.
 

Ak Flyer

Fly the wings off
Mentor
#19
That was one of the first things old timers warned me about when I started doing covering. I think you are best off pulling it and doing it again.
 

FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#20
You could always try heating the material on the opposite side, in order to try to counter the wing twist. If that fails, then pull it off, and try it again.