*Unofficial* FT Simple Cub

JUSS10

I like Biplanes
I have about 10 batteries on mine. I've built two so far. One with the standard design and then one with a flat wing and dedicated flaps. attached are some photos of the one with the flat wing and flaps as well as a video.

One a side note, is anyone else noticing an issue with the wing creasing on the back where the top and bottom of the wing surfaces meet? my wings will not last long as they are all starting to fail there. Seems like a design flaw to me. Maybe I'm just flying it a little to hard? I've been doing loops and rolls and inverted and such and the both my wings are starting to show failure in the same spot due to poor support in the design. Anyone else have this?

https://www.youtube.com/watch?v=NdQxs_o1LQ4
 

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rockyboy

Skill Collector
Mentor
I wonder if a couple of barbeque skewers inserted across the wing (parallel to the fuse) would help keep it's shape under the rubber bands?
 

rockyboy

Skill Collector
Mentor
Looks like that might be an intentional part of the design - puts a smooth airflow down over the fuselage and nice even pressure from the rubber bands over the wing surface. I'd say if it's not impacting you functionally, let 'er fly! :)
 

rockyboy

Skill Collector
Mentor
Ahh - I didn't see that at first - maybe on a future build try sticking a skewer crosswise into the wing before putting the skewer on the trailing edge to protect the wing from the rubber band. That might force the bending part of the wing to stay down flat to the fuse instead of 'bunching up'. FWIW I haven't built one of these yet, but plan to at FFE - so I might be completely off my rocker here :confused:
 

Gazoo

Well-known member
Ahh - I didn't see that at first - maybe on a future build try sticking a skewer crosswise into the wing before putting the skewer on the trailing edge to protect the wing from the rubber band. That might force the bending part of the wing to stay down flat to the fuse instead of 'bunching up'. FWIW I haven't built one of these yet, but plan to at FFE - so I might be completely off my rocker here :confused:

Or maybe just a foam board spacer under the trailing edge?
 

tamuct01

Well-known member
The Storch has the very same issue. I cut a foam wedge to fill in the gap and reinforced with with popsicle sticks to retain the wing shape. Looks like something similar could be done here. The curling of the wing would change the angle of attack and potentially cause other problems.
 

basslord1124

Master member
Yeah I had the same experience with my Storch. I inserted some wood dowels/BBQ skewers into the wing and then put some foam over top of that (cut grooves into the foam for the skewers too). Helped a lot and made it real strong.
 

basslord1124

Master member
If I resided in the US and with the knowledge that for a lot of users they end up building 3 copies of most designs they choose to fly, I would proceed the following way......

So to answer your dilemma do both!

Have fun!


I like that approach. :) Awesome, thanks!
 

Enos Shenk

New member
I glued a popsicle stick to the trailing edge where the bands cross just to strengthen the area.

Anyway, my Cub had a mishap. I landed and the wheels caught in grass and the nose dug in. Went out and fetched it, gave it a check over, everything looked good so I sent her up again. About 15 feet up it sounded like the prop ate something and the motor died, which didn't make for a good emergency landing.

DiF4L3t.jpg

It turned out the B pack motor loosened from the mount, and the armature spun, winding its wires up pretty good. Amazingly the wires didn't short and the ESC survived the experience. I picked up a new motor today from the local hobby shop (For a ludicrous markup price), a proper standard style motor. Interestingly the new motor says it's a 950kv but the thing flies incredibly better. It's quieter, almost all of the adverse roll I was getting is gone, and it flies much smoother. I'm wondering if I just got a wonky B-pack motor, or I didn't tighten that janky little motor mount down enough. I never did trust those old style ones.

Pictured, a Tubby Cubby in a natural environment.

I22lgG6.jpg
 

Hai-Lee

Old and Bold RC PILOT
With the motor type shown above, (I have used and eventually destroyed about a dozen of them), I discovered that the grub screws which hold the motor to the mount were 3mm and because I could not make them tight enough without stripping them, (where the key fitted in), I removed them and sourced a replacement 3mm cheese head type screw. Now I can tighten them so tight that they will not become loose even after a crash or 100 hours of flight, (often with a bent motor shaft).

Sadly your experience is typical of the motor design and not specifically related to the FT Simple Cub design.

Just what I do to make them reliable!

Have fun!
 

Hai-Lee

Old and Bold RC PILOT
Not intentional. The wing is lifting off the fuselage underneath if you look closely.

It is also altering the main wing incidence!

I build a lot from FB and some models out of 3mm. The issue is caused because the flat hinge line/bend allows stresses in the wing from the rubber bands to be focused in line with the hinge line. Net result the FB will eventually fold along the hinge line.

With my 3mm builds I found that I could relieve the stresses by doing a few cuts on the underside of the mounting tail and inserting some glue covered toothpicks.

To retro fit I would make 3 or 4 slits in the underside of the tail and push the glue covered toothpicks into the foam past the wing joint, (top to bottom sheet) and then force them into the slots I had cut for access. Clamp the mounting tail straight!

When dry I would seal the slits with a little additional glue if required.

Weight increase just the weight of 3 or 4 toothpicks and a few drops of glue!

Once done the wing is more stable in shape and in incidence whilst flying.

Just what works for me!

Have fun!
 

wedgetailaus

New member
It is also altering the main wing incidence!

I build a lot from FB and some models out of 3mm. The issue is caused because the flat hinge line/bend allows stresses in the wing from the rubber bands to be focused in line with the hinge line. Net result the FB will eventually fold along the hinge line.

With my 3mm builds I found that I could relieve the stresses by doing a few cuts on the underside of the mounting tail and inserting some glue covered toothpicks.

To retro fit I would make 3 or 4 slits in the underside of the tail and push the glue covered toothpicks into the foam past the wing joint, (top to bottom sheet) and then force them into the slots I had cut for access. Clamp the mounting tail straight!

When dry I would seal the slits with a little additional glue if required.

Weight increase just the weight of 3 or 4 toothpicks and a few drops of glue!

Once done the wing is more stable in shape and in incidence whilst flying.

Just what works for me!

Have fun!

Thanks for the advice! I'm not quite sure I fully grasp what you are describing. Could you elaborate or throw in a diagram please? My wing has the same issue.

My wing has a similar issue.
 

Hai-Lee

Old and Bold RC PILOT
I will supply the pics when I get around to building my Simple Cub. Until then before I fold the wing I cut a few slots, just simple half depth cuts really past the hinge line, (line of aileron and flap hinges).

Normally for a plane the size of the cau I would make 4 cuts equally spaced between the 2 flaps and shove glue covered toothpicks into the slots, (one per slot). The seal up the slots I would then put a line of glue over each slot thereby permanently burying the toothpicks in the FB.

Once the glue is dry I would continue folding and gluing the wing as per normal.

What I referred to as the mounting tail is the central part of the wing rear slope portion between the flaps, from the wings most rearwards spanwise bend and the wing trailing edge.

With the usage of the WRFB the stiffening effect of the Minwax is no longer present for most builders so this weak spot could become more of the problem in similar builds.

As I did not have a Minwax equivalent until recently this bending issue is well known to me and almost a thing of the past.

Just what works for me!

(Pics not too far away!)

Have fun!
 

JUSS10

I like Biplanes
cub with wheels.jpg

Went ahead and drew up some big "balloon" tires for the cub in cad. Printed them out this morning and tossed them on. I think it looks pretty awesome!

Justin
 

tomlogan1

Elite member
Simple Cub Wheels

Made the mistake of not ordering wheels when I ordered the Cub. Can't seem to order the ones on the site without buying another Cub! Much as I like it, I do have a wife too..

Any ideas on commercial wheels that will fit the landing gear wire provided in the kit?

Thanks.