WIP: Swappable Piper PA-12 Super Cruiser

[Jaxx]

He chewed through the metal with his own dang teeth.

Augernaught,

Did you make the landing gear on your plane as well? That's a nice bird too. I wish I had the skill to build these birds without plans, the way you guys do. I have some aluminum, but I don't think I have the right tools to cut and join the pieces together. Any advice would be greatly appreciated.

 

[NewZee]

What did you use to cut it?

I used a metal cutting blade on a "jig" saw, You can also use a "hack" saw, I used channel because that what I had laying around, you could have easily used some flat bar stock 1/16" X 1" and just cut a taper on each leg, To form the shape I just bent it in a vise. Try it first using a piece of cardboard to get the bends right.

As far as the plans go I used a plan found on the internet and scaled it up and transferred to foam board, Making sure that power pod would fit.

It's not rally that important to be exact, if it looks like an airplane it should fly, more important to get a CG over (under) the fat part of the wing!


don't get me wrong, I applaud you guys that take the time to do formal plans, By the time I got this done, I'd have the plane built!

 

[thatjoshguy]

ok, version 3 of the wings. This time with dihedral and two servos. I think I'm finally happy with the wings this way. Not sure where to put the other servos yet. I'd like them to be hidden if possible, but I may need to enlarge the fuselage a bit for that. Does anyone think it'd be an issue if the rudder's control horn was on the bottom? Would flexing be as much an issue there as it would have been on the previous ailerons?

 

[NewZee]

ok, version 3 of the wings. This time with dihedral and two servos. I think I'm finally happy with the wings this way. Not sure where to put the other servos yet. I'd like them to be hidden if possible, but I may need to enlarge the fuselage a bit for that. Does anyone think it'd be an issue if the rudder's control horn was on the bottom? Would flexing be as much an issue there as it would have been on the previous ailerons?

Looks good to me! I put my rudder and elevator servos at the rear of the fuselage like on the Spitfire (you can see the holes in the pic above), I don't think you'll have any problem with the horns on the bottom (unless it interferes with any planed steerable tail wheel?). your ailerons are small (just like my cub) I did this on purpose as I was looking for a "trainer" and not a stunt plane. Your plans look great! Please post some pics as you start cutting foam!

One other thing!!! I initially located my landing gear faithful to the real cub, but it never tracked good on take offs, so I moved it forward about an inch, and it tracked much better! (also moved my CG a little further forward (which was a good thing)! I didn't use a tail wheel, just a skid.

 

[thatjoshguy]

View attachment 18145
Looks good to me! I put my rudder and elevator servos at the rear of the fuselage like on the Spitfire (you can see the holes in the pic above), I don't think you'll have any problem with the horns on the bottom (unless it interferes with any planed steerable tail wheel?). your ailerons are small (just like my cub) I did this on purpose as I was looking for a "trainer" and not a stunt plane. Your plans look great! Please post some pics as you start cutting foam!

One other thing!!! I initially located my landing gear faithful to the real cub, but it never tracked good on take offs, so I moved it forward about an inch, and it tracked much better! (also moved my CG a little further forward (which was a good thing)! I didn't use a tail wheel, just a skid.

Ahh! I thought you had hidden the servos inside somehow, and the holes were for the pushrods to exit the body! I see now that they are the holes for the (missing) servos.

I had them like that at one point, and may go back to that for simplicity's sake. I did want to add a steerable rear wheel, but I'm not sure my son will lend me one of his Lego wheels, lol.

 

[Jaxx]

Josh,
How long have you been using SketchUp? Can't wait to see the finished product!

NewZee,
Thanks for the info. I will pick up a metal cutting blade for my jig saw today.

 

[thatjoshguy]

Not long honestly, just for a couple projects here and there. I do have a tiny bit of experience in 3d animation though (another long lost hobby of mine) so maybe that helps? Really it just takes getting used to the tools... once you know what does what it's super easy.

 

[thatjoshguy]

Just about ready to start laying out the plans

 

[thatjoshguy]

::sigh:: may have gone a bit overboard with my curved tops. Some of the shapes may not be possible back to the drawing board!

unless someone has access to a kick-ass complex structure unfolding program?

Edit: Nevermind, I'll find a way to make it work. May delay releasing the plans a bit, but I'm going to go for it.

 

[NewZee]

Josh,
How long have you been using SketchUp? Can't wait to see the finished product!

NewZee,
Thanks for the info. I will pick up a metal cutting blade for my jig saw today.

Just be sure to hold the piece securely in a vise while cutting, if you use channel you will need to "effectively" cut off one leg to make flat bar stock, this is another pic that shows the gear a little better

 

[thatjoshguy]

Roughly cut out the fuselage last night to test my measurements. Need to tighten up a few parts, I had set my widths at 3/16" but it turns out the $tree foam I purchased is closer to 4mm. Tiny difference really, not super noticeable, but it's there. I've decided to separate the long center portion that runs down the center of the fuselage into two pieces, one for the front and one for the rear, as it was a pain to glue in something that long and I was going to need to cut holes into it anyway for the servo leads.

Also, the bottom has been moved to the inside of the two sides vs. glued to the bottom as it is here.

 

[Blenderite]

How did you convert the 3D model into the 2D plan?

 

[thatjoshguy]

How did you convert the 3D model into the 2D plan?

I use a plugin called Flatterly that will "flatten" a 3d model by selecting faces to align. It takes a bit of work, but it's not as hard as you'd think. The hard part is, once it's flat, figuring out where your A and B folds need to be.

I think i'm happy with the latest design. It's not as smooth as I had originally wanted, but such is life when working with poster paper and foam core board.

NewZee, I hope you don't mind, but as much as I tried to avoid it our models are going to be rather similar. I wasn't aware you had made the cub when I started, and there's not a huge difference in the cub vs. the super cruiser that translates. Probably doesn't help that we both started with the Spitfire either, lol.

Anyway, here's a preview of the flattened pieces. I'm going to get this built before releasing the plans as I want to make sure it doesn't have any giant gaping flaws.

 

[Blenderite]

Cool. I might try making my own custom plane.

 

[augernaught]

Jaxx,
yes, I did build the landing gear. It's just a strip of 1/2"x 1/16" aluminum.
It was nice and light but a touch flimsy, so I made a torsion bar out of
a coat hanger and mounted it to the main gear with electrical eye connectors
epoxied on the ends and some 3mm screws. The main is screwed into the 3/16"
hobby grade plywood with some small sheet metal screws, and the torsion bar and rear
support bar are held on with telephone wire hold downs with the nail removed
and it's hole drilled out to fit another small/longer sheet metal screw,
and with some plastic tubing around the coat hangars to make for a tighter fit.
Bolt on axles from the FlyZone Beaver complete the assembly.


thatjoshguy,
I see you designed servo cutouts in the rear/sides of the fuselage already,
but you don't need much room in the fuse to hide the servos
if you cut the servo arms a bit short and use longer control horns on the rudder/elevator
to maintain enough travel. If you don't have any spare control wire setups,
that wire from the marker flags and a few cocktail mixing straws work just as well.
It is common to place the control horns where you did,
but most folks will support the thin crossover on the elevator with something to beef it up.
Many people use popsicle sticks, but I went with a half moon piece of styrene I cut
out of .030 sheet stock and glued it to the top of the elevator because my design
didn't favor anything being mounted on the under side. I also cut a similar plate
to stiffen up the lower section of the rudder that you mentioned in an earlier post.

 

[Jaxx]

Augernaught,
This is brilliant! Hope you don't mind if I "borrow" this design. I especially like what you did with the coat hanger.

 

[augernaught]

Augernaught,
This is brilliant! Hope you don't mind if I "borrow" this design. I especially like what you did with the coat hanger.

Please do!
That torsion bar makes for a fantastic shock absorber,
and the flat aluminum strip gives you a great place to
glue on that triangular landing gear fairing that's on Cubs!

 

[thatjoshguy]

Jaxx,
thatjoshguy,
I see you designed servo cutouts in the rear/sides of the fuselage already,
but you don't need much room in the fuse to hide the servos
if you cut the servo arms a bit short and use longer control horns on the rudder/elevator
to maintain enough travel. If you don't have any spare control wire setups,
that wire from the marker flags and a few cocktail mixing straws work just as well.
It is common to place the control horns where you did,
but most folks will support the thin crossover on the elevator with something to beef it up.
Many people use popsicle sticks, but I went with a half moon piece of styrene I cut
out of .030 sheet stock and glued it to the top of the elevator because my design
didn't favor anything being mounted on the under side. I also cut a similar plate
to stiffen up the lower section of the rudder that you mentioned in an earlier post.

Thanks for the ideas! I tried several ways to get the servos into the tail section, but it really is pretty tight in there. Your model seems to be a good deal larger than mine, and my fuselage is just a bit wider than the power pod (as thick as the foam core on either side).

I like the idea of a popsicle stick on the rudder to stiffen it up, so I may try that. It will fit with my current measurements already. I'm trying to stick to readily available parts/materials as much as possible so that anyone can build this model. For instance, I've designed the landing gear to be similar to the other swappables in that it is made with piano wire, but has a poster board cover to get the look right. Still nice and bouncy too.

My last real concern is the wing. In my current design the wing is glued on. I happen to like that, but the more I think about it it may be better to hold the wing on with rubber bands similar to how NewZee has done. The design doesn't change much, jsut glue the wing or add sticks and bands... guess I can leave it as an option.

If anyone wants an early copy of the plans I can post them. Can't guarantee they'll be super easy to follow but if you have a good eye you can probably figure it out. I'll eventually write up instructions, maybe do a build video with sketchup animations

 

[Flynn]

Insanely great work guys!

 

[Jaxx]

This is why i love this community!

Augernaught,

Will you be releasing plans for your design as well?