Ode to a Fat Little Flier (**UPDATE** Build Log Finished, Plans Posted) - RC Groups
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Sep 30, 2007, 02:01 AM
bobskinner's Avatar
Build Log

Ode to a Fat Little Flier (**UPDATE** Build Log Finished, Plans Posted)

(Update: Build log starts in post 29, Plans at the end of 1st Post and Letter page size plans in post 62)

Here follows my first scratchbuild foamie thread. It is the first plane I made a promise to, that I would make for it its own special thread, if it flies, and it does so I do not want to hurt its feelings.

Some history:

Some time ago I stumbled across Fred Reese’s Buttercup and I thought to myself, “That’s a pretty cute plane.” Not too long after that Steven’s Aero released the Mud Bug and I thought to myself, once again, “dang that’s a pretty cute plane!” My mind was made up when I saw an animated plane fly by on a TV commercial (I have no idea what commercial) and I decided to attempt to make my own (hopefully cute) plane.

Some more:

The original plan was, and still is, to build this little critter out of balsa and some solite but having little faith in my still somewhat untested ability at creating something from sticks (and not returning the poor creation to its pre-conceived state on the first flight). I decided to build from some depronish foam I found lying on a dump at a construction site walking home from the supermarket one day. The foam (3mm) is about 1.6 times the weight of depron (as I know it in the US) for a sheet of similar dimensions, but it was free so the weight to cost ratio was just about right 

I am still not totally sure about the name, but I like “Tubby” since it is just that. Any comments\critiques are welcome on any part of this creation.

Her Specs:

Wingspan: ~24 inches
Dihedral: ~+4 degrees per wing half from horizontal
Length: ~15.5 inches
Wing Area: ~0.82 sq-ft
AUW: ~6.33oz (yes I know she’s tubby)
Wing Loading: ~7.2oz/sq-ft

Motor: ELE C-20 kit from Strong RC, wound 16T
Prop: GWS 6x5SF till I broke it, now APC 5x5 because it’s all I have
Battery: Kokam 3s 350mAh
ESC: GWS 15A, didn’t want to risk my CC Phoenix 10 and am waiting for a Pentium 6A
RX: GWS pico 4Ch with The Don’s base loaded antenna
Servos: 2x Futaba s3110 (Rudder, Elevator)

The construction was quite straight forward. The fuse went together pretty quickly. The wing was made in two halves, the foam scored and folded over a foam spar to get a flat bottomed airfoil of sorts (Saw that done somewhere on here, thanks!). The wingtips raised, the area at the joint sanded to get the dihedral, glued and taped at the joint. The wing joint is surprisingly quite strong and has not broken after a few crashes. The wing is attached to the fuse using rubber bands. The rudder was based loosely off an Aeronca Champ as I love how it looks and the elevator I secretly “borrowed” from Demon-Leather’s “Pseudo Pa-Nee” no plans thread, I hope he doesn’t mind. When I saw the elevator I knew that was what I wanted for my little Tubby. I was hoping to put some Trexler balloon wheels on her, like the Mud Bug, but I don’t have the funds to pay for such expensive wheels right now, so I used some GWS 3” wheels that I had lying around until I get a set of foam 3” wheels in the near future and then maybe one day I’ll save up enough for some balloon wheels. The tail skid is just a piece of 3x0.5mm carbon fiber glued into the back of the fuse. Ground clearance at the lowest point of the plane is maybe 05 inches, not much but she handles rough ground OK.

Trimming was a bit of a challenge and I am still fine tuning the thrust angle on the motor, right now it’s very roughly 3 degrees right and almost the same down. The short tail moment has not been as hard to fly as I thought it might be, she actually flies very nicely. Not much, but a bit of speed is needed to remain airborne and land, I blame the heavier electronics and foam. She does not like much wind, as can be seen at the end of the video clip.

Video's are located here

The videos are, first: a flight ending in a bit of a crash, second: some flying with music and lastly the maiden flight. These are my first ever video creations and posting so go easy on me please. The last “landing” on the third video I turned downwind and the wind picked up, I struggled to turn back upwind, stalled, and she turned gymnast on me and cart wheeled. Had I been a better pilot I’m sure I could have landed or done something fancy, but I have to work with the limited skills I got at this time. The only damage was the foam around the landing gear tore a little, some glue and she’s flying again.

I have spent many, MANY hours reading and learning here on RC groups, I haven’t posted much but I would like to thank everyone for all time and effort spent typing and putting together all this great info to learn from. Those that have helped me via email or PM, thank you! A special thank you to my cute, loving and supportive girlfriend, who took all the video and remained patient through hours of: “Which one looks cuter?” and “What do you think about this dearest?” I wanted to name the plane after her but the whole “tubby” thing didn’t sit too well… I will continue my quest of getting this critter balsa-fied with a little more confidence and probably make another foam version or 2 in the process, just because.

Once again, any comments\critiques, even questions, are welcome.

Thanks for looking,


**Plans Added**

Here are the plans as I have them right now, I will look into the PDF thing but for now here are the .dft (Free Solid Edge 2D) and .DWG files as best as I could make them. If anyone feels any changes are necessary, please let me know I'll do my best.

I will start another build of Tubby this week to check the plans also the current "test run" Tubby is a little sad looking with holes cut to save some weight and some scruffy balsa reinforcing the landing gear.

The landing gear is a bit sensitive to overly hard landings (read: cartwheeling crashes), feel free to modify and/or give some suggestions, it handles most landings pretty well though.

I only included the easier to make under camber wing as the original does not fly as well and I didn't feel like trying to recreate it in CAD, will do it though if anyone is interested. I did not change the fuse to support the camber of the wing better but it should be easy to do, the wing holds just fine as is.

Video will be posted another day, I need to go to bed.

I hope someone out there gives Tubby a try, and if you do I'd love to see some ideas for color schemes.


**PDF Plans added**

I think I figured out the PDF thing, files added in PDF format, let me know if it's OK, PDF page size is 11x17inches

The latest Tubby 2:

Last edited by bobskinner; Dec 15, 2009 at 09:53 AM. Reason: Build Log Finished
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Sep 30, 2007, 02:57 AM
My plans are in my blog
Rusty-Gunn's Avatar
This is a cool looking plane. I enjoy fattie foamies, too.
Sep 30, 2007, 03:47 AM
tris10g's Avatar
Thats cool, nice job bob
Sep 30, 2007, 03:48 AM
bobskinner's Avatar
Thanks for the compliments.

Rusty-Gunn, I love the fattie DR-1 you did for the contest a while back, I really enjoyed following the contest and your build. Also your build of Firstshirt's Cub has me wanting to try one too.

Sep 30, 2007, 10:19 AM
Registered User
I love it, it has character. Great backgroud story also.
Sep 30, 2007, 11:03 AM
Registered User
its verry nice almost reminds me of the stevens aero new sa mud duck with the fat fuse any chance of any rough drawings of your plane ? you do super nice work
Sep 30, 2007, 11:40 AM
You deserve my opinion
FirstShirt's Avatar
Fat! Guys, where is your cooth? What we have here is a great example of a "Full Figured Foamie!"

Looks great!
Last edited by FirstShirt; Sep 30, 2007 at 10:59 PM.
Sep 30, 2007, 08:30 PM
bobskinner's Avatar
Thank you guys for the kind words.

FirstShirt, Tubby is touched to be in the company of a refined gentleman such as yourself and if I had a pink marker she would be blushing right now.

lgliser, I have been fighting with CAD for a while now working on the balsa framing, I just printed out the outline and filled the rest in with pieces of foam where I thought necessary. The wing was built using a method I saw somewhere on here, can't remember where though. I will gladly fix up the CAD as best I can for a foam build if you or anyone else is interested. This is my first project using CAD so it is taking me a little while.

While on the topic of CAD, if I might add a bit of free advertising for the program I'm trying to use (I have no affiliation with the company whatsoever). I have found it easier to learn on thus far, easier (for me) than many of the other free CAD demo's and freeware I tried (By tried I mean installed, ran and tried to draw at least a basic shape, like a square ). It's called Solid Edge 2D and besides being a HUGE file to download it is free, all you have to do is register online. Just a side note if anyone cares to know.

Another note: The more I look at her the more I realize she needs a bit of make-up but I can't decide what colors or where for that matter. I have always much preferred building and flying so color and details are not something I've really worked with. I think I'll build another and try some color. If anyone has any ideas, please speak up.

Thank you again for taking the time to look and for the kind words,

Sep 30, 2007, 11:08 PM
You deserve my opinion
FirstShirt's Avatar
Bob, Again, great job. I built a foam Buttercup a while back. It's one of my favorite larger foamies. Flies nice and slow and handles beautifully. I'm not a balsa guy, but just ordered a Mudbug. (Actually, I was thinking of using the plan to build a larger foamie version.) I mention all that in order to say that I really admire your little Full Figured Foamie. If you publish your plane I'll be one of the first to download it. Keep us the great work. Pat
Oct 01, 2007, 07:25 PM
bobskinner's Avatar
Firstshirt, thank you again for your kind words! I truly appreciate the encouragement. I am working on getting the plans into a usable form, will hopefully be done soonish.

I am still planning on building a buttercup in the near future and when I get back to the US I hope to acquire a Mudbug for myself Your cute little cub is also a temptation I need to find time for, the list goes on and on, but that doesn't seem an uncommon thing in this hobby

Let me go play with the plans a bit, if they get one download I'll be ecstatic.

Oct 02, 2007, 12:29 AM
You deserve my opinion
FirstShirt's Avatar

To use a presidential term, I think you're "misunderestimating" your talent.

Here are a couple of Buttercup threads:



Video on post 69:

Enjoy your FFF!


PS My daughter leaves next week to teach English in Quito, Ecuador.
Oct 02, 2007, 09:22 AM
My plans are in my blog
Rusty-Gunn's Avatar
Bob... I do recommend Pat's "full-figured" foamie cub, it's an enjoyable plane to fly. Due to the enlargened frontal area I put into it (as compared to how it was originally designed) it does seem to drop fast during landing because of the increased drag. Other then this it's a wonderful plane. I'll need to do another sometimes, too. With skies, since winter is upon us up here. Beginning to snow some.
Oct 04, 2007, 01:45 AM
bobskinner's Avatar
Pat, once again, thank you for your encouragement. Also, for the links to the Buttercup threads. All the best to your daughter and her adventure and to you and the family staying at home. I am loving my job here in Korea but it definitely takes a bit of adjusting. I do try call home once a week to chat with my folks

Rusty-Gunn, I will most definitely be attempting the Cub soon, first have to finish the plans and perhaps do another Tubby build to document the process. Apparently it snows quite a bit in the City I'm staying so I have begun to ponder making some skis for the tubby, any suggestions on how to go about it?

Thanks again, plans will be done soon.

Oct 04, 2007, 09:03 AM
My plans are in my blog
Rusty-Gunn's Avatar
Bob... it would seem that I should be an expert with skies, living in northern Alaska, but I've yet to actually fly with them! We tend to belly land on the snow or ice instead. Someday I'll get a pair from Dubro.
Oct 04, 2007, 11:00 AM
Multi discipline RC'er
MrHmmm's Avatar
Bob!! My girlfriend loved your plane.... I couldn't see your face in the video but I think you were smiling from ear to ear... Nice build and keep up the good work!!

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