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Papercraft - Trying a new source of inspiration

FoamyDM

Building Fool-Flying Noob
#1
Cessna A/T-37 - Papercraft Method
Lately I've been looking into different methods of design design inspiration and final product outcomes. I'm referring to tape colored tape color printed skins spray painting and other covering methods for planes as well as design methods for the Master series. One of the things that keeps jumping out is papercraft models.
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If you don't know what papercraft models are they are people who have meticulously put together scale models made of paper and Fiddler'sGreen.net is one great source and there are thousands of others and many people are inspired by airplanes. This means that there are many opportunities to learn from these papercraft masters and possibly turn that to foam board, and radio control.
I'm trying to brute Force direct method here and I'd like to thank the original maker of the Cessna T-37 plans I'm using here from stahlhart papercraft.
My idea is to take these plans and scale them up to fit onto Dollar tree foam or Dollar general foam, and paste them on and see how they build. Similar the theHangarRC.com and @Rasterize . Then look at what kinds of adjustments needs to be made for the foam. Even printed large this model won't be terribly big. My estimate is a 20-in wingspan and I estimate the weight I'm thinking will be around 200 g. As I will use about two DTFB sheets.
Step 1: plane sizing and plan mounting
I have taken the PDFs and printed them so one page prints on a DTFB sheet, however, I have chosen to mount them to Dollar General artskills trifold foam board. This board is 28 in x 44 in and is the rough equivalent of two Dollar tree foam board sheets in size, but half the thickness. This should help me overcome the thickness issued I may come up against.
The process is straightforward. determine the increased scale and print it as a poster through Acrobat reader which divides that larger size into standard printable sheet sizes to print. Then, put it together like a tiled plan set aligning the edges and trimming off excess with tape. Normally I use a light pass of spray glue on one side. It allows me to attach it to the foam board sheet but not make it permanent., However, I want it stuck good, so I use a heavier pass. I then remove the paper on one side of the foam board and carefully mount the plans. Then put a stack of board and some weight to keep if flat as the glue sets. hopefully leaving a flat sheet with plans on one side. There is a slight bow, but it Turns out to be perfect.
Step 2: Cutout
with that complete the next step is to cut all the pieces out. The big difference here is you don't need the assembly tabs, so, as you go you cut them all off.
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You will need to make a FB thickness allowance at the formers and any internal parts. Like the spar and gear bays.
Step 3: Assemble
This step is very similar to the papercraft model steps follow along, roll, fold, glue in a similar fashion to the Master series construction methods. One thing the papercraft doesn't typically need much of is intermediary supports or a core frame this is evident by only two formers. I found it this seems to be adequate enough.
To get a tapered edge I cut at a 60° angle along the trailing edges of the wings and tail section. This can be done with two pases, sanding, or a long sharp knife at a low angle. Similar to @nerdnic speed builds. The result is a good look.
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A word of caution, place the wing spar, THEN glue the wings on. Because it won't glue in after.
Step 4: Details
One of the great things about these papercraft models is that they not only detail the craft itself, but they detail the innards and include exposed features like landing gear and cockpits.
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I was struck by how accurate the airfoils seem to be. Even the tail had an airfoil. One decision that needed to happen was how to reinforce the tail section as it appeared the main spar method build method was adequate enough. For them I used craft sticks.
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Another piece was how much of the inner detail do I use? I choose to include the landing gear bays and I plan to put the cockpit together but the landing gear will remain stationary, built from landscaping wire and 3ply for the main tires, And 2 for the nose. Retracts will be nearly impossible at that size for me.
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Step 5: Size and electronics
My finished plane, the A-37B Fuerza Aerea Colombiana skin variant. (It looks like a dragon!) measures in at a 21" wingspan, 18" long with a root chord of 4" and tip of 2.75".
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the base model with no electronics weighs 101g and needs about 25g in the nose to balance.
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The plane needs around 200g of thrust. This rules out 30mm and a 50mm edf is almost too big. I plan to make it a twin micro-motor with 3" props. (Twin H-pack) possibly a 2S or 3S.
Servos, 2-9g. I want to use 5g, but I don't trust them anymore. I will use diff thrust for yaw control.
More to come
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Current thoughts on the build:
The plane skin is holding up well as printer paper, and weight was just slightly heavier than the stock paper. The biggest adjustment I needed for thickness was for the wing spar construction, and the fitment to the wing. And after building the spar box, I cut it in half to slide it into the built fuse. And to strengthen it I inserted craft sticks in each half. It is VERY strong now.

Last item is CG appears to be at the front of the spar box.
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leaded50

Legendary member
#2
papercraft models, can easy help to make foamboard planes. It needs some adjustments though, as paper is under 1mm thick, foamboard approx 5mm, and on papercrafts its a lot of "tongues" to help glue things together.
I used such paperplans time to time with great help to make the mains in the idea, even if needed adjustmenst to get things right in foamboard :)
 

synjin

Well-known member
#3
I got interested in this type of RC about 12-15 years ago because of the Fiddlers Green models. I sat on a brick of fanfold blue foam for years and had a 300% print of the F4F Wildcat FG plans ready. I didn't continue because the guys doing that were baking their wings, and I wasn't ready to make a wing oven.

Now I'm thinking I can pop the FG plans into Inkscape and use them as a starting point. Scaling the FG plans would be dead simple! You'd have to redesign some of the parts, but that's not a big issue. Hmmm...
 

synjin

Well-known member
#4
Dropped the FG FJ-1 Fury plans into Inkscape. Found cross sections and sized them up to the right scale. This is the section of fuselage right behind the cockpit. It wasn’t all that hard to trace the pieces in Inkscape, and apparently they work out as well in the foam board as they do in cardstock.

If I make this plan slightly larger I’ll have a 24 inch wingspan FJ-1 Fury powered by a 50 mm EDF. We’ll see. It’s about four down on the list of designs.
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Stress Test

Well-known member
#5
A/T 37's are surprising compact and heavy when you see them up close and find out empty they weigh 4000 + lbs.

I had flown Cessna 150's and a clipped wing beefed up super cub (had a bigger engine and reinforced air frame) on floats and they were much lighter but about the same general size. Of course the T-37 was much stronger than a fabric covered cub or the 150 to handle the jet engines. (And the Air Force trainees, ;) )

Since a 50 mm edf is almost too big could you scale the plane up a small amount to fit the motors? Then your 9gram servos would also fit easier.
 

FoamyDM

Building Fool-Flying Noob
#6
I'm glad to hear your experience @Stress Test . I'm noticing the same thing, the foam works like the card stock. I was planning to size it up for 2 - 64mm. Then use metal gear 9g (12g) servos. Yeah, that is step 2.
 

Rasterize

Maker of skins for foam board RC planes
Mentor
#8
Here is the guy that inspired me many years ago. Check out some of the work on RCGroups by a guy that goes by the handle Dmerino. Recreated paper craft planes, prints them on paper and ends up with flying works of art. Shots of his Fokker DV II below. Check out his FW190 here.


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Stress Test

Well-known member
#9
I forgot I have this
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Problem solved... So onto printing a motor mount.
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This one from thingiverse is what I went with.

Time to figure out where to solder what.
Finding supplies you forgot about is like having Christmas early! LOL. I have not gotten into 3d printing. I had planned to build the Foam Cutting Needle thing, (I want to call it a "Needler" but its not a weapon in a game) this winter but I am not sure its going to happen.
 

2jujube7

Well-known member
#10
Finding supplies you forgot about is like having Christmas early! LOL. I have not gotten into 3d printing. I had planned to build the Foam Cutting Needle thing, (I want to call it a "Needler" but its not a weapon in a game) this winter but I am not sure its going to happen.
I'm hoping to get some needle cutter parts this Christmas, I already got 90% of the parts I need from an old 3D printer my friend gave me. :D Total cost would be around $120 for me.
 

FoamyDM

Building Fool-Flying Noob
#12
I decided to see how the cockpit came together tonight.
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these small parts are a small challenge to put together but with patients and sharp knife it comes together pretty well. The hardest part about this is trying to figure out which pieces can tolerate the thickness of the foam board and which can't. It seems that most pieces can afford some of the foam board thickness. Well pieces like the seat edging didn't work out as well.
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And then it all seemed to work out pretty well now does anybody have a shoe horn for cockpits?
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Rasterize

Maker of skins for foam board RC planes
Mentor
#13
Looks great FoamyDM! Loving your work thus far. Good luck with the shoehorn. lol
When I did my mini Mustang cockpit I did it almost all out of 80lbs cardstock.
Was nice and stiff where it needed to be. Took several version before
I started liking it. Also using Sharpie colored toothpicks ect is a great way to add details. Most small details I just printed on.
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FoamyDM

Building Fool-Flying Noob
#14
@Rasterize thanks. 80# card looks great. Part of my experiment was how far can I take the foam, and with that, learn where to print on card stock, or heavy paper, or where to get out the DTFB vs the DGFB. The takeaways here will be about that very topic.

I finished the shoe horning...
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Then I started figuring out where the electronics go. It's the wrong order, I know. It started with wonder how I was going to run the pre-soldered motors out to where they will be mounted. After seeing how they could fit through the exhaust...I started cutting holes.
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Then I glued the 3D printed mount just outboard of the engine buldges.
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The fiber optics was part of the dream to light the instrument panel up. The dream is still strong. The battery sits in the luggage compartment in the nose resting on the nose gear bay.
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FoamyDM

Building Fool-Flying Noob
#15
I installed the 2 9051 servos, and 1 generic 3.7g Servos. It uses a 550mAh 3S battery I also set differential thrust for ground control and yaw control. AUW, It appears to be 249g.
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After some quick math, I figured 2 things. 1) This is 1:18th scale. And 2) 3 3/4" action figures (a common toy figure size) are very close to scale, so I may just find a few quick pilots. I need a few g of ballast anyway! :D

Here is the taxi test;
It taxis like an rc car with slow steer connected to the gas pedal.

Flight attempts are coming soon
 

FoamyDM

Building Fool-Flying Noob
#16
Proof of flight:
Then the battery sags out at 2.7 volts.

This wasn't the only flight... Or crash. She is durable. The rudder needs some counter roll. I can't wait to open her up with a full battery
 

FoamyDM

Building Fool-Flying Noob
#17
Oh, right. I forgot to post the damage se too after slamming into the ground, cartwheeling and nosing in on a few "landings"
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As you can see, the nose luggage/battery bay was crumpled. I think designing a battery bay liner would improve the strength in this area.
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The cartwheeling cause the wings both to crease. this is likely due to the lack of a proper spar or reinforcement from the wheel bay to the wing end.
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This is the nose crumpled from the underside. As you can see the gear bay did a good job of strengthing this section.

I am very surprised at how well the end-glued fuse sections hold together. A little work and a full battery should yield a lot of fun!
 

Stress Test

Well-known member
#18
I found a similar foam board at Hobby Lobby that is like 1/8 inch or 2mm thick. It comes in a really big flat sheet so no trifold creases to deal with. So I snagged a sheet just because.

I had thought about using it to build a thin FT Scout, to get the weight down so it would fly really slow. I have an area like your cul-de-sac so a small slow plane would offer more flying time.

Now ya got me looking at paper craft, like I need another project ... :)
 

FoamyDM

Building Fool-Flying Noob
#19
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Today I went to the field and flew it for real. The t37 flew out of my hands quite well. I found it hard to find a place to hold for hand launch, as my field has no paved runway. It went out and climbed well. It did the turn leg fine and had good control. I was coming back on the return leg, things were looking good and I was about to check trim and diff thrust. It was just about entering the static shot I had set up. When something went wrong. The plane flipped over and went straight back down to the ground. I was able to turn the throttle off and almost completely level it out before it kind of flopped on the ground hard. :oops: Fortunately the fields are soft and there was very little damage. :D

It turns out the cause for the failure were motors coming off of their moorings. One was dangling and the other's paper had come off of the foam and so it was vibrating. Well that of course makes perfect sense now.:cautious:
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It's an easy fix and I'm sure I'll try it again tomorrow. I'm out of light today. I might convince my cameraman to take part tomorrow, to get some good footage.:unsure:
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#20
I am wanting to use some of the paper planes plans on a future project. ( try saying that 5 times fast) I tried to make an A5m4 on my own with only a scaled up 3 view but if I could get the plans working than it would be much better looking.